Influence of Kaolin in Fly Ash Based Geopolymer Concrete: Destructive and Non-Destructive Testing

NASA Astrophysics Data System (ADS)

Yahya, Z.; Abdullah, M. M. A. B.; Ramli, N. Mohd; Burduhos-Nergis, D. D.; Razak, R. Abd

2018-06-01

Development of geopolymer concrete is mainly to reduce the production of ordinary Portland cement (OPC) that adverse the natural effect. Fly ash is a by-product collected from electrical generating power plant which resulted from burning pulverized coal. Since fly ash is waste materials, it can be recycled for future advantages particularly as pozzolanic materials in construction industry. This study focused on the feasibility of fly ash based geopolymer concrete to which kaolin has been added. The main constituents of geopolymer production for this study were class F fly ash, sodium silicate and sodium hydroxide (NaOH) solution. The concentration of NaOH solution was fixed at 12 Molar, ratio of fly ash/alkaline activator and sodium silicate/NaOH fixed at 1.5 and 2.5, respectively. Kaolin was added in range 5% to 15% from the mass of fly ash and all the samples were cured at room temperature. Destructive and non-destructive test were performed on geopolymer concrete to evaluate the best mix proportions that yield the highest strength as well as the quality of the concrete. Compressive strength, flexural strength, rebound hammer and ultrasonic pulse velocity (UPV) result have been obtained. It shown that 5% replacement of kaolin contributed to maximum compressive strength and flexural strength of 40.4 MPa and 12.35 MPa at 28 days. These result was supported by non-destructive test for the same mix proportion.

Effects of sodium hydroxide (NaOH) solution concentration on fly ash-based lightweight geopolymer

NASA Astrophysics Data System (ADS)

Ibrahim, W. M. W.; Hussin, K.; Abdullah, M. M. A.; Kadir, A. A.; Deraman, L. M.

2017-09-01

In this study, the effects of NaOH concentration on properties of fly ash-based lightweight geopolymer were investigated. Lightweight geopolymer was produced using fly ash as source materials and synthetic foaming agents as air entraining agent. The alkaline solutions used in this study are combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solution. Different molarities of NaOH solution (6M, 8M, 10M, 12M, and 14M) are taken for preparation of 50 x 50 x 50 mm cubes of lightweight geopolymer. The ratio of fly ash/alkaline solution, Na2SiO3/NaOH solution, foaming agent/water and foam/geopolymer paste were kept constant at 2.0, 2.5, 1:10 and 1:1 respectively. The samples were cured at 80°C for 24 hours and left at room temperature for tested at 7 days of ageing. Physical and mechanical properties such as density, water absorption, compressive strength and microstructure property were determined from the cube dried samples. The results show that the NaOH molarity had effects on the properties of lightweight geopolymer with the optimum NaOH molarity found is 12M due to the high strength of 15.6 MPa, lower water absorption (7.3%) and low density (1440 kg/m3). Microstructure analysis shows that the lightweight geopolymer contain some porous structure and unreacted fly ash particles remains.

The influence of Pb addition on the properties of fly ash-based geopolymers.

PubMed

Nikolić, Violeta; Komljenović, Miroslav; Džunuzović, Nataša; Miladinović, Zoran

2018-05-15

Preventing or reducing negative effects on the environment from the waste landfilling is the main goal defined by the European Landfill Directive. Generally geopolymers can be considered as sustainable binders for immobilization of hazardous wastes containing different toxic elements. In this paper the influence of addition of high amount of lead on structure, strength, and leaching behavior (the effectiveness of Pb immobilization) of fly ash-based geopolymers depending on the geopolymer curing conditions was investigated. Lead was added during the synthesis of geopolymers in the form of highly soluble salt - lead-nitrate. Structural changes of geopolymers as a result of lead addition/immobilization were assessed by means of XRD, SEM/EDS, and 29 Si MAS NMR analysis. Investigated curing conditions significantly influenced structure, strength and leaching behavior of geopolymers. High addition of lead caused a sizeable decrease in compressive strength of geopolymers and promoted formation of aluminum-deficient aluminosilicate gel (depolymerization of aluminosilicate gel), regardless of the curing conditions investigated. According to the EUWAC limitations, 4% of lead was successfully immobilized by fly ash-based geopolymers cured for 28 days in a humid chamber at room temperature. Copyright © 2018 Elsevier B.V. All rights reserved.

The Influence of Pre-Heated Treatment to Improve Adhesion Bond Coating Strength of Fly Ash Based Geopolymer Ceramic

NASA Astrophysics Data System (ADS)

Jamaludin, L.; Abdullah, M. M. A. B.; Hussin, K.; Kadir, A. Abdul

2018-06-01

The study focus on effect of pre-heated ceramic surface on the adhesion bond strength between geopolymer coating coating and ceramic substrates. Ceramic substrates was pre-heated at different temperature (400 °C, 600 °C, 800 °C and 1000 °C). Fly ash geopolymer coating material potential used to protect surface used in exposure conditions after sintering at high temperature. Fly ash and alkali activator (Al2O3/Na2SiO3) were mixed with 2.0 solids-to-liquid ratios to prepare geopolymer coating material at constant NaOH concentration of 12M. Adhesion test was conducted to determine the adhesion bond between ceramic substrates and fly ash coating material. The results showed the pre-heated ceramic substrates effect the adhesion bond of coating compared with untreated substrates with increasing of strength up to 20 % for temperature 600 °C.

Performance of fly ash based geopolymer incorporating palm kernel shell for lightweight concrete

NASA Astrophysics Data System (ADS)

Razak, Rafiza Abd; Abdullah, Mohd Mustafa Al Bakri; Yahya, Zarina; Jian, Ang Zhi; Nasri, Armia

2017-09-01

A concrete which cement is totally replaced by source material such as fly ash and activated by highly alkaline solutions is known as geopolymer concrete. Fly ash is the most common source material for geopolymer because it is a by-product material, so it can get easily from all around the world. An investigation has been carried out to select the most suitable ingredients of geopolymer concrete so that the geopolymer concrete can achieve the desire compressive strength. The samples were prepared to determine the suitable percentage of palm kernel shell used in geopolymer concrete and cured for 7 days in oven. After that, other samples were prepared by using the suitable percentage of palm kernel shell and cured for 3, 14, 21 and 28 days in oven. The control sample consisting of ordinary Portland cement and palm kernel shell and cured for 28 days were prepared too. The NaOH concentration of 12M, ratio Na2SiO3 to NaOH of 2.5, ratio fly ash to alkaline activator solution of 2.0 and ratio water to geopolymer of 0.35 were fixed throughout the research. The density obtained for the samples were 1.78 kg/m3, water absorption of 20.41% and the compressive strength of 14.20 MPa. The compressive strength of geopolymer concrete is still acceptable as lightweight concrete although the compressive strength is lower than OPC concrete. Therefore, the proposed method by using fly ash mixed with 10% of palm kernel shell can be used to design geopolymer concrete.

Fly Ash Porous Material using Geopolymerization Process for High Temperature Exposure

PubMed Central

Abdullah, Mohd Mustafa Al Bakri; Jamaludin, Liyana; Hussin, Kamarudin; Bnhussain, Mohamed; Ghazali, Che Mohd Ruzaidi; Ahmad, Mohd Izzat

2012-01-01

This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure. PMID:22605984

Optimising Ambient Setting Bayer Derived Fly Ash Geopolymers

PubMed Central

Jamieson, Evan; Kealley, Catherine S.; van Riessen, Arie; Hart, Robert D.

2016-01-01

The Bayer process utilises high concentrations of caustic and elevated temperature to liberate alumina from bauxite, for the production of aluminium and other chemicals. Within Australia, this process results in 40 million tonnes of mineral residues (Red mud) each year. Over the same period, the energy production sector will produce 14 million tonnes of coal combustion products (Fly ash). Both industrial residues require impoundment storage, yet combining some of these components can produce geopolymers, an alternative to cement. Geopolymers derived from Bayer liquor and fly ash have been made successfully with a compressive strength in excess of 40 MPa after oven curing. However, any product from these industries would require large volume applications with robust operational conditions to maximise utilisation. To facilitate potential unconfined large-scale production, Bayer derived fly ash geopolymers have been optimised to achieve ambient curing. Fly ash from two different power stations have been successfully trialled showing the versatility of the Bayer liquor-ash combination for making geopolymers. PMID:28773513

Optimising Ambient Setting Bayer Derived Fly Ash Geopolymers.

PubMed

Jamieson, Evan; Kealley, Catherine S; van Riessen, Arie; Hart, Robert D

2016-05-19

The Bayer process utilises high concentrations of caustic and elevated temperature to liberate alumina from bauxite, for the production of aluminium and other chemicals. Within Australia, this process results in 40 million tonnes of mineral residues (Red mud) each year. Over the same period, the energy production sector will produce 14 million tonnes of coal combustion products (Fly ash). Both industrial residues require impoundment storage, yet combining some of these components can produce geopolymers, an alternative to cement. Geopolymers derived from Bayer liquor and fly ash have been made successfully with a compressive strength in excess of 40 MPa after oven curing. However, any product from these industries would require large volume applications with robust operational conditions to maximise utilisation. To facilitate potential unconfined large-scale production, Bayer derived fly ash geopolymers have been optimised to achieve ambient curing. Fly ash from two different power stations have been successfully trialled showing the versatility of the Bayer liquor-ash combination for making geopolymers.

Self-compacting geopolymer concrete-a review

NASA Astrophysics Data System (ADS)

Ukesh Praveen, P.; Srinivasan, K.

2017-11-01

In this construction world, Geopolymer concrete is a special concrete which doesn’t requires the Ordinary Portland Cement and also reduces the emission of carbon-dioxide. The Geopolymer Concrete is made up of industrial by-products (which contains more Silica and Alumina) and activated with the help of Alkaline solution (combination of sodium hydroxide & sodium silicate or potassium hydroxide & potassium silicate). The high viscosity nature of Geopolymer Concrete had the ability to fail due to lack of compaction. In improvising the issue, Self Compacting Geopolymer Concrete has been introduced. The SCGC doesn’t require any additional compaction it will flow and compacted by its own weight. This concrete is made up of industrial by-products like Fly ash, GGBFS and Silica Fume and activated with alkaline solution. The earlier research was mostly on Fly ash based SCGC. In few research works Fly ash was partially replaced with GGBS and Silica Fume. They evaluated the compressive strength of concrete with varying molarities of NaOH; curing time and curing temperature. The flexural behaviour of the concrete also examined. The Fly ash based SCGC was got high compressive strength in heat curing as well as low compressive strength in ambient curing. The presence of GGBS improves the strength in ambient curing. For aiming the high strength in ambient curing Fly ash will be completely replace and examine with different mineral admixtures.

Effect of different sintering temperature on fly ash based geopolymer artificial aggregate

NASA Astrophysics Data System (ADS)

Abdullah, Alida; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Tahir, Muhammad Faheem Mohd

2017-04-01

This research was conducted to study the mechanical and morphology of fly ash based geopolymer as artificial aggregate at different sintering temperature. The raw material that are used is fly ash, sodium hydroxide, sodium silicate, geopolymer artificial aggregate, Ordinary Portland Cement (OPC), coarse aggregate and fine aggregate. The research starts with the preparation of geopolymer artificial aggregate. Then, geopolymer artificial aggregate will be sintered at six difference temperature that is 400°C, 500°C, 600°C, 700°C, 800°C and 900°C to known at which temperature the geopolymer artificial aggregate will become a lightweight aggregate. In order to characterize the geopolymer artificial aggregate the X-ray Diffraction (XRD) and X-Ray Fluorescence (XRF) was done. The testing and analyses involve for the artificial aggregate is aggregate impact test, specific gravity test and Scanning Electron Microscopy (SEM). After that the process will proceed to produce concrete with two type of different aggregate that is course aggregate and geopolymer artificial aggregate. The testing for concrete is compressive strength test, water absorption test and density test. The result obtained will be compared and analyse.

Effect of Na2SiO3/NaOH on mechanical properties and microstructure of geopolymer mortar using fly ash and rice husk ash as precursor

NASA Astrophysics Data System (ADS)

Saloma, Hanafiah, Elysandi, Debby Orjina; Meykan, Della Garnesia

2017-11-01

Geopolymer concrete is an eco-friendly concrete that can reduce carbon emissions on the earth surface because it used industrial waste material such as fly ash, rice husk ash, bagasse ash, and palm oil fuel. Geopolymer is semi-crystalline amorphous materials which has irregular chemical bonds structure. The material is produced by geosynthesis of aluminosilicates and alkali-silicates which produce the Si-O-Al polymer structure. This research used the ratio of fly ash and rice husk ash as precursors e.g. 100:0, 75:25, 50:50, and 25:75. NaOH solutions of 14 M and Na2SiO3 solutions with the variation e.g. 2.5, 2.75, 3.00, and 3.25 were used as activators on mortar geopolymer mixture. The tests of fresh mortar were slump flow and setting time. The optimum compressive strength is 68.36 MPa for 28 days resulted from mixture using 100% fly ash and Na2SiO3 and NaOH with ratio 2.75. The largest value of slump flow test resulted from mixture using Na2SiO3 and NaOH with ratio 2.50 is 17.25 cm. Based on SEM test results, mortar geopolymer microstructure with mixture RHA 0% has less pores and denser CSH structure.

Strength and Durability of Fly Ash-Based Fiber-Reinforced Geopolymer Concrete in a Simulated Marine Environment

NASA Astrophysics Data System (ADS)

Martinez Rivera, Francisco Javier

This research is aimed at investigating the corrosion durability of polyolefin fiberreinforced fly ash-based geopolymer structural concrete (hereafter referred to as GPC, in contradistinction to unreinforced geopolymer concrete referred to as simply geopolymer concrete), where cement is completely replaced by fly ash, that is activated by alkalis, sodium hydroxide and sodium silicate. The durability in a marine environment is tested through an electrochemical method for accelerated corrosion. The GPC achieved compressive strengths in excess of 6,000 psi. Fiber reinforced beams contained polyolefin fibers in the amounts of 0.1%, 0.3%, and 0.5% by volume. After being subjected to corrosion damage, the GPC beams were analyzed through a method of crack scoring, steel mass loss, and residual flexural strength testing. Fiber reinforced GPC beams showed greater resistance to corrosion damage with higher residual flexural strength. This makes GPC an attractive material for use in submerged marine structures.

Effect of Alkali Concentration on Fly Ash Geopolymers

NASA Astrophysics Data System (ADS)

Fatimah Azzahran Abdullah, Siti; Yun-Ming, Liew; Bakri, Mohd Mustafa Al; Cheng-Yong, Heah; Zulkifly, Khairunnisa; Hussin, Kamarudin

2018-03-01

This paper presents the effect of NaOH concentration on fly ash geopolymers with compressive up to 56 MPa at 12M. The physical and mechanical on fly ash geopolymer are investigated. Test results show that the compressive strength result complied with bulk density result whereby the higher the bulk density, the higher the strength. Thus, the lower water absorption and porosity due to the increasing of NaOH concentration.

Optimum mix for fly ash geopolymer binder based on workability and compressive strength

NASA Astrophysics Data System (ADS)

Arafa, S. A.; Ali, A. Z. M.; Awal, A. S. M. A.; Loon, L. Y.

2018-04-01

The request of concrete is increasing every day for sustaining the necessity of development of structure. The production of OPC not only consumes big amount of natural resources and energy, but also emit significant quantity of CO2 to the atmosphere. Therefore, it is necessary to find alternatives like Geopolymer to make the concrete environment friendly. Geopolymer is an inorganic alumino-silicate compound, produced from fly ash. This paper describes the experimental work conducted by casting 40 geopolymer paste mixes, and was cured at 80°C for 24 h to evaluate the effect of various parameters affecting the workability and compressive strength. Alkaline solution to fly ash ratio and sodium hydroxide (NaOH) concentration were chosen as the key parameters of strength and workability. Laboratory investigation with different percentage of sodium hydroxide concentration and different alkaline liquid to fly ash ratio reveals that the optimum ratios are 10 M, AL/FA=0.5. It has generally been found that the workability decreased and the compressive strength increased with an increase in the concentration of sodium hydroxide solution. However, workability was increased and the compressive strength was decreased with the increase in the ratio of fly ash to alkaline solution.

The effect of slag addition on strength development of Class C fly ash geopolymer concrete at normal temperature

NASA Astrophysics Data System (ADS)

Wardhono, Arie; Law, David W.; Sutikno, Dani, Hasan

2017-09-01

This paper presents the effect of slag addition on strength development and workability of fly ash/slag based geopolymer (FASLG) concrete cured at normal temperature. Class C fly ash with high ferrite (Fe) content was used as the primary material. The proportions of fly ash (FA) to slag (SL) are: 1 FA : 0 SL, 0.9 FA : 0.1 SL, 0.7 FA : 0.3 SL, and 0.5 FA : 0.5 SL. The workability and strength properties were determined by slump, vikat, and compressive strength tests. The result shows that the highest compressive strength was achieved by FASLG-3 concrete with 30% slag addition and exhibited a comparable strength to that normal concrete at 28 days. The 30% slag addition also improve the workability and increase the setting time of FASLG concrete specimens. It can be concluded that the slag inclusion on fly ash will improve the performance of geopolymer concrete at normal temperature.

Parameters Affecting the Mechanical Properties of Fly Ash-Based Geopolymer Binders – Experimental Results

NASA Astrophysics Data System (ADS)

Lăzărescu, A.; Szilagyi, H.; Ioani, A.; Baeră, C.

2018-06-01

As the demand for concrete and the needs to satisfy development of infrastructure facilities increase, it is essential to find alternatives to create environment-friendly concrete. The particular procedure of alkaline activation of fly ash - in which ash resulting from a power plant is combined with a specific alkaline activator in order to create a solid material, then dried at a certain temperature - opened new opportunities for this new material to get attention worldwide. In order to obtain a material with similar properties of ordinary Portland cement concrete and to obtain desirable compressive strengths, the parameters that affect this type of binders should be fully understood. The aim of this paper is to study the main parameters affecting the mechanical strength of the fly ash-based geopolymer paste and their interactions. Parameters such as molarity of sodium hydroxide (from 8M to 12M) and alkaline activators ratio (from 0,5 to 2,5) were analysed to observe how they affect the mechanical properties of the geopolymer paste. Experimental results show that the compressive strength of the fly ash-based geopolymer paste produced using Romanian local raw materials increases with the increase of the concentration of sodium hydroxide and higher ratios of Na2SiO3/NaOH solution.

Effect of mixing geopolymer and peat on bearing capacity in Ogan Komering Ilir (OKI) by California bearing ratio (CBR) test

NASA Astrophysics Data System (ADS)

Raharja, Danang S.; Hadiwardoyo, Sigit P.; Rahayu, Wiwik; Zain, Nasuhi

2017-06-01

Geopolymer is binder material that consists of solid material and the activator solution. Geopolymer material has successfully replaced cement in the manufacture of concrete with aluminosilicate bonding system. Geopolymer concrete has properties similar to cement concrete with high compressive strength, low shrinkage value, relatively low creep value, as well as acid-resistant. Based on these, the addition of polymers in peat soils is expected to improve the bearing capacity of peat soils. A study on the influence of geopolymer addition in peat soils was done by comparing before and after the peat soil was mixed with geopolymer using CBR (California Bearing Ratio) test in unsoaked and soaked conditions. 10% mixture content of the peat dry was used, weighted with a variety of curing time 4 hours, 5 days, and 10 days. There were two methods of mixing: first, peat was mixed with fly ash geopolymer activators and mixed solution (waterglass, NaOH, water), and second, peat was mixed with fly ash and mixed geopolymer (waterglass, NaOH, water, fly ash). Changes were observed in specific gravity, dry density, acidity (pH), and the microscopic structure with Scanning Electron Microscope (SEM). Curing time did not significantly affect the CBR value. It even shows a tendency to decline with longer curing time. The first type mixture obtained CBR value of: 5.4% for 4 hours curing, 4.6% for 5 days curing and 3.6% for 10 days curing. The second type mixture obtained CBR value of: 6.1% for 4 hours curing, 5.2% for 5 days curing and 5.2% for 10 days curing. Furthermore, the specific gravity value, dry density, pH near neutral and swelling percentage increased. From both variants, the second type mixture shows better results than the first type mixture. The results of SEM (Scanning Electron Microscopy) show the structure of the peat which became denser with the fly ash particles filling the peat microporous. Also, the reaction of fly ash with geopolymer is indicated by the solid agglomerates that are larger than normal fly ash particle size.

Effect of hydrated lime on compressive strength mortar of fly ash laterite soil geopolymer mortar

NASA Astrophysics Data System (ADS)

Wangsa, F. A.; Tjaronge, M. W.; Djamaluddin, A. R.; Muhiddin, A. B.

2017-11-01

This paper explored the suitability of fly ash, hydrated lime, and laterite soil with several activator (sodium hydroxide and sodium tiosulfate) to produce geopolymer mortar. Furthermore, the heat that released by hydrated lime was used instead of oven curing. In order to produce geopolymer mortar without oven curing, three variations of curing condition has been applied. Based on the result, all the curing condition showed that the hardener mortar can be produced and exhibited the increasing of compressive strength of geopolymer mortar from 3 days to 7 days without oven curing.

The effects of the sequential addition of synthesis parameters on the performance of alkali activated fly ash mortar

NASA Astrophysics Data System (ADS)

Dassekpo, Jean-Baptiste Mawulé; Zha, Xiaoxiong; Zhan, Jiapeng; Ning, Jiaqian

Geopolymer is an energy efficient and sustainable material that is currently used in construction industry as an alternative for Portland cement. As a new material, specific mix design method is essential and efforts have been made to develop a mix design procedure with the main focus on achieving better compressive strength and economy. In this paper, a sequential addition of synthesis parameters such as fly ash-sand, alkaline liquids, plasticizer and additional water at well-defined time intervals was investigated. A total of 4 mix procedures were used to study the compressive performance on fly ash-based geopolymer mortar and the results of each method were analyzed and discussed. Experimental results show that the sequential addition of sodium hydroxide (NaOH), sodium silicate (Na2SiO3), plasticizer (PL), followed by adding water (WA) increases considerably the compressive strengths of the geopolymer-based mortar. These results clearly demonstrate the high significant influence of sequential addition of synthesis parameters on geopolymer materials compressive properties, and also provide a new mixing method for the preparation of geopolymer paste, mortar and concrete.

The High Teperature Influence on Geopolymer Fly Ash Mixture’s Compressisive Strength with Insudtrial Waste Material Substitution

NASA Astrophysics Data System (ADS)

Bayuaji, R.; Wibowo, B.; Subekti, S.; Santoso, S. E.; Hardiyanto, E.; Kaelani, Y.; Mallu, L. L.

2017-11-01

This research aimed to figure out the influence of fly ash mixture from the industrial waste at the temperatures of 150°C, 450°C, 750°C viewed from the strength and resistance of geopolymer paste. As a result, cement will be substituted by industrial waste like fly ash. This experimental research was conducted on the mix design of geopolymer concrete which was made by dimension with 2.5 cm in diameter and 5 cm in height from four mixture composition of fly ash and industrial waste i.e. 100% fly ash, 50% fly ash+50% bottom ash, 50% fly ash+50% sandblast, and 50% fly ash+50% carbide waste. Each mixture was tested in terms of porosity and compressive strength. In conclusion, in the mixture of 50% fly ash+50% Sandblast and 50% fly ash+50% bottom ash in 12 molars, 1.5 activator comparison can be used to substitute fly ash at high temperature. Meanwhile, the mixture of 50% fly ash+50% carbide waste in 8 molars, 0.5 activator comparison has very small strength remaining if it is compared to the mixture of fly ash and other industrial waste (Bottom ash and Sandblast). The performance of mixture paste of 50% fly ash+50% carbide waste was very vulnerable after being burnt. Consequently, it cannot be used as the main structure at high temperature.

Durability of Bricks Coated with Red mud Based Geopolymer Paste

NASA Astrophysics Data System (ADS)

Singh, Smita; Basavanagowda, S. N.; Aswath, M. U.; Ranganath, R. V.

2016-09-01

The present study is undertaken to assess the durability of concrete blocks coated with red mud - fly ash based geopolymer paste. Concrete blocks of size 200 x 200 x 100mm were coated with geopolymer paste synthesized by varying the percentages of red mud and fly ash. Uncoated concrete blocks were also tested for the durability for comparison. In thermal resistance test, the blocks were subjected to 600°C for an hour whereas in acid resistance test, they were kept in 5% sulphuric acid solution for 4 weeks. The specimens were thereafter studied for surface degradation, strength loss and weight loss. Pastes with red mud percentage greater than 50% developed lot of shrinkage cracks. The blocks coated with 30% and 50% red mud paste showed better durability than the other blocks. The use of blocks coated with red mud - fly ash geopolymer paste improves the aesthetics, eliminates the use of plaster and improves the durability of the structure.

Spectroscopic studies of fly ash-based geopolymers

NASA Astrophysics Data System (ADS)

Rożek, Piotr; Król, Magdalena; Mozgawa, Włodzimierz

2018-06-01

In the present work fly-ash based geopolymers with different contents of alkali-activator and water were prepared. Alkali-activation was conducted with sodium hydroxide (NaOH) at the SiO2/Na2O molar ratio of 3, 4, and 5. Water content was at the ratio of 30, 40, and 50 wt% in respect to the weight of the fly ash. Structural and microstructural characterization (FT-IR spectroscopy, 29Si and 27Al MAS NMR, X-ray diffraction, SEM) of the specimens as well as compressive strength and apparent density measurements were carried out. The obtained geopolymers are mainly amorphous due to the presence of disordered aluminosilicate phases. However, hydroxysodalite have been identified as a crystalline product of geopolymerization. The major band in the mid-infrared spectra (at about 1000 cm-1) is related to Sisbnd O(Si,Al) asymmetric stretching vibrations and is an indicator of the geopolymeric network formation. Several component bands in this region can be noticed after the decomposition process. Decomposition of band at 1450 cm-1 (vibrations of Csbnd O bonds in bicarbonate group) has been also conducted. Higher NaOH content favors carbonation, inasmuch as the intensity of the band then increases. Both water and alkaline activator contents have an influence on compressive strength and microstructure of the obtained fly-ash based geopolymers.

Optimization of activator solution and heat treatment of ground lignite type fly ash geopolymers

NASA Astrophysics Data System (ADS)

Molnár, Z.; Szabó, R.; Rácz, Á.; Lakatos, J.; Debreczeni, Á.; Mucsi, G.

2017-02-01

Geopolymers are inorganic polymers which can be produced by the reaction between silico aluminate oxides and alkali silicates in alkaline medium. Materialscontaining silica and alumina compounds are suitable for geopolymer production. These can beprimary materials or industrial wastes, i. e. fly ash, metallurgical slag and red mud. In this paper, the results of the systematic experimental series are presented which were carried out in order to optimize the geopolymer preparation process. Fly ash was ground for different residence time (0, 5, 10, 30, 60 min) in order to investigate the optimal specific surface area. NaOH activator solution concentration also varied (6, 8, 10, 12, 14 M). Furthermore, sodium silicate was added to NaOH as a network builder solution. In this last serie different heat curing temperatures (30, 60, 90°C) were also applied. After seven days of ageing the physical properties of the geopolymer(compressive strength and specimen density)were measured. Chemical leaching tests on the rawmaterial and the geopolymers were carried out to determine the elements which can be mobilized by different leaching solutions. It was found that the above mentioned parameters (fly ash fineness, molar concentration and composition of activator solution, heat curing) has great effect on the physical and chemical properties of geopolymer specimens. Optimal conditions were as follows: specific surface area of the fly ash above 2000 cm2/g, 10 M NaOH, 30°C heat curing temperature which resulted in 21 MPa compressive strength geopolymer.

Fly-ash geo-polymer foamed concrete

NASA Astrophysics Data System (ADS)

Kargin, Aleksey; Baev, Vladimir; Mashkin, Nikolay

2017-01-01

In recent years, the interest of researchrs in using fly-ash as a raw material for the geo-polymer synthesis is increasing. Kuzbass region (in Russia) has a large amount of ash wastes generated, which defined the relevace of the study performed in this paper. Results of investigating load-bearing capacity of structural insulating material produced by geo-polymerization of fly-ash of Kemerovo hydro-electric power plant with the addition of complex activator are described in the paper. Hydrogen peroxide solution was used as the foaming agent. The activation time, the temperature of isothermal holding and hardening in normal conditions for all samples were constant. The compressive strength and the mean density of geo-polymer foamed concrete were determined. The influence of the material composition on its properties was revealed. It is found that of the geo-polymer foamed concrete with the optimum composition has hardness of 1,1-3,5 MPa at the density of 400 to 900 kg/m3. Thus, the production of the fly-ash geo-polymer concretes and mortars is feasible, justified and promising.

Superplasticizer Addition to Carbon Fly Ash Geopolymers Activated at Room Temperature.

PubMed

Carabba, Lorenza; Manzi, Stefania; Bignozzi, Maria Chiara

2016-07-18

Present concerns about global warming due to the greenhouse emissions in the atmosphere have pushed the cement industry to research alternatives to ordinary Portland cement (OPC). Geopolymer binder may constitute a possible breakthrough in the development of sustainable materials: understanding the effectiveness and the influences of superplasticizers on geopolymer systems is one of the essential requirements for its large-scale implementation. This study aims to investigate the possibility of using commercially available chemical admixtures designed for OPC concrete, to improve fresh properties of fly ash-based geopolymers and mortars. A special emphasis is laid upon evaluating their influence on mechanical and microstructural characteristics of the hardened material realized under room-temperature curing conditions. Results indicate that the addition of a polycarboxylic ether-based superplasticizer, in the amount of 1.0 wt. % by mass of fly ash, promotes an improvement in workability without compromising the final strength of the hardened material. Moreover, the addition of the polycarboxylic ether- and acrylic-based superplasticizers induces a refinement in the pore structure of hardened mortar leading to a longer water saturation time.

Superplasticizer Addition to Carbon Fly Ash Geopolymers Activated at Room Temperature

PubMed Central

Carabba, Lorenza; Manzi, Stefania; Bignozzi, Maria Chiara

2016-01-01

Present concerns about global warming due to the greenhouse emissions in the atmosphere have pushed the cement industry to research alternatives to ordinary Portland cement (OPC). Geopolymer binder may constitute a possible breakthrough in the development of sustainable materials: understanding the effectiveness and the influences of superplasticizers on geopolymer systems is one of the essential requirements for its large-scale implementation. This study aims to investigate the possibility of using commercially available chemical admixtures designed for OPC concrete, to improve fresh properties of fly ash-based geopolymers and mortars. A special emphasis is laid upon evaluating their influence on mechanical and microstructural characteristics of the hardened material realized under room-temperature curing conditions. Results indicate that the addition of a polycarboxylic ether-based superplasticizer, in the amount of 1.0 wt. % by mass of fly ash, promotes an improvement in workability without compromising the final strength of the hardened material. Moreover, the addition of the polycarboxylic ether- and acrylic-based superplasticizers induces a refinement in the pore structure of hardened mortar leading to a longer water saturation time. PMID:28773707

Variations in Compressive Strength of Geopolymer due to the CaO Added Fly Ash

NASA Astrophysics Data System (ADS)

Zhao, Yuqing; Koumoto, Tatsuya; Kondo, Fumiyoshi

Recently, geopolymer has been a noteworthy material which can be used as a replacement for portland cement. The mechanical characteristics and consistency of the geopolymer are strongly affected by its chemical components of fly ash. The variations in compressive strength of geopolymer due to the CaO added fly ash were investigated in this paper. The compressive strengths of geopolymer were increased with an increase in the curing period, and the characteristics changed from the one of plastic soil material to brittle material such as concrete, regardless of CaO content. Also, the results of compressive strength and modulus of deformation showed their maximum value in the case of 8-10% CaO content. From this result, the maximum characteristics of the strengths were assumed to be exerted in case which the water draining process of geopolymer was balanced with the water absorbing process of additional CaO.

Study on The Geopolymer Concrete Properties Reinforced with Hooked Steel Fiber

NASA Astrophysics Data System (ADS)

Abdullah, M. M. A. B.; Tahir, M. F. M.; Tajudin, M. A. F. M. A.; Ekaputri, J. J.; Bayuaji, R.; Khatim, N. A. M.

2017-11-01

In this research, Class F fly ash and a mixture of alkaline activators and different amount of hooked steel fiber were used for preparing geopolymer concrete. In order to analyses the effect of hooked steel fiber on the geopolymer concrete, the analysis such as chemical composition of fly ash, workability of fresh geopolymer, water absorption, density, compressive strength of hardened geopolymer concrete have been carried out. Mixtures were prepared with fly ash to alkaline liquid ratio of 2.0 with hooked steel fibers were added to the mix with different amounts which are 1%, 3%, 5% and 7% by the weight of the concrete. Experimental results showed that the compressive strength of geopolymer concrete increases as the hooked steel fibers increases. The optimum compressive strength obtained was up to 87.83 MPa on the 14th day. The density of geopolymer concrete are in the range between 2466 kg/m3 to 2501 kg/m3. In addition, the workability value of geopolymer without hooked steel fibers is 100 mm while the workability value of geopolymer with hooked steel fibers are between 60 mm to 30 mm.

Compressive and bonding strength of fly ash based geopolymer mortar

NASA Astrophysics Data System (ADS)

Zailani, Warid Wazien Ahmad; Abdullah, Mohd Mustafa Al Bakri; Zainol, Mohd Remy Rozainy Mohd Arif; Razak, Rafiza Abd.; Tahir, Muhammad Faheem Mohd

2017-09-01

Geopolymer which is produced by synthesizing aluminosilicate source materials with an alkaline activator solution promotes sustainable and excellent properties of binder. The purpose of this paper is to determine the optimum binder to sand ratio of geopolymer mortars based on mechanical properties. In order to optimize the formulation of geopolymer mortar, various binder to sand ratios (0.25, 0.33, 0.5, 1.0, 2.0, 3.0, and 4.0) are prepared. The investigation on the effect of sand inclusion to the compressive and bonding strength of geopolymer mortar is approached. The experimental results show that the bonding strength performance of geopolymer is also depends on the various binder to sand ratio, where the optimum ratio 0.5 gives a highest strength of 12.73 MPa followed by 12.35 MPa, which corresponds the ratio 1.0 for geopolymer, while the compared value of OPC bonding strength is given by 9.3 MPa. The morphological structure at the interface zone is determined by Scanning Electron Microscope (SEM) and the homogenous bonding between geopolymer and substrate can be observed. Fly ash based geopolymers reveal a new category of mortar which has high potential to be used in the field of concrete repair and rehabilitation.

Rice husk (RH) as additive in fly ash based geopolymer mortar

NASA Astrophysics Data System (ADS)

Yahya, Zarina; Razak, Rafiza Abd; Abdullah, Mohd Mustafa Al Bakri; Rahim, Mohd Azrin Adzhar; Nasri, Armia

2017-09-01

In recent year, the Ordinary Portland Cement (OPC) concrete is vastly used as main binder in construction industry which lead to depletion of natural resources in order to manufacture large amount of OPC. Nevertheless, with the introduction of geopolymer as an alternative binder which is more environmental friendly due to less emission of carbon dioxide (CO2) and utilized waste materials can overcome the problems. Rice husk (RH) is an agricultural residue which can be found easily in large quantity due to production of paddy in Malaysia and it's usually disposed in landfill. This paper investigated the effect of rice husk (RH) content on the strength development of fly ash based geopolymer mortar. The fly ash is replaced with RH by 0%, 5%, 10%, 15% and 20% where the sodium silicate and sodium hydroxide was used as alkaline activator. A total of 45 cubes were casted and their compressive strength, density and water absorption were evaluated at 1, 3, and 7 days. The result showed compressive strength decreased when the percentage of RH increased. At 5% replacement of RH, the maximum strength of 17.1MPa was recorded at day 7. The geopolymer has lowest rate of water absorption (1.69%) at 20% replacement of RH. The density of the sample can be classified as lightweight geopolymer concrete.

Immobilization of MSWI fly ash through geopolymerization: effects of water-wash.

PubMed

Zheng, Lei; Wang, Chengwen; Wang, Wei; Shi, Yunchun; Gao, Xingbao

2011-02-01

The present research explored the role played by water-wash on geopolymerization for the immobilization and solidification of municipal solid waste incineration (MSWI) fly ash. The water-wash pretreatment substantially promoted the early strength of geopolymer and resulted in a higher ultimate strength compared to the counterpart without water-wash. XRD pattern of water-washed fly ash (WFA) revealed that NaCl and KCl were nearly eliminated in the WFA. Aside from geopolymer, ettringite (Ca(6)Al(2)(SO(4))(3)(OH)(12)·26H(2)O) was formed in MSWI fly ash-based geopolymer (Geo-FA). Meanwhile, calcium aluminate hydrate (Ca(2)Al(OH)(7)·3H(2)O), not ettringite, appeared in geopolymer that was synthesized with water-washed fly ash (Geo-WFA). Leached Geo-WFA (Geo-WFA-L) did not exhibit any signs of deterioration, while there was visual cracking on the surface of leached Geo-FA (Geo-FA-L). The crack may be caused by the migration of K(+), Na(+), and Cl(-) ions outside Geo-FA and the negative effect from crystallization of expansive compounds can not be excluded. Furthermore, transformation of calcium aluminate hydrate in Geo-WFA to ettringite in Geo-WFA-L allowed the reduction of the pore size of the specimen. IR spectrums suggested that Geo-WFA can supply more stable chemical encapsulation for heavy metals. Static monolithic leaching tests were conducted for geopolymers to estimate the immobilization efficiency. Heavy metal leaching was elucidated using the first-order reaction/diffusion model. Combined with the results from compressive strength and microstructure of samples, the effects of water-wash on immobilization were inferred in this study. Copyright © 2010 Elsevier Ltd. All rights reserved.

Performance of steel wool fiber reinforced geopolymer concrete

NASA Astrophysics Data System (ADS)

Faris, Meor Ahmad; Abdullah, Mohd Mustafa Al Bakri; Ismail, Khairul Nizar; Muniandy, Ratnasamy; Ariffin, Nurliayana

2017-09-01

In this paper, performance of geopolymer concrete was studied by mixing of Class F fly ash from Manjung power station, Lumut, Perak, Malaysia with alkaline activator which are combination of sodium hydroxide and sodium silicate. Steel wool fiber were added into the geopolymer concrete as reinforcement with different weight percentage vary from 0 % - 5 %. Chemical compositions of Malaysian fly ash was first analyzed by using X-ray fluorescence. All geopolymer concrete reinforced with steel wool fiber with different weight percentage were tested in terms of density, workability, and compression. Result shows Malaysian fly ash identified by using XRF was class F. Density of geopolymer concrete close to density of OPC which is approximately 2400 kg/m3 and the density was increase gradually with the additions of steel fiber. However, the inclusions of steel fibers also shows some reduction to the workability of geopolymer concrete. Besides, the compressive strength was increased with the increasing of fibers addition until maximum of 18.6 % improvement at 3 % of steel fibers.

Innovative Fly Ash Geopolymer-Epoxy Composites: Preparation, Microstructure and Mechanical Properties.

PubMed

Roviello, Giuseppina; Ricciotti, Laura; Tarallo, Oreste; Ferone, Claudio; Colangelo, Francesco; Roviello, Valentina; Cioffi, Raffaele

2016-06-09

The preparation and characterization of composite materials based on geopolymers obtained from fly ash and epoxy resins are reported for the first time. These materials have been prepared through a synthetic method based on the concurrent reticulation of the organic and inorganic components that allows the formation of hydrogen bonding between the phases, ensuring a very high compatibility between them. These new composites show significantly improved mechanical properties if compared to neat geopolymers with the same composition and comparable performances in respect to analogous geopolymer-based composites obtained starting from more expensive raw material such as metakaolin. The positive combination of an easy synthetic approach with the use of industrial by-products has allowed producing novel low cost aluminosilicate binders that, thanks to their thixotropicity and good adhesion against materials commonly used in building constructions, could be used within the field of sustainable building.

Innovative Fly Ash Geopolymer-Epoxy Composites: Preparation, Microstructure and Mechanical Properties

PubMed Central

Roviello, Giuseppina; Ricciotti, Laura; Tarallo, Oreste; Ferone, Claudio; Colangelo, Francesco; Roviello, Valentina; Cioffi, Raffaele

2016-01-01

The preparation and characterization of composite materials based on geopolymers obtained from fly ash and epoxy resins are reported for the first time. These materials have been prepared through a synthetic method based on the concurrent reticulation of the organic and inorganic components that allows the formation of hydrogen bonding between the phases, ensuring a very high compatibility between them. These new composites show significantly improved mechanical properties if compared to neat geopolymers with the same composition and comparable performances in respect to analogous geopolymer-based composites obtained starting from more expensive raw material such as metakaolin. The positive combination of an easy synthetic approach with the use of industrial by-products has allowed producing novel low cost aluminosilicate binders that, thanks to their thixotropicity and good adhesion against materials commonly used in building constructions, could be used within the field of sustainable building. PMID:28773582

Mechanical Properties and Microstructure of Class C Fly Ash-Based Geopolymer Paste and Mortar.

PubMed

Li, Xueying; Ma, Xinwei; Zhang, Shoujie; Zheng, Enzu

2013-04-09

This paper presents workability, compressive strength and microstructure for geopolymer pastes and mortars made of class C fly ash at mass ratios of water-to-fly ash from 0.30 to 0.35. Fluidity was in the range of 145-173 mm for pastes and 131-136 mm for mortars. The highest strengths of paste and mortar were 58 MPa and 85 MPa when they were cured at 70 °C for 24 h. In XRD patterns, unreacted quartz and some reacted product were observed. SEM examination indicated that reacted product has formed and covered the unreacted particles in the paste and mortar that were consistent with their high strength.

Strength Performance of Blended Ash Based Geopolymer Mortar

NASA Astrophysics Data System (ADS)

Zahib, Zaidahtulakmal M.; Kamaruddin, Kartini; Saman, Hamidah M.

2018-03-01

Geopolymer is a based on inorganic alumino-silicate binder system. Geopolymeric materials are formed using materials that containing silica and aluminium such as fly ash and rice husk ash, which activated by alkaline solution. This paper presents the study on the effect of replacement of SSA in RHA based geopolymer, types of curing and different molarity of NaOH used on the strength of Sewage Sludge Ash (SSA) and Rice Husk Ash (RHA) based geopolymer mortar incorporating with three (3) different mix proportions. Based geopolymer mortar was synthesized from treated sewage sludge and rice husk undergoing incineration process in producing ashes, activated with sodium silicate and sodium hydroxide solution by ratio of 2.5:1 and solution to ash ratio of 1:1. Molarity of 8M and 10M NaOH were used. The percentages of SSA replacement were 0%, 10% and 20% by weight. Compressive strength was conducted at age 7, 14 and 28 days to see the development of strength with two curing regimes, which are air curing and oven curing (60°C for 24 hours). From the research conducted, the ultimate compressive strength (6.28MPa) was obtained at zero replacement of SSA taken at 28 days of oven curing with 10M of NaOH. This shows that RHA, which is rich in silica content is enough to enhance the strength of geopolymer mortar especially with high molarity of NaOH.

Recycling of Pre-Washed Municipal Solid Waste Incinerator Fly Ash in the Manufacturing of Low Temperature Setting Geopolymer Materials

PubMed Central

Ferone, Claudio; Colangelo, Francesco; Messina, Francesco; Santoro, Luciano; Cioffi, Raffaele

2013-01-01

In this work, three samples of municipal solid waste incinerators fly ash (MSWI-FA) have been stabilized in systems containing coal fly ash to create geopolymers through a polycondensation reaction. Monolithic products have been obtained with both MSWI fly ash as received and after the partial removal of chloride and sulfate by water washing. The polycondensation products have been characterized qualitatively by means of Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy and quantitatively, through the determination of the volume of reacted water and silicate. Furthermore, the heavy metals and chloride releases together with the physico-mechanical properties have been evaluated on the hardened products. In conclusion, considering the technological and environmental performances of the obtained geopolymers, they could be suitable for many non-structural applications, such as backfilling of abandoned quarries, decorative materials or brick fireplaces, hearths, patios, etc. PMID:28811443

Durability of Fly Ash Based Geopolymer Concrete Infilled with Rubber Crumb in Seawater Exposure

NASA Astrophysics Data System (ADS)

Yahya, Z.; Abdullah, M. M. A. B.; Ramli, S. N. H.; Minciuna, M. G.; Razak, R. Abd

2018-06-01

Geopolymer is an alternative binder to replace Ordinary Portland Cement (OPC)in construction industry. Source materials that rich in silica (Si) and alumina (Al) were activated by using alkaline solution. Production of tires keep increasing every year and due to its non-biodegradable properties it causes problems for disposal process. In current scenario, waste materials should be used or recycled so that the existing natural resources can be saved and at the same times it can protected environment. In this paper, the effect of rubber crumb on fly ash based geopolymer concrete have been investigated by immersing the samples in seawater for 28 and 60 days. The rubber crumb was used to replace coarse aggregates from range 5% until 20%. The ratio of fly ash/alkaline activator and sodium silicate/sodium hydroxide(NaOH) ratio were fixed at 2.0 and 2.5. It has been shown that the compressive strength decreased when the content of rubber crumb increased. The highest compressive strength (39.6 MPa) was obtained at 5% replacement of rubber crumb when exposure to seawater for 28 days. The density of geopolymer samples also increased when immersed in seawater for all samples. The lack of bonding between rubber crumb and geoplymer paste cause increasing in porosity hence reduced the strength, increment in density and changes in weight of geopolymer samples.

Mechanical Properties and Microstructure of Class C Fly Ash-Based Geopolymer Paste and Mortar

PubMed Central

Li, Xueying; Ma, Xinwei; Zhang, Shoujie; Zheng, Enzu

2013-01-01

This paper presents workability, compressive strength and microstructure for geopolymer pastes and mortars made of class C fly ash at mass ratios of water-to-fly ash from 0.30 to 0.35. Fluidity was in the range of 145–173 mm for pastes and 131–136 mm for mortars. The highest strengths of paste and mortar were 58 MPa and 85 MPa when they were cured at 70 °C for 24 h. In XRD patterns, unreacted quartz and some reacted product were observed. SEM examination indicated that reacted product has formed and covered the unreacted particles in the paste and mortar that were consistent with their high strength. PMID:28809222

Effect of silica fume on the fresh and hardened properties of fly ash-based self-compacting geopolymer concrete

NASA Astrophysics Data System (ADS)

Memon, Fareed Ahmed; Nuruddin, Muhd Fadhil; Shafiq, Nasir

2013-02-01

The effect of silica fume on the fresh and hardened properties of fly ash-based self-compacting geopolymer concrete (SCGC) was investigated in this paper. The work focused on the concrete mixes with a fixed water-to-geopolymer solid (W/Gs) ratio of 0.33 by mass and a constant total binder content of 400 kg/m3. The mass fractions of silica fume that replaced fly ash in this research were 0wt%, 5wt%, 10wt%, and 15wt%. The workability-related fresh properties of SCGC were assessed through slump flow, V-funnel, and L-box test methods. Hardened concrete tests were limited to compressive, splitting tensile and flexural strengths, all of which were measured at the age of 1, 7, and 28 d after 48-h oven curing. The results indicate that the addition of silica fume as a partial replacement of fly ash results in the loss of workability; nevertheless, the mechanical properties of hardened SCGC are significantly improved by incorporating silica fume, especially up to 10wt%. Applying this percentage of silica fume results in 4.3% reduction in the slump flow; however, it increases the compressive strength by 6.9%, tensile strength by 12.8% and flexural strength by 11.5%.

Selected durability studies of geopolymer concrete with respect to carbonation, elevated temperature, and microbial induced corrosion

NASA Astrophysics Data System (ADS)

Badar, Mohammad Sufian

This thesis reports a comprehensive study related to the experimental evaluation of carbonation in reinforced geopolymer concrete, the evaluation of geopolymer concretes at elevated temperature, and the resistance of geopolymer concrete to microbial induced corrosion (MIC). Carbonation: Reinforced concretes, made of geopolymer, prepared from two class F fly ashes and one class C fly ash, were subjected to accelerated carbonation treatment for a period of 450 days. Electrochemical, microstructure and pore structure examinations were performed to evaluate the effect of corrosion caused due to carbonation. GPC specimens prepared from class F fly ash exhibited lower corrosion rates by a factor of 21, and higher pH values (pH>12) when compared with concrete specimens prepared from class C Fly ash (GPCMN). Microstructure and pore characterization of GPC prepared using class F fly ash revealed lower porosity by a factor of 2.5 as compared with thier counterparts made using GPC-MN. The superior performace of GPC prepared with the class F fly ash could be attributed to the dense pore structure and formation of the protective layer of calcium and sodium alumino silicate hydrates (C/N-A-S-H) geopolymeric gels around the steel reinforcement. Elevated Temperature: Geopolymers are an emerging class of cementitious binders which possess a potential for high temperature resistance that could possibly be utilized in applications such as nozzles, aspirators and refractory linings. This study reports on the results of an investigation into the performance of a fly ash based geopolymer binder in high temperature environments. Geopolymer concrete (GPC) was prepared using eleven types of fly ashes obtained from four countries. High content alumina and silica sand was used in the mix for preparing GPC. GPC was subjected to thermal shock tests following ASTM C 1100-88. The GPC samples prepared with tabular alumina were kept at 1093° C and immediately quenched in water. GPC specimens prepared with certain fly ashes exhibited signs of expansion along with cracking and spalling, while GPC prepared with specific class F fly ash showed superior resistance to thermal shock. Microstructural analysis revealed that the resistance of GPC at elevated temperatures was dependent on the type of fly ash used, its particle size distribution, formation of zeolitic phases such as sodalite, analcime and nepheline, and the overall pore structure of the geopolymer concrete. The work indicates that the chemical composition and particle size distribution of the fly ash, type of fly ash (Class C & F) and the geopolymerization process that took place a vital role in the performance of geopolymer concretes in high temperature applications. Microbial Induced Corrosion: Corrosion is a major form of deterioration in concrete structures. According to a report published by the U.S. FHWA 2002, the cost of corrosion in water and wastewater conveyance, and storage and treatment facilities in the U.S. is about $138 billions. A main form of corrosion in wastewater collection systems is Microbial Induced Corrosion (MIC). However, the conditions present in industrial or municipal wastewater pipes, or storage facility are induced by the production of sulfuric acid by biological processes, which cannot be fully mimicked by simple acid corrosion. The present study intends to provide similar conditions inside pipe specimens that mimic a true sewer atmosphere. The experimental setup consisted of three 12" diameter and 30" long concrete pipe specimens, 2 specimens were coated with different formulations of GPC while the third was a control. Both ends of each pipe specimen were sealed to prevent hydrogen sulfide gas from escaping. One pipe was coated with GPC that had a biocide agent entrained. Another pipe specimen was coated with OPC and the 3rd pipe was used as a control and was not coated. Parameters measured can be divided into three groups: general environmental parameters like pH and temperature: pH is measured at regular intervals. Substrates and products that include Chemical Oxygen Demand (COD) and sulfide concentrations: COD is measured using the Hach Method (APHA, 5220D).Temperature (65 - 70° F) and humidity (50 - 60%) were maintained throughout the experiment. Sulfide concentration was measured by the methylene blue method (APHA, 4500-S-2D). Bacterial count was measured by Spectrophotometer (APHA, 9215B). In addition, the thickness of the slime layer was measured and the end of the 16-week test. Test data revealed that the use of the antibacteria agent has initial input on the rate of pH reduction, but that effect were out after 6 weeks, The slime lyer band on the wall of the geopolymer coated pipes was to be 1/4 of that found on the non-coated pipe, suggesting the geopolymer matrices provide a less suitable substrate for sulfate reducing bacteria (Desulfovibrio desulfuricans) compound with a standard OPC substate.

Workability enhancement of geopolymer concrete through the use of retarder

NASA Astrophysics Data System (ADS)

Umniati, B. Sri; Risdanareni, Puput; Zein, Fahmi Tarmizi Zulfikar

2017-09-01

Geopolymer concrete is a type of concrete manufactured without the addition of cement. In geopolymer concrete, along with an activator, cement as the concrete binder can be replaced by the fly ash. This will reduce global demand on cement, and therefore will reduce CO2 emission due to cement production. Thus, geopolymer concrete is commonly known as an eco-friendly concrete. Geopolymer concrete also offers a solution concerning with the utilization of the fly ash waste. However, despite of its environmental advantages, geopolymer concrete has a drawback, namelygeopolymer concrete set quickly, thus reducing its workability. This research aimed to increase the workability of geopolymer concrete by using retarder admixture (Plastocrete RT6 Plus). Retarder used varies within 0.2%, 0.4% and 0.6% of fly ash mass. As a control, geopolymer concrete without retarder (0%) were also made. Activator used in this research was Na2SiO3 mixed with NaOH 10 M solution, with ratio of 1:5. The results showed an optimum composition of geopolymer concrete with 0.6% retarder, where initial setting time occured after 6.75 hours, and the final setting time reached after 9.5 hours. Moreover, the slump of the geopolymer concrete was 8.8 cm, and the slump flow was 24 cm. The compressive strength of the geopolymer concrete at 28 days was 47.21 MPa. The experiment showed that the more retarder added, the setting time of the geopolymer concrete will be increased, thus increasing its workability.

Fly ash/Kaolin based geopolymer green concretes and their mechanical properties

PubMed Central

Okoye, F.N.; Durgaprasad, J.; Singh, N.B.

2015-01-01

Geopolymer concrete mixes were cast using fly ash, kaolin, sodium hydroxide, potassium hydroxide, sodium silicate and aggregates. Portland cement concrete (M30) was used as a reference sample. The effect of silica fume, temperature (40 °C, 60 °C, 80 °C, 100 °C and 120 °C), sodium and potassium hydroxides and different superplasticizers on the compressive strength are reported [1]. Maximum strength was found at 100 °C and 14 M alkali solution [1]. PMID:26693505

Fly ash/Kaolin based geopolymer green concretes and their mechanical properties.

PubMed

Okoye, F N; Durgaprasad, J; Singh, N B

2015-12-01

Geopolymer concrete mixes were cast using fly ash, kaolin, sodium hydroxide, potassium hydroxide, sodium silicate and aggregates. Portland cement concrete (M30) was used as a reference sample. The effect of silica fume, temperature (40 °C, 60 °C, 80 °C, 100 °C and 120 °C), sodium and potassium hydroxides and different superplasticizers on the compressive strength are reported [1]. Maximum strength was found at 100 °C and 14 M alkali solution [1].

Synthesis of geopolymer from biomass-coal ash blends

NASA Astrophysics Data System (ADS)

Samadhi, Tjokorde Walmiki; Wulandari, Winny; Prasetyo, Muhammad Iqbal; Fernando, Muhammad Rizki; Purbasari, Aprilina

2017-09-01

Geopolymer is an environmentally attractive Portland cement substitute, owing to its lower carbon footprint and its ability to consume various aluminosilicate waste materials as its precursors. This work describes the development of geopolymer formulation based on biomass-coal ash blends, which is predicted to be the prevalent type of waste when biomass-based thermal energy production becomes mainstream in Indonesia. The ash blends contain an ASTM Class F coal fly ash (FA), rice husk ash (RHA), and coconut shell ash (CSA). A mixture of Na2SiO3 and concentrated KOH is used as the activator solution. A preliminary experiment identified the appropriate activator/ash mass ratio to be 2.0, while the activator Na2SiO3/KOH ratio varies from 0.8 to 2.0 with increasing ash blend Si/Al ratio. Both non-blended FA and CSA are able to produce geopolymer mortars with 7-day compressive strength exceeding the Indonesian national SNI 15-2049-2004 standard minimum value of 2.0 MPa stipulated for Portland cement mortars. Ash blends have to be formulated with a maximum RHA content of approximately 50 %-mass to yield satisfactory 7-day strength. No optimum ash blend composition is identified within the simplex ternary ash blend compositional region. The strength decreases with Si/Al ratio of the ash blends due to increasing amount of unreacted silicate raw materials at the end of the geopolymer hardening period. Overall, it is confirmed that CSA and blended RHA are feasible raw materials for geopolymer production..

Effective properties of a fly ash geopolymer: Synergistic application of X-ray synchrotron tomography, nanoindentation, and homogenization models

DOE PAGES

Das, Sumanta; Yang, Pu; Singh, Sudhanshu S.; ...

2015-09-02

Microstructural and micromechanical investigation of a fly ash-based geopolymer using: (i) synchrotron x-ray tomography (XRT) to determine the volume fraction and tortuosity of pores that are influential in fluid transport, (ii) mercury intrusion porosimetry (MIP) to capture the volume fraction of smaller pores, (iii) scanning electron microscopy (SEM) combined with multi-label thresholding to identify and characterize the solid phases in the microstructure, and (iv) nanoindentation to determine the component phase elastic properties using statistical deconvolution, is reported in this paper. The phase volume fractions and elastic properties are used in multi-step mean field homogenization (Mori- Tanaka and double inclusion) modelsmore » to determine the homogenized macroscale elastic modulus of the composite. The homogenized elastic moduli are in good agreement with the flexural elastic modulus determined on macroscale paste beams. As a result, the combined use of microstructural and micromechanical characterization tools at multiple scales provides valuable information towards the material design of fly ash geopolymers.« less

Optimizing and Characterizing Geopolymers from Ternary Blend of Philippine Coal Fly Ash, Coal Bottom Ash and Rice Hull Ash.

PubMed

Kalaw, Martin Ernesto; Culaba, Alvin; Hinode, Hirofumi; Kurniawan, Winarto; Gallardo, Susan; Promentilla, Michael Angelo

2016-07-15

Geopolymers are inorganic polymers formed from the alkaline activation of amorphous alumino-silicate materials resulting in a three-dimensional polymeric network. As a class of materials, it is seen to have the potential of replacing ordinary Portland cement (OPC), which for more than a hundred years has been the binder of choice for structural and building applications. Geopolymers have emerged as a sustainable option vis-à-vis OPC for three reasons: (1) their technical properties are comparable if not better; (2) they can be produced from industrial wastes; and (3) within reasonable constraints, their production requires less energy and emits significantly less CO₂. In the Philippines, the use of coal ash, as the alumina- and silica- rich geopolymer precursor, is being considered as one of the options for sustainable management of coal ash generation from coal-fired power plants. However, most geopolymer mixes (and the prevalent blended OPC) use only coal fly ash. The coal bottom ash, having very few applications, remains relegated to dumpsites. Rice hull ash, from biomass-fired plants, is another silica-rich geopolymer precursor material from another significantly produced waste in the country with only minimal utilization. In this study, geopolymer samples were formed from the mixture of coal ash, using both coal fly ash (CFA) and coal bottom ash (CBA), and rice hull ash (RHA). The raw materials used for the geopolymerization process were characterized using X-ray fluorescence spectroscopy (XRF) for elemental and X-ray diffraction (XRD) for mineralogical composition. The raw materials' thermal stability and loss on ignition (LOI) were determined using thermogravimetric analysis (TGA) and reactivity via dissolution tests and inductively-coupled plasma mass spectrometry (ICP) analysis. The mechanical, thermal and microstructural properties of the geopolymers formed were analyzed using compression tests, Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Using a Scheffé-based mixture design, targeting applications with low thermal conductivity, light weight and moderate strength and allowing for a maximum of five percent by mass of rice hull ash in consideration of the waste utilization of all three components, it has been determined that an 85-10-5 by weight ratio of CFA-CBA-RHA activated with 80-20 by mass ratio of 12 M NaOH and sodium silicate (55% H₂O, modulus = 3) produced geopolymers with a compressive strength of 18.5 MPa, a volumetric weight of 1660 kg/m³ and a thermal conductivity of 0.457 W/m-°C at 28-day curing when pre-cured at 80 °C for 24 h. For this study, the estimates of embodied energy and CO₂ were all below 1.7 MJ/kg and 0.12 kg CO₂/kg, respectively.

Utilisation of steel furnace slag coarse aggregate in a low calcium fly ash geopolymer concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, M. S.H.,; Castel, Arnaud; Akbarnezhad, A.

This paper evaluates the performance of steel furnace slag (SFS) coarse aggregate in blended slag and low calcium fly ash geopolymer concrete (GPC). The geopolymer binder is composed of 90% of low calcium fly ash and 10% of ground granulated blast furnace slag (GGBFS). Mechanical and physical properties, shrinkage, and detailed microstructure analysis were carried out. The results showed that geopolymer concrete with SFS aggregate offered higher compressive strength, surface resistivity and pulse velocity than that of GPC with traditional aggregate. The shrinkage results showed no expansion or swelling due to delayed calcium oxide (CaO) hydration after 320 days. Nomore » traditional porous interfacial transition zone (ITZ) was detected using scanning electron microscopy, indicating a better bond between SFS aggregate and geopolymer matrix. Energy dispersive spectroscopy results further revealed calcium (Ca) diffusion at the vicinity of ITZ. Raman spectroscopy results showed no new crystalline phase formed due to Ca diffusion. X-ray fluorescence result showed Mg diffusion from SFS aggregate towards geopolymer matrix. The incorporation of Ca and Mg into the geopolymer structure and better bond between SFS aggregate and geopolymer matrix are the most likely reasons for the higher compressive strength observed in GPC with SFS aggregate.« less

Influence of Curing on the Strength Development of Calcium-Containing Geopolymer Mortar

PubMed Central

Li, Xueying; Wang, Zheng; Jiao, Zhenzhen

2013-01-01

This paper investigated the curing effects on the mechanical properties of calcium-containing geopolymer mortar. Three precursors are used: Class C fly ash, Class F fly ash plus calcium hydroxide and Class F fly ash plus slag. Curing conditions included: (1) standard curing at 20 ± 3 °C and RH 95% (C); (2) steam curing at 60 °C for 24 h (S); (3) steam curing at 60 °C for 6 h (S6); and (4) oven curing at 60 °C for 24 h (O), then the latter three followed by the standard curing. Under the standard conditions, the flexural strength and compressive strength of Class C fly ash geopolymer mortars developed quickly until the age of 7 days, followed by a gradual increase. Specimens with Class F fly ash plus Ca(OH)2 showed slow increase till the age of 28 days. Under these non-standard conditions (2–4), all specimens showed higher 3-day strength, while later strengths were either higher or lower than those in standard conditions, depending on the type of the precursor. PMID:28788377

Influence of Curing on the Strength Development of Calcium-Containing Geopolymer Mortar.

PubMed

Li, Xueying; Wang, Zheng; Jiao, Zhenzhen

2013-11-07

This paper investigated the curing effects on the mechanical properties of calcium-containing geopolymer mortar. Three precursors are used: Class C fly ash, Class F fly ash plus calcium hydroxide and Class F fly ash plus slag. Curing conditions included: (1) standard curing at 20 ± 3 °C and RH 95% (C); (2) steam curing at 60 °C for 24 h (S); (3) steam curing at 60 °C for 6 h (S6); and (4) oven curing at 60 °C for 24 h (O), then the latter three followed by the standard curing. Under the standard conditions, the flexural strength and compressive strength of Class C fly ash geopolymer mortars developed quickly until the age of 7 days, followed by a gradual increase. Specimens with Class F fly ash plus Ca(OH)₂ showed slow increase till the age of 28 days. Under these non-standard conditions (2-4), all specimens showed higher 3-day strength, while later strengths were either higher or lower than those in standard conditions, depending on the type of the precursor.

Graphene/fly ash geopolymeric composites as self-sensing structural materials

NASA Astrophysics Data System (ADS)

Saafi, Mohamed; Tang, Leung; Fung, Jason; Rahman, Mahbubur; Sillars, Fiona; Liggat, John; Zhou, Xiangming

2014-06-01

The reduction of graphene oxide during the processing of fly ash-based geopolymers offers a completely new way of developing low-cost multifunctional materials with significantly improved mechanical and electrical properties for civil engineering applications such as bridges, buildings and roads. In this paper, we present for the first time the self-sensing capabilities of fly ash-based geopolymeric composites containing in situ reduced graphene oxide (rGO). Geopolymeric composites with rGO concentrations of 0.0, 0.1 and 0.35% by weight were prepared and their morphology and conductivity were determined. The piezoresistive effect of the rGO-geopolymeric composites was also determined under tension and compression. The Fourier transform infrared spectroscopy (FTIR) results indicate that the rGO sheets can easily be reduced during synthesis of geopolymers due to the effect of the alkaline solution on the functional groups of GO. The scanning electron microscope (SEM) images showed that the majority of pores and voids within the geopolymers were significantly reduced due to the addition of rGO. The rGO increased the electrical conductivity of the fly ash-based rGO-geopolymeric composites from 0.77 S m-1 at 0.0 wt% to 2.38 S m-1 at 0.35 wt%. The rGO also increased the gauge factor by as much as 112% and 103% for samples subjected to tension and compression, respectively.

Alkali-aggregate reactivity of typical siliceious glass and carbonate rocks in alkali-activated fly ash based geopolymers

NASA Astrophysics Data System (ADS)

Lu, Duyou; Liu, Yongdao; Zheng, Yanzeng; Xu, Zhongzi; Shen, Xiaodong

2013-08-01

For exploring the behaviour of alkali-aggregate reactivity (AAR) in alkali-activated geopolymeric materials and assessing the procedures for testing AAR in geopolymers, the expansion behaviour of fly ash based geopolymer mortars with pure silica glass and typical carbonate rocks were studied respectively by curing at various conditions, i.e. 23°C and 38°C with relative humidity over 95%, immersed in 1M NaOH solution at 80°C. Results show that, at various curing conditions, neither harmful ASR nor harmful ACR was observed in geopolymers with the criteria specified for OPC system. However, with the change of curing conditions, the geopolymer binder and reactive aggregates may experience different reaction processes leading to quite different dimensional changes, especially with additional alkalis and elevated temperatures. It suggests that high temperature with additional alkali for accelerating AAR in traditional OPC system may not appropriate for assessing the alkali-aggregate reactivity behaviour in geopolymers designed for normal conditions. On the other hand, it is hopeful to control the dimensional change of geopolymer mortar or concrete by selecting the type of aggregates and the appropriate curing conditions, thus changing the harmful AAR in OPC into beneficial AAR in geopolymers and other alkali-activated cementitious systems.

Mechanically activated fly ash as a high performance binder for civil engineering

NASA Astrophysics Data System (ADS)

Rieger, D.; Kullová, L.; Čekalová, M.; Novotný, P.; Pola, M.

2017-01-01

This study is aimed for investigation of fly ash binder with suitable properties for civil engineering needs. The fly ash from Czech brown coal power plant Prunerov II was used and mechanically activated to achieve suitable particle size for alkaline activation of hardening process. This process is driven by dissolution of aluminosilicate content of fly ash and by subsequent development of inorganic polymeric network called geopolymer. Hardening kinetics at 25 and 30 °C were measured by strain controlled small amplitude oscillatory rheometry with strain of 0.01 % and microstructure of hardened binder was evaluated by scanning electron microscopy. Strength development of hardened binder was investigated according to compressional and flexural strength for a period of 180 days. Our investigation finds out, that mechanically activated fly ash can be comparable to metakaolin geopolymers, according to setting time and mechanical parameters even at room temperature curing. Moreover, on the bases of long time strength development, achieved compressional strength of 134.5 after 180 days is comparable to performance of high grade Portland cement concretes.

Tentative to use wastes from thermal power plants for construction building materials

NASA Astrophysics Data System (ADS)

Bui, Quoc-Bao; Phan, To-Anh-Vu; Tran, Minh-Tung; Le, Duc-Hien

2018-04-01

Thermal power plants (TPP) generates wastes (bottom and fly ashes) which become a serious environmental problem in Vietnam. Indeed, although in several countries fly ash can be used for cement industry, fly ash from actual TPP in Vietnam does not have enough good quality for cement production, because the fly ash treatment phase has not yet included in the generations of existing Vietnamese TPP. That is why bottom ash and fly ash purely become wastes and their evacuation is an urgent demand of the society. This paper presents an investigation using fly and bottom ashes in the manufacturing of construction materials. The main aims of this study is to reduce environmental impacts of fly and bottom ashes, and to test another non-conventional binder to replace cement in the manufacture of unburnt bricks. Several proportions of fly ash, bottom ash, cement, gravel, sand and water were tested to manufacture concretes. Then, geopolymer was prepared from the fly ash and an activator. Specimens were tested in uniaxial compressions. Results showed that the cement concrete tested had the compressive strengths which could be used for low rise constructions and the material using geopolymer could be used for non-load-bearing materials (unburnt bricks).

Performance and Characterization of Geopolymer Concrete Reinforced with Short Steel Fiber

NASA Astrophysics Data System (ADS)

Abdullah, M. M. A. B.; Faris, M. A.; Tahir, M. F. M.; Kadir, A. A.; Sandu, A. V.; Mat Isa, N. A. A.; Corbu, O.

2017-06-01

In the recent years, geopolymer concrete are reporting as the greener construction technology compared to conventional concrete that made up of ordinary Portland cement. Geopolymer concrete is an innovative construction material that utilized fly ash as one of waste material in coal combustion industry as a replacement for ordinary Portland cement in concrete. The uses of fly ash could reduce the carbon dioxide emission to the atmosphere, redundant of fly ash waste and costs compared to ordinary Portland cement concrete. However, the plain geopolymer concrete suffers from numerous drawbacks such as brittleness and low durability. Thus, in this study the addition of steel fiber is introduced in plain geopolymer concrete to improve its mechanical properties especially in compressive and flexural strength. Characterization of raw materials also determined by using chemical composition analysis. Short type of steel fiber is added to the mix in weight percent of 1 wt%, 3 wt%, 5 wt% and 7 wt% with fixed molarity of sodium hydroxide of 12M and solid to liquid ratio as 2.0. The addition of steel fiber showed the excellent improvement in the mechanical properties of geopolymer concrete that are determined by various methods available in the literature and compared with each other.

Thermal Resistance Variations of Fly Ash Geopolymers: Foaming Responses

NASA Astrophysics Data System (ADS)

Cheng-Yong, Heah; Yun-Ming, Liew; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin

2017-03-01

This paper presents a comparative study of the characteristic of unfoamed and foamed geopolymers after exposure to elevated temperatures (200-800 °C). Unfoamed geopolymers were produced with Class F fly ash and sodium hydroxide and liquid sodium silicate. Porous geopolymers were prepared by foaming with hydrogen peroxide. Unfoamed geopolymers possessed excellent strength of 44.2 MPa and degraded 34% to 15 MPa in foamed geopolymers. The strength of unfoamed geopolymers decreased to 5 MPa with increasing temperature up to 800 °C. Foamed geopolymers behaved differently whereby they deteriorated to 3 MPa at 400 °C and increased up to 11 MPa at 800 °C. Even so, the geopolymers could withstand high temperature without any disintegration and spalling up to 800 °C. The formation of crystalline phases at higher temperature was observed deteriorating the strength of unfoamed geopolymers but enhance the strength of foamed geopolymers. In comparison, foamed geopolymer had better thermal resistance than unfoamed geopolymers as pores provide rooms to counteract the internal damage.

Thermal Resistance Variations of Fly Ash Geopolymers: Foaming Responses

PubMed Central

Cheng-Yong, Heah; Yun-Ming, Liew; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin

2017-01-01

This paper presents a comparative study of the characteristic of unfoamed and foamed geopolymers after exposure to elevated temperatures (200–800 °C). Unfoamed geopolymers were produced with Class F fly ash and sodium hydroxide and liquid sodium silicate. Porous geopolymers were prepared by foaming with hydrogen peroxide. Unfoamed geopolymers possessed excellent strength of 44.2 MPa and degraded 34% to 15 MPa in foamed geopolymers. The strength of unfoamed geopolymers decreased to 5 MPa with increasing temperature up to 800 °C. Foamed geopolymers behaved differently whereby they deteriorated to 3 MPa at 400 °C and increased up to 11 MPa at 800 °C. Even so, the geopolymers could withstand high temperature without any disintegration and spalling up to 800 °C. The formation of crystalline phases at higher temperature was observed deteriorating the strength of unfoamed geopolymers but enhance the strength of foamed geopolymers. In comparison, foamed geopolymer had better thermal resistance than unfoamed geopolymers as pores provide rooms to counteract the internal damage. PMID:28345643

Reuse of Coconut Shell, Rice Husk, and Coal Ash Blends in Geopolymer Synthesis

NASA Astrophysics Data System (ADS)

Walmiki Samadhi, Tjokorde; Wulandari, Winny; Prasetyo, Muhammad Iqbal; Rizki Fernando, Muhammad

2017-10-01

Mixtures of biomass and coal ashes are likely to be produced in increasing volume as biomass-based energy production is gaining importance in Indonesia. This work highlights the reuse of coconut shell ash (CSA), rice husk ash (RHA), and coal fly ash (FA) for geopolymer synthesis by an activator solution containing concentrated KOH and Na2SiO3. Ash blend compositions are varied according to a simplex-centroid mixture experimental design. Activator to ash mass ratios are varied from 0.8 to 2.0, the higher value being applied for ash compositions with higher Si/Al ratio. The impact of ash blend composition on early strength is adequately modeled by an incomplete quadratic mixture model. Overall, the ashes can produce geopolymer mortars with an early strength exceeding the Indonesian SNI 15-2049-2004 standard minimum value of 2.0 MPa. Good workability of the geopolymer is indicated by their initial setting times which are longer than the minimum value of 45 mins. Geopolymers composed predominantly of RHA composition exhibit poor strength and excessive setting time. FTIR spectroscopy confirms the geopolymerization of the ashes by the shift of the Si-O-Si/Al asymmetric stretching vibrational mode. Overall, these results point to the feasibility of geopolymerization as a reuse pathway for biomass combustion waste.

A Comprehensive Study of the Polypropylene Fiber Reinforced Fly Ash Based Geopolymer

PubMed Central

Ranjbar, Navid; Mehrali, Mehdi; Behnia, Arash; Javadi Pordsari, Alireza; Mehrali, Mohammad; Alengaram, U. Johnson; Jumaat, Mohd Zamin

2016-01-01

As a cementitious material, geopolymers show a high quasi-brittle behavior and a relatively low fracture energy. To overcome such a weakness, incorporation of fibers to a brittle matrix is a well-known technique to enhance the flexural properties. This study comprehensively evaluates the short and long term impacts of different volume percentages of polypropylene fiber (PPF) reinforcement on fly ash based geopolymer composites. Different characteristics of the composite were compared at fresh state by flow measurement and hardened state by variation of shrinkage over time to assess the response of composites under flexural and compressive load conditions. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that incorporation of PPF up to 3 wt % into the geopolymer paste reduces the shrinkage and enhances the energy absorption of the composites. While, it might reduce the ultimate flexural and compressive strength of the material depending on fiber content. PMID:26807825

A Comprehensive Study of the Polypropylene Fiber Reinforced Fly Ash Based Geopolymer.

PubMed

Ranjbar, Navid; Mehrali, Mehdi; Behnia, Arash; Javadi Pordsari, Alireza; Mehrali, Mohammad; Alengaram, U Johnson; Jumaat, Mohd Zamin

2016-01-01

As a cementitious material, geopolymers show a high quasi-brittle behavior and a relatively low fracture energy. To overcome such a weakness, incorporation of fibers to a brittle matrix is a well-known technique to enhance the flexural properties. This study comprehensively evaluates the short and long term impacts of different volume percentages of polypropylene fiber (PPF) reinforcement on fly ash based geopolymer composites. Different characteristics of the composite were compared at fresh state by flow measurement and hardened state by variation of shrinkage over time to assess the response of composites under flexural and compressive load conditions. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that incorporation of PPF up to 3 wt % into the geopolymer paste reduces the shrinkage and enhances the energy absorption of the composites. While, it might reduce the ultimate flexural and compressive strength of the material depending on fiber content.

The Effect of Sodium Hydroxide Molarity on Strength Development of Non-Cement Class C Fly Ash Geopolymer Mortar

NASA Astrophysics Data System (ADS)

Wardhono, A.

2018-01-01

The use of fly ash as cement replacement material can overcome the environmental issues, especially the global warming problem caused by the greenhouse effect. This is attributed to the CO2 gas produced during the cement manufacturing process, which 1 ton of cement is equivalent to 1 ton CO2. However, the major problem of fly ash is the requirement of activators to activate the polymer reactions. The most common activator used in non-cement or geopolymer material is the combination of sodium hydroxide (NaOH) and sodium silicate. This study aims to identify the effect of NaOH molarity as activator on strength development of non-cement class C fly ash geopolymer mortar. The molarity variations of NaOH were 6 Molar (M), 8M, 10M, 12M, 14M and 15M. The compressive strength test was performed at the age of 3, 7 and 28 days in accordance with ASTM standard, and the specimens were cured at room temperature. The results show that the highest compressive strength was achieved by geopolymer mortar with a molarity of 12M. It exhibits a higher strength to that normal mortar at 28 days. However, the use of NaOH molarity more than 12M tends to decrease the strength of non-cement geopolymer mortar specimens.

Optimizing and Characterizing Geopolymers from Ternary Blend of Philippine Coal Fly Ash, Coal Bottom Ash and Rice Hull Ash

PubMed Central

Kalaw, Martin Ernesto; Culaba, Alvin; Hinode, Hirofumi; Kurniawan, Winarto; Gallardo, Susan; Promentilla, Michael Angelo

2016-01-01

Geopolymers are inorganic polymers formed from the alkaline activation of amorphous alumino-silicate materials resulting in a three-dimensional polymeric network. As a class of materials, it is seen to have the potential of replacing ordinary Portland cement (OPC), which for more than a hundred years has been the binder of choice for structural and building applications. Geopolymers have emerged as a sustainable option vis-à-vis OPC for three reasons: (1) their technical properties are comparable if not better; (2) they can be produced from industrial wastes; and (3) within reasonable constraints, their production requires less energy and emits significantly less CO2. In the Philippines, the use of coal ash, as the alumina- and silica- rich geopolymer precursor, is being considered as one of the options for sustainable management of coal ash generation from coal-fired power plants. However, most geopolymer mixes (and the prevalent blended OPC) use only coal fly ash. The coal bottom ash, having very few applications, remains relegated to dumpsites. Rice hull ash, from biomass-fired plants, is another silica-rich geopolymer precursor material from another significantly produced waste in the country with only minimal utilization. In this study, geopolymer samples were formed from the mixture of coal ash, using both coal fly ash (CFA) and coal bottom ash (CBA), and rice hull ash (RHA). The raw materials used for the geopolymerization process were characterized using X-ray fluorescence spectroscopy (XRF) for elemental and X-ray diffraction (XRD) for mineralogical composition. The raw materials’ thermal stability and loss on ignition (LOI) were determined using thermogravimetric analysis (TGA) and reactivity via dissolution tests and inductively-coupled plasma mass spectrometry (ICP) analysis. The mechanical, thermal and microstructural properties of the geopolymers formed were analyzed using compression tests, Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Using a Scheffé-based mixture design, targeting applications with low thermal conductivity, light weight and moderate strength and allowing for a maximum of five percent by mass of rice hull ash in consideration of the waste utilization of all three components, it has been determined that an 85-10-5 by weight ratio of CFA-CBA-RHA activated with 80-20 by mass ratio of 12 M NaOH and sodium silicate (55% H2O, modulus = 3) produced geopolymers with a compressive strength of 18.5 MPa, a volumetric weight of 1660 kg/m3 and a thermal conductivity of 0.457 W/m-°C at 28-day curing when pre-cured at 80 °C for 24 h. For this study, the estimates of embodied energy and CO2 were all below 1.7 MJ/kg and 0.12 kg CO2/kg, respectively. PMID:28773702

TiO₂-Based Photocatalytic Geopolymers for Nitric Oxide Degradation.

PubMed

Strini, Alberto; Roviello, Giuseppina; Ricciotti, Laura; Ferone, Claudio; Messina, Francesco; Schiavi, Luca; Corsaro, Davide; Cioffi, Raffaele

2016-06-24

This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin), composite systems (siloxane-hybrid, foamed hybrid), and curing temperatures (room temperature and 60 °C) were investigated for the same photocatalyst content (i.e., 3% TiO₂ by weight of paste). The geopolymer matrices were previously designed for different applications, ranging from insulating (foam) to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features.

Effect of fly ash calcination in geopolymer synthesis

NASA Astrophysics Data System (ADS)

Samadhi, Tjokorde Walmiki; Jatiningrum, Mirna; Arisiani, Gresia

2015-12-01

Geopolymer, a largely amorphous class of inorganic polymer consisting of aluminosilicate repeat units, is an environmentally attractive engineering material due to its ability to consume aluminosilicate waste as raw materials. This work studies the effect of the calcination temperature of a coal fly ash generated by a low-efficiency boiler on the mechanical strength of geopolymer mortar synthesized using a mixture of the fly ash, potassium hydroxide as the alkali activator, and locally available sand as the filler aggregate. The calcination temperature is varied between 500-700 °C, with a calcination period of 2 hours in an electric furnace. Two sand samples with different particle size distributions are used. The key response variable is the compressive strength at room temperature, measured after curing at 80 °C for 7 and 14 days. Uncalcined ash, with a carbon content of approximately 31.0%, is not amenable for geopolymer synthesis. Analysis of experimental data using the ANOVA method for general factorial design identifies significant main effects for all three experimental variables. Two-way interactions are significant, except that between sand type and curing period. Higher calcination temperature significantly improves the strength of the mortar. However, the strength of the obtained geopolymer mortars are still significantly lower than that of ordinary Portland cement mortar.

Environmental, physical and structural characterisation of geopolymer matrixes synthesised from coal (co-)combustion fly ashes.

PubMed

Alvarez-Ayuso, E; Querol, X; Plana, F; Alastuey, A; Moreno, N; Izquierdo, M; Font, O; Moreno, T; Diez, S; Vázquez, E; Barra, M

2008-06-15

The synthesis of geopolymer matrixes from coal (co-)combustion fly ashes as the sole source of silica and alumina has been studied in order to assess both their capacity to immobilise the potentially toxic elements contained in these coal (co-)combustion by-products and their suitability to be used as cement replacements. The geopolymerisation process has been performed using (5, 8 and 12 M) NaOH solutions as activation media and different curing time (6-48 h) and temperature (40-80 degrees C) conditions. Synthesised geopolymers have been characterised with regard to their leaching behaviour, following the DIN 38414-S4 [DIN 38414-S4, Determination of leachability by water (S4), group S: sludge and sediments. German standard methods for the examination of water, waste water and sludge. Institut für Normung, Berlin, 1984] and NEN 7375 [NEN 7375, Leaching characteristics of moulded or monolithic building and waste materials. Determination of leaching of inorganic components with the diffusion test. Netherlands Normalisation Institute, Delft, 2004] procedures, and to their structural stability by means of compressive strength measurements. In addition, geopolymer mineralogy, morphology and structure have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. It was found that synthesised geopolymer matrixes were only effective in the chemical immobilisation of a number of elements of environmental concern contained in fly ashes, reducing (especially for Ba), or maintaining their leachable contents after the geopolymerisation process, but not for those elements present as oxyanions. Physical entrapment does not seem either to contribute in an important way, in general, to the immobilisation of oxyanions. The structural stability of synthesised geopolymers was mainly dependent on the glass content of fly ashes, attaining at the optimal activation conditions (12 M NaOH, 48 h, 80 degrees C) compressive strength values about 60 MPa when the fly ash glass content was higher than 90%.

Geopolymer lightweight bricks manufactured from fly ash and foaming agent

NASA Astrophysics Data System (ADS)

Ibrahim, Wan Mastura Wan; Hussin, Kamarudin; Abdullah, Mohd Mustafa Al Bakri; Kadir, Aeslina Abdul

2017-04-01

This paper deals with the development of lightweight geopolymer bricks by using foaming agent and fly ash. The mix parameters analysed through a laboratory experiment with fix ratio of sodium silicate/sodium hydroxide solution mass ratio 2.5, fly ash/alkaline activator solution mass ratio 2.0, foaming agent/paste mass ratio 1:2 and molarity of sodium hydroxide solution used was 12M. Different curing temperature (Room Temperature, 60, 80) and foaming agent/water mass ratio (1:10 and 1:20) were studied. Compressive strength, density analysis, and water absorption has been investigated. The results show that the foamed geopolymer bricks with a lower foam/water mass ratio (1:10)and high curing temperature (80°C) leading to a better properties. Mixtures with a low density of around 1420 kg/m3 and a compressive strength of around 10 MPa were achieved.

Experimental Study on Rise Husk Ash & Fly Ash Based Geo-Polymer Concrete Using M-Sand

NASA Astrophysics Data System (ADS)

Nanda Kishore, G.; Gayathri, B.

2017-08-01

Serious environmental problems by means of increasing the production of Ordinary Portland cement (OPC), which is conventionally used as the primary binder to produce cement concrete. An attempt has been made to reduce the use of ordinary Portland cement in cement concrete. There is no standard mix design of geo-polymer concrete, an effort has been made to know the physical, chemical properties and optimum mix of geo-polymer concrete mix design. Concrete cubes of 100 x 100 x 100 mm were prepared and cured under steam curing for about 24 hours at temperature range of 40°C to 60°C. Fly ash is replaced partially with rice husk ash at percentage of 10%, 15% and 25%. Sodium hydroxide and sodium silicate are of used as alkaline activators with 5 Molar and 10 Molar NaOH solutions. Natural sand is replaced with manufacture sand. Test results were compared with controlled concrete mix of grade M30. The results shows that as the percentage of rice husk ash and water content increases, compressive strength will be decreases and as molarity of the alkaline solution increases, strength will be increases.

Effect of basaltic pumice aggregate addition on the material properties of fly ash based lightweight geopolymer concrete

NASA Astrophysics Data System (ADS)

Top, Soner; Vapur, Hüseyin

2018-07-01

In this study, fly ash (FA) based geopolymer (GP) concretes were produced by using a mixture of basaltic pumice (BP) aggregates and a fly ash (Class F) for lightweight concrete production. ANOVA Yates' test technique was applied to find out the effective curing parameters. BP aggregates were ground four different fractions of particle sizes as -12 + 4 mm, -4+0.425 mm, -0.425 + 0 mm and the one containing the size distribution of Turkish Standard 802. Also, effects of the curing time in the oven were investigated. The uniaxial compressive strength (UCS) (20-55 MPa), the point load strength (4-14 kN), the water absorption (1.05%-17%), the Mohs hardness (5.5-3) and the sonic speed values (4.12-2.72 km/sn) were measured. Stress-strain curves were graphed. The density of the concrete ranged from 1700 kg/m3 to 1792 kg/m3 which confirm the lightweight concretes.

TiO2-Based Photocatalytic Geopolymers for Nitric Oxide Degradation

PubMed Central

Strini, Alberto; Roviello, Giuseppina; Ricciotti, Laura; Ferone, Claudio; Messina, Francesco; Schiavi, Luca; Corsaro, Davide; Cioffi, Raffaele

2016-01-01

This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin), composite systems (siloxane-hybrid, foamed hybrid), and curing temperatures (room temperature and 60 °C) were investigated for the same photocatalyst content (i.e., 3% TiO2 by weight of paste). The geopolymer matrices were previously designed for different applications, ranging from insulating (foam) to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features. PMID:28773634

Engineering properties of lightweight geopolymer synthesized from coal bottom ash and rice husk ash

NASA Astrophysics Data System (ADS)

Thang, Nguyen Hoc; Hoa, Nguyen Ngoc; Quyen, Pham Vo Thi Ha; Tuyen, Nguyen Ngoc Kim; Anh, Tran Vu Thao; Kien, Pham Trung

2018-04-01

Geopolymer technology was developed by Joseph Davidovits in 1970s based on reactions among alumino-silicate resources in high alkaline conditions. Geopolymer has been recently gaining attention as an alternative binder for Ordinary Portland cement (OPC) due to its low energy and CO2 burden. The raw materials used for geopolymerization normally contain high SiO2 and Al2O3 in the chemical compositions such as meta-kaoline, rice husk ash, fly ash, bottom ash, blast furnace slag, red mud, and others. Moreover, in this paper, coal bottom ash (CBA) and rice husk ash (RHA), which are industrial and agricultural wastes, respectively, were used as raw materials with high alumino-silicate resources. Both CBA and RHA were mixed with sodium hydroxide (NaOH) solution for 20 minutes to obtain the geopolymer pastes. The pastes were filled in 5-cm cube molds according to ASTM C109/C109M 99, and then cured at room condition for hardening of the geopolymer specimens. After 24 hours, the specimens were removed out of the molds and continuously cured at room condition for 27 days. The geopolymer-based materials were then tested for engineering properties such as compressive strength (MPa), volumetric weight (kg/m3), and water absorption (kg/m3). Results indicated that the material can be considered lightweight with volumetric weight from 1192 to 1425 kg/m3; compressive strength at 28 days is in the range of 12.38 to 37.41 MPa; and water absorption is under 189.92 kg/m3.

An Experimental Study in the Mechanical Response of Polymer Modified Geopolymers

DTIC Science & Technology

2012-04-01

Compressive and Bending Strength of Fly ash Geopolymers ... 22 LIST OF TABLES Page Table 1. Chemical Composition of Aluminosilicates in Mass... geopolymer matrix composites .” Ceramic Transactions, 153, 227-250. 3. Davidovits J., 1991. “ Geopolymers , inorganic polymeric materials.” Journal of...Understanding the relationship between geopolymer composition , microstructure and mechanical properties.” Colloids and Surfaces.A, Physicochemical

Parametric study on the compressive strength geopolymer paving block

NASA Astrophysics Data System (ADS)

Aman; Awaluddin, A.; Ahmad, A.; Olivia, M.

2018-04-01

This paper reported about the investigated of sodium hidroxida concentration, effect of ratio liquid to solid (L/S), temperature and time on the compressive strength of geopolymer paving block using fly ash and fine aggregate as base material and combination of sodium hidroxida and sodium silicate as alkaline activator and the ratio of Na2SiO3/NaOH was 2 and fly ash to aggregate of 1: 3. The experiments were conducted with variation of the sodium hidroxida concentration of (10-16 M) liquid to solid (L/S) 0.1- 0.7 ratio, curing temperature 30-100 °C and curing time (7-28 day). The main evaluation techniques in this experimental were Compressive strength, X-ray diffraction (XRD),and Scaning Electron Microscope (SEM). The result showed that the compressive strength of Geopolymer Paving block has increased with an increasing of concentration, liquid to solid ratio, curing temperature and curing time.

High calcium fly ash geopolymer stabilized lateritic soil and granulated blast furnace slag blends as a pavement base material.

PubMed

Phummiphan, Itthikorn; Horpibulsuk, Suksun; Rachan, Runglawan; Arulrajah, Arul; Shen, Shui-Long; Chindaprasirt, Prinya

2018-01-05

Granulated Blast Furnace Slag (GBFS) was used as a replacement material in marginal lateritic soil (LS) while class C Fly Ash (FA) was used as a precursor for the geopolymerization process to develop a low-carbon pavement base material at ambient temperature. Unconfined Compression Strength (UCS) tests were performed to investigate the strength development of geopolymer stabilized LS/GBFS blends. Scanning Electron Microscopy and X-ray Diffraction analysis were undertaken to examine the role of the various influencing factors on UCS development. The influencing factors studied included GBFS content, Na 2 SiO 3 :NaOH ratio (NS:NH) and curing time. The 7-day soaked UCS of FA geopolymer stabilized LS/GBFS blends at various NS:NH ratios tested was found to satisfy the specifications of the Thailand national road authorities. The GBFS replacement was found to be insignificant for the improvement of the UCS of FA geopolymer stabilized LS/GBFS blends at low NS:NH ratio of 50:50. Microstructural analysis indicated the coexistence of Calcium Silicate Hydrate (CSH) and Sodium Alumino Silicate Hydrate products in FA geopolymer stabilized LS/GBFS blends. This research enables GBFS, which is traditionally considered as a waste material, to be used as a replacement and partially reactive material in FA geopolymer pavement applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of Coconut Trunk Fiber Geopolymer Hybrid Composite for Structural Engineering Materials

NASA Astrophysics Data System (ADS)

Amalia, F.; Akifah, N.; Nurfadilla; Subaer

2017-03-01

A research on the influence of coconut fiber trunk on mechanical properties based on fly ash has been conducted. The aims of this study was to examine the mechanical properties of geopolymer composites by varrying the concentration of coconut trunk fiber. Geopolymer synthesized by alkali activated (NaOH+H2O+Na2O.3SiO2) and cured at the temperature 700C for one hour. Specimens were synthesized into 5 different mass of fiber 0 g, 0.25 g, 0.50 g, 0.75 g, and 1.00 g keeping fly ash constant. The highest compressive strength was 89.44 MPa for specimen added with 0.50 g of fiber. The highest flexural strength was 7.64 MPa for the same sample. The interfacial transition zone (ITZ) between the matrix of geopolymers and coconut fiber was conducted by using Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS). The chemical composition of the specimen was examined by using X-Ray Diffraction (XRD). The thermal properties of coconut fiber trunk was analyzed using Differential Scanning Calorimetry (DSC). It was found that coconut fiber was able to improve the mechanical and microstructure properties of geopolymers composites.

In Situ Elevated Temperature Testing of Fly Ash Based Geopolymer Composites.

PubMed

Vickers, Les; Pan, Zhu; Tao, Zhong; van Riessen, Arie

2016-06-03

In situ elevated temperature investigations using fly ash based geopolymers filled with alumina aggregate were undertaken. Compressive strength and short term creep tests were carried out to determine the onset temperature of viscous flow. Fire testing using the standard cellulose curve was performed. Applying a load to the specimen as the temperature increased reduced the temperature at which viscous flow occurred (compared to test methods with no applied stress). Compressive strength increased at the elevated temperature and is attributed to viscous flow and sintering forming a more compact microstructure. The addition of alumina aggregate and reduction of water content reduced the thermal conductivity. This led to the earlier onset and shorter dehydration plateau duration times. However, crack formation was reduced and is attributed to smaller thermal gradients across the fire test specimen.

Characterization of geopolymer fly-ash based foams obtained with the addition of Al powder or H{sub 2}O{sub 2} as foaming agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ducman, V., E-mail: vilma.ducman@zag.si; Korat, L.

Recent innovations in geopolymer technology have led to the development of various different types of geopolymeric products, including highly porous geopolymer-based foams, which are formed by the addition of foaming agents to a geopolymer fly-ash based matrix. These agents decompose, or react with the liquid matrix or oxygen in the matrix, resulting in the release of gases which form pores prior to the hardening of the gel. The hardened structure has good mechanical and thermal properties, and can therefore be used for applications in acoustic panels and in lightweight pre-fabricated components for thermal insulation purposes. This study presents the resultsmore » of the pore-forming process in the case when two different foaming agents, i.e. aluminium powder amounting to 0.07, 0.13 and 0.20 mass. % and H{sub 2}O{sub 2} amounting to 0.5, 1.0, 1.5 and 2.0 mass. %, were added to a fly-ash geopolymer matrix. The physical, mechanical, and microstructural properties of the thus obtained foams, and the effects of the type and amount of the added foaming agent, are presented and discussed. Highly porous structures were obtained in the case of both of the investigated foaming agents, with overall porosities up to 59% when aluminium powder was added, and of up 48% when H{sub 2}O{sub 2} was added. In the latter case, when 2% of the H{sub 2}O{sub 2} foaming agent was added, finer pores (with diameters up to 500 μm) occurred in the structure, whereas somewhat larger pores (some had diameters greater than 1 mm) occurred when the same amount of aluminium powder was added. The mechanical properties of the investigated foams depended on their porosity. In the case of highly porous structures a compressive strength of 3.3 MPa was nevertheless achieved for the samples containing 0.2% of aluminium powder, and 3.7 MPa for those containing 2.0% of H{sub 2}O{sub 2}. - Highlights: • Preparation of geopolymer foams based on fly ash with the addition of Al powder or H{sub 2}O{sub 2} as foaming agents • Determination of density, porosity and mechanical properties of such foams • Characterization of foaming process by means of X-ray micro-tomography (μcT)« less

Self-degradable Slag/Class F Fly Ash-Blend Cements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugama, T.; Warren, J.; Butcher, T.

2011-03-01

Self-degradable slag/Class F fly ash blend pozzolana cements were formulated, assuming that they might serve well as alternative temporary fracture sealers in Enhanced Geothermal System (EGS) wells operating at temperatures of {ge} 200 C. Two candidate formulas were screened based upon material criteria including an initial setting time {ge} 60 min at 85 C, compressive strength {ge} 2000 psi for a 200 C autoclaved specimen, and the extent of self-degradation of cement heated at {ge} 200 C for it was contacted with water. The first screened dry mix formula consisted of 76.5 wt% slag-19.0 wt% Class F fly ash-3.8 wt%more » sodium silicate as alkali activator, and 0.7 wt% carboxymethyl cellulose (CMC) as the self-degradation promoting additive, and second formula comprised of 57.3 wt% slag, 38.2 wt% Class F fly ash, 3.8 wt% sodium silicate, and 0.7 wt% CMC. After mixing with water and autoclaving it at 200 C, the aluminum-substituted 1.1 nm tobermorite crystal phase was identified as hydrothermal reaction product responsible for the development of a compressive strength of 5983 psi. The 200 C-autoclaved cement made with the latter formula had the combined phases of tobermorite as its major reaction product and amorphous geopolymer as its minor one providing a compressive strength of 5271 psi. Sodium hydroxide derived from the hydrolysis of sodium silicate activator not only initiated the pozzolanic reaction of slag and fly ash, but also played an important role in generating in-situ exothermic heat that significantly contributed to promoting self-degradation of cementitious sealers. The source of this exothermic heat was the interactions between sodium hydroxide, and gaseous CO{sub 2} and CH{sub 3}COOH by-products generated from thermal decomposition of CMC at {ge} 200 C in an aqueous medium. Thus, the magnitude of this self-degradation depended on the exothermic temperature evolved in the sealer; a higher temperature led to a sever disintegration of sealer. The exothermic temperature was controlled by the extent of thermal decomposition of CMC, demonstrating that CMC decomposed at higher temperature emitted more gaseous reactants. Hence, such large emission enhanced the evolution of in-situ exothermic heat. In contrast, the excessive formation of geopolymer phase due to more incorporation of Class F fly ash into this cementitious system affected its ability to self-degrade, reflecting that there was no self-degradation. The geopolymer was formed by hydrothermal reactions between sodium hydroxide from sodium silicate and mullite in Class F fly ash. Thus, the major reason why geopolymer-based cementitiuos sealers did not degrade after heated sealers came in contact with water was their lack of free sodium hydroxide.« less

Inclusion of geopolymers derivate from fly ash and pumice in reinforced concrete

NASA Astrophysics Data System (ADS)

Montaño, A. M.; González, C. P.; Castro, D.; Gualdron, G.; Atencio, R.

2017-12-01

This paper presents results of a research project related to the development of alkali-activated geopolymers, synthesized from alumina-silicate minerals (fly ash and pumice) which are added to concrete. Alkali sources used in geopolymer synthesis were sodium hydroxide and sodium silicate solution. New materials were structurally characterized by Infra-Red spectroscopy (IR) and X-Ray Diffraction (XRD). Concretes obtained after geopolymers addition as Portland cement substitutes at 10%, 20% and 30%, were mechanically analysed by compression resistance at 7, 14, 28 and 90 drying days. Results were referred to standard (concrete of Portland cement) allows to know cementitious characteristics of geopolymers are lower than those for standard, but it keeps growing at longer drying time than Portland cement. By Electrochemical Impedance Spectroscopy (EIS) it is found that this new material shows high electrical resistance and have been proved as a protection agent against corrosion in reinforced concrete exhibiting anticorrosive properties higher than those showed by the conventional concrete mixture.

Mechanical properties and microstructure analysis of fly ash geopolymeric recycled concrete.

PubMed

Shi, X S; Collins, F G; Zhao, X L; Wang, Q Y

2012-10-30

Six mixtures with different recycled aggregate (RA) replacement ratios of 0%, 50% and 100% were designed to manufacture recycled aggregate concrete (RAC) and alkali-activated fly ash geopolymeric recycled concrete (GRC). The physical and mechanical properties were investigated indicating different performances from each other. Optical microscopy under transmitted light and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) were carried out in this study in order to identify the mechanism underlying the effects of the geopolymer and RA on concrete properties. The features of aggregates, paste and interfacial transition zone (ITZ) were compared and discussed. Experimental results indicate that using alkali-activated fly ash geopolymer as replacement of ordinary Portland cement (OPC) effectively improved the compressive strength. With increasing of RA contents in both RAC and GRC, the compressive strength decreased gradually. The microstructure analysis shows that, on one hand, the presence of RA weakens the strength of the aggregates and the structure of ITZs; on the other hand, due to the alkali-activated fly ash in geopolymer concrete, the contents of Portlandite (Ca(OH)(2)) and voids were reduced, as well as improved the matrix homogeneity. The microstructure of GRC was changed by different reaction products, such as aluminosilicate gel. Copyright © 2012 Elsevier B.V. All rights reserved.

In Situ Elevated Temperature Testing of Fly Ash Based Geopolymer Composites

PubMed Central

Vickers, Les; Pan, Zhu; Tao, Zhong; van Riessen, Arie

2016-01-01

In situ elevated temperature investigations using fly ash based geopolymers filled with alumina aggregate were undertaken. Compressive strength and short term creep tests were carried out to determine the onset temperature of viscous flow. Fire testing using the standard cellulose curve was performed. Applying a load to the specimen as the temperature increased reduced the temperature at which viscous flow occurred (compared to test methods with no applied stress). Compressive strength increased at the elevated temperature and is attributed to viscous flow and sintering forming a more compact microstructure. The addition of alumina aggregate and reduction of water content reduced the thermal conductivity. This led to the earlier onset and shorter dehydration plateau duration times. However, crack formation was reduced and is attributed to smaller thermal gradients across the fire test specimen. PMID:28773568

Low-reactive circulating fluidized bed combustion (CFBC) fly ashes as source material for geopolymer synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu Hui; Li Qin; Shen Lifeng

2010-01-15

In this contribution, low-reactive circulating fluidized bed combustion (CFBC) fly ashes (CFAs) have firstly been utilized as a source material for geopolymer synthesis. An alkali fusion process was employed to promote the dissolution of Si and Al species from the CFAs, and thus to enhance the reactivity of the ashes. A high-reactive metakaolin (MK) was also used to consume the excess alkali needed for the fusion. Reactivities of the CFAs and MK were examined by a series of dissolution tests in sodium hydroxide solutions. Geopolymer samples were prepared by alkali activation of the source materials using a sodium silicate solutionmore » as the activator. The synthesized products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffractography (XRD), as well as Fourier transform infrared spectroscopy (FTIR). The results of this study indicate that, via enhancing the reactivity by alkali fusion and balancing the Na/Al ratio by additional aluminosilicate source, low-reactive CFAs could also be recycled as an alternative source material for geopolymer production.« less

Geopolymer concretes: a green construction technology rising from the ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allouche, E.

2009-07-01

Researchers at Louisiana Tech University have embarked on a multi-year research initiative to develop applications for inorganic polymer concrete, or geopolymer concrete, in the area of civil construction, and to bring solve of these applications to market. One objective was to produce a spray-on coating for use in the harsh environment of wastewater conveyance and treatment facilities. Another project is to establish relationships between fly ash composition and particle size distribution and the mechanical attributes and workability of the resulting geopolymer concrete. A third project is to develop a 'smart' geopolymer concrete whose response to a given electric current canmore » be correlated to the stress level to which the structure is subjected. 1 fig., 6 photos.« less

Mechanical and chemical properties of composite materials made of dredged sediments in a fly-ash based geopolymer.

PubMed

Lirer, S; Liguori, B; Capasso, I; Flora, A; Caputo, D

2017-04-15

Dredging activity in harbours and channels produces huge quantities of sediments, generally considered as waste soil (WS) to be disposed: the management of such sediments is a great environmental problem for many countries worldwide. Among the recycling possibilities, the use of dredged sediments for the manufacture of geopolymer-based materials seems to be an interesting alternative to disposal, due to their low cost and easy availability. In order to analyse the possibility to use these geopolymer materials as building materials - for instance as precast construction elements in maritime projects - a multi-disciplinary research activity has been developed at the Federico II University of Napoli (Italy). Some experimental tests have been carried out on different geopolymeric specimens made by mixing sediments from Napoli 'harbour and industrial fly ashes produced by a power plant in the South of Italy. A siliceous sand was used for comparison as an inert reference material. Chemical, morphological and mechanical properties of different specimens have been studied by X-ray diffraction, Scanning Electron Microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR) and finally unconfined compression tests. The experimental results highlight that the use of dredged sediments in combination with fly ash can lead to geopolymeric matrices with interesting mechanical performances. Some differences in the microstructure of the geocomposite built with the siliceous sand or the dredged materials were found. In terms of environmental impacts, on the basis of standard leaching tests and according to Italian thresholds, the adopted dredged mixtures satisfy the prescribed limit for inert or non hazardous waste. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantification of geopolymers production by chemical methods- A short review

NASA Astrophysics Data System (ADS)

Siyal, Ahmer Ali; Azizli, Khairun Azizi; Ismail, Lukman; Man, Zakaria; Khan, Muhammad Irfan

2015-07-01

Inorganic polymers are the aluminosilicate materials possessing properties superior than ordinary Portland cement. In this review paper the chemical techniques used for determining degree of reaction of fly ash or the quantity of geopolymer material produced have been discussed. These methods determine the amount of product formed in percentages. The methods include HCl method, salicylic acid method, and picric acid method. These methods are not only used for fly ash but they are being used for determining the degree of reactions of metakaolin and other pozzolanic materials. The picric acid is an explosive material and its transportation in high concentration is dangerous. During its use in laboratory there is also the risk of fire associated with it. According to the microscopic analysis results the picric acid attack dissolves small amount of fine unreacted fly ash particles also. The salicylic acid is easily available but the residue from its treatment contains unreacted fly ash particles, hydration phases, and certain parts of unreacted OPC. The residue from HCl and salicylic acid attack contains MgO particles which is the part of the hydration product. The HCl method is mostly used due to simple process and lower standard deviation.

Low-CO2 Acid-Base Binders Made with Fly Ash

NASA Astrophysics Data System (ADS)

Erdogan, S. T.

2016-12-01

Portland cement (PC) is the ubiquitous binding material for constructions works in urban areas. It is, however, responsible for 5-10 % of all anthropogenic CO2 emissions, nearly half of which arise from the decomposition of calcareous raw materials, and the other half from kiln fuel combustion and cement clinker grinding operations. As such, PC production contributes to global warming and climate change. Lately, efforts to develop alternative binders with lower greenhouse gas emissions have gained interest. An important class of such binders is geopolymers, typically formed by activating natural or waste materials with suitable alkaline solutions. These binders can have very low CO2 emissions from grinding of the starting materials, and some from the production of the activating chemical but the total CO2 emissions can be as low as 1/5th - 1/10th of those of PC concrete mixtures with comparable properties. Less commonly researched, acidic activating chemicals can also be used with powder materials to produce pastes that can set and harden into durable solids. One such powder is fly ash from coal-burning power plants. This ash is mostly stockpiled and can be an environmental hazard such as exacerbating air pollution in cities. This study investigates the chemical activation of fly ashes from Turkey using solutions of acids such as orthophosphoric acid. Amorphous and crystalline reaction products are observed to form, yielding a strong binder that sets much more rapidly than PC-based mixtures or alkali-activated geopolymers. As the change in the rheological properties and mechanical properties of these pastes can be balanced by combining different ashes, as well as by adjusting solution properties, they can offer environmental, energetic, and economical advantages over conventional PC-based mixtures.

Mechanical properties on geopolymer brick: A review

NASA Astrophysics Data System (ADS)

Deraman, L. M.; Abdullah, M. M. A.; Ming, L. Y.; Ibrahim, W. M. W.; Tahir, M. F. M.

2017-09-01

Bricks has stand for many years as durable construction substantial, especially in the area of civil engineering to construct buildings. Brick commonly used in the structure of buildings as a construction wall, cladding, facing perimeter, paving, garden wall and flooring. The contribution of ordinary Portland cement (OPC) in cement bricks production worldwide to greenhouse gas emissions. Due to this issue, some researchers have done their study with other materials to produce bricks, especially as a by-product material. Researchers take effort in this regard to synthesizing from by-product materials such as fly ash, bottom ash and kaolin that are rich in silicon and aluminium in the development of inorganic alumina-silicate polymer, called geopolymer Geopolymer is a polymerization reaction between various aluminosilicate oxides with silicates solution or alkali hydroxide solution forming polymerized Si-O-Al-O bonds. This paper summarized some research finding of mechanical properties of geopolymer brick using by-product materials.

Recycled asphalt pavement - fly ash geopolymer as a sustainable stabilized pavement material

NASA Astrophysics Data System (ADS)

Horpibulsuk, S.; Hoy, M.; Witchayaphong, P.; Rachan, R.; Arulrajah, A.

2017-11-01

Strength, durability, microstructure and leachate characteristics of Recycled Asphalt Pavement and Fly Ash (RAP-FA) geopolymers and RAP-FA blends as a sustainable pavement material are evaluated in this paper. The strength development of the stabilized materials with and without effect wetting-drying (w-d) cycles was determined by Unconfined Compression Strength (UCS) test. The mineralogical and microstructural changes of the stabilized material were analyzed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The leachability of the heavy metals were measured by Toxicity Characteristic Leaching Procedure (TCLP) and compared with international standard. The results show that both RAP-FA blend and RAP-FA geopolymer increase with increasing the number of w-d cycles (C), reaching its peak at 6 w-d cycles. The XRD and SEM analyses indicate that the strength development of RAP-FA blend occurs due to stimulation of the chemical reaction between the high amount to Calcium in RAP and the high amount of Silica and Alumina in FA leaching to production of Calcium Aluminium (Silicate) Hydrate, while the geopolymerization reaction is observed in RAP-FA geopolymer. For C> 6, the significant macro- and micro-cracks developed during w-d cycles cause strength reduction for both RAP-FA blend and geopolymer. The TCLP results demonstrate that there is no environmental risk for these stabilized materials. Furthermore, FA-geopolymer can reduce the leachability of heavy metal in RAP-FA blend. The outcome from this research confirms the viability of using RAP-FA blend and RAP-FA geopolymer as alternative sustainable pavement materials.

Durability of Geopolymer Lightweight Concrete Infilled LECA in Seawater Exposure

NASA Astrophysics Data System (ADS)

Razak, R. A.; Abdullah, M. M. A. B.; Yahya, Z.; Hamid, M. S. A.

2017-11-01

This paper describes a development of lightweight concrete using lightweight expanded clay aggregate (LECA) in fly ash (FA) based geopolymer immersed in seawater. The objective of this research is to compare the performance of geopolymer concrete (GPC) with ordinary Portland cement (OPC) concrete infilled lightweight expanded clay aggregate (LECA) in seawater exposure. Geopolymer concrete is produced by using alkaline activator to activate the raw material, FA. The highest compressive strength of this study is 42.0 MPa at 28 days and 49.8 MPa at 60 days. The density for this concrete is in the range of 1580 kg/m3 to 1660 kg/m3. The result for water absorption is in the range of 6.82% to 14.72%. However, the test results of weight loss is in the range between 0.30% to 0.43%.

Alkaline Activator Impact on the Geopolymer Binders

NASA Astrophysics Data System (ADS)

Błaszczyński, Tomasz Z.; Król, Maciej R.

2017-10-01

Concrete structures are constantly moving in the direction of improving the durability. Durability depends on many factors, which are the composition of concrete mix, the usage of additives and admixtures and the place, where material will work and carry the load. The introduction of new geopolymer binders for geopolymer structures adds a new aspect that is type of used activator. This substance with strongly alkaline reaction is divided because of the physical state, the alkaline degree and above all the chemical composition. Taking into account, that at present the geopolymer binders are made essentially from waste materials or by-products from the combustion of coal or iron ore smelting, unambiguous determination of the effect of the activator on the properties of the geopolymer material requires a number of trials, researches and observation. This paper shows the influence of the most alkaline activators on the basic parameters of the durability of geopolymer binders. In this study there were used highly alkaline hydroxides, water glasses and granules, which are waste materials in a variety of processes taking place in chemical plants. As the substrate of geopolymer binders there were used fly ash which came from coal and high calcareous ash from the burning of lignite.

DuraLith geopolymer waste form for Hanford secondary waste: correlating setting behavior to hydration heat evolution.

PubMed

Xu, Hui; Gong, Weiliang; Syltebo, Larry; Lutze, Werner; Pegg, Ian L

2014-08-15

The binary furnace slag-metakaolin DuraLith geopolymer waste form, which has been considered as one of the candidate waste forms for immobilization of certain Hanford secondary wastes (HSW) from the vitrification of nuclear wastes at the Hanford Site, Washington, was extended to a ternary fly ash-furnace slag-metakaolin system to improve workability, reduce hydration heat, and evaluate high HSW waste loading. A concentrated HSW simulant, consisting of more than 20 chemicals with a sodium concentration of 5 mol/L, was employed to prepare the alkaline activating solution. Fly ash was incorporated at up to 60 wt% into the binder materials, whereas metakaolin was kept constant at 26 wt%. The fresh waste form pastes were subjected to isothermal calorimetry and setting time measurement, and the cured samples were further characterized by compressive strength and TCLP leach tests. This study has firstly established quantitative linear relationships between both initial and final setting times and hydration heat, which were never discovered in scientific literature for any cementitious waste form or geopolymeric material. The successful establishment of the correlations between setting times and hydration heat may make it possible to efficiently design and optimize cementitious waste forms and industrial wastes based geopolymers using limited testing results. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and characterization of palm oil fuel ash (POFA) and metakaolin based geopolymer for possible application in nanocoating

NASA Astrophysics Data System (ADS)

Khan, Ihsan Ullah; Bhat, A. H.; Masset, Patrick J.; Khan, Farman Ullah; Rehman, Wajid Ur

2016-11-01

The main aim of this study was to synthesize and characterize highly amorphous geopolymer from palm oil fuel ash (POFA) and metakaolin, to be used as nanocoating. Geopolymers are man-made aluminosilicate materials that are amorphous analogues of zeolites. The geopolymers were made by condensing a mixture of raw materials metakaolin and palm oil fuel ash (POFA) with alkaline activator at a fixed ratio at room temperature. The kaolin type clay was calcined at 700 °C for 4hrs to transform it into amorphous metakaolin which is more reactive precursor for geopolymer formation. The characteristics of metakaolin and geopolymers (metakaolin and palm oil fuel ash based geopolymers) were analyzed by using x-ray fluorescence (XRF), Fourier transform infra-red spectrometry (FTIR), Thermogravimetric analysis (TG/DTA) and scanning electron microscopy with energy dispersive x-ray analysis (SEM-EDX). FTIR revealed the presence of Al-O and Si-O stretching vibrations of amorphous alumino-silicate structure for metakaolin, palm oil fuel ash and geopolymers. SEM-EDX images showed the presence of reaction product complementary to NASH (N = Na2O, A = Al2O3, S = SiO2, H = H2O) solid. The resulting geopolymers that were synthesized with NaOH/Na2SiO3 solution cured at 60 °C for 3 days. The results demonstrated the suitability of metakaolin and palm oil fuel ash (POFA) for synthesis of geopolymer at room temperatures.

Strength and Density of Geopolymer Mortar Cured at Ambient Temperature for Use as Repair Material

NASA Astrophysics Data System (ADS)

Warid Wazien, A. Z.; Bakri Abdullah, Mohd Mustafa Al; Abd. Razak, Rafiza; Mohd Remy Rozainy, M. A. Z.; Faheem Mohd Tahir, Muhammad

2016-06-01

Geopolymers produced by synthesizing aluminosilicate source materials with an alkaline activator solution promised an excellent properties akin to the existing construction material. This study focused on the effect of various binder to sand ratio on geopolymer mortar properties. Mix design of geopolymer mortar was produced using NaOH concentration of 12 molars, ratio of fly ash/alkaline activator and ratio Na2SiO3/NaOH of 2.0 and 2.5 respectively. Samples subsequently ware cured at ambient temperature. The properties of geopolymer mortar were analysed in term of compressive strength and density at different period which are on the 3rd and 7th day of curing. Experimental results revealed that the addition of sand slightly increase the compressive strength of geopolymer. The optimum compressive strength obtained was up to 31.39 MPa on the 7th day. The density of geopolymer mortar was in the range between 2.0 g/cm3 to 2.23 g/cm3. Based on this findings, the special properties promoted by geopolymer mortar display high potential to be implemented in the field of concrete patch repair.

Ambient Cured Alkali Activated Flyash Masonry Units

NASA Astrophysics Data System (ADS)

Venugopal, K.; Radhakrishna; Sasalatti, Vinod M.

2016-09-01

Geopolymers belong to a category of non-conventional and non-Portland cement based cementitious binders which are produced using industrial by products like fly ash and ground granulated blast furnace slag (GGBFS). This paper reports on the development of geopolymer mortars for production of masonry units. The geopolymer mortars were prepared by mixing various by products with manufactured sand and a liquid mixture of sodium silicate and sodium hydroxide solutions. After curing at ambient conditions, the masonry units were tested for strength properties such as water absorption, initial rate of absorption, compression, shear- bond, and stress-strain behaviour etc. It was observed that the flexural strength of the blocks is more than 2 MPa and shear bond strength is more than 0.4MPa. It was found that the properties of geopolymer blocks were superior to the traditional masonry units. Hence they can be recommended for structural masonry.

Material and structural characterization of alkali activated low-calcium brown coal fly ash.

PubMed

Skvára, Frantisek; Kopecký, Lubomír; Smilauer, Vít; Bittnar, Zdenek

2009-09-15

The waste low-calcium Czech brown coal fly ash represents a considerable environmental burden due to the quantities produced and the potentially high content of leachable heavy metals. The heterogeneous microstucture of the geopolymer M(n) [-(Si-O)(z)-Al-O](n).wH(2)O, that forms during the alkaline activation, was examined by means of microcalorimetry, XRD, TGA, DSC, MIP, FTIR, NMR MAS ((29)Si, (27)Al, (23)Na), ESEM, EDS, and EBSD. The leaching of heavy metals and the evolution of compressive strength were also monitored. The analysis of raw fly ash identified a number of different morphologies, unequal distribution of elements, Fe-rich rim, high internal porosity, and minor crystalline phases of mullite and quartz. Microcalorimetry revealed exothermic reactions with dependence on the activator alkalinity. The activation energy of the geopolymerization process was determined as 86.2kJ/mol. The X-ray diffraction analysis revealed no additional crystalline phases associated with geopolymer formation. Over several weeks, the (29)Si NMR spectrum testified a high degree of polymerization and Al penetration into the SiO(4) tetrahedra. The (23)Na NMR MAS spectrum hypothesized that sodium is bound in the form of Na(H(2)O)(n) rather than Na(+), thus causing efflorescence in a moisture-gradient environment. As and Cr(6+) are weakly bonded in the geopolymer matrix, while excellent immobilization of Zn(2+), Cu(2+), Cd(2+), and Cr(3+) are reported.

Durability of cement and geopolimer composites

NASA Astrophysics Data System (ADS)

Błaszczyński, T.; Król, M.

2017-10-01

Concrete structures are constantly moving in the direction of improving the durability. This main feature depends on many factors, which are the composition of concrete mix, the usage of additives and admixtures and the place, where material will work and carry the load. The introduction of new geopolymer binders for geopolymer structures adds a new aspect that is type of used activator. This substance with strongly alkaline reaction is divided because of the physical state, the alkaline degree and above all the chemical composition. Taking into account, that at present the geopolymer binders are made essentially from waste materials or by products from the combustion of coal or iron ore smelting, unambiguous determination of the effect of the activator on the properties of the geopolymer material requires a number of trials, researches and observation. This paper shows the influence of the most alkaline activators on the basic parameters of the durability of geopolymer binders. In this study there were used a highly alkaline hydroxides, water glasses and granules, which are waste materials in a variety of processes taking place in a chemical plants. As the substrate of geopolymer binders there were used fly ash which came from coal and high calcium ash from the burning of lignite.

Development of Paper Sludge Ash-Based Geopolymer and Application to Treatment of Hazardous Water Contaminated with Radioisotopes

PubMed Central

Li, Zhuguo; Ohnuki, Toshihiko; Ikeda, Ko

2016-01-01

Ambient temperature geopolymerization of paper sludge ashes (PS-ashes) discharged from paper mills was studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), induction coupled plasma atomic emission spectrometry (ICP-AES), and X-ray absorption near edge structure (XANES). Two varieties of alkaline liquors were used in the PS-ash based geopolymers, corresponding to aqueous Na-metasilicate and Na-disilicate compositions. PS-ashes were found to be semi-crystalline and to have porous structures that make it possible to absorb much liquor. Flexural strengths of PS-ash-based geopolymers with liquor/filler ratios (L/F) of 1.0–1.5 ranged from 0.82 to 1.51 MPa at 4 weeks age, depending on PS-ashes and liquors used. The reaction process of the constituent minerals of the PS-ash is discussed. Furthermore, we attempted to solidify hazardous water contaminated with radioisotopes. Non-radioactive strontium and cesium nitrates were added as surrogates at a dosage of 1% into the PS-ash-based geopolymers. Generally, high immobilization ratios up to 99.89% and 98.77% were achieved for Sr2+ and Cs+, respectively, depending on the source of PS-ashes, alkaline liquors, and material ages. However, in some cases, poor immobilization ratios were encountered, and we further discussed the causes of the instability of derived geopolymer gels on the basis of XANES spectra. PMID:28773754

Recycled asphalt pavement - fly ash geopolymers as a sustainable pavement base material: Strength and toxic leaching investigations.

PubMed

Hoy, Menglim; Horpibulsuk, Suksun; Rachan, Runglawan; Chinkulkijniwat, Avirut; Arulrajah, Arul

2016-12-15

In this research, a low-carbon stabilization method was studied using Recycled Asphalt Pavement (RAP) and Fly Ash (FA) geopolymers as a sustainable pavement material. The liquid alkaline activator (L) is a mixture of sodium silicate (Na 2 SiO 3 ) and sodium hydroxide (NaOH), and high calcium FA is used as a precursor to synthesize the FA-RAP geopolymers. Unconfined Compressive Strength (UCS) of RAP-FA blend and RAP-FA geopolymer are investigated and compared with the requirement of the national road authorities of Thailand. The leachability of the heavy metals is measured by Toxicity Characteristic Leaching Procedure (TCLP) and compared with international standards. The Scanning Electron Microscopy (SEM) analysis of RAP-FA blend indicates the Calcium Aluminate (Silicate) Hydrate (C-A-S-H) formation, which is due to a reaction between the high calcium in RAP and high silica and alumina in FA. The low geopolymerization products (N-A-S-H) of RAP-FA geopolymer at NaOH/Na 2 SiO 3 =100:0 are detected at the early 7days of curing, hence its UCS is lower than that of RAP-FA blend. The 28-day UCS of RAP-FA geopolymers at various NaOH/Na 2 SiO 3 ratios are significantly higher than that of the RAP-FA blend, which can be attributed to the development of geopolymerization reactions. With the input of Na 2 SiO 3 , the highly soluble silica from Na 2 SiO 3 reacted with leached silica and alumina from FA and RAP and with free calcium from FA and RAP; hence the coexistence of N-A-S-H gel and C-A-S-H products. Therefore, the 7-day UCS values of RAP-FA geopolymers increase with decreasing NaOH/Na 2 SiO 3 ratio. TCLP results demonstrated that there is no environmental risk for both RAP-FA blends and RAP-FA geopolymers in road construction. The geopolymer binder reduces the leaching of heavy metal in RAP-FA mixture. The outcomes from this research will promote the move toward increased applications of recycled materials in a sustainable manner in road construction. Copyright © 2016 Elsevier B.V. All rights reserved.

Immobilization of Chromium from Liquid Waste of Electroplating Home-Industries by Fly Ash Geopolymerization

NASA Astrophysics Data System (ADS)

Fansuri, H.; Erviana, E.; Rosyidah, M.; Iqbal, R. M.; Utomo, W. P.; Nurlina

2018-05-01

Immobilization is one of methods that can be used to overcome the problem of water pollution by heavy metals, such as chromium, which is possibly produced in an electroplating home-industry. One method that can be used to immobilize heavy metals is by using the waste water as a reactant in a geopolymerization process. The resulting geopolymer will contain such heavy metals and keep them from being dispersed into the environment. In this research, the immobilization was carried out by geopolymerization of fly ash from PT. IPMOMI (International Power Mitsui Operation and Maintenance) in Probolinggo, Indonesia, which pass through 60 (FA 60), 100 (FA 100), and 200 (FA 200) mesh sieve and using wastewater from electroplating home-industries in Ngingas Village, Sidoarjo-Indonesia, or a solution of Cr(NO3)3.9H2O as one of its reactants. The composition of the geopolymerization follows the results of previous research, i.e using the ratio of Solid to Liquid (S/L) = 3.59, Na2O/SiO2 = 0.67, H2O/Na2O = 3.33 and SiO2/Al2O3 = 6.46. Experimental results show that the compressive strength of geopolymers without heavy metals addition increases when the particle size decreases. Geopolymer made of FA 100 has the highest compressive strength i.e 35.05 MPa. The addition of a chromium-containing wastewater in FA 100 geopolymerization produce a geopolymer with a lower compressive strength i.e 26.42 MPa while the addition of Cr(NO3)3·9H2O solution produce geopolymer with compressive strength of 24.47 MPa. The SEM-EDX photo shows that chrome was evenly dispersed in the geopolymer. Leaching test with TCLP method (Toxicity Characteristic Leaching Procedure) on the geopolymer product showed that no chrome content in the leachate was found. This suggests that chromium is immobilized by geopolymers very well.

Microstructural and strength improvements through the use of Na{sub 2}CO{sub 3} in a cementless Ca(OH){sub 2}-activated Class F fly ash system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeon, Dongho; Jun, Yubin; Jeong, Yeonung

2015-01-15

This study explores the beneficial effects of Na{sub 2}CO{sub 3} as an additive for microstructural and strength improvements in a Ca(OH){sub 2}-activated fly ash system. NaOH-activated fly ash samples were also tested to compare the effect of Na{sub 2}CO{sub 3}. Compressive strength testing, XRD, SEM/BSE/EDS, {sup 29}Si/{sup 27}Al MAS-NMR, MIP and TGA were performed. The testing results indicate that the use of Na{sub 2}CO{sub 3} for Ca(OH){sub 2}-activation led to a noticeable improvement in strength and microstructure, primarily due to (1) more dissolution of raw fly ash at an early age, (2) more formation of C–S–H [or C–S–H(I)], (3) porositymore » reduction, and (4) pore-size refinement. We also found that (1) an early high alkalinity from the NaOH formation was not a major cause of strength, (2) geopolymer was not formed despite the early NaOH formation, and (3) no visible pore-filling action of CaCO{sub 3} was observed. However, Na{sub 2}CO{sub 3} did not produce any improvement in strength for NaOH-activated fly ash. -- Highlights: •The use of Na{sub 2}CO{sub 3} significantly improved strength and microstructure. •The use of Na{sub 2}CO{sub 3} induced more dissolution of raw fly ash at early ages. •The use of Na{sub 2}CO{sub 3} promoted more C–S–H [or C–S–H(I)] formation. •The use of Na{sub 2}CO{sub 3} reduced total porosity and refined pore-size distribution. •The use of Na{sub 2}CO{sub 3} produced neither geopolymer formations nor pore-filling actions from CaCO{sub 3}.« less

Mix design and mechanical performance of geopolymer binder for sustainable construction and building material

NASA Astrophysics Data System (ADS)

Saeli, Manfredi; Novais, Rui M.; Seabra, Maria Paula; Labrincha, João A.

2017-11-01

Sustainability in construction is a major concern worldwide, due to the huge volume of materials and energy consumed by this sector. Associated supplementing industries (e.g. Portland cement production) constitute a significant source of CO2 emissions and global warming. Valorisation and reuse of industrial wastes and by-products make geopolymers a solid and sustainable via to be followed as a valid alternative to Portland cement. In this work the mix design of a green fly ash-based geopolymer is evaluated as an environmentally friendly construction material. In the pursuit of sustainability, wastes from a regional kraft pulp industry are exploited for the material processing. Furthermore, a simple, reproducible, and low-cost manufacture is used. The mix design is hence optimised in order to improve the desirable mechanical performance of the material intended for structural applications in construction. Tests indicate that geopolymers may efficiently substitute the ordinary Portland cement as a mortar/concrete binder. Furthermore, valorisation and reuse of wastes in geopolymers is a suboptimal way of gaining financial surplus for the involved industrial players, while contributes for the implementation of a desirable circular economy.

The effect of foaming agent doses on lightweight geopolymer concrete metakaolin based

NASA Astrophysics Data System (ADS)

Risdanareni, Puput; Hilmi, Aldi; Susanto, Prijono Bagus

2017-04-01

The aims of this study is to obtain optimal doses of foaming agent on lightweight geopolymer concrete using fly Ash (FA) and metakaolin (MK) as raw materials. Several test was conducted in order to obtained characteristics of geopolymer lightweight concrete using foaming agent with different doses. The levels of foaming agent used was 0%, 0.3%, 0.6% and 0.9% from the binder weight. Level of metakolin content of 25% by precursor mass were applied in this research. In addition, activator solution with the ratio of Na2SiO3 / NaOH of 2 and Concentration of NaOH of 10 Molar were performed in this research. Doses of foaming agent of 0%, 0.3%, 0.6% and 0.9% by weight of the binder was used. Based on test results obtained, the best mechanical and physical properties of lightweight concrete was owned by speciment with doses of foam 0%. The recommended foam dosage is 0.3% due to its fair enough mechanical and physical properties of lightweight geopolymer concrete produced.

Reuse of aluminosilicate waste materials to synthesize geopolymer

NASA Astrophysics Data System (ADS)

Walmiki Samadhi, Tjokorde; Wibowo, Nanda Tri; Athaya, Hana

2017-08-01

Geopolymer, a solid alkali-aluminosilicate bonding phase produced by reactions between aluminosilicate solids and concentrated alkali solution, is a potential substitute for ordinary Portland cement (OPC). Geopolymer offers environmental advantages since it can be prepared from various inorganic waste materials, and that its synthesis may be undertaken in mild conditions. This research studies the mechanical and physical characteristics of three-component geopolymer mortars prepared from coal fly ash (FA), rice husk ash (RHA), and metakaolin or calcined kaolin (MK). The ternary aluminosilicate blend formulations are varied according to an extreme vertices mixture experimental design with the RHA content limited to 15% mass. Temperature for initial heat curing of the mortars is combined into the experimental design as a 2-level process variable (30 °C and 60 °C). Compressive strengths of the mortars are measured after setting periods of 7 and 14 d. Higher heat curing temperature increases the strength of the mortar. Compositional shift towards RHA from either MK or FA reduces the strength. The highest strength is exhibited by FA-dominated composition (15.1 MPa), surpassing that of OPC mortar. The compressive strengths at 7 and 14 d are represented by a linear mixture model with a synergistic interaction between FA content and heat curing temperature. Geopolymer with the highest strength contains only FA heat-cured at 60 °C. Further studies are needed to be undertaken to confirm the relationship between biomass ash amorphosity and oxide composition to its geopolymerization reactivity, and to optimize the curing conditions.

Bond Strength Mechanism of Fly Ash Based Geopolymer Mortars: A Review

NASA Astrophysics Data System (ADS)

Zailani, W. W. A.; Abdullah, M. M. A. B.; Razak, R. A.; Zainol, M. R. R. M. A.; Tahir, M. F. M.

2017-11-01

Geopolymer possess many excellent properties such as high compressive and bond strength, long term durability, better acid resistance and also known as a “Sustainable Material” due to its low carbon emission and low energy consumption. Thus, it is a good opportunity to develop and explore not only for cement and concrete but also as geopolymeric repair materials. This reviews showed that good bonding properties between geopolymeric repair material and concrete substrate is important in order to acquire an enhanced resistance against penetration of harmful substances and avoiding respalling of the repair material by understanding the bonding behaviour. Bond strength depends to the properties of the repair materials itself and also the surface preparations of concrete substrate.

Geopolymer encapsulation of a chloride salt phase change material for high temperature thermal energy storage

NASA Astrophysics Data System (ADS)

Jacob, Rhys; Trout, Neil; Raud, Ralf; Clarke, Stephen; Steinberg, Theodore A.; Saman, Wasim; Bruno, Frank

2016-05-01

In an effort to reduce the cost and increase the material compatibility of encapsulated phase change materials (EPCMs) a new encapsulated system has been proposed. In the current study a molten salt eutectic of barium chloride (53% wt.), potassium chloride (28% wt.) and sodium chloride (19% wt.) has been identified as a promising candidate for low cost EPCM storage systems. The latent heat, melting point and thermal stability of the phase change material (PCM) was determined by DSC and was found to be in good agreement with results published in the literature. To cope with the corrosive nature of the PCM, it was decided that a fly-ash based geopolymer met the thermal and economic constraints for encapsulation. The thermal stability of the geopolymer shell was also tested with several formulations proving to form a stable shell for the chosen PCM at 200°C and/or 600°C. Lastly several capsules of the geopolymer shell with a chloride PCM were fabricated using a variety of methods with several samples remaining stable after exposure to 600°C testing.

Preparation and characterization of a hybrid alkaline binder based on a fly ash with no commercial value

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mejia, Johanna M.; Rodriguez, Erich; Mejia de Gutierrez, Ruby

2015-05-18

Alkali-activated Portland fly ash cement (FA/OPC) and alkali activated blast furnace slag-fly ash cement (FA/GBFS) were prepared using 70% of a low quality fly ash (FA). The low quality is associated with a high content of unburned material (loss of ignition of 14.6%). The hybrid cements were activated by the alkaline solution in order to obtain an overall SiO 2/Al 2O 3 molar ratio of 5.0 and 6.0 and unique overall Na 2O/SiO 2 molar ratio of 0.21. The microstructural characterization of the blended pastes generated in the systems showed the coexistence of amorphous gels C-A-S-H and N-A-S-H gels inmore » the hybrid systems. The addition of OPC or GBFS increases the compressive strength (at 28 days of curing) up to 127% compared with the geopolymer systems based only on FA used in this study. The content of silicates soluble also plays an important role in the reaction products and higher SiO 2/Al 2O 3 lead to obtain higher mechanical performance and denser structure. The results obtained show that these hybrid cements are an effective way for valorization the waste used in this study for the production of high strength and low-carbon footprint cement-type material.« less

Environmentally-Friendly Dense and Porous Geopolymers Using Fly Ash and Rice Husk Ash as Raw Materials

PubMed Central

Ziegler, Daniele; Formia, Alessandra; Tulliani, Jean-Marc; Palmero, Paola

2016-01-01

This paper assesses the feasibility of two industrial wastes, fly ash (FA) and rice husk ash (RHA), as raw materials for the production of geopolymeric pastes. Three typologies of samples were thus produced: (i) halloysite activated with potassium hydroxide and nanosilica, used as the reference sample (HL-S); (ii) halloysite activated with rice husk ash dissolved into KOH solution (HL-R); (iii) FA activated with the alkaline solution realized with the rice husk ash (FA-R). Dense and porous samples were produced and characterized in terms of mechanical properties and environmental impact. The flexural and compressive strength of HL-R reached about 9 and 43 MPa, respectively. On the contrary, the compressive strength of FA-R is significantly lower than the HL-R one, in spite of a comparable flexural strength being reached. However, when porous samples are concerned, FA-R shows comparable or even higher strength than HL-R. Thus, the current results show that RHA is a valuable alternative to silica nanopowder to prepare the activator solution, to be used either with calcined clay and fly ash feedstock materials. Finally, a preliminary evaluation of the global warming potential (GWP) was performed for the three investigated formulations. With the mix containing FA and RHA-based silica solution, a reduction of about 90% of GWP was achieved with respect to the values obtained for the reference formulation. PMID:28773587

Development of Alkali Activated Geopolymer Masonry Blocks

NASA Astrophysics Data System (ADS)

Venugopal, K.; Radhakrishna; Sasalatti, Vinod

2016-09-01

Cement masonry units are not considered as sustainable since their production involves consumption of fuel, cement and natural resources and therefore it is essential to find alternatives. This paper reports on making of geopolymer solid & hollow blocks and masonry prisms using non conventional materials like fly ash, ground granulated blast furnace slag (GGBFS) and manufactured sand and curing at ambient temperature. They were tested for water absorption, initial rate of water absorption, dry density, dimensionality, compressive, flexural and bond-strength which were tested for bond strength with and without lateral confinement, modulus of elasticity, alternative drying & wetting and masonry efficiency. The properties of geopolymer blocks were found superior to traditional masonry blocks and the masonry efficiency was found to increase with decrease in thickness of cement mortar joints. There was marginal difference in strength between rendered and unrendered geopolymer masonry blocks. The percentage weight gain after 7 cycles was less than 6% and the percentage reduction in strength of geopolymer solid blocks and hollow blocks were 26% and 28% respectively. Since the properties of geopolymer blocks are comparatively better than the traditional masonry they can be strongly recommended for structural masonry.

The Mechanical Properties and Microstructure Characters of Hybrid Composite Geopolymers-Pineapple Fiber Leaves (PFL)

NASA Astrophysics Data System (ADS)

Amalia, N.; Hidayatullah, S.; Nurfadilla; Subaer

2017-03-01

The objective of this research is to study the influence of organic fibers on the mechanical properties and microstructure characters of hybrid composite geopolymers-pineapple fibers (PFL). Geopolymers were synthesized by using alkali activated of class C-fly ash added manually with short pineapple fiber leaves (PFL) and then cured at 60°C for 1 hour. The resulting composites were stored in open air for 28 days prior to mechanical and microstructure characterizations. The samples were subjected to compressive and flexural strength measurements, heat resistance as well as acid attack (1M H2SO4 solution). The microstructure of the composites were examined by using Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS). The measurement showed that the addition of pineapple fibers was able to improve the compressive and flexural strength of geopolymers. The resulting hybrid composites were able to resist fire to a maximum temperature of 1500°C. SEM examination showed the presence of good bond between geopolymer matrix and pineapple fibers. It was also found that there were no chemical constituents of geopolymers leached out during acid liquid treatment. It is concluded that hybrid composite geopolymers-pineapple fibers are potential composites for wide range applications.

Chemical Treatment of Waste Abaca for Natural Fiber-Reinforced Geopolymer Composite

PubMed Central

Malenab, Roy Alvin J.; Ngo, Janne Pauline S.; Promentilla, Michael Angelo B.

2017-01-01

The use of natural fibers in reinforced composites to produce eco-friendly materials is gaining more attention due to their attractive features such as low cost, low density and good mechanical properties, among others. This work thus investigates the potential of waste abaca (Manila hemp) fiber as reinforcing agent in an inorganic aluminosilicate material known as geopolymer. In this study, the waste fibers were subjected to different chemical treatments to modify the surface characteristics and to improve the adhesion with the fly ash-based geopolymer matrix. Definitive screening design of experiment was used to investigate the effect of successive chemical treatment of the fiber on its tensile strength considering the following factors: (1) NaOH pretreatment; (2) soaking time in aluminum salt solution; and (3) final pH of the slurry. The results show that the abaca fiber without alkali pretreatment, soaked for 12 h in Al2(SO4)3 solution and adjusted to pH 6 exhibited the highest tensile strength among the treated fibers. Test results confirmed that the chemical treatment removes the lignin, pectin and hemicellulose, as well as makes the surface rougher with the deposition of aluminum compounds. This improves the interfacial bonding between geopolymer matrix and the abaca fiber, while the geopolymer protects the treated fiber from thermal degradation. PMID:28772936

Synthesis of inorganic polymers using fly ash and primary lead slag.

PubMed

Onisei, S; Pontikes, Y; Van Gerven, T; Angelopoulos, G N; Velea, T; Predica, V; Moldovan, P

2012-02-29

The present work reports on the synthesis and properties of inorganic polymers ("geopolymers") made of 100% fly ash from lignite's combustion, 100% primary lead slag and mixtures of the two. In the inorganic polymers with both fly ash and lead slag the main crystalline phases detected are wüstite, magnetite, sodium zinc silicate, quartz, anorthite, and gehlenite; litharge partially dissolves. FTIR analysis in these samples revealed that the main peaks and bands of end members also exist, along with a new amorphous reaction product. In terms of microstructure, both fly ash and lead slag dissolve and contribute in the binding phase whereas the larger particles act as aggregates. For an increasing lead slag in the composition, the binding phase is changing in chemistry and reaches PbO values higher than 50 wt.% for the 100% lead slag inorganic polymer. Regarding the properties of fly ash and lead slag inorganic polymers, compressive strength is higher than 35 MPa in all cases and water absorption diminishes as the lead slag content increases. A comparison of leaching results before and after polymerisation reveals that pH is an important factor as Pb is immobilised in the binding phase, unlike Zn and As. Copyright © 2011 Elsevier B.V. All rights reserved.

Leachability of heavy metals in geopolymer-based materials synthesized from red mud and rice husk ash

NASA Astrophysics Data System (ADS)

Nguyen, Hoc Thang; Pham, Vo Thi Ha Quyen; Dang, Thanh Phong; Dao, Thanh Khe

2018-04-01

Red mud is an industrial waste generated during aluminum production from bauxite whereas rice husk ash is an agricultural waste from burning of rice husk that could cause negative impact on the environment if not properly managed. This study demonstrates the utilization of red mud in combination with rice husk ash to form a geopolymer-based material which can be used as bricks or replacement for traditional cement materials. The focus of this study is on the leachability of heavy metals in the raw materials and the geopolymer as this would be significant in assessing the environmental impact of the product. Leachability of metals such as Cu, Zn, Cd, Pb, Fe, and Cr was evaluated based on European (EN 124572-2 EU CEN TC292/ CEN TC 308) standard with pH value 7. Results indicate that the leachability of these metals in the geopolymer matrix is lower than that of the raw materials.

Strength of Geopolymer Cement Curing at Ambient Temperature by Non-Oven Curing Approaches: An Overview

NASA Astrophysics Data System (ADS)

Wattanachai, Pitiwat; Suwan, Teewara

2017-06-01

At the present day, a concept of environmentally friendly construction materials has been intensively studying to reduce the amount of releasing greenhouse gases. Geopolymer is one of the cementitious binders which can be produced by utilising pozzolanic wastes (e.g. fly ash or furnace slag) and also receiving much more attention as a low-CO2 emission material. However, to achieve excellent mechanical properties, heat curing process is needed to apply to geopolymer cement in a range of temperature around 40 to 90°C. To consume less oven-curing energy and be more convenience in practical work, the study on geopolymer curing at ambient temperature (around 20 to 25°C) is therefore widely investigated. In this paper, a core review of factors and approaches for non-oven curing geopolymer has been summarised. The performance, in term of strength, of each non-oven curing method, is also presented and analysed. The main aim of this review paper is to gather the latest study of ambient temperature curing geopolymer and to enlarge a feasibility of non-oven curing geopolymer development. Also, to extend the directions of research work, some approaches or techniques can be combined or applied to the specific properties for in-field applications and embankment stabilization by using soil-cement column.

Mechanical properties of geopolymer lightweight brick with styrofoam pellet

NASA Astrophysics Data System (ADS)

Abdullah, Mohd Mustafa Al Bakri; Tahir, Muhammad Faheem Mohd; Kadir, Aeslina Abdul; Hussin, Kamarudin; Samson, W. Saiful Iskandar W.

2017-09-01

The utilization of fly ash in brick as partial replacement of cement is gaining immense importance today, mainly on account of the improvement in the long-term durability of brick combined with ecological benefits. In this research, the lightweight brick was produced by using fly ash (class F) as a main material to replace Ordinary Portland Cement (OPC) in the composition of brick. Class F Fly Ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and styrofoam pellet was added to the geopolymer mixture to produce lightweight brick. The brick was prepared in two methods that is wet method and dry method due to different brick composition which is dry method for composition with sand and wet method for composition without sand. The bricks were cured in room temperature at 7 aging days. After 7 days, the compressive strength, water absorption, and density of the brick were investigated, where the optimum ratio for the best bricks has been determined from the lightweight density and has compressive strength more than minimum standard requirement. The best bricks are further produce for curing at 60°C in oven at 28 aging days. Those bricks also were characterized using optical microscope to measure the distribution of styrofoam in brick structure. From the result obtained, the brick that cured at 60°C in oven at 28 aging days has high strength compare to brick that cured in room temperature and at 7 day cured. The water absorption is decreasing as the curing temperature and aging days increased whereas density is increasing.

Development of heat resistant geopolymer-based materials from red mud and rice husk ash

NASA Astrophysics Data System (ADS)

Thang, Nguyen Hoc; Nhung, Le Thuy; Quyen, Pham Vo Thi Ha; Phong, Dang Thanh; Khe, Dao Thanh; Van Phuc, Nguyen

2018-04-01

Geopolymer is an inorganic polymer composite developed by Joseph Davidovits in 1970s. Such material has potentials to replace Ordinary Portland Cement (OPC)-based materials in the future because of its lower energy consumption, minimal CO2 emissions and lower production cost as it utilizes industrial waste resources. Hence, geopolymerization and the process to produce geopolymers for various applications like building materials can be considered as green industry. Moreover, in this study, red mud and rice husk ash were used as raw materials for geopolymeric production, which are aluminum industrial and agricultural wastes that need to be managed to reduce their negative impact to the environment. The red mud and rice husk ash were mixed with sodium silicate (water glass) solution to form geopolymer paste. The geopolymer paste was filled into 5-cm cube molds according to ASTM C109/C109M 99, and then cured at room temperature for 28 days. These products were then tested for compressive strength and volumetric weight. Results indicated that the material can be considered lightweight with a compressive strength at 28 days that are in the range of 6.8 to 15.5 MPa. Moreover, the geopolymer specimens were also tested for heat resistance at a temperature of 1000oC for 2 hours. Results suggest high heat resistance with an increase of compressive strength from 262% to 417% after exposed at high temperature.

Possibility of Coal Combustion Product Conditioning

NASA Astrophysics Data System (ADS)

Błaszczyński, Tomasz Z.; Król, Maciej R.

2018-03-01

This paper is focused on properties of materials known as green binders. They can be used to produce aluminium-siliceous concrete and binders known also as geopolymers. Comparing new ecological binders to ordinary cements we can see huge possibility of reducing amount of main greenhouse gas which is emitted to atmosphere by 3 to even 10 times depending of substrate type used to new green material production. Main ecological source of new materials obtaining possibility is to use already available products which are created in coal combustion and steel smelting process. Most of them are already used in many branches of industry. They are mostly civil engineering, chemistry or agriculture. Conducted research was based on less popular in civil engineering fly ash based on lignite combustion. Materials were examine in order to verify possibility of obtaining hardened mortars based of different factors connected with process of geopolymerization, which are temperature, amount of reaction reagent and time of heat treatment. After systematizing the matrices for the basic parameters affecting the strength of the hardened mortars, the influence of the fly ash treatment for increasing the strength was tested.

Fly Ash-based Geopolymer Lightweight Concrete Using Foaming Agent

PubMed Central

Al Bakri Abdullah, Mohd Mustafa; Hussin, Kamarudin; Bnhussain, Mohamed; Ismail, Khairul Nizar; Yahya, Zarina; Razak, Rafiza Abdul

2012-01-01

In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity. PMID:22837687

Fly ash-based geopolymer lightweight concrete using foaming agent.

PubMed

Al Bakri Abdullah, Mohd Mustafa; Hussin, Kamarudin; Bnhussain, Mohamed; Ismail, Khairul Nizar; Yahya, Zarina; Razak, Rafiza Abdul

2012-01-01

In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity.

An investigation of waste glass-based geopolymers supplemented with alumina

NASA Astrophysics Data System (ADS)

Christiansen, Mary U.

An increased consideration of sustainability throughout society has resulted in a surge of research investigating sustainable alternatives to existing construction materials. A new binder system, called a geopolymer, is being investigated to supplement ordinary portland cement (OPC) concrete, which has come under scrutiny because of the CO2 emissions inherent in its production. Geopolymers are produced from the alkali activation of a powdered aluminosilicate source by an alkaline solution, which results in a dense three-dimensional matrix of tetrahedrally linked aluminosilicates. Geopolymers have shown great potential as a building construction material, offering similar mechanical and durability properties to OPC. Additionally, geopolymers have the added value of a considerably smaller carbon footprint than OPC. This research considered the compressive strength, microstructure and composition of geopolymers made from two types of waste glass with varying aluminum contents. Waste glass shows great potential for mainstream use in geopolymers due to its chemical and physical homogeneity as well as its high content of amorphous silica, which could eliminate the need for sodium silicate. However, the lack of aluminum is thought to negatively affect the mechanical performance and alkali stability of the geopolymer system. 39 Mortars were designed using various combinations of glass and metakaolin or fly ash to supplement the aluminum in the system. Mortar made from the high-Al glass (12% Al2O3) reached over 10,000 psi at six months. Mortar made from the low-Al glass (<1% Al2O3) did not perform as well and remained sticky even after several weeks of curing, most likely due to the lack of Al which is believed to cause hardening in geopolymers. A moderate metakaolin replacement (25-38% by mass) was found to positively affect the compressive strength of mortars made with either type of glass. Though the microstructure of the mortar was quite indicative of mechanical performance, composition was also found to be important. The initial stoichiometry of the bulk mixture was maintained fairly closely, especially in mixtures made with fine glass. This research has shown that glass has great potential for use in geopolymers, when care is given to consider the compositional and physical properties of the glass in mixture design.

Radioactive Demonstration Of Mineralized Waste Forms Made From Hanford Low Activity Waste (Tank Farm Blend) By Fluidized Bed Steam Reformation (FBSR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, C. M.; Crawford, C. L.; Bannochie, C. J.

The U.S. Department of Energy’s Office of River Protection (ORP) is responsible for the retrieval, treatment, immobilization, and disposal of Hanford’s tank waste. A key aspect of the River Protection Project (RPP) cleanup mission is to construct and operate the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The WTP will separate the tank waste into high-level and low-activity waste (LAW) fractions, both of which will subsequently be vitrified. The projected throughput capacity of the WTP LAW Vitrification Facility is insufficient to complete the RPP mission in the time frame required by the Hanford Federal Facility Agreement and Consent Order,more » also known as the Tri-Party Agreement (TPA), i.e. December 31, 2047. Supplemental Treatment is likely to be required both to meet the TPA treatment requirements as well as to more cost effectively complete the tank waste treatment mission. The Supplemental Treatment chosen will immobilize that portion of the retrieved LAW that is not sent to the WTP’s LAW Vitrification facility into a solidified waste form. The solidified waste will then be disposed on the Hanford site in the Integrated Disposal Facility (IDF). Fluidized Bed Steam Reforming (FBSR) offers a moderate temperature (700-750°C) continuous method by which LAW can be processed irrespective of whether the waste contain organics, nitrates, sulfates/sulfides, chlorides, fluorides, volatile radionuclides or other aqueous components. The FBSR technology can process these wastes into a crystalline ceramic (mineral) waste form. The mineral waste form that is produced by co-processing waste with kaolin clay in an FBSR process has been shown to be comparable to LAW glass, i.e. leaches Tc-99, Re and Na at <2g/m 2 during ASTM C1285 (Product Consistency) durability testing. Monolithing of the granular FBSR product was investigated to prevent dispersion during transport or burial/storage. Monolithing in an inorganic geopolymer binder, which is amorphous, macro-encapsulates the granules, and the monoliths pass ANSI/ANS 16.1 and ASTM C1308 durability testing with Re achieving a Leach Index (LI) of 9 (the Hanford Integrated Disposal Facility, IDF, criteria for Tc-99) after a few days and Na achieving an LI of >6 (the Hanford IDF criteria for Na) in the first few hours. The granular and monolithic waste forms also pass the EPA Toxicity Characteristic Leaching Procedure (TCLP) for all Resource Conservation and Recovery Act (RCRA) components at the Universal Treatment Standards (UTS). Two identical Benchscale Steam Reformers (BSR) were designed and constructed at SRNL, one to treat non-radioactive simulants and the other to treat actual radioactive wastes. The results from the non-radioactive BSR were used to determine the parameters needed to operate the radioactive BSR in order to confirm the findings of non-radioactive FBSR pilot scale and engineering scale tests and to qualify an FBSR LAW waste form for applications at Hanford. Radioactive testing commenced using SRS LAW from Tank 50 chemically trimmed to look like Hanford’s blended LAW known as the Rassat simulant as this simulant composition had been tested in the non-radioactive BSR, the non-radioactive pilot scale FBSR at the Science Applications International Corporation-Science and Technology Applications Research (SAIC-STAR) facility in Idaho Falls, ID and in the TTT Engineering Scale Technology Demonstration (ESTD) at Hazen Research Inc. (HRI) in Denver, CO. This provided a “tie back” between radioactive BSR testing and non-radioactive BSR, pilot scale, and engineering scale testing. Approximately six hundred grams of non-radioactive and radioactive BSR product were made for extensive testing and comparison to the non-radioactive pilot scale tests performed in 2004 at SAIC-STAR and the engineering scale test performed in 2008 at HRI with the Rassat simulant. The same mineral phases and off-gas species were found in the radioactive and non-radioactive testing. The granular ESTD and BSR products (radioactive and non-radioactive) were analyzed for total constituents and durability tested as a granular waste form. A subset of the granular material was stabilized in a clay based geopolymer matrix at 42% and 65% FBSR loadings and durability tested as a monolith waste form. The 65 wt% FBSR loaded monolith made with clay (radioactive) was more durable than the 67-68 wt% FBSR loaded monoliths made from fly ash (non-radioactive) based on short term PCT testing. Long term, 90 to 107 day, ASTM C1308 testing (similar to ANSI/ANS 16.1 testing) was only performed on two fly ash geopolymer monoliths at 67-68 wt% FBSR loading and three clay geopolymer monoliths at 42 wt% FBSR loading. More clay geopolymers need to be made and tested at longer times at higher FBSR loadings for comparison to the fly ash monoliths. Monoliths made with metakaolin (heat treated) clay are of a more constant composition and are very reactive as the heat treated clay is amorphous and alkali activated. The monoliths made with fly ash are subject to the inherent compositional variation found in fly ash as it is a waste product from burning coal and it contains unreactive components such as mullite. However, both the fly ash and the clay based monoliths perform well in long term ASTM C1308 testing.« less

Benefits of aggregates surface modification in concrete production

NASA Astrophysics Data System (ADS)

Junak, J.; Sicakova, A.

2017-10-01

In our study, recycled concrete aggregates (RCA), which surfaces had been modified by geopolymer material based on coal fly ash, were used to produce the concrete samples. In these samples, fraction 4/8 mm was replaced by recycled concrete aggregate with a range of 100%. To modify the surface of RCA was “Solo” and “Triple stage” modification used. On these samples real density, total water absorption and compressive strength were examined after 28, 90, 180 and 365 days of hardening. The highest compressive strength 56.8 MPa, after 365 days hardening, reached sample which had improved RCA surface by “Triple stage mixing”.

New-Generation Sealing Slurries For Borehole Injection Purposes

NASA Astrophysics Data System (ADS)

Stryczek, Stanisław; Gonet, Andrzej; Wiśniowski, Rafał; Złotkowski, Albert

2015-12-01

The development of techniques and technologies thanks to which parameters of the ground medium can be modified makes specialists look for new recipes of geopolymers - binders for the reinforcing and sealing of unstable and permeable grounds. The sealing slurries are expected to meet a number of strict requirements, therefore it is important to find new admixtures and additives which could modify the fresh and hardened slurry. Special attention has been recently paid to the fluid ash - a by-product of the combustion of hard coals. However, the use of this additive is associated with the application of appropriate superplastifier. Laboratory analyses of rheological parameters of fresh sealing slurries and the ways of improving their liquidity by a properly selected third-generation superplastifier are presented in the paper. The slurries were based on Portland cement CEM I, milled granulated large-furnace slag and fly ash from fluidized-bed combustion of hard coal.

Elasticity and expansion test performance of geopolymer as oil well cement

NASA Astrophysics Data System (ADS)

Ridha, S.; Hamid, A. I. Abd; Halim, A. H. Abdul; Zamzuri, N. A.

2018-04-01

History has shown that geopolymer cement provides high compressive strength as compared to Class G cement. However, the research had been done at ambient temperature, not at elevated condition which is the common oil well situation. In this research, the physical and mechanical properties performance of the oil well cement were investigated by laboratory work for two types of cement that are geopolymer and Class G cement. The cement samples were produced by mixing the cement according to the API standards. Class C fly ash was used in this study. The alkaline solution was prepared by mixing sodium silicate with NaOH solution. The NaOH solution was prepared by diluting NaOH pellets with distilled water to 8M. The cement samples were cured at a pressure of 3000 psi and a temperature of 130 °C to simulate the downhole condition. After curing, the physical properties of the cement samples were investigated using OYO Sonic Viewer to determine their elastic properties. Autoclave expansion test and compressive strength tests were conducted to determine the expansion value and the strength of the cement samples, respectively. The results showed that the geopolymer cement has a better physical and mechanical properties as compared with Class G cement at elevated condition.

Strength and Durability Performance of Alkali-Activated Rice Husk Ash Geopolymer Mortar

PubMed Central

Kim, Yun Yong; Lee, Byung-Jae; Saraswathy, Velu

2014-01-01

This paper describes the experimental investigation carried out to develop the geopolymer concrete based on alkali-activated rice husk ash (RHA) by sodium hydroxide with sodium silicate. Effect on method of curing and concentration of NaOH on compressive strength as well as the optimum mix proportion of geopolymer mortar was investigated. It is possible to achieve compressive strengths of 31 N/mm2 and 45 N/mm2, respectively for the 10 M alkali-activated geopolymer mortar after 7 and 28 days of casting when cured for 24 hours at 60°C. Results indicated that the increase in curing period and concentration of alkali activator increased the compressive strength. Durability studies were carried out in acid and sulfate media such as H2SO4, HCl, Na2SO4, and MgSO4 environments and found that geopolymer concrete showed very less weight loss when compared to steam-cured mortar specimens. In addition, fluorescent optical microscopy and X-ray diffraction (XRD) studies have shown the formation of new peaks and enhanced the polymerization reaction which is responsible for strength development and hence RHA has great potential as a substitute for ordinary Portland cement concrete. PMID:25506063

Strength and durability performance of alkali-activated rice husk ash geopolymer mortar.

PubMed

Kim, Yun Yong; Lee, Byung-Jae; Saraswathy, Velu; Kwon, Seung-Jun

2014-01-01

This paper describes the experimental investigation carried out to develop the geopolymer concrete based on alkali-activated rice husk ash (RHA) by sodium hydroxide with sodium silicate. Effect on method of curing and concentration of NaOH on compressive strength as well as the optimum mix proportion of geopolymer mortar was investigated. It is possible to achieve compressive strengths of 31 N/mm(2) and 45 N/mm(2), respectively for the 10 M alkali-activated geopolymer mortar after 7 and 28 days of casting when cured for 24 hours at 60°C. Results indicated that the increase in curing period and concentration of alkali activator increased the compressive strength. Durability studies were carried out in acid and sulfate media such as H2SO4, HCl, Na2SO4, and MgSO4 environments and found that geopolymer concrete showed very less weight loss when compared to steam-cured mortar specimens. In addition, fluorescent optical microscopy and X-ray diffraction (XRD) studies have shown the formation of new peaks and enhanced the polymerization reaction which is responsible for strength development and hence RHA has great potential as a substitute for ordinary Portland cement concrete.

Alkali-activated complex binders from class C fly ash and Ca-containing admixtures.

PubMed

Guo, Xiaolu; Shi, Huisheng; Chen, Liming; Dick, Warren A

2010-01-15

Processes that maximize utilization of industrial solid wastes are greatly needed. Sodium hydroxide and sodium silicate solution were used to create alkali-activated complex binders (AACBs) from class C fly ash (CFA) and other Ca-containing admixtures including Portland cement (PC), flue gas desulfurization gypsum (FGDG), and water treatment residual (WTR). Specimens made only from CFA (CFA100), or the same fly ash mixed with 40 wt% PC (CFA60-PC40), with 10 wt% FGDG (CFA90-FGDG10), or with 10 wt% WTR (CFA90-WTR10) had better mechanical performance compared to binders using other mix ratios. The maximum compressive strength of specimens reached 80.0 MPa. Geopolymeric gel, sodium polysilicate zeolite, and hydrated products coexist when AACB reactions occur. Ca from CFA, PC, and WTR precipitated as Ca(OH)(2), bonded in geopolymers to obtain charge balance, or reacted with dissolved silicate and aluminate species to form calcium silicate hydrate (C-S-H) gel. However, Ca from FGDG probably reacted with dissolved silicate and aluminate species to form ettringite. Utilization of CFA and Ca-containing admixtures in AACB is feasible. These binders may be widely utilized in various applications such as in building materials and for solidification/stabilization of other wastes, thus making the wastes more environmentally benign.

Alkali activation processes for incinerator residues management.

PubMed

Lancellotti, Isabella; Ponzoni, Chiara; Barbieri, Luisa; Leonelli, Cristina

2013-08-01

Incinerator bottom ash (BA) is produced in large amount worldwide and in Italy, where 5.1 millionstons of municipal solid residues have been incinerated in 2010, corresponding to 1.2-1.5 millionstons of produced bottom ash. This residue has been used in the present study for producing dense geopolymers containing high percentage (50-70 wt%) of ash. The amount of potentially reactive aluminosilicate fraction in the ash has been determined by means of test in NaOH. The final properties of geopolymers prepared with or without taking into account this reactive fraction have been compared. The results showed that due to the presence of both amorphous and crystalline fractions with a different degree of reactivity, the incinerator BA geopolymers exhibit significant differences in terms of Si/Al ratio and microstructure when reactive fraction is considered. Copyright © 2013 Elsevier Ltd. All rights reserved.

Volcanic ash-based geopolymer cements/concretes: the current state of the art and perspectives.

PubMed

Djobo, Jean Noël Yankwa; Elimbi, Antoine; Tchakouté, Hervé Kouamo; Kumar, Sanjay

2017-02-01

The progress achieved with the use of volcanic ash for geopolymer synthesis has been critically reviewed in this paper. This consists of an overview of mineralogy and chemistry of volcanic ash. The role of chemical composition and mineral contents of volcanic ash on their reactivity during geopolymerization reaction and, consequently, mechanical properties have been accessed. An attempt has been made to establish a relationship between synthesis factors and final properties. A critical assessment of some synthesis conditions has been addressed and some practical recommendations given along with suggestions of future works that have to be done. All this has shown that there are still many works such as durability tests (carbonation, freeze-thaw, resistance, etc.), life cycle analysis, etc. that need to be done in order to satisfy both suitability and sustainability criteria for a large-scale or industrial application.

Power plant wastes capitalization as geopolymeric building materials

NASA Astrophysics Data System (ADS)

Ciobanu, Gabriela; Litu, Loredana; Harja, Maria

2017-11-01

In this innovative study, we are present an investigation over the properties of geopolymeric materials prepared using ash supplied by power plant Iasi, Romania and sodium hydroxide solutions/pellets. Having as objective a minimum consumption of energy and materials was developed a class of advanced eco-materials. New synthesized materials can be used as a binder for cement replacement or for the removal/immobilization of pollutants from waste waters or soils. It offers an advanced and low cost-effective solution too many problems, where waste must be capitalized. The geopolymer formation, by hydrothermal method, is influenced by: temperature (20-600°C), alkali concentration (2M-6M), solid /liquid ratio (1-2), ash composition, time of heating (2-48 h), etc. The behaviour of the FTIR peak of 6M sample indicated upper quantity of geopolymer formation at the first stage of the reaction. XRD spectra indicated phases like sodalite, faujasite, Na-Y, which are known phases of geopolymer/zeolite. Advanced destroyed of ash particles due to geopolymerisation reaction were observed when the temperature was higher. At the constant temperature the percentage of geopolymer increases with increasing of curing time, from 4-48 h. Geopolymer materials are environmentally friendly, for its obtaining energy consumption, and CO2 emission is reduced compared to cement binder.

The influence of plain bar on bond strength of geopolymer concrete

NASA Astrophysics Data System (ADS)

Dewi, Evrianti Syntia; Ekaputri, Januarti Jaya

2017-06-01

This paper presents some results of experimental study of bond strength of plain bar embedded in geopolymer concrete. Fly ash class F was used as a raw material activated with alkali solutions. The combination of 8 Molar of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) as alkali activators was examined in the mixture with ratio of 2.5 by weight. Nine cubical specimens with a size of 150 × 150 × 150 mm were prepared to measure bond strength and slip between reinforcement and concrete. The influential factors studied for the experimental investigation were the diameter of reinforcement bar, bond area, and concrete cover to diameter (c/d) of reinforcement. The result showed that the average bond strength decreased as the diameter of plain bar and bonded length were increased from 16 mm to 19 mm. However, the 12 mm showed the different result allegedly caused by the effect of bond area and the passive confined provided by the concrete. Based on several equations used to compare the bond strength, it is clear that deformed bar of 12 mm in diameter is potential to increase the bond strength.

High-efficiency cogeneration boiler bagasse-ash geochemistry and mineralogical change effects on the potential reuse in synthetic zeolites, geopolymers, cements, mortars, and concretes.

PubMed

Clark, Malcolm W; Despland, Laure M; Lake, Neal J; Yee, Lachlan H; Anstoetz, Manuela; Arif, Elisabeth; Parr, Jeffery F; Doumit, Philip

2017-04-01

Sugarcane bagasse ash re-utilisation has been advocated as a silica-rich feed for zeolites, pozzolans in cements and concretes, and geopolymers. However, many papers report variable success with the incorporation of such materials in these products as the ash can be inconsistent in nature. Therefore, understanding what variables affect the ash quality in real mills and understanding the processes to characterise ashes is critical in predicting successful ash waste utilisation. This paper investigated sugarcane bagasse ash from three sugar mills (Northern NSW, Australia) where two are used for the co-generation of electricity. Data shows that the burn temperatures of the bagasse in the high-efficiency co-generation boilers are much higher than those reported at the temperature measuring points. Silica polymorph transitions indicate the high burn temperatures of ≈1550 °C, produces ash dominated α -quartz rather than expected α-cristobilite and amorphous silica; although α-cristobilite, and amorphous silica are present. Furthermore, burn temperatures must be ≤1700 °C, because of the absence of lechatelierite where silica fusing and globulisation dominates. Consequently, silica-mineralogy changes deactivate the bagasse ash by reducing silica solubility, thus making bagasse ash utilisation in synthetic zeolites, geopolymers, or a pozzolanic material in mortars and concretes more difficult. For the ashes investigated, use as a filler material in cements and concrete has the greatest potential. Reported mill boiler temperatures discrepancies and the physical characteristics of the ash, highlight the importance of accurate temperature monitoring at the combustion seat if bagasse ash quality is to be prioritised to ensure a usable final ash product.

A study on hardness behavior of geopolymer paste in different condition

NASA Astrophysics Data System (ADS)

Zainal, Farah Farhana; Hussin, Kamarudin; Rahmat, Azmi; Abdullah, Mohd Mustafa Al Bakri; Shamsudin, Shaiful Rizam

2016-07-01

This study has been conducted to understand the hardness behavior of geopolymer paste in different conditions; with and without being immersed in water. Geopolymer paste has been used nowadays as an alternative way to reduce global warming pollution by carbon dioxide (CO2) released to the air caused from the production of Ordinary Portland Cement (OPC). Geopolymer has many advantages such as high compressive strength, lower water absorption and lower porosity. Geopolymer paste in this study was made from a mixture of fly ash and alkaline activators. The alkaline activators that have been used were sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3) solution. Then the mixture was allowed to harden for 24hrs at ambient temperature and then placed in the oven for 24hrs with 60°C for the curing process. The hardness testing was conducted after a few months when the samples already achieved the optimum design. The samples were divided to two conditions; without immersion which was placed at ambient temperature (S1) and immersed in water for one week (S2). The samples then are divided into two at the center and testing was conducted into 4 parts which are part 1, part 2, part 3 and part 4. Various methods of non-destructively testing concrete and mortar have been in use for many years such as Vickers hardness test, Rockwell hardness test, Brinell hardness test and many more. The Rockwell hardness test method as defined in ASTM E-18 is the most commonly used hardness test method which is also used in this study. From the results, S1 has higher hardness value than S2 for all parts with the maximum value of S1 is 118.6 and the minimum value is 71.8. The maximum value of S2 is 114.4 and the minimum value is 0. The central part of the geopolymer paste also showed greater hardness values than the edge area of the samples.

Treatment of fly ash for use in concrete

DOEpatents

Boxley, Chett [Park City, UT; Akash, Akash [Salt lake City, UT; Zhao, Qiang [Natick, MA

2012-05-08

A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with an activator solution sufficient to initiate a geopolymerization reaction and for a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 35% of the foam index of the untreated fly ash, and in some cases less than 10% of the foam index of the untreated fly ash. The activator solution may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

Treatment of fly ash for use in concrete

DOEpatents

Boxley, Chett; Akash, Akash; Zhao, Qiang

2013-01-08

A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with an activator solution sufficient to initiate a geopolymerization reaction and for a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 35% of the foam index of the untreated fly ash, and in some cases less than 10% of the foam index of the untreated fly ash. The activator solution may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

Treatment of fly ash for use in concrete

DOEpatents

Boxley, Chett [Park City, UT

2012-05-15

A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with a quantity of spray dryer ash (SDA) and water to initiate a geopolymerization reaction and form a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 40%, and in some cases less than 20%, of the foam index of the untreated fly ash. An optional alkaline activator may be mixed with the fly ash and SDA to facilitate the geopolymerization reaction. The alkaline activator may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

Effect of Alkaline Solution with Varying Mix Proportion on Geopolymer Mortar

NASA Astrophysics Data System (ADS)

Karuppuchamy, K.; Ananthkumar, M.; Raghavapriya, S. M.

2018-02-01

Cement production is attributed by emission of carbon dioxide which causes severe environmental impacts. This has led to the invention of special construction materials which can replace cement. On the other hand, these construction materials (like Fly ash, Metakaolin) also need to be inexpensive and should possess all the characteristics of cementitious materials. In this project, the effect of geopolymerization on the properties of the end product were studied with varying distillation of NaOH solution (10M, 12M and 15M) for different mix proportion (1:1, 1:2 and 1:3). Curing was done for 1 day at a temperature of 60°C and 80°C respectively. The densities, compressive strength, alkalinity, co-efficient of absorption were determined. As a result, the experiments showed the effect of factors such as mix proportion, curing temperature and curing day on the physical and mechanical properties such as mix proportion of the geopolymer concrete. Results of NaOH concentration of 12M concentration cured for 24 hours at 80°C and 60°C showed better mechanical performance than the rest of the concentrations.

CO.sub.2 utilization in electrochemical systems

DOEpatents

Boxley, Chett; Akash, Akash; Zhao, Qiang

2013-01-22

A process for treating fly ash to render it highly usable as a concrete additive. A quantity of fly ash is obtained that contains carbon and which is considered unusable fly ash for concrete based upon foam index testing. The fly ash is mixed with a quantity of spray dryer ash (SDA) and water to initiate a geopolymerization reaction and form a geopolymerized fly ash. The geopolymerized fly ash is granulated. The geopolymerized fly ash is considered usable fly ash for concrete according to foam index testing. The geopolymerized fly ash may have a foam index less than 40%, and in some cases less than 20%, of the foam index of the untreated fly ash. An optional alkaline activator may be mixed with the fly ash and SDA to facilitate the geopolymerization reaction. The alkaline activator may contain an alkali metal hydroxide, carbonate, silicate, aluminate, or mixtures thereof.

Multi-scale analytical investigation of fly ash in concrete

NASA Astrophysics Data System (ADS)

Aboustait, Mohammed B.

Much research has been conducted to find an acceptable concrete ingredient that would act as cement replacement. One promising material is fly ash. Fly ash is a by-product from coal-fired power plants. Throughout this document work on the characterization of fly ash structure and composition will be explored. This effort was conducted through a mixture of cutting edge multi-scale analytical X-ray based techniques that use both bulk experimentation and nano/micro analytical techniques. Furtherly, this examination was coupled by performing Physical/Mechanical ASTM based testing on fly ash-enrolled-concrete to examine the effects of fly ash introduction. The most exotic of the cutting edge characterization techniques endorsed in this work uses the Nano-Computed Tomography and the Nano X-ray Fluorescence at Argonne National Laboratory to investigate single fly ash particles. Additional Work on individual fly ash particles was completed by laboratory-based Micro-Computed Tomography and Scanning Electron Microscopy. By combining the results of individual particles and bulk property tests, a compiled perspective is introduced, and accessed to try and make new insights into the reactivity of fly ash within concrete.

Effect of Molarity of Sodium Hydroxide and Curing Method on the Compressive Strength of Ternary Blend Geopolymer Concrete

NASA Astrophysics Data System (ADS)

Sathish Kumar, V.; Ganesan, N.; Indira, P. V.

2017-07-01

Concrete plays a vital role in the development of infrastructure and buildings all over the world. Geopolymer based cement-less concrete is one of the current findings in the construction industry which leads to a green environment. This research paper deals with the results of the use of Fly ash (FA), Ground Granulated Blast Furnace Slag (GGBS) and Metakaolin (MK) as a ternary blend source material in Geopolymer concrete (GPC). The aspects that govern the compressive strength of GPC like the proportion of source material, Molarity of Sodium Hydroxide (NaOH) and Curing methods were investigated. The purpose of this research is to optimise the local waste material and use them effectively as a ternary blend in GPC. Seven combinations of binder were made in this study with replacement of FA with GGBS and MK by 35%, 30%, 25%, 20%, 15%, 10%, 5% and 5%, 10%, 15%, 20%, 25%, 30%, 35% respectively. The molarity of NaOH solution was varied by 12M, 14M and 16M and two types of curing method were adopted, viz. Hot air oven curing and closed steam curing for 24 hours at 60°C (140°F). The samples were kept at ambient temperature till testing. The compressive strength was obtained after 7 days and 28 days for the GPC cubes. The test data reveals that the ternary blend GPC with molarity 14M cured by hot air oven produces the maximum compressive strength. It was also observed that the compressive strength of the oven cured GPC is approximately 10% higher than the steam cured GPC using the ternary blend.

Characteristics of Commercial SiC and Synthetic SiC as an Aggregate in Geopolymer Composites

NASA Astrophysics Data System (ADS)

Irfanita, R.; Afifah, K. N.; Asrianti; Subaer

2017-03-01

This main objective of this study is to investigate the effect silicon carbide (SiC) as an aggregate on the mechanical strength and microstructure of the geopolymer composites. The geopolymers binder were produced by using alkaline activation method of metakaolin and cured at 70oC for 2 hours. In this study commercial and synthetic SiC were used as aggregate to produce composite structure. Synthetic SiC was produced from rice husk ash and coconut shell carbon calcined at 750oC for 2 hours. The addition of SiC in geopolymers paste was varied from 0.25g, 0.50g to 0.75g to form geopolymers composites. The chemical compositions and crystallinity level of SiC and the resulting composites were measured by means of Rigaku MiniFlexII X-Ray Diffraction (XRD). The microstructure of SiC and the composites were examined by using Tescan Vega3SB Scanning Electron Microscopy (SEM). The physical and mechanical properties of the samples were determined based on apparent porosity, bulk density, and three bending flexural strength measurements. The results showed that the commercial and synthetic SiC were effectively produced geopolymers composites with different microstructure, physical and mechanical strength.

Fly ash in landfill top covers - a review.

PubMed

Brännvall, E; Kumpiene, J

2016-01-01

Increase of energy recovery from municipal solid waste by incineration results in the increased amounts of incineration residues, such as fly ash, that have to be taken care of. Material properties should define whether fly ash is a waste or a viable resource to be used for various applications. Here, two areas of potential fly ash application are reviewed: the use of fly ash in a landfill top cover either as a liner material or as a soil amendment in vegetation layer. Fly ashes from incineration of three types of fuel are considered: refuse derived fuel (RDF), municipal solid waste incineration (MSWI) and biofuel. Based on the observations, RDF and MSWI fly ash is considered as suitable materials to be used in a landfill top cover liner. Whereas MSWI and biofuel fly ashes based on element availability for plant studies, could be considered suitable for the vegetation layer of the top cover. Responsible application of MSWI ashes is, however, warranted in order to avoid element accumulation in soil and elevation of background values over time.

Geochemically structural characteristics of municipal solid waste incineration fly ash particles and mineralogical surface conversions by chelate treatment.

PubMed

Kitamura, Hiroki; Sawada, Takaya; Shimaoka, Takayuki; Takahashi, Fumitake

2016-01-01

Leaching behaviors of heavy metals contained in municipal solid waste incineration (MSWI) fly ash have been studied well. However, micro-characteristics of MSWI fly ash particles are still uncertain and might be non-negligible to describe their leaching behaviors. Therefore, this study investigated micro-characteristics of MSWI fly ash particles, especially their structural properties and impacts of chelate treatment on surface characteristics. According to SEM observations, raw fly ash particles could be categorized into four types based on their shapes. Because chelate treatment changed the surface of fly ash particles dramatically owing to secondary mineral formations like ettringite, two more types could be categorized for chelate-treated fly ash particles. Acid extraction experiments suggest that fly ash particles, tested in this study, consist of Si-base insoluble core structure, Al/Ca/Si-base semi-soluble matrices inside the body, and KCl/NaCl-base soluble aggregates on the surface. Scanning electron microscope (SEM) observations of the same fly ash particles during twice moistening treatments showed that KCl/NaCl moved under wet condition and concentrated at different places on the particle surface. However, element mobility depended on secondary mineral formations. When insoluble mineral like gypsum was generated and covered the particle surface, it inhibited element transfer under wet condition. Surface characteristics including secondary mineral formation of MSWI fly ash particles are likely non-negligible to describe trace element leaching behaviors.

Greener durable concretes through geopolymerisation of blast furnace slag

NASA Astrophysics Data System (ADS)

Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

2015-05-01

The eco-friendliness of concrete is quantified by parameters such as ‘embodied energy’ (EE) and ‘embodied CO2 emission’ (ECO2e), besides duration of designed ‘service life’. It may be noted that ECO2e is also referred as carbon footprint (CF) in the literature. Geopolymer (GP) is an inorganic polymeric gel, a type of amorphous alumino-silicate product, which can be synthesised by polycondensation reactions. The concrete reported in this paper was prepared using industrial wastes in the form of blast furnace slag, fly ash as geopolymeric source materials and sodium silicate and sodium hydroxide as activators. Many mechanical properties such as compressive strength, chloride diffusion, steel corrosion, rapid chloride permeability test and rapid migration test are compared with Portland cement.

Geopolymers based on the valorization of Municipal Solid Waste Incineration residues

NASA Astrophysics Data System (ADS)

Giro-Paloma, J.; Maldonado-Alameda, A.; Formosa, J.; Barbieri, L.; Chimenos, J. M.; Lancellotti, I.

2017-10-01

The proper management of Municipal Solid Waste (MSW) has become one of the main environmental commitments for developed countries due to the uncontrolled growth of waste caused by the consumption patterns of modern societies. Nowadays, municipal solid waste incineration (MSWI) is one of the most feasible solutions and it is estimated to increase in Europe where the accessibility of landfill is restricted. Bottom ash (BA) is the most significant by-product from MSWI as it accounts for 85 - 95 % of the solid product resulting from combustion, which is classified as a non-hazardous residue that can be revalorized as a secondary aggregate in road sub-base, bulk lightweight filler in construction. In this way, revalorization of weathered BA (WBA) for the production of geopolymers may be a good alternative to common reuse as secondary aggregate material; however, the chemical process to obtain these materials involves several challenges that could disturb the stability of the material, mainly from the environmental point of view. Accordingly, it is necessary that geopolymers are able to stabilize heavy metals contained in the WBA in order to be classified as non-hazardous materials. In this regard, the SiO2/Al2O3 ratio plays an important role for the encapsulation of heavy metals and other toxic elements. The aim of this research is to formulate geopolymers starting from the 0 - 2 mm particle size fraction of WBA, as a unique raw material used as aluminumsilicate precursor. Likewise, leaching tests of the geopolymers formulated were performed to assess their environmental impact. The findings show that it is possible to formulate geopolymers using 100 % WBA as precursor, although more investigations are needed to sustain that geopolymer obtained can be considered as non-hazardous materials.

Eco-friendly fly ash utilization: potential for land application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malik, A.; Thapliyal, A.

2009-07-01

The increase in demand for power in domestic, agricultural, and industrial sectors has increased the pressure on coal combustion and aggravated the problem of fly ash generation/disposal. Consequently the research targeting effective utilization of fly ash has also gained momentum. Fly ash has proved to be an economical substitute for expensive adsorbents as well as a suitable raw material for brick manufacturing, zeolite synthesis, etc. Fly ash is a reservoir of essential minerals but is deficient in nitrogen and phosphorus. By amending fly ash with soil and/or various organic materials (sewage sludge, bioprocess materials) as well as microbial inoculants likemore » mycorrhizae, enhanced plant growth can be realized. Based on the sound results of large scale studies, fly ash utilization has grown into prominent discipline supported by various internationally renowned organizations. This paper reviews attempts directed toward various utilization of fly ash, with an emphasis on land application of organic/microbial inoculants amended fly ash.« less

CO₂ carbonation under aqueous conditions using petroleum coke combustion fly ash.

PubMed

González, A; Moreno, N; Navia, R

2014-12-01

Fly ash from petroleum coke combustion was evaluated for CO2 capture in aqueous medium. Moreover the carbonation efficiency based on different methodologies and the kinetic parameters of the process were determined. The results show that petroleum coke fly ash achieved a CO2 capture yield of 21% at the experimental conditions of 12 g L(-1), 363°K without stirring. The carbonation efficiency by petroleum coke fly ash based on reactive calcium species was within carbonation efficiencies reported by several authors. In addition, carbonation by petroleum coke fly ash follows a pseudo-second order kinetic model. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structure, properties, and surfactant adsorption behavior of fly ash carbon

NASA Astrophysics Data System (ADS)

Kulaots, Indrek

The objective of this research was to suggest methods by which certain problems associated with use of coal fly ash as a pozzolanic agent in concrete mixtures could be alleviated, guided by a better characterization of fly ash properties. A sample suite of eighty fly ashes was gathered from utilities across the world (mainly US-based) and included ashes from coals ranging in rank from bituminous to lignite. The widely used foam index test is used to characterize ashes with respect to their propensity to adsorb surfactants (called Air Entraining Admixtures or AEAs) used to impart freeze-thaw resistance to concrete. In ash-containing concrete mixtures, AEAs are adsorbed from the polar concrete-water solution onto non-polar unburned carbon surfaces in the ash. The AEA uptake by fly ashes only crudely correlates with the amount of carbon in the fly ash, because carbon surface area, accessibility and polarity all play a role in determining adsorption capacities. Fly ash carbon particle size distribution is also a key factor. Fine carbon particles in fly ash fractions of <106mum are responsible for about 90% of surfactant adsorption capacity. Surfactant adsorption on fly ash carbon is, in the foam index test, a dynamic process. The time of the test (typically <10 minutes) is not long enough to permit penetration of small porosity by the relatively large AEA molecules, and only the most readily available adsorption surface near the geometrical surface of the carbon particles is utilized. The nature of the foam index test was also examined, and it is recommended that a more standardized test procedure based upon pure reagents be adopted for examining the nature of fly ashes. Several possible reagents were identified. Room temperature fly ash ozonation is a powerful technique that allows increasing fly ash surface polarity in a relatively short time and thus is very effective for decreasing the AEA uptake capacity. Depending on the ozone input concentration, sample amount and contact time, surfactant uptake capacity decreases by a factor of two or more following reaction of only 0--1g O3/kg-ash, bringing many ashes into compliance with AEA uptake requirements.

Stabilization of chromium-bearing electroplating sludge with MSWI fly ash-based Friedel matrices.

PubMed

Qian, Guangren; Yang, Xiaoyan; Dong, Shixiang; Zhou, Jizhi; Sun, Ying; Xu, Yunfeng; Liu, Qiang

2009-06-15

This work investigated the feasibility and effectiveness of MSWI fly ash-based Friedel matrices on stabilizing/solidifying industrial chromium-bearing electroplating sludge using MSWI fly ash as the main raw material with a small addition of active aluminum. The compressive strength, leaching behavior and chemical speciation of heavy metals and hydration phases of matrices were characterized by TCLP, XRD, FTIR and other experimental methods. The results revealed that MSWI fly ash-based Friedel matrices could effectively stabilize chromium-bearing electroplating sludge, the formed ettringite and Friedel phases played a significant role in the fixation of heavy metals in electroplating sludge. The co-disposal of chromium-bearing electroplating sludge and MSWI fly ash-based Friedel matrices with a small addition of active aluminum is promising to be an effective way of stabilizing chromium-bearing electroplating sludge.

Gypsum treated fly ash as a liner for waste disposal facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivapullaiah, Puvvadi V., E-mail: siva@civil.iisc.ernet.in; Baig, M. Arif Ali, E-mail: reach2arif@gmail.com

2011-02-15

Fly ash has potential application in the construction of base liners for waste containment facilities. While most of the fly ashes improve in the strength with curing, the ranges of permeabilities they attain may often not meet the basic requirement of a liner material. An attempt has been made in the present context to reduce the hydraulic conductivity by adding lime content up to 10% to two selected samples of class F fly ashes. The use of gypsum, which is known to accelerate the unconfined compressive strength by increasing the lime reactivity, has been investigated in further improving the hydraulicmore » conductivity. Hydraulic conductivities of the compacted specimens have been determined in the laboratory using the falling head method. It has been observed that the addition of gypsum reduces the hydraulic conductivity of the lime treated fly ashes. The reduction in the hydraulic conductivity of the samples containing gypsum is significantly more for samples with high amounts of lime contents (as high as 1000 times) than those fly ashes with lower amounts of lime. However there is a relatively more increase in the strengths of the samples with the inclusion of gypsum to the fly ashes at lower lime contents. This is due to the fact that excess lime added to fly ash is not effectively converted into pozzolanic compounds. Even the presence of gypsum is observed not to activate these reactions with excess lime. On the other hand the higher amount of lime in the presence of sulphate is observed to produce more cementitious compounds which block the pores in the fly ash. The consequent reduction in the hydraulic conductivity of fly ash would be beneficial in reducing the leachability of trace elements present in the fly ash when used as a base liner.« less

Mechanical and Microstructural Evaluations of Lightweight Aggregate Geopolymer Concrete before and after Exposed to Elevated Temperatures

PubMed Central

Abdulkareem, Omar A.; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Ismail, Khairul Nizar; Binhussain, Mohammed

2013-01-01

This paper presents the mechanical and microstructural characteristics of a lightweight aggregate geopolymer concrete (LWAGC) synthesized by the alkali-activation of a fly ash source (FA) before and after being exposed to elevated temperatures, ranging from 100 to 800 °C. The results show that the LWAGC unexposed to the elevated temperatures possesses a good strength-to-weight ratio compared with other LWAGCs available in the published literature. The unexposed LWAGC also shows an excellent strength development versus aging times, up to 365 days. For the exposed LWAGC to the elevated temperatures of 100 to 800 °C, the results illustrate that the concretes gain compressive strength after being exposed to elevated temperatures of 100, 200 and 300 °C. Afterward, the strength of the LWAGC started to deteriorate and decrease after being exposed to elevated temperatures of 400 °C, and up to 800 °C. Based on the mechanical strength results of the exposed LWAGCs to elevated temperatures of 100 °C to 800 °C, the relationship between the exposure temperature and the obtained residual compressive strength is statistically analyzed and achieved. In addition, the microstructure investigation of the unexposed LWAGC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ). However, this bonding is subjected to deterioration as the LWAGC is exposed to elevated temperatures of 400, 600 and 800 °C by increasing the microcrack content and swelling of the unreacted silicates. PMID:28788339

Mechanical and Microstructural Evaluations of Lightweight Aggregate Geopolymer Concrete before and after Exposed to Elevated Temperatures.

PubMed

Abdulkareem, Omar A; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Ismail, Khairul Nizar; Binhussain, Mohammed

2013-10-09

This paper presents the mechanical and microstructural characteristics of a lightweight aggregate geopolymer concrete (LWAGC) synthesized by the alkali-activation of a fly ash source (FA) before and after being exposed to elevated temperatures, ranging from 100 to 800 °C. The results show that the LWAGC unexposed to the elevated temperatures possesses a good strength-to-weight ratio compared with other LWAGCs available in the published literature. The unexposed LWAGC also shows an excellent strength development versus aging times, up to 365 days. For the exposed LWAGC to the elevated temperatures of 100 to 800 °C, the results illustrate that the concretes gain compressive strength after being exposed to elevated temperatures of 100, 200 and 300 °C. Afterward, the strength of the LWAGC started to deteriorate and decrease after being exposed to elevated temperatures of 400 °C, and up to 800 °C. Based on the mechanical strength results of the exposed LWAGCs to elevated temperatures of 100 °C to 800 °C, the relationship between the exposure temperature and the obtained residual compressive strength is statistically analyzed and achieved. In addition, the microstructure investigation of the unexposed LWAGC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ). However, this bonding is subjected to deterioration as the LWAGC is exposed to elevated temperatures of 400, 600 and 800 °C by increasing the microcrack content and swelling of the unreacted silicates.

Potential use of fly ash to soil treatment in the Morava region

NASA Astrophysics Data System (ADS)

Bulíková, Lucia; Kresta, František; Rochovanský, Martin

2017-09-01

Soil treatment by binders is a standard technology and leads to optimal utilization of excavated soils in road constructions. Soil treatment is controlled in the Czech Republic by EN 14227-15 and Technical Requirement TP 94. Soil treatment using fly ash has not been performed in the Czech Republic, although there is a sufficient normative base. Fly ash produced by burning of hard coal in the Moravian region was tested as a potential binder. Fly ash samples were mixed with loess loams (CI). Tested siliceous fly ash of class F (ASTM C618) did not showed hydraulic properties but it showed positive effect on reducing maximum dry density of mixtures, increasing the IBI value (Immediate bearing index) and decreasing tendency to volume changes when the amount of fly ash was increased. The results of laboratory tests demonstrate the possibility of using fly ashes as a binder for soil treatment.

Evaluation of fly ash in lean Portland Cement Concrete base "Econocrete".

DOT National Transportation Integrated Search

1986-08-01

Fly ash was used in this evaluation study to replace 30, 50 and 70 : percent of the 400 1bs. of cement currently used in each cu. yd. of : portland cement econocrete base paving mix. : Two Class "c" ashes and one Class "F" ash from Iowa approved sour...

Synthesis and characterization of grinding aid fly ash blended mortar effect on bond strength of masonry prisms

NASA Astrophysics Data System (ADS)

Krishnaraj, L.; Ravichandran, P. T.; Sagadevan, Suresh

2018-04-01

The aim of the present work is to study the effect of particle size reduction by applying top-down nanotechnology such as ball mill grinding process with the addition of amine-based grinding aids. The particle size reduction in synthesis process and its characterization were investigated for fly ash particles. The Rosin-Rammler-Bennet (RRB) distribution model using mathematical formulations were studied for fly ash ground particles. The hardened properties of grinding aid fly ash composite mortar were studied using compressive strength test. The optimum grinding time was 120 min identified through the particle size distribution analysis. The mean particle size decreased from 92.09 μm to 10.5 μm in which there is 89% reduction in particle size due to the grinding of fly ash particle with grinding aids. The compressive strength results show that substitutions of Ordinary Portland Cement (OPC) mortar by Amine-based Grinding aid Fly Ash (AGFA) 15% gives 12, 23% and at 30% gives 6, 8% of higher strength compare to the substitutions of raw fly ash. The addition of grinding aids in grinding process gives more advantages to reduce the particle size without changing chemical composition. The AGFA sample shows better performance in compressive strength and bond strength behavior of masonry prism. It may suggest that amine based grinding aids play a vital role and feasible to use in fly ash grinding process.

Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated carbonation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernal, Susan A., E-mail: s.bernal@sheffield.ac.uk; Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD; Provis, John L., E-mail: j.provis@sheffield.ac.uk

2013-11-15

Binders formed through alkali-activation of slags and fly ashes, including ‘fly ash geopolymers’, provide appealing properties as binders for low-emissions concrete production. However, the changes in pH and pore solution chemistry induced during accelerated carbonation testing provide unrealistically low predictions of in-service carbonation resistance. The aluminosilicate gel remaining in an alkali-activated slag system after accelerated carbonation is highly polymerised, consistent with a decalcification mechanism, while fly ash-based binders mainly carbonate through precipitation of alkali salts (bicarbonates at elevated CO{sub 2} concentrations, or carbonates under natural exposure) from the pore solution, with little change in the binder gel identifiable by nuclearmore » magnetic resonance spectroscopy. In activated fly ash/slag blends, two distinct gels (C–A–S–H and N–A–S–H) are formed; under accelerated carbonation, the N–A–S–H gel behaves comparably to fly ash-based systems, while the C–A–S–H gel is decalcified similarly to alkali-activated slag. This provides new scope for durability optimisation, and for developing appropriate testing methodologies. -- Highlights: •C-A-S-H gel in alkali-activated slag decalcifies during accelerated carbonation. •Alkali-activated fly ash gel changes much less under CO{sub 2} exposure. •Blended slag-fly ash binder contains two coexisting gel types. •These two gels respond differently to carbonation. •Understanding of carbonation mechanisms is essential in developing test methods.« less

Updating Physical and Chemical Characteristics of Fly Ash for Use in Concrete

DOT National Transportation Integrated Search

2017-12-22

When incorporated in concrete mixtures, fly ashes are known to influence both its fresh and hardened properties. An accurate and quick technique to predict the extent of this influence based on the characteristics of fly ash would be highly beneficia...

Fly ash based zeolitic pigments for application in anticorrosive paints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, Ruchi, E-mail: shawruchi1@gmail.com; Tiwari, Sangeeta, E-mail: stiwari2@amity.edu

2016-04-13

The purpose of this work is to evaluate the utilization of waste fly ash in anticorrosive paints. Zeolite NaY was synthesized from waste fly ash and subsequently modified by exchanging its nominal cation Na{sup +} with Mg{sup 2+} and Ca{sup 2+} ions. The metal ion exchanged zeolite was then used as anticorrosive zeolitic pigments in paints. The prepared zeolite NaY was characterized using X-Ray diffraction technique and Scanning electron microscopy. The size, shape and density of the prepared fly ash based pigments were determined by various techniques. The paints were prepared by using fly ash based zeolitic pigments in epoxymore » resin and the percentages of pigments used in paints were 2% and 5%. These paints were applied to the mild steel panels and the anticorrosive properties of the pigments were assessed by the electrochemical spectroscopy technique (EIS).« less

Comparative Study on Synergetic Degradation of a Reactive Dye Using Different Types of Fly Ash in Combined Adsorption and Photocatalysis

NASA Astrophysics Data System (ADS)

Giri Babu, P. V. S.; Swaminathan, G.

2016-09-01

A comprehensive study was carried out on four different fly ashes used as a catalyst for the degradation of Acid Red 1 using ultraviolet rays. These fly ashes are collected from different thermal power stations located at various places in India and having different chemical compositions. Three fly ashes are from lignite-based thermal power plants, and one is from the coal-based power plant. One fly ash is classified as Class F, two fly ashes are classified as Class C and remaining one is not conforming to ASTM C618 classification. X-Ray Fluorescence analysis was used to identify the chemical composition of fly ashes and SiO2, Al2O3, CaO, Fe2O3 and TiO2 were found to be the major elements present in different proportions. Various analysis were carried out on all the fly ashes like Scanning Electron Microscopy to identify the microphysical properties, Energy Dispersive X-Ray spectroscopy to quantify the elements present in the catalyst and X-Ray Diffraction to identify the catalyst phase analysis. The radical generated during the reaction was identified by Electron paramagnetic resonance spectroscopy. The parameters such as initial pH of the dye solution, catalyst dosage and initial dye concentration which influence the dye degradation efficiency were studied and optimised. In 60 min duration, the dye degradation efficiency at optimum parametric values of pH 2.5, initial dye concentration of 10 mg/L and catalyst dosage of 1.0 g/L using various fly ashes, i.e., Salam Power Plant, Barmer Lignite Power Plant, Kutch Lignite Power Plant and Neyveli Lignite Thermal Power plant (NLTP) were found to be 40, 60, 67 and 95 % respectively. The contribution of adsorption alone was 18 % at the above mentioned optimum parametric values. Among the above four fly ash NLTP fly ashes proved to be most efficient.

Relation between leaching characteristics of heavy metals and physical properties of fly ashes from typical municipal solid waste incinerators.

PubMed

Ni, Peng; Li, Hailong; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

2017-09-01

Due to the alkalinity and high concentration of potentially hazardous heavy metals, fly ash from a municipal solid waste (MSW) incinerator is classified as hazardous waste, which should be of particular concern. Physical and chemical characterizations of the contrasted fly ashes were investigated to explore the relation between leaching characteristics of heavy metals and physical properties of fly ashes. The results showed that CaClOH, NaCl, Ca(OH) 2 , KCl and SiO 2 were primary mineral compositions in the MSWI fly ashes, and the particle size distribution of fly ash ranged between 10 μm and 300 μm. The smaller the particle size distribution of fly ash, the larger the BET-specific surface area, which was beneficial to the leaching of heavy metals. As a result of various pores, it easily accumulated heavy metals as well. The leaching tests exhibited a high leachability of heavy metals and the leaching concentration of Pb in almost all of the fly ash samples went far beyond the Standard for Pollution Control on the Landfill Site of Municipal Solid Waste. Thereupon, it is necessary to establish proper disposal systems and management strategies for environmental protection based on the characteristics of MSW incineration (MSWI) fly ash in China.

Construction procedures using self hardening fly ash

NASA Astrophysics Data System (ADS)

Thornton, S. I.; Parker, D. G.

1980-07-01

Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

Trends in the Rare Earth Element Content of U.S.-Based Coal Combustion Fly Ashes.

PubMed

Taggart, Ross K; Hower, James C; Dwyer, Gary S; Hsu-Kim, Heileen

2016-06-07

Rare earth elements (REEs) are critical and strategic materials in the defense, energy, electronics, and automotive industries. The reclamation of REEs from coal combustion fly ash has been proposed as a way to supplement REE mining. However, the typical REE contents in coal fly ash, particularly in the United States, have not been comprehensively documented or compared among the major types of coal feedstocks that determine fly ash composition. The objective of this study was to characterize a broad selection of U.S. fly ashes of varied geological origin in order to rank their potential for REE recovery. The total and nitric acid-extractable REE content for more than 100 ash samples were correlated with characteristics such as the major element content and coal basin to elucidate trends in REE enrichment. Average total REE content (defined as the sum of the lanthanides, yttrium, and scandium) for ashes derived from Appalachian sources was 591 mg kg(-1) and significantly greater than in ashes from Illinois and Powder River basin coals (403 and 337 mg kg(-1), respectively). The fraction of critical REEs (Nd, Eu, Tb, Dy, Y, and Er) in the fly ashes was 34-38% of the total and considerably higher than in conventional ores (typically less than 15%). Powder River Basin ashes had the highest extractable REE content, with 70% of the total REE recovered by heated nitric acid digestion. This is likely due to the higher calcium content of Powder River Basin ashes, which enhances their solubility in nitric acid. Sc, Nd, and Dy were the major contributors to the total REE value in fly ash, based on their contents and recent market prices. Overall, this study shows that coal fly ash production could provide a substantial domestic supply of REEs, but the feasibility of recovery depends on the development of extraction technologies that could be tailored to the major mineral content and origins of the feed coal for the ash.

Effect of Solids-To-Liquids, Na2SiO3-To-NaOH and Curing Temperature on the Palm Oil Boiler Ash (Si + Ca) Geopolymerisation System

PubMed Central

Yahya, Zarina; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Ismail, Khairul Nizar; Abd Razak, Rafiza; Sandu, Andrei Victor

2015-01-01

This paper investigates the effect of the solids-to-liquids (S/L) and Na2SiO3/NaOH ratios on the production of palm oil boiler ash (POBA) based geopolymer. Sodium silicate and sodium hydroxide (NaOH) solution were used as alkaline activator with a NaOH concentration of 14 M. The geopolymer samples were prepared with different S/L ratios (0.5, 1.0, 1.25, 1.5, and 1.75) and Na2SiO3/NaOH ratios (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0). The main evaluation techniques in this study were compressive strength, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The results showed that the maximum compressive strength (11.9 MPa) was obtained at a S/L ratio and Na2SiO3/NaOH ratio of 1.5 and 2.5 at seven days of testing.

Leaching characteristics of fly ash from thermal power plants of Soma and Tuncbilek, Turkey.

PubMed

Baba, Alper; Kaya, Abidin

2004-02-01

Use of lignite in power generation has led to increasing environmental problems associated not only with gaseous emissions but also with the disposal of ash residues. In particular, use of low quality coal with high ash content results in huge quantities of fly ash to be disposed of. The main problem related to fly ash disposal is the heavy metal content of the residue. In this regard, experimental results of numerous studies indicate that toxic trace metals may leach when fly ash contacts water. In this study, fly ash samples obtained from thermal power plants, namely Soma and Tunçbilek, located at the west part of Turkey, were subjected to toxicity tests such as European Committee for standardization (CEN) and toxicity characteristic leaching (TCLP) procedures of the U.S. Environmental Protection Agency (U.S. EPA). The geochemical composition of the tested ash samples from the power plant show variations depending on the coal burned in the plants. Furthermore, the CEN and TCLP extraction results showed variations such that the ash samples were classified as 'toxic waste' based on TCLP result whereas they were classified as 'non-toxic' wastes based on CEN results, indicating test results are pH dependent.

Experimental and numerical analysis of metal leaching from fly ash-amended highway bases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cetin, Bora; Aydilek, Ahmet H., E-mail: aydilek@umd.edu; Li, Lin

2012-05-15

Highlights: Black-Right-Pointing-Pointer This study is the evaluation of leaching potential of fly ash-lime mixed soils. Black-Right-Pointing-Pointer This objective is met with experimental and numerical analysis. Black-Right-Pointing-Pointer Zn leaching decreases with increase in fly ash content while Ba, B, Cu increases. Black-Right-Pointing-Pointer Decrease in lime content promoted leaching of Ba, B and Cu while Zn increases. Black-Right-Pointing-Pointer Numerical analysis predicted lower field metal concentrations. - Abstract: A study was conducted to evaluate the leaching potential of unpaved road materials (URM) mixed with lime activated high carbon fly ashes and to evaluate groundwater impacts of barium, boron, copper, and zinc leaching. Thismore » objective was met by a combination of batch water leach tests, column leach tests, and computer modeling. The laboratory tests were conducted on soil alone, fly ash alone, and URM-fly ash-lime kiln dust mixtures. The results indicated that an increase in fly ash and lime content has significant effects on leaching behavior of heavy metals from URM-fly ash mixture. An increase in fly ash content and a decrease in lime content promoted leaching of Ba, B and Cu whereas Zn leaching was primarily affected by the fly ash content. Numerically predicted field metal concentrations were significantly lower than the peak metal concentrations obtained in laboratory column leach tests, and field concentrations decreased with time and distance due to dispersion in soil vadose zone.« less

Determination of the elastic modulus of fly ash-based stabilizer applied in the trackbed

NASA Astrophysics Data System (ADS)

Lojda, Vít; Lidmila, Martin; Pýcha, Marek

2017-09-01

This paper describes a unique application of a fly ash-based stabilizer in the trackbed of a railway main line. The key goals of the stabilizer application are to protect the subgrade against the ingress of rain water, to increase the frost resistance and to remediate the natural ground constituted of weathered rock. The stabilizer was designed as a mixture of fly ash, generated as a waste material from coal plants, gypsum, calcium oxide and water. The mixture recipe was developed in a laboratory over several years. In 2005, a trial section of a railway line with subgrade consisting of clay limestone (weathered marlite) was built in the municipality of Smiřice. Since then, periodical measurements including collection of samples for laboratory evaluation of the fly ash-based stabilizer have taken place. Over the time span of the measurements, changes in mineral composition and development of fly ash transforming structures leading to the formation of C-A-S-H gel were detected. This paper describes the experimental laboratory investigation of the influence of dynamic loading on the elastic modulus of fly ash stabilizer samples and the development of permanent deformation of the samples with increasing number of loading cycles.

The effect of different parameters on the development of compressive strength of oil palm shell geopolymer concrete.

PubMed

Kupaei, Ramin Hosseini; Alengaram, U Johnson; Jumaat, Mohd Zamin

2014-01-01

This paper presents the experimental results of an on-going research project on geopolymer lightweight concrete using two locally available waste materials--low calcium fly ash (FA) and oil palm shell (OPS)--as the binder and lightweight coarse aggregate, respectively. OPS was pretreated with three different alkaline solutions of sodium hydroxide (NaOH), potassium hydroxide, and sodium silicate as well as polyvinyl alcohol (PVA) for 30 days; afterwards, oil palm shell geopolymer lightweight concrete (OPSGPC) was cast by using both pretreated and untreated OPSs. The effect of these solutions on the water absorption of OPS, and the development of compressive strength in different curing conditions of OPSGPC produced by pretreated OPS were investigated; subsequently the influence of NaOH concentration, alkaline solution to FA ratio (A/FA), and different curing regimes on the compressive strength and density of OPSGPC produced by untreated OPS was inspected. The 24-hour water absorption value for OPS pretreated with 20% and 50% PVA solution was about 4% compared to 23% for untreated OPS. OPSGPC produced from OPS treated with 50% PVA solution produced the highest compressive strength of about 30 MPa in ambient cured condition. The pretreatment with alkaline solution did not have a significant positive effect on the water absorption of OPS aggregate and the compressive strength of OPSGPC. The result revealed that a maximum compressive strength of 32 MPa could be obtained at a temperature of 65°C and curing period of 4 days. This investigation also found that an A/FA ratio of 0.45 has the optimum amount of alkaline liquid and it resulted in the highest level of compressive strength.

The Effect of Different Parameters on the Development of Compressive Strength of Oil Palm Shell Geopolymer Concrete

PubMed Central

Kupaei, Ramin Hosseini; Alengaram, U. Johnson; Jumaat, Mohd Zamin

2014-01-01

This paper presents the experimental results of an on-going research project on geopolymer lightweight concrete using two locally available waste materials—low calcium fly ash (FA) and oil palm shell (OPS)—as the binder and lightweight coarse aggregate, respectively. OPS was pretreated with three different alkaline solutions of sodium hydroxide (NaOH), potassium hydroxide, and sodium silicate as well as polyvinyl alcohol (PVA) for 30 days; afterwards, oil palm shell geopolymer lightweight concrete (OPSGPC) was cast by using both pretreated and untreated OPSs. The effect of these solutions on the water absorption of OPS, and the development of compressive strength in different curing conditions of OPSGPC produced by pretreated OPS were investigated; subsequently the influence of NaOH concentration, alkaline solution to FA ratio (A/FA), and different curing regimes on the compressive strength and density of OPSGPC produced by untreated OPS was inspected. The 24-hour water absorption value for OPS pretreated with 20% and 50% PVA solution was about 4% compared to 23% for untreated OPS. OPSGPC produced from OPS treated with 50% PVA solution produced the highest compressive strength of about 30 MPa in ambient cured condition. The pretreatment with alkaline solution did not have a significant positive effect on the water absorption of OPS aggregate and the compressive strength of OPSGPC. The result revealed that a maximum compressive strength of 32 MPa could be obtained at a temperature of 65°C and curing period of 4 days. This investigation also found that an A/FA ratio of 0.45 has the optimum amount of alkaline liquid and it resulted in the highest level of compressive strength. PMID:25531006

Leaching characteristics of toxic constituents from coal fly ash mixed soils under the influence of pH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Komonweeraket, Kanokwan; Cetin, Bora, E-mail: bora.cetin@sdsmt.edu; Benson, Craig H., E-mail: chbenson@wisc.edu

Highlights: • The impact of pH on the leaching of elements and metals from fly ash mixed soils. • Generally Ca, Cd, Mg, and Sr follows a cationic leaching pattern. • The leaching of As and Se shows an oxyanionic leaching pattern. • The leaching behavior of elements does not change based on material type. • Different fly ash types show different abilities in immobilizing trace elements. - Abstract: Leaching behaviors of Arsenic (As), Barium (Ba), Calcium (Ca), Cadmium (Cd), Magnesium (Mg), Selenium (Se), and Strontium (Sr) from soil alone, coal fly ash alone, and soil-coal fly ash mixtures, weremore » studied at a pH range of 2–14 via pH-dependent leaching tests. Seven different types of soils and coal fly ashes were tested. Results of this study indicated that Ca, Cd, Mg, and Sr showed cationic leaching pattern while As and Se generally follows an oxyanionic leaching pattern. On the other hand, leaching of Ba presented amphoteric-like leaching pattern but less pH-dependent. In spite of different types and composition of soil and coal fly ash investigated, the study reveals the similarity in leaching behavior as a function of pH for a given element from soil, coal fly ash, and soil-coal fly ash mixtures. The similarity is most likely due to similar controlling mechanisms (e.g., solubility, sorption, and solid-solution formation) and similar controlling factors (e.g., leachate pH and redox conditions). This offers the opportunity to transfer knowledge of coal fly ash that has been extensively characterized and studied to soil stabilized with coal fly ash. It is speculated that unburned carbon in off-specification coal fly ashes may provide sorption sites for Cd resulting in a reduction in concentration of these elements in leachate from soil-coal fly ash mixture. Class C fly ash provides sufficient CaO to initiate the pozzolanic reaction yielding hydrated cement products that oxyanions, including As and Se, can be incorporated into.« less

Selenium in pollen gathered by bees foraging on fly ash-grown plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Jong, D.; Morse, R.A.; Gutenmann, W.H.

1977-10-01

Fly ash is the material collected in the stacks of coal burning electric power-generating plants by electrostatic precipitators. About 26 million metric tons of fly ash was estimated to have been produced in 1975 (BRACKETT, 1970). Aside from a small percentage of the material which is used as a base material for roads and in concrete, the bulk of it is deposited in landfills. It was first reported by Gutenmann et al. (1976) that sweet clover, found voluntarily growing on a fly ash landfill site, contained up to 200 ppM of selenium. Fly ashes from 21 states were found tomore » contain the element. Cabbage grown on each of these fly ashes added (7 percent w/w) to soil was shown to absorb selenium in proportion to its concentration in the particular ash (GUTENMANN et al., 1976). The percentage of fly ash in soil was also shown to dictate the extent of selenium absorption by a variety of plants (FURR et al., 1976). In the work reported, pollen collected by honey bees foraging on plants growing on a fly ash landfill was analyzed for selenium and compared with that collected by bees from the same plants growing on soil.« less

Recyclability of Concrete Pavement Incorporating High Volume of Fly Ash.

PubMed

Yoshitake, Isamu; Ishida, Takeo; Fukumoto, Sunao

2015-08-21

Recyclable concrete pavement was made from fly ash and crushed limestone sand and gravel as aggregates so that the concrete pavement could be recycled to raw materials for cement production. With the aim to use as much fly ash as possible for the sustainable development of society, while achieving adequate strength development, pavement concrete having a cement-replacement ratio of 40% by mass was experimentally investigated, focusing on the strength development at an early age. Limestone powder was added to improve the early strength; flexural strength at two days reached 3.5 MPa, the minimum strength for traffic service in Japan. The matured fly ash concrete made with a cement content of 200 kg/m3 achieved a flexural strength almost equal to that of the control concrete without fly ash. Additionally, Portland cement made from the tested fly ash concrete was tested to confirm recyclability, with the cement quality meeting the Japanese classification of ordinary Portland cement. Limestone-based recyclable fly ash concrete pavement is, thus, a preferred material in terms of sustainability.

Recyclability of Concrete Pavement Incorporating High Volume of Fly Ash

PubMed Central

Yoshitake, Isamu; Ishida, Takeo; Fukumoto, Sunao

2015-01-01

Recyclable concrete pavement was made from fly ash and crushed limestone sand and gravel as aggregates so that the concrete pavement could be recycled to raw materials for cement production. With the aim to use as much fly ash as possible for the sustainable development of society, while achieving adequate strength development, pavement concrete having a cement-replacement ratio of 40% by mass was experimentally investigated, focusing on the strength development at an early age. Limestone powder was added to improve the early strength; flexural strength at two days reached 3.5 MPa, the minimum strength for traffic service in Japan. The matured fly ash concrete made with a cement content of 200 kg/m3 achieved a flexural strength almost equal to that of the control concrete without fly ash. Additionally, Portland cement made from the tested fly ash concrete was tested to confirm recyclability, with the cement quality meeting the Japanese classification of ordinary Portland cement. Limestone-based recyclable fly ash concrete pavement is, thus, a preferred material in terms of sustainability. PMID:28793518

Biomass fly ash incorporation in cement based materials =

NASA Astrophysics Data System (ADS)

Rajamma, Rejini

In recent years, pressures on global environment and energy security have led to an increasing demand on renewable energy sources, and diversification of Europe's energy supply. Among these resources the biomass could exert an important role, since it is considered a renewable and CO2 neutral energy resource once the consumption rate is lower than the growth rate, and can potentially provide energy for heat, power and transports from the same installation. Currently, most of the biomass ash produced in industrial plants is either disposed of in landfill or recycled on agricultural fields or forest, and most times this goes on without any form of control. However, considering that the disposal cost of biomass ashes are raising, and that biomass ash volumes are increasing worldwide, a sustainable ash management has to be established. The main objective of the present study is the effect of biomass fly ashes in cement mortars and concretes in order to be used as a supplementary cementitious material. The wastes analyzed in the study were collected from the fluidized bed boilers and grate boilers available in the thermal power plants and paper pulp plants situated in Portugal. The physical as well as chemical characterisations of the biomass fly ashes were investigated. The cement was replaced by the biomass fly ashes in 10, 20 and 30% (weight %) in order to investigate the fresh properties as well as the hardened properties of biomass fly ash incorporated cement mortar and concrete formulations. Expansion reactions such as alkali silica reaction (ASR), sulphate attack (external and internal) were conducted in order to check the durability of the biomass fly ash incorporated cement mortars and concretes. Alternative applications such as incorporation in lime mortars and alkali activation of the biomass fly ashes were also attempted. The biomass fly ash particles were irregular in shape and fine in nature. The chemical characterization revealed that the biomass fly ashes were similar to a class C fly ash. The mortar results showed a good scope for biomass fly ashes as supplementary cementitious materials in lower dosages (<20%). The poor workability, concerns about the organic content, alkalis, chlorides and sulphates stand as the reasons for preventing the use of biomass fly ash in high content in the cement mortars. The results obtained from the durability tests have shown a clear reduction in expansion for the biomass fly ash mortars/concretes and the binder blend made with biomass fly ash (20%) and metakaolin (10%) inhibited the ASR reaction effectively. The biomass fly ash incorporation in lime mortars did not improve the mortar properties significantly though the carbonation was enhanced in the 15-20% incorporation. The biomass fly ash metakaolin blend worked well in the alkali activated complex binder application also. Portland cement free binders (with 30-40 MPa compressive strength) were obtained on the alkali activation of biomass fly ashes (60-80%) blended with metakaolin (20-40%).

The Impact of Coal Combustion Fly Ash Used as a Supplemental Cementitious Material on the Leaching of Constituents from Cements and Concretes

EPA Science Inventory

The objective of this report is to compare the leaching of portland cement-based materials that have been prepared with and without coal combustion fly ash to illustrate whether there is evidence that the use of fly ash in cement and concrete products may result in increased leac...

MEASUREMENT OF NATURAL RADIONUCLIDES AND EXTERNAL RADIATION EXPOSURE DUE TO FLY ASH FROM A COAL-FIRED POWER PLANT (SPAIN) DEPOSITED ON SOILS. COMPARISON USING TWO DIFFERENT MEASUREMENT TECHNIQUES.

PubMed

Corbacho, J A; Baeza, A

2018-05-17

The evaluation of the radiological impact in soils due to the fly-ash ponds using both in situ techniques and laboratory based measurements is presented. In order to check the in situ techniques capabilities for monitoring this type of industries, a comparison between both techniques was performed. A characterization of external radiation exposure in the fly-ash pond and in its surrounding soils was made. The associated external radiological hazard due to the fly-ash pond has been evaluated. In situ techniques could be used to determine the radiological impact on soils due to fly-ash deposition, but its use could be limited due to the associated uncertainties.

The secondary release of mercury in coal fly ash-based flue-gas mercury removal technology.

PubMed

He, Jingfeng; Duan, Chenlong; Lei, Mingzhe; Zhu, Xuemei

2016-01-01

The secondary release of mercury from coal fly ash is a negative by-product from coal-fired power plants, and requires effective control to reduce environmental pollution. Analysing particle size distribution and composition of the coal fly ash produced by different mercury removing technologies indicates that the particles are generally less than 0.5 mm in size and are composed mainly of SiO2, Al2O3, and Fe2O3. The relationships between mercury concentration in the coal fly ash, its particle size, and loss of ignition were studied using different mercury removing approaches. The research indicates that the coal fly ash's mercury levels are significantly higher after injecting activated carbon or brominating activated carbon when compared to regular cooperating-pollution control technology. This is particularly true for particle size ranges of >0.125, 0.075-0.125, and 0.05-0.075 mm. Leaching experiments revealed the secondary release of mercury in discarded coal fly ash. The concentration of mercury in the coal fly ash increases as the quantity of injecting activated carbon or brominating activated carbon increases. The leached concentrations of mercury increase as the particle size of the coal fly ash increases. Therefore, the secondary release of mercury can be controlled by adding suitable activated carbon or brominating activated carbon when disposing of coal fly ash. Adding CaBr2 before coal combustion in the boiler also helps control the secondary release of mercury, by increasing the Hg(2+) concentration in the leachate. This work provides a theoretical foundation for controlling and removing mercury in coal fly ash disposal.

Leachate concentrations from water leach and column leach tests on fly ash-stabilized soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bin-Shafique, S.; Benson, C.H.; Edil, T.B.

2006-01-15

Batch water leaching tests (WLTs) and column leaching tests (CLTs) were conducted on coal-combustion fly ashes, soil, and soil-fly ash mixtures to characterize leaching of Cd, Cr, Se, and Ag. The concentrations of these metals were also measured in the field at two sites where soft fine-grained soils were mechanically stabilized with fly ash. Concentrations in leachate from the WLTs on soil-fly ash mixtures are different from those on fly ash alone and cannot be accurately estimated based on linear dilution calculations using concentrations from WLTs on fly ash alone. The concentration varies nonlinearly with fly ash content due tomore » the variation in pH with fly ash content. Leachate concentrations are low when the pH of the leachate or the cation exchange capacity (CEC) of the soil is high. Initial concentrations from CLTs are higher than concentrations from WLTs due to differences in solid-liquid ratio, pH, and solid-liquid contact. However, both exhibit similar trends with fly ash content, leachate pH, and soil properties. Scaling factors can be applied to WLT concentrations (50 for Ag and Cd, 10 for Cr and Se) to estimate initial concentrations for CLTs. Concentrations in leachate collected from the field sites were generally similar or slightly lower than concentrations measured in CLTs on the same materials. Thus, CLTs appear to provide a good indication of conditions that occur in the field provided that the test conditions mimic the field conditions. In addition, initial concentrations in the field can be conservatively estimated from WLT concentrations using the aforementioned scaling factors provided that the pH of the infiltrating water is near neutral.« less

Basic characteristics of leachate produced by various washing processes for MSWI ashes in Taiwan.

PubMed

Yang, Renbo; Liao, Wing-Ping; Wu, Pin-Han

2012-08-15

Approximately 19.2% of Taiwan's municipal solid waste (MSW) that passes through incineration disposal is converted into ashes (including bottom ash and fly ash). Although bottom ash can pass nearly all of the standards of the toxicity characteristic leaching procedure (TCLP), its high chloride content makes its reuse limited; it generally cannot be used as a fine aggregate material in concrete applications. This research examined washing four types of bottom ash (BA) and fly ash (FA) with water to reduce their chloride content. The optimal water intensity for washing pretreated bottom ash was found to be 7-8L of water per kg of bottom ash, and the optimal water intensity for washing untreated fly ash was found to be 20-25 L of water per kg of fly ash. Based on regression analyses of the chloride concentrations of the leachates and their electrical conductivity (EC) values, each MSW incineration plant has its own ash characteristics as well as a specific regression line in bottom or fly ash leachate. Clearly, it is possible to monitor the EC values of the leachates online by estimation from regression equations to determine the chloride concentrations in the leachates. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Experimental Studies on Behaviour of Reinforced Geopolymer Concrete Beams Subjected to Monotonic Static Loading

NASA Astrophysics Data System (ADS)

Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Ramesh, G.

2015-06-01

This work describes the experimental investigation on behaviour of reinforced GPC beams subjected to monotonic static loading. The overall dimensions of the GPC beams are 250 mm × 300 mm × 2200 mm. The effective span of beam is 1600 mm. The beams have been designed to be critical in shear as per IS:456 provisions. The specimens were produced from a mix incorporating fly ash and ground granulated blast furnace slag, which was designed for a compressive strength of 40 MPa at 28 days. The reinforced concrete specimens are subjected to curing at ambient temperature under wet burlap. The parameters being investigated include shear span to depth ratio (a/d = 1.5 and 2.0). Experiments are conducted on 12 GPC beams and four OPCC control beams. All the beams are tested using 2000 kN servo-controlled hydraulic actuator. This paper presents the results of experimental studies.

Effect of Feed Forms on the Results of Melting of Fly Ash by a DC Plasma Arc Furnace

NASA Astrophysics Data System (ADS)

Chen, Mingzhou; Meng, Yuedong; Shi, Jiabiao; Ni, Guohua; Jiang, Yiman; Yu, Xinyao; ZHAO, Peng

2009-10-01

Fly ash from a municipal solid waste incinerator (MSWI) without preprocessing (original fly ash, OFA) was melted by a direct current (DC) plasma arc furnace to investigate how the feed forms governed the results. Dioxins in flue gas from stack and bag-filter ash (BFA) were detected. The distribution of heavy metals of Pb, Cd, As, and Cr along the flue gas process system was analyzed. Through a comparison of the results for dioxins and heavy metals in this study and previous work, carrying-over of fly ash particles with the flue gas stream can be deduced. Based on the magnetic induction equation and Navier-Stokes equations, a magnetohydrodynamic (MHD) model for the plasma arc was developed to describe the particle-carrying effect. The results indicate that, a. when melted, the feed forms of MSWI fly ash affect the results significantly; b. it is not preferable to melt MSWI fly ash directly, and efforts should be made to limit the mass transfer of OFA from the plasma furnace.

Kinetics of fly ash beneficiation by carbon burnout. [Quarterly report], October 1, 1995--January 30, 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodoo, J.N.; Okoh, J.M.; Yilmaz, E.

The objective is to investigate the kinetics of beneficiation of fly ash by carbon burnout. The three year project that was proposed is a joint venture between Delmarva Power, a power generating company on the eastern shore of Maryland, and the University of Maryland Eastern Shore. The studies have focused on the beneficiation of fly ash by carbon burnout. The increasing use of coal fly ash as pozzolanic material in Portland cement concrete means that there is the highest economic potential in marketability of large volumes of fly ash. For the concrete industry to consider large scale use the flymore » ash must be of the highest quality. This means that the residual carbon content of the fly ash must have an acceptable loss on ignition (LOI) value, usually between 7--2% residual carbon. The economic gains to be had from low-carbon ash is a fact that is generally accepted by the electricity generating companies. However, since the cost of producing low-carbon in large quantities, based on present technology, far outweighs any financial gains, no electrical power company using coal as its fuel at present considers the effort worthwhile. The concrete industry would use fly ash in cement concrete mix if it can be assured of its LOI value. At present no utility company would give such assurance. Hence with several million tons of fly ash produced by a single power plant per year all that can be done is to dump the fly ash in landfills. The kinetics of fly ash beneficiation have been investigated in the zone II kinetic regime, using a Cahn TG 121 microbalance in the temperature 550--750{degrees}C. The P{sub 02} and total surface area dependence of the reaction kinetics were determined using a vacuum accessory attached to the microbalance and a surface area analyzer (ASAP 2010), respectively.« less

Study on Strength Behavior of Organic Soil Stabilized with Fly Ash

PubMed Central

Molla, Md. Keramat Ali; Sarkar, Grytan

2017-01-01

The aim of this study is to investigate the effect of fly ash on the consistency, compactness, acidic properties, and strength of organic soil. The presence of organic content in the soil has detrimental impacts on the physical and strength behavior of soil. To investigate the effectiveness of fly ash in the stabilization of organic soil, two types of fly ashes (Type I and Type II) at different percentages were used. It is found that fly ash significantly reduces the plasticity index of the organic soil, whereas the liquid and plastic limits increase. The dry density of the fly ash-soil mixture increases significantly, while the water requirement reduces due to the addition of fly ash. The increase of dry density compromises higher strength. The increase of qu with the increase of fly ash content is mainly due to the pozzolanic reaction of fly ash, although the reduction in water content results from the addition of dry fly ash solid. Moreover, Type I fly ash contributes a higher value of qu compared to Type II fly ash. This is attributed to the characteristics of fly ash including CaO and CaO/SiO2 ratio. PMID:29085881

Properties of Fly Ash Blocks Made from Adobe Mould

NASA Astrophysics Data System (ADS)

Chokhani, Alankrit; Divakar, B. S.; Jawalgi, Archana S.; Renukadevi, M. V.; Jagadish, K. S.

2018-02-01

Fly ash being one of the industrial waste products poses a serious disposal problem. This paper presents an experimental study of utilization of fly ash to produce blocks with varying proportions and mix combinations. Composition of fly ash blocks mainly consist of fly ash and sand, with cementitious product as either cement, lime or both, such as fly ash-sand-cement, fly ash-sand-lime and fly ash-sand-cement-lime are used. Four different proportions for each of the mix combinations are experimented. Compressive strength, water absorption, Initial rate of absorption, and dry density of fly ash blocks are studied. The influence of partial and complete replacement of cement by lime is examined.

Properties of Fly Ash Blocks Made from Adobe Mould

NASA Astrophysics Data System (ADS)

Chokhani, Alankrit; Divakar, B. S.; Jawalgi, Archana S.; Renukadevi, M. V.; Jagadish, K. S.

2018-06-01

Fly ash being one of the industrial waste products poses a serious disposal problem. This paper presents an experimental study of utilization of fly ash to produce blocks with varying proportions and mix combinations. Composition of fly ash blocks mainly consist of fly ash and sand, with cementitious product as either cement, lime or both, such as fly ash-sand-cement, fly ash-sand-lime and fly ash-sand-cement-lime are used. Four different proportions for each of the mix combinations are experimented. Compressive strength, water absorption, Initial rate of absorption, and dry density of fly ash blocks are studied. The influence of partial and complete replacement of cement by lime is examined.

Mechanical and Durability Properties of Fly Ash Based Concrete Exposed to Marine Environment

NASA Astrophysics Data System (ADS)

Kagadgar, Sarfaraz Ahmed; Saha, Suman; Rajasekaran, C.

2017-06-01

Efforts over the past few years for improving the performance of concrete suggest that cement replacement with mineral admixtures can enhance the strength and durability of concrete. Feasibility of producing good quality concrete by using alccofine and fly ash replacements is investigated and also the potential benefits from their incorporation were looked into. In this study, an attempt has been made to assess the performance of concrete in severe marine conditions exposed upto a period of 150 days. This work investigates the influence of alccofine and fly ash as partial replacement of cement in various percentages (Alccofine - 5% replacement to cement content) and (fly ash - 0%, 15%, 30%, 50% & 60% to total cementitious content) on mechanical and durability properties (Permit ion permeability test and corrosion current density) of concrete. Usage of alccofine and high quantity of fly ash as additional cementitious materials in concrete has resulted in higher workability of concrete. Inclusion of alccofine shows an early strength gaining property whereas fly ash results in gaining strength at later stage. Concrete mixes containing 5% alccofine with 15% fly ash replacement reported greater compressive strength than the other concrete mixes cured in both curing conditions. Durability test conducted at 56 and 150 days indicated that concrete containing higher percentages of fly ash resulted in lower permeability as well lesser corrosion density.

Chemical composition and physical properties of filter fly ashes from eight grate-fired biomass combustion plants.

PubMed

Lanzerstorfer, Christof

2015-04-01

For the handling, treatment and utilization of fly ash from biomass combustion its chemical composition and physical properties are important. In this study eight filter fly ashes from different grate-fired biomass combustion plants were investigated. In fly ash from straw combustion high concentrations of (K) were found, whereas in the fly ash from wood combustion the concentrations of Ca and Mg were higher. The average concentration of PO4(3-) was similar in both types of fly ashes. In all wood fly ashes some measured heavy metal concentrations were above the limits for utilization. The straw fly ashes were much less contaminated and can be utilized. For wood fly ash most parameters showed little variation, except from one fly ash where the dust pre-separator is in poor condition. The average values were: mass median diameter 4.3±0.8 μm, spread of particle size distribution 19±11, particle density 2620±80 kg/m3 and angle of repose 50°±1°. The density of the straw fly ashes is lower (2260±80 kg/m3) and the spread of the size distribution is higher (72±24). For one straw combustion fly ash the values of the mass median diameter and the angle of repose were similar to the values of wood combustion fly ash, for the other straw fly ash the values differed considerably. While the particle size of this fly ash was much smaller, surprisingly the angle of repose was also lower. This can be attributed to the formation of small agglomerates in this fly ash, which were not disintegrated without a certain stress. Copyright © 2015. Published by Elsevier B.V.

Synthesis of geopolymer from rice husk ash for biodiesel production of Calophyllum inophyllum seed oil

NASA Astrophysics Data System (ADS)

Saputra, E.; Nugraha, M. W.; Helwani, Z.; Olivia, M.; Wang, S.

2018-04-01

In this work, geopolymer was prepared from rice husk ash (RHA) made into sodium silicate then synthesized by reacting metakaolin, NaOH, and water. The catalyst was characterized using Scanning Electron Microscopy (SEM), Energy-dispersive X-Ray analysis (EDX), Brunaeur Emmet Teller (BET), and basic strength. Then, the catalyst used for transesterification of Calophyllum inophyllum seed oil in order to produce biodiesel. The variation of process variables conducted to assess the effect on the yield of biodiesel. The highest yield obtained 87.68% biodiesel with alkyl ester content 99.29%, density 866 kg/m3, viscosity 4.13 mm2/s, the acid number of 0.42 mg-KOH/g biodiesel and the flash point 140 °C. Generally, variations of %w/w catalyst provides a dominant influence on the yield response of biodiesel. The physicochemical properties of the produced biodiesel comply with ASTM standard specifications.

The role of fly-ash particulate material and oxide catalysts in stone degradation

NASA Astrophysics Data System (ADS)

Hutchinson, A. J.; Johnson, J. B.; Thompson, G. E.; Wood, G. C.; Sage, P. W.; Cooke, M. J.

Studies of fly-ash composition identified the presence of calcium and sulphur, indicating their potential role as sources of calcium sulphate. Residual acidity (particularly for oil fly ash) suggested the possibility of enhanced chemical reaction, and the presence of transition metals, probably as oxides, might accelerate the oxidation of SO 2 to SO 42-. Exposure tests in a laboratory-based rig simulating dry deposition on Portland and Monks Park limestone, either seeded or unseeded with fly-ash particulate material or transition metal oxide catalysts, were carried out using an SO 2-containing environment at 95% r.h. Enhanced sulphation of these seeded limestones due to the above factors was minimal; at high loadings of fly ash, there was even evidence of masking the limestone surface, reducing sulphation. However, pure CaCO 3 powder in the exposure rig showed increases in sulphation when seeded with metal oxide catalysts. Thus the limestones examined contained sufficient inherent catalysts for the oxidation of SO 2 to SO 42- to proceed at such a rate that external catalysts were superfluous. This implies that dissolution rate of SO 2 in moisture films controls the availability of species for reaction with these carbonate-based stones and that fly ash deposited from the atmosphere does not enhance the reaction.

Physical and chemical characterization of fly ashes from Swiss waste incineration plants and determination of the ash fraction in the nanometer range.

PubMed

Buha, Jelena; Mueller, Nicole; Nowack, Bernd; Ulrich, Andrea; Losert, Sabrina; Wang, Jing

2014-05-06

Waste incineration had been identified as an important source of ultrafine air pollutants resulting in elaborated treatment systems for exhaust air. Nowadays, these systems are able to remove almost all ultrafine particles. However, the fate of ultrafine particles caught in the filters has received little attention so far. Based on the use of engineered nano-objects (ENO) and their transfer into the waste stream, it can be expected that not only combustion generated nanoparticles are found in fly ashes but that many ENO finally end up in this matrix. A more detailed characterization of the nanoparticulate fraction of fly ashes is therefore needed. Physical and chemical characterizations were performed for fly ashes from five selected waste incineration plants (WIPs) with different input materials such as municipal waste, wood and sewage sludge. The intrinsic densities of the fly ashes were in the range of 2.7-3.2 g/cm(3). When the fly ash particle became airborne, the effective density depended on the particle size, increasing from 0.7-0.8 g/cm(3) for 100-150 nm to 2 g/cm(3) for 350-500 nm. The fly ash samples were fractionated at 2 μm, yielding fine fractions (<2 μm) and coarse fractions (>2 μm). The size distributions of the fine fractions in the airborne form were further characterized, which allowed calculation of the percentage of the fly ash particles below 100 nm. We found the highest mass-based percentage was about 0.07%; the number percentage in the fine fraction was in the range of 4.8% to 22%. Comparison with modeling results showed that ENO may constitute a considerable part of the fly ash particles below 100 nm. Chemical analyses showed that for the municipal waste samples Ca and Al were present in higher concentrations in the coarse fraction; for the mixed wood and sludge sample the P concentration was higher in the coarse fraction; for most other samples and elements they were enriched in the fine fraction. Electron microscopic images of fly ashes showed a wide range of particle sizes, from nanometer range to micrometer range. Many aggregated particles were observed, demonstrating that ENO, bulk-derived nano-objects and combustion-generated nano-objects can form aggregates in the incineration process.

Evaluation of fly ash concrete durability containing class II durability aggregates.

DOT National Transportation Integrated Search

1986-07-01

Fly ash was used in this evaluation study to replace 15% of the cement in : Class C-3 concrete paving mixes. One Class "c" ash from Iowa approved : sources was examined in each mix. Substitution rate was based on 1 to 1 : basis, for each pound of cem...

Hydration of Hybrid Alkaline Cement Containing a Very Large Proportion of Fly Ash: A Descriptive Model

PubMed Central

Garcia-Lodeiro, Inés; Donatello, Shane; Fernández-Jiménez, Ana; Palomo, Ángel

2016-01-01

In hybrid alkaline fly ash cements, a new generation of binders, hydration, is characterized by features found in both ordinary portland cement (OPC) hydration and the alkali activation of fly ash (AAFA). Hybrid alkaline fly ash cements typically have a high fly ash (70 wt % to 80 wt %) and low clinker (20 wt % to 30 wt %) content. The clinker component favors curing at ambient temperature. A hydration mechanism is proposed based on the authors’ research on these hybrid binders over the last five years. The mechanisms for OPC hydration and FA alkaline activation are summarized by way of reference. In hybrid systems, fly ash activity is visible at very early ages, when two types of gel are formed: C–S–H from the OPC and N–A–S–H from the fly ash. In their mutual presence, these gels tend to evolve, respectively, into C–A–S–H and (N,C)–A–S–H. The use of activators with different degrees of alkalinity has a direct impact on reaction kinetics but does not modify the main final products, a mixture of C–A–S–H and (N,C)–A–S–H gels. The proportion of each gel in the mix does, however, depend on the alkalinity generated in the medium. PMID:28773728

Combining sieving and washing, a way to treat MSWI boiler fly ash.

PubMed

De Boom, Aurore; Degrez, Marc

2015-05-01

Municipal Solid Waste Incineration (MSWI) fly ashes contain some compounds that could be extracted and valorised. A process based on wet sieving and washing steps has been developed aiming to reach this objective. Such unique combination in MSWI fly ash treatment led to a non-hazardous fraction from incineration fly ashes. More specifically, MSWI Boiler Fly Ash (BFA) was separately sampled and treated. The BFA finer particles (13wt%) were found to be more contaminated in Pb and Zn than the coarser fractions. After three washing steps, the coarser fractions presented leaching concentrations acceptable to landfill for non-hazardous materials so that an eventual subsequent valorisation may be foreseen. At the contrary, too much Pb leached from the finest particles and this fraction should be further treated. Wet sieving and washing permit thus to reduce the leachability of MSWI BFA and to concentrate the Pb and Zn contamination in a small (in particle size and volume) fraction. Such combination would therefore constitute a straightforward and efficient basis to valorise coarse particles from MSWI fly ashes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detoxifying PCDD/Fs and heavy metals in fly ash from medical waste incinerators with a DC double are plasma torch.

PubMed

Pan, Xinchao; Yan, Jianhua; Xie, Zhengmiao

2013-07-01

Medical waste incinerator (MWI) fly ash is regarded as a highly toxic waste because it contains high concentrations of heavy metals and dioxins, including polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Therefore fly ash from MWI must be appropriately treated before being discharged into the environment. A melting process based on a direct current thermal plasma torch has been developed to convert MWI fly ash into harmless slag. The leaching characteristics of heavy metals in fly ash and vitrified slag were investigated using the toxicity characteristic leaching procedure, while the content of PCDD/Fs in the fly ashes and slags was measured using method 1613 of the US EPA. The experimental results show that the decomposition rate of PCDD/Fs is over 99% in toxic equivalent quantity value and the leaching of heavy metals in the slag significantly decreases after the plasma melting process. The produced slag has a compact and homogeneous microstructure with density of up to 2.8 g/cm3.

Determination of the Cd-bearing phases in municipal solid waste and biomass single fly ash particles using SR-microXRF spectroscopy.

PubMed

Camerani, Maria Caterina; Somogyi, Andrea; Vekemans, Bart; Ansell, Stuart; Simionovici, Alexandre S; Steenari, Britt-Marie; Panas, Itai

2007-09-01

By using an excitation energy of 27.0 keV, synchrotron radiation-induced micro-X-ray fluorescence (SR-microXRF) is employed to extract information regarding the composition and distribution of Cd-bearing phases in municipal solid waste (MSW) and biomass fly ashes. Significance of observation is based on statistics of totally more than 100 individual MSW and biomass fly ash particles from a fluidized bed combustion (FBC) plant. Cd concentrations in the parts-per-million range are determined. In general, although previous leaching studies have indicated Cd to be predominant in the smaller-size ash particles, in the present study Cd is more evenly distributed throughout all the particle sizes. For MSW fly ashes, results indicate the presence of Cd mainly as CdBr2 hot-spots, whereas for biomass fly ashes, which exhibit lower CdX2 concentration, a thin Cd layer on/in the particles is reported. For both ashes, Ca-containing matrixes are found to be the main Cd-bearing phases. Support for this observation is found from independent first-principles periodic density functional theory calculations. The observations are condensed into a schematic mechanism for Cd adsorption on the fly ash particles.

Field and lab evaluation of the use of lime fly ash to replace soil cement as a base course : final report.

DOT National Transportation Integrated Search

1997-09-01

This study evaluates the performance of lime/fly ash stabilized base as an alternative to soil cement stabilized base for flexible pavement systems on reconstructed highways in Louisiana. Louisiana has historically used soil cement for most flexible ...

Extraction of trace metals from fly ash

DOEpatents

Blander, M.; Wai, C.M.; Nagy, Z.

1983-08-15

A process is described for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous. The fly ash has a silicate base and contains surface deposits of the trace metals as oxides, chlorides or the like. The process is carried out by contacting the fly ash with AlCl/sub 3/ in an alkali halide melt to react the trace metals with the AlCl/sub 3/ to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Extraction of trace metals from fly ash

DOEpatents

Blander, Milton; Wai, Chien M.; Nagy, Zoltan

1984-01-01

A process for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous, the fly ash having a silicate base and containing surface deposits of the trace metals as oxides, chlorides or the like, with the process being carried out by contacting the fly ash with AlCl.sub.3 in an alkali halide melt to react the trace metals with the AlCl.sub.3 to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Fly ash carbon passivation

DOE Office of Scientific and Technical Information (OSTI.GOV)

La Count, Robert B; Baltrus, John P; Kern, Douglas G

A thermal method to passivate the carbon and/or other components in fly ash significantly decreases adsorption. The passivated carbon remains in the fly ash. Heating the fly ash to about 500 and 800 degrees C. under inert gas conditions sharply decreases the amount of surfactant adsorbed by the fly ash recovered after thermal treatment despite the fact that the carbon content remains in the fly ash. Using oxygen and inert gas mixtures, the present invention shows that a thermal treatment to about 500 degrees C. also sharply decreases the surfactant adsorption of the recovered fly ash even though most ofmore » the carbon remains intact. Also, thermal treatment to about 800 degrees C. under these same oxidative conditions shows a sharp decrease in surfactant adsorption of the recovered fly ash due to the fact that the carbon has been removed. This experiment simulates the various "carbon burnout" methods and is not a claim in this method. The present invention provides a thermal method of deactivating high carbon fly ash toward adsorption of AEAs while retaining the fly ash carbon. The fly ash can be used, for example, as a partial Portland cement replacement in air-entrained concrete, in conductive and other concretes, and for other applications.« less

Treatment of fly ash from power plants using thermal plasma.

PubMed

Al-Mayman, Sulaiman; AlShunaifi, Ibrahim; Albeladi, Abdullah; Ghiloufi, Imed; Binjuwair, Saud

2017-01-01

Fly ash from power plants is very toxic because it contains heavy metals. In this study fly ash was treated with a thermal plasma. Before their treatment, the fly ash was analyzed by many technics such as X-ray fluorescence, CHN elemental analysis, inductively coupled plasma atomic emission spectroscopy and scanning electron microscopy. With these technics, the composition, the chemical and physical proprieties of fly ash are determined. The results obtained by these analysis show that fly ash is mainly composed of carbon, and it contains also sulfur and metals such as V, Ca, Mg, Na, Fe, Ni, and Rh. The scanning electron microscopy analysis shows that fly ash particles are porous and have very irregular shapes with particle sizes of 20-50 μm. The treatment of fly ash was carried out in a plasma reactor and in two steps. In the first step, fly ash was treated in a pyrolysis/combustion plasma system to reduce the fraction of carbon. In the second step, the product obtained by the combustion of fly ash was vitrified in a plasma furnace. The leaching results show that the fly ash was detoxified by plasma vitrification and the produced slag is amorphous and glassy.

Treatment of fly ash from power plants using thermal plasma

PubMed Central

Al-Mayman, Sulaiman; AlShunaifi, Ibrahim; Albeladi, Abdullah; Binjuwair, Saud

2017-01-01

Fly ash from power plants is very toxic because it contains heavy metals. In this study fly ash was treated with a thermal plasma. Before their treatment, the fly ash was analyzed by many technics such as X-ray fluorescence, CHN elemental analysis, inductively coupled plasma atomic emission spectroscopy and scanning electron microscopy. With these technics, the composition, the chemical and physical proprieties of fly ash are determined. The results obtained by these analysis show that fly ash is mainly composed of carbon, and it contains also sulfur and metals such as V, Ca, Mg, Na, Fe, Ni, and Rh. The scanning electron microscopy analysis shows that fly ash particles are porous and have very irregular shapes with particle sizes of 20–50 μm. The treatment of fly ash was carried out in a plasma reactor and in two steps. In the first step, fly ash was treated in a pyrolysis/combustion plasma system to reduce the fraction of carbon. In the second step, the product obtained by the combustion of fly ash was vitrified in a plasma furnace. The leaching results show that the fly ash was detoxified by plasma vitrification and the produced slag is amorphous and glassy. PMID:28546898

Influence of Cements Containing Calcareous Fly Ash as a Main Component Properties of Fresh Cement Mixtures

NASA Astrophysics Data System (ADS)

Gołaszewski, Jacek; Kostrzanowska-Siedlarz, Aleksandra; Ponikiewski, Tomasz; Miera, Patrycja

2017-10-01

The main goal of presented research was to examine usability of cements containing calcareous fly ash (W) from technological point of view. In the paper the results of tests concerning the influence of CEM II and CEM IV cements containing fly ash (W) on rheological properties, air content, setting times and plastic shrinkage of mortars are presented and discussed. Moreover, compatibility of plasticizers with cements containing fly ash (W) was also studied. Additionally, setting time and hydration heat of cements containing calcareous fly ash (W) were determined. In a broader aspect, the research contributes to promulgation of the possibility of using calcareous fly ash (W) in cement and concrete technology, what greatly benefits the environment protection (utilization of waste fly ash). Calcareous fly ash can be used successfully as the main component of cement. Cements produced by blending with processed fly ash or cements produced by interginding are characterized by acceptable technological properties. In respect to CEM I cements, cements containing calcareous fly ash worsen workability, decrease air content, delay setting time of mixtures. Cements with calcareous fly ash show good compatibility with plasticizers.

The leaching characteristics of selenium from coal fly ashes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, T.; Wang, J.; Burken, J.G.

2007-11-15

The leaching characteristics of selenium from several bituminous and subbituminous coal fly ashes under different pH conditions were investigated using batch methods. Results indicated that pH had a significant effect on selenium leaching from bituminous coal ash. The minimum selenium leaching occurred in the pH range between 3 and 4, while the maximum selenium leaching occurred at pH 12. The release of selenium from subbituminous coal ashes was very low for the entire experimental pH range, possibly due to the high content of calcium which can form hydration or precipitation products as a sink for selenium. The adsorption results formore » different selenium species indicated that Se(VI) was hardly adsorbable on either bituminous coal ashes or subbitumminous coal ashes at any pH. However, Se(I) was highly adsorbed by bituminous coal ashes under acidic pH conditions and was mostly removed by subbitumminous coal ashes across the entire pH range. This result suggests that the majority of selenium released from the tested fly ashes was Se(IV). A speciation-based model was developed to simulate the adsorption of Se(IV) on bituminous coal fly ash, and the pH-independent adsorption constants of HSeO{sup 3-} and SeO{sub 3}{sup 2-} were determined. The modeling approach is useful for understanding and predicting the release process of selenium from fly ash.« less

Evaluation of Pollutant Leaching Potential of Coal Ashes for Recycling

NASA Astrophysics Data System (ADS)

Park, D.; Woo, N. C.; Kim, H.; Yoon, H.; Chung, D.

2011-12-01

By 2009, coal ashes produced from coal-based power plants in Korea have been reused as cement supplement materials; however, the rest is mostly disposed in landfills inside the plant properties. Continuous production of coal ashes and limited landfill sites require more recycles of coal ashes as base materials, specifically in constructions of roads and of huge industrial complex. Previous researches showed that coal ashes could contain various metals such as arsenic(As), chromium(Cr), lead(Pb), nickel(Ni), selenium(Se), etc. In this study, we collected four types of bottom ashes and two of fly ashes from four coal-based power plants. These ash samples were tested with distilled water through the column leaching process in oxidized conditions. The column test results were compared with those of total digestion, sequential extraction processes and TCLP. Concentrations of metals in outflows from columns are generally greater in fly ashes than in bottom ashes, specifically for As, Se, B, Sr and SO4. Only one fly ash (J2-F) shows high concentrations of arsenic and selenium in leachate. Sequential extraction results indicate that these metals are in readily soluble forms, such as adsorbed, carbonated, and reducible forms. Results of TCLP analysis indicate no potential contaminants leached from the ashes. In conclusion, recycling of coal combustion ashes could be encouraged with proper tests such as sequential and leaching experiments.

Comparison of heterogeneous photolytic reduction of Hg(II) in the coal fly ashes and synthetic aerosols

NASA Astrophysics Data System (ADS)

Tong, Yindong; Eichhorst, Terry; Olson, Michael R.; Rutter, Andrew P.; Shafer, Martin M.; Wang, Xuejun; Schauer, James J.

2014-03-01

In this study, we examined the heterogeneous reduction of Hg(II) on the coal fly ash samples and synthetic aerosols under different light conditions in a controlled laboratory reactor. Three types of coal fly ashes were studied: a high carbon fly ash from a stoker boiler, a low carbon/low sulfate fly ash from a pulverized coal combustor burning low sulfur coal, and a high sulfate fly ash from a pulverized coal combustor burning high sulfur coal. The rate of Hg(II) reduction on the three diverse fly ash samples was found to be relatively fast with an average half-life of 1.6 h under clear sky atmospheric conditions (under the irradiance of 1000 W/m2). The reduction rate in the low sulfate/low carbon fly ash was approximately 1.5 times faster than with the other coal fly ash samples. Synthetic aerosols made of carbon black and levoglucosan produced Hg(II) reduction rates similar to coal fly ashes. However, aerosols composed of adipic acid resulted in reduction rates that were 3-5 times faster. The sensitivity of adipic acid reduction to light source wavelength was found to be greater than for the coal fly ash and other synthetic aerosols. Aerosols made from the water extracts of coal fly ash samples produced reduction rates equal to or slightly higher than with the native fly ash suggesting that the soluble components of fly ash play a significant role in the reduction mechanism. The measured reduction rates are likely important in the chemical processing of mercury in power plant plumes and potentially in the atmosphere and should be considered for incorporation in atmospheric transport models that are used to understand the fate of atmospheric mercury.

Sulfidation treatment of molten incineration fly ashes with Na2S for zinc, lead and copper resource recovery.

PubMed

Kuchar, D; Fukuta, T; Onyango, M S; Matsuda, H

2007-04-01

The present study focuses on the conversion of heavy metals involved in molten incineration fly ashes to metal sulfides which could be thereafter separated by flotation. The sulfidation treatment was carried out for five molten incineration fly ashes (Fly ash-A to Fly ash-E) by contacting each fly ash with Na(2)S solution for a period of 10 min to 6h. The initial molar ratio of S(2-) to Me(2+) was adjusted to 1.20. The conversion of heavy metals to metal sulfides was evaluated by measuring the S(2-) residual concentrations using an ion selective electrode. The formation of metal sulfides was studied by XRD and SEM-EDS analyses. In the case of Fly ash-A to Fly ash-D, more than 79% of heavy metals of zinc, lead and copper was converted to metal sulfides within the contacting period of 0.5h owing to a fast conversion of metal chlorides to metal sulfides. By contrast, the conversion of about 35% was achieved for Fly ash-E within the same contacting period, which was attributed to a high content of metal oxides. Further, the S(2-) to Me(2+) molar ratio was reduced to 1.00 to minimize Na(2)S consumption and the conversions obtained within the contacting period of 0.5h varied from 76% for Fly ash-D to 91% for Fly ash-C. Finally, soluble salts such as NaCl and KCl were removed during the sulfidation treatment, which brought about a significant enrichment in metals content by a factor varying from 1.5 for Fly ash-D to 4.9 for Fly ash-A.

Physical-durable performance of concrete incorporating high loss on ignition-fly ash

NASA Astrophysics Data System (ADS)

Huynh, Trong-Phuoc; Ngo, Si-Huy; Hwang, Chao-Lung

2018-04-01

This study investigates the feasibility of using raw fly ash with a high loss on ignition in concrete. The fly ash-free concrete samples were prepared with different water-to-binder (w/b) ratios of 0.35, 0.40, and 0.45, whereas the fly ash concrete samples were prepared with a constant w/b of 0.40 and with various fly ash contents (10%, 20%, and 30%) as a cement substitution. The physical properties and durability performance of the concretes were evaluated through fresh concrete properties, compressive strength, strength efficiency of cement, ultrasonic pulse velocity, and resistance to sulfate attack. Test results show that the w/b ratio affected the concrete properties significantly. The incorporation of fly ash increased the workability and reduced the unit weight of fresh concrete. In addition, the fly ash concrete samples containing up to 20% fly ash exhibited an improved strength at long-term ages. Further, all of the fly ash concrete samples showed a good durability performance with ultrasonic pulse velocity value of greater than 4100 m/s and a comparable sulfate resistance to the no-fly ash concrete.

Laboratory evaluation of fly ash treated embankment and base materials : final report.

DOT National Transportation Integrated Search

1988-04-01

This study was undertaken to provide the Louisiana DOTD with a data base from which recommendations can be made concerning the modification or stabilization of soils using a Class C fly ash as a full or partial replacement for hydraulic cement or hyd...

Optimum reaction ratio of coal fly ash to blast furnace cement for effective removal of hydrogen sulfide.

PubMed

Asaoka, Satoshi; Okamura, Hideo; Kim, Kyunghoi; Hatanaka, Yuzuru; Nakamoto, Kenji; Hino, Kazutoshi; Oikawa, Takahito; Hayakawa, Shinjiro; Okuda, Tetsuji

2017-02-01

Reducing hydrogen sulfide concentration in eutrophic marine sediments is crucial to maintaining healthy aquatic ecosystems. Managing fly ash, 750 million tons of which is generated annually throughout the world, is another serious environmental problem. In this study, we develop an approach that addresses both these issues by mixing coal fly ash from coal-fired power plants with blast furnace cement to remediate eutrophic sediments. The purpose of this study is to optimize the mixing ratio of coal fly ash and blast furnace cement to improve the rate of hydrogen sulfide removal based on scientific evidence obtained by removal experiments and XAFS, XRD, BET, and SEM images. In the case of 10 mg-S L -1 of hydrogen sulfide, the highest removal rate of hydrogen sulfide was observed for 87 wt% of coal fly ash due to decreased competition of adsorption between sulfide and hydroxyl ions. Whereas regarding 100 mg-S L -1 , the hydrogen sulfide removal rate was the highest for 95 wt% of coal fly ash. However, for both concentrations, the removal rate obtained by 87 wt% and 95 wt% were statistically insignificant. The crushing strength of the mixture was over 1.2 N mm -2 when the coal fly ash mixing ratio was less than 95 wt%. Consequently, the mixing ratio of coal fly ash was optimized at 87 wt% in terms of achieving both high hydrogen sulfide removal rate and sufficient crushing strength. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment and comparison of three high-aluminum fly ash utilization scenarios in Inner Mongolia, China using an eco-efficiency indicator.

PubMed

Yang, Shuo; Lin, Ling; Li, Shao Peng; Li, Qiang; Wang, Xiu Teng; Sun, Liang

2017-05-01

Utilization of fly ash is of great importance in China in the context of resource and environmental crises. Different fly ash utilization processes are proposed, and some have been practically applied. However, none of these fly ash utilization pathways has been evaluated comprehensively by integrating both environmental and economic perspectives. In this study, three high-aluminum fly ash utilization methods in Mongolia were assessed and compared based on the concept of eco-efficiency. The environmental assessment was conducted in accordance with life-cycle assessment principles, and a monetization-weighting approach was applied to obtain social willingness-to-pay as a reflection of environmental impact. The environmental assessment results revealed that the reuse of fly ash had significant advantage for saving primary resource, while solid waste, depletion of water, and global warming were the three highest environmental impacts from the life cycle perspective. The economic performance assessment showed positive net profits for fly ash utilization, but high value-added products were not necessarily indicative of better economic performance due to the relatively high operation cost. Comparison of the eco-efficiency indicators (EEIs) implied that the process of scenario 1#, which produced mullite ceramic and active calcium silicate, was the most recommended out of the three scenarios on the present scale. This judgment was consistent with the evaluation of the resource utilization rate. The present study showed that the EEI could be used to compare different fly ash utilization processes in a comprehensive and objective manner, thus providing definitive and insightful suggestions for decision-making and technical improvement.

MSW fly ash stabilized with coal ash for geotechnical application.

PubMed

Kamon, M; Katsumi, T; Sano, Y

2000-09-15

The solidification and stabilization of municipal solid waste (MSW) fly ash for the purpose of minimizing the geo-environmental impact caused by toxic heavy metals as well as ensuring engineering safety (strength and soaking durability) are experimentally evaluated. The mixtures of MSW fly ash stabilized with cement and fluidized bed combustion coal fly ash (FCA) were used for unconfined compressive strength tests, leachate tests, and soaking tests. The behavior of soluble salts contained in the MSW fly ash significantly affects strength development, soaking durability, and the hardening reaction of the stabilized MSW fly ash mixtures. The cement stabilization of the MSW fly ash does not have enough effect on strength development and soaking durability. The addition of cement only contributes to the containment of heavy metals due to the high level of alkalinity. When using FCA as a stabilizing agent for MSW fly ash, the mixture exhibits high strength and durability. However, the Cd leachate cannot be prevented in the early stages of curing. Using a combination of cement and FCA as a MSW fly ash stabilizer can attain high strength, high soaking durability, and the containment of heavy metals. The stabilized MSW fly ash with cement and FCA can be practically applied to embankments.

Field and lab evaluation of the use of lime fly ash to replace soil cement as a base course : technical summary.

DOT National Transportation Integrated Search

1997-09-01

The purpose of this project was to design and construct lime/fly ash stabilized base course test sections which would be economical compared to a soil cement stabilized base, utilize a recyclable material, and possibly reduce shrinkage cracking on ba...

EVALUATION OF THE EFFECTS OF COAL FLY ASH AMENDMENTS ON THE TOXICITY OF A CONTAMINATED MARINE SEDIMENT

PubMed Central

Burgess, Robert M.; Perron, Monique M.; Friedman, Carey L.; Suuberg, Eric M.; Pennell, Kelly G.; Cantwell, Mark G.; Pelletier, Marguerite C.; Ho, Kay T.; Serbst, Jonathan R.; Ryba, Stephan A.

2013-01-01

Approaches for cleaning-up contaminated sediments range from dredging to in situ treatment. In the present report, we discuss the effects of amending reference and contaminated sediments with coal fly ash to reduce the bioavailability and toxicity of a field sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Six fly ashes and a coconut charcoal were evaluated in 7 d whole sediment toxicity tests with a marine amphipod (Ampelisca abdita) and mysid (Americamysis bahia). Fly ashes with high carbon content and the coconut charcoal showed proficiency at reducing toxicity. Some of the fly ashes demonstrated toxicity in the reference treatments. It is suspected that some of this toxicity is related to the presence of ammonia associated with fly ashes as a result of post-oxidation treatment to reduce nitrous oxides emissions. Relatively simple methods exist to remove ammonia from fly ash prior to use and fly ashes with low ammonia content are available. Fly ashes were also shown to effectively reduce overlying water concentrations of several PAHs. There was no evidence of the release of the metals cadmium, copper, nickel or lead from the fly ashes. A preliminary 28 d polychaete bioaccumulation study with one of the high carbon fly ashes and a reference sediment was also performed. Although preliminary, there was no evidence of adverse effects to worm growth or lipid content, or the accumulation of PAHs or mercury from exposure to the fly ash. These data show fly ashes with high carbon contents may represent viable remedial materials for reducing the bioavailability of organic contaminants in sediments. PMID:18717615

Utilization of coal fly ash in solidification of liquid radioactive waste from research reactor.

PubMed

Osmanlioglu, Ahmet Erdal

2014-05-01

In this study, the potential utilization of fly ash was investigated as an additive in solidification process of radioactive waste sludge from research reactor. Coal formations include various percentages of natural radioactive elements; therefore, coal fly ash includes various levels of radioactivity. For this reason, fly ashes have to be evaluated for potential environmental implications in case of further usage in any construction material. But for use in solidification of radioactive sludge, the radiological effects of fly ash are in the range of radioactive waste management limits. The results show that fly ash has a strong fixing capacity for radioactive isotopes. Specimens with addition of 5-15% fly ash to concrete was observed to be sufficient to achieve the target compressive strength of 20 MPa required for near-surface disposal. An optimum mixture comprising 15% fly ash, 35% cement, and 50% radioactive waste sludge could provide the solidification required for long-term storage and disposal. The codisposal of radioactive fly ash with radioactive sludge by solidification decreases the usage of cement in solidification process. By this method, radioactive fly ash can become a valuable additive instead of industrial waste. This study supports the utilization of fly ash in industry and the solidification of radioactive waste in the nuclear industry.

The influence of sugarcane bagasse ash as fly ash on cement quality

NASA Astrophysics Data System (ADS)

Rauf, N.; Damayanti, M. C.; Pratama, S. W. I.

2017-01-01

Fly ash often is used as the third material for cement. The fly ash from sugarcane bagasse is usually considered as industrial waste material that can be added to the base material of cement (clinker, trash, gypsum and lime stone) for economic and environment reason. The amount of fly ash usually up to 30 % of cement material, but in this research the percentage of sugarcane bagasse ash (SBA) is added to cement material is up to 15% total weight. Then the x-rays fluorescence (XRF) was used to determine its chemical composition of raw material and cement samples. The physical properties of cement such as fineness, setting time, expansion, and compressive strength were measured using Automatic Blaine, Vicat, Autoclave, respectively. The result show that the percentage of sugarcane bagasse ash influences the quality of cement and concrete, and this is confirmed with Indonesia National Standard (SNI). It is showed that the sugarcane bagasse ash could be use as material to improve the quality of cement and will solve the environment waste material

Experimental study on durability improvement of fly ash concrete with durability improving admixture.

PubMed

Quan, Hong-zhu; Kasami, Hideo

2014-01-01

In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%-20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized.

Pore Structure Characterization in Concrete Prepared with Carbonated Fly Ash

NASA Astrophysics Data System (ADS)

Sahoo, Sanjukta

2018-03-01

Carbon dioxide capture and storage (CCS) is a technique to address the global concern of continuously rising CO2 level in the atmosphere. Fly ash is considered as a suitable medium for CCS due to presence of metal oxides. The fly ash which has already sequestered carbon dioxide is referred to as carbonated fly ash. Recent research reveals better durability of concretes using carbonated fly ash as part replacement of cement. In the present research pore structure characterization of the carbonated fly ash concrete has been carried out. Mercury Intrusion porosimetry test has been conducted on control concrete and concrete specimens using fly ash and carbonated fly ash at replacement levels of 25% and 40%. The specimens have been water cured for 28 days and 90 days. It is observed that porosity reduction rate is more pronounced in carbonated fly ash concrete compared to control concrete at higher water curing age. Correlation analysis is also carried out which indicates moderately linear relationship between porosity % and pore distribution with particle size and water curing.

Sulfate resistance of high calcium fly ash concrete

NASA Astrophysics Data System (ADS)

Dhole, Rajaram

Sulfate attack is one of the mechanisms which can cause deterioration of concrete. In general, Class C fly ash mixtures are reported to provide poor sulfate resistance. Fly ashes, mainly those belonging to the Class C, were tested as per the ASTM C 1012 procedure to evaluate chemical sulfate resistance. Overall the Class C fly ashes showed poor resistance in the sulfate environment. Different strategies were used in this research work to improve the sulfate resistance of Class C fly ash mixes. The study revealed that some of the strategies such as use of low W/CM (water to cementing materials by mass ratio), silica fume or ultra fine fly ash, high volumes of fly ash and, ternary or quaternary mixes with suitable supplementary cementing materials, can successfully improve the sulfate resistance of the Class C fly ash mixes. Combined sulfate attack, involving physical and chemical action, was studied using sodium sulfate and calcium sulfate solutions. The specimens were subjected to wetting-drying cycles and temperature changes. These conditions were found to accelerate the rate of degradation of concrete placed in a sodium sulfate environment. W/CM was found to be the main governing factor in providing sulfate resistance to mixes. Calcium sulfate did not reveal damage as a result of mainly physical action. Characterization of the selected fly ashes was undertaken by using SEM, XRD and the Rietveld analysis techniques, to determine the relation between the composition of fly ashes and resistance to sulfate attack. The chemical composition of glass represented on the ternary diagram was the main factor which had a significant influence on the sulfate resistance of fly ash mixtures. Mixes prepared with fly ashes containing significant amounts of vulnerable crystalline phases offered poor sulfate resistance. Comparatively, fly ash mixes containing inert crystalline phases such as quartz, mullite and hematite offered good sulfate resistance. The analysis of hydrated lime-fly ash pastes confirmed that fly ash mortar or concrete mixes forming more monosulfate than ettringite before exposure to sulfates would offer poor sulfate resistance and vice versa. During quantitative Rietveld analysis carried out for determining ettringite, monosulfate and gypsum formed in the fly ash pastes, it was observed that fly ash mixtures showing more ettringite after exposures to sulfates, give poor sulfate resistance. A good relationship between the amounts of ettringite formed and expansions of mortar specimens in the ASTM C 1012 test was found.

Long-term strength properties of HVFA concretes

NASA Astrophysics Data System (ADS)

Špak, M.; Bašková, R.

2015-01-01

Fly ash from coal burning is used as active addition for concrete in Middle-Europe region for several decades. The intensity of its utilization increases still. In the role of supplementary cement addition it serves as binder, whereby it helps to reduce final price of concrete as well as improves both the rheological properties of fresh concrete and several characteristics of hardened concrete. Fly ash presents the co-product of energetic industry. Its production increases together with growth of energy consumption. These factors bring the opportunity and requirement of production of concretes with high volume of fly ash based addition. Thus, significant economic, environmental, technological and technical benefits can be achieved by using of high amount of fly ash for concrete production.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burgess, R.M.; Perron, M.M.; Friedman, C.L.

Approaches for cleaning up contaminated sediments range from dredging to in situ treatment. In this study, we discuss the effects of amending reference and contaminated sediments with coal fly ash to reduce the bioavailability and toxicity of a field sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Six fly ashes and a coconut charcoal were evaluated in 7-d whole sediment toxicity tests with a marine amphipod (Ampelisca abdita) and mysid (Americamysis bahia). Fly ashes with high carbon content and the coconut charcoal showed proficiency at reducing toxicity. Some of the fly ashes demonstrated toxicity in the reference treatments. It is suspectedmore » that some of this toxicity is related to the presence of ammonia associated with fly ashes as a result of postoxidation treatment to reduce nitrous oxide emissions. Relatively simple methods exist to remove ammonia from fly ash before use, and fly ashes with low ammonia content are available. Fly ashes were also shown to effectively reduce overlying water concentrations of several PAHs. No evidence was seen of the release of the metals cadmium, copper, nickel, or lead from the fly ashes. A preliminary 28-d polychaete bioaccumulation study with one of the high-carbon fly ashes and a reference sediment was also performed. Although preliminary, no evidence was seen of adverse effects to worm growth or lipid content or of accumulation of PAHs or mercury from exposure to the fly ash. These data show fly ashes with high carbon content could represent viable remedial materials for reducing the bioavailability of organic contaminants in sediments.« less

Growth and physiological response of lemongrass (Cymbopogon citratus (D.C.) Stapf.) under different levels of fly ash-amended soil.

PubMed

Panda, Debabrata; Panda, Dibyajyoti; Padhan, Bandana; Biswas, Meghali

2018-05-12

Revegetation with metal tolerant plants for management of fly ash deposits is an important environmental perspective nowadays. Growth performance, photosynthesis, and antioxidant defense of lemongrass (Cymbopogon citratus (D.C.) Stapf.) were evaluated under various combination of fly ash amended with garden soil in order to assess its fly ash tolerance potential. Under low level of fly ash (25%) amended soil, the plant growth parameters such as shoot, root, and total plant biomass as well as metal tolerance index were increased compared to the control plants grown on garden soil, followed by decline under higher concentration of fly ash (50%, 75% and 100%). In addition, leaf photosynthetic rate, stomatal conductance, and photosystem (PS) II activity were not significantly changed under low level of fly ash (25%) amended soil compared to the garden soil but these parameters were significantly decreased further with increase of fly ash concentrations. Furthermore, increase of activities of some antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase over control were noticed in lemongrass under all fly ash treatments. Taken together, the study suggests that lemongrass can be used for phytoremediation of fly ash at 25% amended soil.

Co-detoxification of transformer oil-contained PCBs and heavy metals in medical waste incinerator fly ash under sub- and supercritical water.

PubMed

Wang, Chunfeng; Zhu, Nengmin; Wang, Yanmin; Zhang, Fushen

2012-01-17

The simultaneous detoxification processes of transformer oil-contained PCBs and heavy metals in medical waste incinerator (MWI) fly ash were developed under sub- and supercritical water. The addition of MWI fly ash to transformer oil-contained PCBs was found to increase the destruction efficiency of PCBs, at the same time, it facilitated reducing the leaching concentration of toxic metals from residues (obtained after reaction) for harmless disposal. In this study, we elucidated primarily the catalysis possibility of heavy metals in raw MWI fly ash for PCBs degradation by adopting the sequential extraction procedure. For both MWI fly ashes, more than 90% destruction efficiency of PCBs was achieved at ≥375 °C for 30 min, and trichlorobenzene (TCB) existing in the transformer oil was also completely decomposed. The correlation of catalytic performance to PCBs degradation was discussed based on structural characteristics and dechlorinated products. Likewise, such process rendered residues innocuous through supercritical water treatment for reuse or disposal in landfill.

Aluminum-fly ash metal matrix composites for automotive parts. [Reports for April 1 to June 30, 1999, and July 1 to September 30, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, David; Purgert, Robert; Rhudy, Richard

1999-10-15

Some highlights are: (1) During this quarter's field trials, sand mold castings of parts and permanent mold tensile testing bars, K mold bars, and ingots were made from aluminum alloy-fly ash melts. (2) Another objective was met, i.e., to use class ''F'' type precipitator fly ash consisting of particle sizes less than 100 microns. It was possible to pour the composite melt into the sand mold through a filter. (3) Trials were run to determine the required amount of the wetting agent, magnesium, to ensure appropriate mixing of the aluminum alloy and fly ash. The magnesium content required to mixmore » ''F'' fly ash was much lower compared to that required to mix hybrid ''C-F'' fly ash in similar melts. Fly ash particles of less than 100 microns were mixed in aluminum melt. Large scale field trials were undertaken at Eck Industries with the goal of standardizing procedures for producing aluminum-fly ash composite melts and to analyze the structure and properties of the resulting material. Limited testing of tensile properties has been done on pressure die cast parts, and attempts are underway to improve the distribution of fly ash in both sand cast and pressure die cast samples. Eck Industries performed radiographic, heat treatment, and tensile tests on permanent mold cast tensile test bars. After fly ash mixing experiments, the Lanxide high speed-high shear mixer (originally designed for mixing Al-SiC melts) was employed in an attempt to avoid fly ash agglomeration. It led to demixing (instead of deagglomerating) of some fly ash. However, the permanent mold tensile bars poured after high shear mixing displayed good distribution of fly ash in castings. A modified impeller design is being considered for high speed-high shear mixing of aluminum-fly ash melts.« less

Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash

DOEpatents

Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

1997-10-28

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a hardenable mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the hardenable mixture. The invention further relates to such hardenable mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a hardenable mixture. The hardenable mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points. 2 figs.

Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash

DOEpatents

Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

1997-01-01

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a hardenable mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the hardenable mixture. The invention further relates to such hardenable mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a hardenable mixture. The hardenable mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points.

Possibilities of municipal solid waste incinerator fly ash utilisation.

PubMed

Hartmann, Silvie; Koval, Lukáš; Škrobánková, Hana; Matýsek, Dalibor; Winter, Franz; Purgar, Amon

2015-08-01

Properties of the waste treatment residual fly ash generated from municipal solid waste incinerator fly ash were investigated in this study. Six different mortar blends with the addition of the municipal solid waste incinerator fly ash were evaluated. The Portland cement replacement levels of the municipal solid waste incinerator fly ash used were 25%, 30% and 50%. Both, raw and washed municipal solid waste incinerator fly ash samples were examined. According to the mineralogical composition measurements, a 22.6% increase in the pozzolanic/hydraulic properties was observed for the washed municipal solid waste incinerator fly ash sample. The maximum replacement level of 25% for the washed municipal solid waste incinerator fly ash in mortar blends was established in order to preserve the compressive strength properties. Moreover, the leaching characteristics of the crushed mortar blend was analysed in order to examine the immobilisation of its hazardous contents. © The Author(s) 2015.

The National Shipbuilding Research Program: Contaminated Sediment Management Guide for NSRP Shipyards. Appendix 5: Treatment Technologies

DTIC Science & Technology

1999-10-22

soils, baghouse ash, and cyclone ash) were collected every 30 minutes. Composite samples of both water and oil were also collected from each run every 30...Pthalate) > 99.99 %. EmissionslByProducts: Typical flue gas compositions (COZ. N2, H20. etc.) with trace pollutants within permit levels. Description...and polysilicates react in alkali conditions to form “gcopolymers”. In general, the “ geopolymers ” physically stabilize tbe contaminants, heavy metals

Geopolymer Porous Nanoceramics for Structural Smart and Thermal Shock Resistant Applications

DTIC Science & Technology

2011-02-02

porous membranes and foams, ceramic armor composites , iron-based geopolymer analogues, geopolymer composites reinforced with chopped polypropylene... geopolymers and geopolymer composites , as fabricated and upon conversion to ceramics with heating. The microstucture consisted of nanoporous...ceramic armore composites , iron-based geopolymer analogues, geopolymer composites reinforced with chopped polypropylene or basalt fibers and

Physical and Chemical Character of Fly Ash of Coal Fired Power Plant in Java

NASA Astrophysics Data System (ADS)

Triwulan; Priadana, K. A.; Ekaputri, J. J.; Bayuaji, R.

2017-11-01

Quality of fly ash is varying widely in the field, it depends on the combustion process and the quality of the basic ingredients, namely coal. It will affect the physical and mechanical properties of the concrete mixtures used. This study used 12 samples of fly ash. The physical and chemical properties and finesse modulus were analyzed. The fly ash was mixed with OPC (Ordinary Portland Cement) with the proportion of 20% fly ash and 80% OPC. The specimens were form with mortar dimension of 5cm x 5 cm. The test was affected by the correlation of fly ash fineness modulus to compressive strength, correlation density of fly ash to compressive strength, and correlation of carbon content to the compressive strength.

Comparison of leaching characteristics of heavy metals from bottom and fly ashes in Korea and Japan.

PubMed

Shim, Young-Sook; Rhee, Seung-Whee; Lee, Woo-Keun

2005-01-01

The objective of this research was to compare the leaching characteristics of heavy metals such as cadmium, chromium, copper, nickel, lead, etc., in Korean and Japanese municipal solid waste incineration (MSWI) ash. The rate of leaching of heavy metal was measured by KSLT and JTL-13, and the amount of heavy metals leached was compared with the metal content in each waste component. Finally, bio-availability testing was performed to assess the risks associated with heavy metals leached from bottom ash and fly ash. From the results, the value of neutralization ability in Japanese fly ash was four times higher than that in Korean fly ash. The reason was the difference in the content of Ca(OH)(2) in fly ash. The amount of lead leached exceeded the regulatory level in both Japanese and Korean fly ash. The rate of leaching was relatively low in ash with a pH in the range of 6-10. The bio-availability test in fly ash demonstrated that the amount of heavy metals leached was Pb>Cd>Cr, but the order was changed to Pb>Cr>Cd in the bottom ash. The leaching concentration of lead exceeded the Japanese risk level in all fly ashes from the two countries, but the leaching concentration of cadmium exceeded the regulatory level in Korean fly ash only.

Experimental Study on Durability Improvement of Fly Ash Concrete with Durability Improving Admixture

PubMed Central

Quan, Hong-zhu; Kasami, Hideo

2014-01-01

In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%–20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized. PMID:25013870

Environmental hazard of oil shale combustion fly ash.

PubMed

Blinova, Irina; Bityukova, Liidia; Kasemets, Kaja; Ivask, Angela; Käkinen, Aleksandr; Kurvet, Imbi; Bondarenko, Olesja; Kanarbik, Liina; Sihtmäe, Mariliis; Aruoja, Villem; Schvede, Hedi; Kahru, Anne

2012-08-30

The combined chemical and ecotoxicological characterization of oil shale combustion fly ash was performed. Ash was sampled from the most distant point of the ash-separation systems of the Balti and Eesti Thermal Power Plants in North-Eastern Estonia. The fly ash proved potentially hazardous for tested aquatic organisms and high alkalinity of the leachates (pH>10) is apparently the key factor determining its toxicity. The leachates were not genotoxic in the Ames assay. Also, the analysis showed that despite long-term intensive oil-shale combustion accompanied by considerable fly ash emissions has not led to significant soil contamination by hazardous trace elements in North-Eastern Estonia. Comparative study of the fly ash originating from the 'new' circulating fluidized bed (CFB) combustion technology and the 'old' pulverized-fired (PF) one showed that CFB fly ash was less toxic than PF fly ash. Thus, complete transfer to the 'new' technology will reduce (i) atmospheric emission of hazardous trace elements and (ii) fly ash toxicity to aquatic organisms as compared with the 'old' technology. Copyright © 2012 Elsevier B.V. All rights reserved.

Geopolymer Porous Nanoceramics for Structural, for Smart and Thermal Shock Resistant Applications

DTIC Science & Technology

2011-02-02

porous membranes and foams, ceramic armor composites , iron-based geopolymer analogues, geopolymer composites reinforced with chopped polypropylene...the microstructure of geopolymers and geopolymer composites , as fabricated and upon conversion to ceramics with heating. The microstructure consisted...porous membranes and foams, ceramic armor composites , iron-based geopolymer analogues, geopolymer composites reinforced with chopped polypropylene or

Evaluation of Fly Ash Quality Control Tools

DOT National Transportation Integrated Search

2010-06-30

Many entities currently use fly ash in portland cement concrete (PCC) pavements and structures. Although the body of knowledge is : great concerning the use of fly ash, several projects per year are subject to poor performance where fly ash is named ...

Evaluation of fly ash quality control tools.

DOT National Transportation Integrated Search

2010-06-30

Many entities currently use fly ash in portland cement concrete (PCC) pavements and structures. Although the body of knowledge is : great concerning the use of fly ash, several projects per year are subject to poor performance where fly ash is named ...

Evaluation of sewage sludge incineration ash as a potential land reclamation material.

PubMed

Lin, Wenlin Yvonne; Ng, Wei Cheng; Wong, Belinda Shu Ee; Teo, Serena Lay-Ming; Sivananthan, Gayathiri D/O; Baeg, Gyeong Hun; Ok, Yong Sik; Wang, Chi-Hwa

2018-05-23

This study evaluated the potential of utilising sewage sludge incineration ash as a land reclamation material. Toxicity assessment of the leachate of the ash was carried out for both terrestrial and marine organisms. Both the fruit fly Drosophila melanogaster and barnacle Amphibalanus amphitrite showed that both bottom and fly ash leached at liquid-to-solid (L/S) ratio 5 did not substantially affect viabilities. The leachate carried out at L/S 10 was compared to the European Waste Acceptance Criteria and the sewage sludge ashes could be classified as non-hazardous waste. The geotechnical properties of the sewage sludge ash were studied and compared to sand, a conventional land reclamation material, for further evaluation of its potential as a land reclamation material. It was found from direct shear test that both bottom and fly ashes displayed similar and comparable shear strength to that of typical compacted sandy soil based on the range of internal friction angle obtained. However, the consolidation profile of bottom ash was significantly different from sand, while that of fly ash was more similar to sand. Our study showed that the sewage sludge ash has the potential to be used as a land reclamation material. Copyright © 2018 Elsevier B.V. All rights reserved.

A brief review on fly ash and its use in surface engineering

NASA Astrophysics Data System (ADS)

Bhajantri, Vishwanath; Krishna, Prasad; Jambagi, Sudhakar

2018-04-01

Fly ash is a by-product obtained from coal power plants. Over the past two decades, handling this industrial waste has been a great challenge for many developing countries. However, this menace can be used in many industrial applications viz., civil, automobile and aerospace applications. In civil industry, the fly ash has been used in concreate to enhance the porosity that increases the curing time of the concrete. The fly ash has been gaining importance these days as a feedstock material for many thermal spray processes. In automobile sector, the fly ash has been used as a thermal barrier coating in IC engines, whereas in aerospace industry, which demands lighter and stronger materials, the fly ash has been used as a reinforcement material. Hence, so far, fly ash has been used as an either single or a composite feed stock material in thermal spray processes. The fly ash with other materials like alumina, titania and red mud have been deposited using thermal spray processes. These coatings have exhibited higher wear, corrosion and erosion resistance as compared to the uncoated specimens. In this paper, a brief review on fly ash and its use, especially its use as a feed stock in thermal spray coating, is presented. Therefore, the use of fly ash has opened a new frontier of research in thermal spray coating area where economically viable coatings can be produced using industrial waste like fly ash.

Alkali content of fly ash : measuring and testing strategies for compliance.

DOT National Transportation Integrated Search

2015-04-01

Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence : problems in concrete products and raise concern about the effectiveness of the fly ash to mitigate alkali-silica reaction (...

Experimental use of fly ash concrete in prefabricated bridge-deck slabs.

DOT National Transportation Integrated Search

1987-01-01

Hydraulic cement concretes with and without fly ash were investigated to assess the suitability of using fly ash in bridge-deck concrete. Eight prefabricated concrete slabs were prepared: four were control and the remaining contained fly ash. They we...

Characterization of metals released from coal fly ash during dredging at the Kingston ash recovery project.

PubMed

Bednar, A J; Averett, D E; Seiter, J M; Lafferty, B; Jones, W T; Hayes, C A; Chappell, M A; Clarke, J U; Steevens, J A

2013-09-01

A storage-pond dike failure occurred on December 22, 2008 at the Tennessee Valley Authority Kingston Fossil Plant resulting in the release of over 4million cubic meters (5million cubic yards) of fly ash. Approximately half of the released ash was deposited in the main channel of the Emory River, Tennessee, USA. Remediation efforts of the Emory River focused on hydraulic dredging, as well as mechanical excavation in targeted areas. However, agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could promote dissolution and desorption of metals from the solid fly ash material. Furthermore, aeration of the dredge slurry could alter the redox state of metals in the fly ash material and thereby change their sorption, mobility, and toxicity properties. The research presented here focuses on the concentrations and speciation of metals during the fly ash recovery from the Emory River. Our results indicate that arsenite [As(III)] released from the fly ash material during dredging was slowly oxidized to arsenate [As(V)] in the slurry recovery system with subsequent removal through precipitation or sorption reactions with suspended fly ash material. Concentrations of other dissolved metals, including iron and manganese, also generally decreased in the ash recovery system prior to water discharge back to the river. Published by Elsevier Ltd.

FILTRATION MODEL FOR COAL FLY ASH WITH GLASS FABRICS

EPA Science Inventory

The report describes a new mathematical model for predicting woven glass filter performance with coal fly ash aerosols from utility boilers. Its data base included: an extensive bench- and pilot-scale laboratory investigation of several dust/fabric combinations; field data from t...

Leaching characteristics of toxic constituents from coal fly ash mixed soils under the influence of pH.

PubMed

Komonweeraket, Kanokwan; Cetin, Bora; Benson, Craig H; Aydilek, Ahmet H; Edil, Tuncer B

2015-04-01

Leaching behaviors of Arsenic (As), Barium (Ba), Calcium (Ca), Cadmium (Cd), Magnesium (Mg), Selenium (Se), and Strontium (Sr) from soil alone, coal fly ash alone, and soil-coal fly ash mixtures, were studied at a pH range of 2-14 via pH-dependent leaching tests. Seven different types of soils and coal fly ashes were tested. Results of this study indicated that Ca, Cd, Mg, and Sr showed cationic leaching pattern while As and Se generally follows an oxyanionic leaching pattern. On the other hand, leaching of Ba presented amphoteric-like leaching pattern but less pH-dependent. In spite of different types and composition of soil and coal fly ash investigated, the study reveals the similarity in leaching behavior as a function of pH for a given element from soil, coal fly ash, and soil-coal fly ash mixtures. The similarity is most likely due to similar controlling mechanisms (e.g., solubility, sorption, and solid-solution formation) and similar controlling factors (e.g., leachate pH and redox conditions). This offers the opportunity to transfer knowledge of coal fly ash that has been extensively characterized and studied to soil stabilized with coal fly ash. It is speculated that unburned carbon in off-specification coal fly ashes may provide sorption sites for Cd resulting in a reduction in concentration of these elements in leachate from soil-coal fly ash mixture. Class C fly ash provides sufficient CaO to initiate the pozzolanic reaction yielding hydrated cement products that oxyanions, including As and Se, can be incorporated into. Copyright © 2014 Elsevier Ltd. All rights reserved.

Long-term carcinogenicity study in Syrian golden hamster of particulate emissions from coal- and oil-fired power plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Persson, S.A.; Ahlberg, M.; Berghem, L.

1988-04-01

Male Syrian golden hamsters were given 15 weekly intratracheal instillations with suspensions of coal fly ash or oil fly ash. Controls were instilled with saline containing gelatine (0.5 g/100 mL) or to check particle effects with suspensions of hematite (Fe/sub 2/O/sub 3/). The common weekly dose was 4.5 mg/hamster. In addition, one subgroup of hamsters was treated with oil fly ash at a weekly dose of 3.0 mg/hamster and another with coal fly ash at a weekly dose of 6.0 mg/hamster. Other groups of hamsters were treated with suspensions of benzo(a)pyrene (BaP) or with suspensions on coal fly ash, oilmore » fly ash, or Fe/sub 2/O/sub 3/ coated with BaP. The mass median aerodynamic diameters of the coal and oil fly ashes were 4.4 microns and 28 microns, respectively. Hamsters treated with oil fly ash showed a higher frequency of bronchiolar-alveolar hyperplasia than hamsters in the other treatment groups. Squamous dysplasia and squamous metaplasia were most frequent in animals treated with suspensions of BaP or BaP-coated particles. The earliest appearance of a tumor, the highest incidence of tumors, and the highest incidence of malignant tumors were observed in hamsters treated with oil fly ash coated with BaP. Squamous cell carcinoma and adenosquamous carcinoma were the most frequent malignant tumors. No malignant tumors and only few benign tumors were observed in hamsters instilled with suspensions of fly ash not coated with BaP. The present study gives no indication that coal fly ash could create more serious health problems than oil fly ash.« less

Recycling of Sustainable Co-Firing Fly Ashes as an Alkali Activator for GGBS in Blended Cements

PubMed Central

Wu, Yann-Hwang; Huang, Ran; Tsai, Chia-Jung; Lin, Wei-Ting

2015-01-01

This study investigates the feasibility of co-firing fly ashes from different boilers, circulating fluidized beds (CFB) or stokers as a sustainable material in alkali activators for ground granulated blast-furnace slag (GGBS). The mixture ratio of GGBS and co-firing fly ashes is 1:1 by weight. The results indicate that only CF fly ash of CFB boilers can effectively stimulate the potential characteristics of GGBS and provide strength as an alkali activator. CF fly ash consists of CaO3 (48.5%), SiO2 (21.1%), Al2O3 (13.8%), SO3 (10.06%), Fe2O3 (2.25%) and others (4.29%). SA fly ash consists of Al2O3 (19.7%), SiO2 (36.3%), Fe2O3 (28.4%) and others (15.6%). SB fly ash consists of Al2O3 (15%), SiO2 (25.4%), Zn (20.6%), SO3 (10.9%), Fe2O3 (8.78%) and others (19.32%). The mixtures of SA fly ash and SB fly ash with GGBS, respectively, were damaged in the compressive strength test during seven days of curing. However, the built up strength of the CF fly ash and GGBS mixture can only be maintained for 7–14 days, and the compressive strength achieves 70% of that of a controlled group (cement in hardening cement paste). The strength of blended CF fly ash and GGBS started to decrease after 28 days, and the phenomenon of ettrigite was investigated due to the high levels of sulfur content. The CaO content in sustainable co-firing fly ashes must be higher than a certain percentage in reacting GGBS to ensure the strength of blended cements. PMID:28787970

A novel silica alumina-based backfill material composed of coal refuse and fly ash.

PubMed

Yao, Yuan; Sun, Henghu

2012-04-30

In this paper, a systematic study was conducted to investigate a novel silica alumina-based backfill material composed of coal refuse and fly ash. The coal refuse and fly ash had different properties under various thermal activation temperatures (20 °C, 150 °C, 350 °C, 550 °C, 750 °C and 950 °C). It is known that a thermal activation temperature ranging from 20 °C to 950 °C significantly increases the flowability and pozzolanic properties of the coal refuse; however, the flowability of fly ash decreases when the activation temperature is higher than 550 °C because of a severe agglomeration phenomenon on its surface. An optimal design for this backfill material was determined to include an activated portion composed of 5% coal refuse at 750 °C and 15% fly ash at 20 °C. This combination yields the best performance with excellent flowability, a high compressive strength and a low bleeding rate. The microanalysis results corresponded well with the performance tests at different activation conditions. In the coal refuse, kaolinite peaks began to decrease because of their transformation into metakaolin at 550 °C. Chlorite peaks disappeared at 750 °C. Muscovite peaks decreased at 750 °C and disappeared at 950 °C. During this process, muscovite 2M(1) gradually dehydroxylated to muscovite HT. Furthermore, this paper examined the environmental acceptance and economic feasibility of this technology and found that this silica alumina-based backfill material composed of coal refuse and fly ash not only meets EPA requirements but also has several advantages in industry feasibility when compared with hydraulic backfill, rock backfill and paste backfill. Published by Elsevier B.V.

Detection of fly ash in Portland cement fly ash concrete : final report.

DOT National Transportation Integrated Search

1991-12-01

The chemical composition, phases present, and textural characteristics of suite of 113 fly ashes were studied. The fly ashes came from Gifford-Hill & Co., Inc. power plants in Cason, TX; Gentry, AR; Westlake, LA; Boyce, LA; Choteau, OK and Oologah, O...

Evaluation of the mechanical properties of class-F fly ash.

PubMed

Kim, Bumjoo; Prezzi, Monica

2008-01-01

Coal-burning power plants in the United States (US) generate more than 70 million tons of fly ash as a by-product annually. Recycling large volumes of fly ash in geotechnical applications may offer an attractive alternative to the disposal problem as most of it is currently dumped in ponds or landfills. Class-F fly ash, resulting from burning of bituminous or anthracite coals, is the most common type of fly ash in the US. In the present study, the mechanical characteristics (compaction response, compressibility, and shear strength) of class-F fly ash were investigated by performing various laboratory tests (compaction test, one-dimensional compression test, direct shear test and consolidated-drained triaxial compression test) on fly ash samples collected from three power plants in the state of Indiana (US). Test results have shown that despite some morphological differences, class-F fly ash exhibits mechanical properties that are, in general, comparable to those observed in natural sandy soils.

Water holding capacities of fly ashes: Effect of size fractionation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, A.; Rano, R.

2007-07-01

Water holding capacities of fly ashes from different thermal power plants in Eastern India have been compared. Moreover, the effect of size fractionation (sieving) on the water holding capacities has also been determined. The desorption rate of water held by the fly ash fractions at ambient temperature (25-30{sup o}C) has been investigated. The effect of mixing various size fractions of fly ash in increasing the water holding capacities of fly ash has been studied. It is observed that the fly ash obtained from a thermal power plant working on stoker-fired combustor has the highest water holding capacity, followed by themore » one that works on pulverized fuel combustor. Fly ash collected from super thermal power plant has the least water holding capacity (40.7%). The coarser size fractions of fly ashes in general have higher water holding capacities than the finer ones. An attempt has been made to correlate the results obtained, with the potential use in agriculture.« less

Physical and biological studies of coal and oil fly ash.

PubMed Central

Fisher, G L; McNeill, K L; Prentice, B A; McFarland, A R

1983-01-01

Studies were performed to compare the physical and chemical characteristics and the in vitro macrophage cytotoxicity of oil and coal fly ash. Sampling methodology was developed to collect size-fractionated particulate matter from the smokestack of either a coal-fired or an oil-fired power plant. Morphological studies demonstrated particle heterogeneity, although most coal fly ash particles appeared to be spherical. Oil fly ash contained two major morphologies; nonopaque amorphous particles and opaque amorphous particles. Elemental analysis indicates that the coal ash is predominantly composed of aluminosilicate particles, while the oil ash is predominantly inorganic sulfates and carbonaceous particles. In vitro macrophage assays demonstrate that the finest coal fly ash particles are the most cytotoxic; the cytotoxicity is significantly less than that of alpha-quartz, the positive control particle. In contrast, the oil fly ash particles are more cytotoxic than quartz. The cytotoxicity of oil fly ash is due to soluble components, possibly vanadium salts. Images FIGURE 2. A FIGURE 2. B FIGURE 2. C FIGURE 2. D PMID:6641653

Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Zhikun; Zhang, Lei; Li, Aimin, E-mail: leeam@dlut.edu.cn

Highlights: • Glass ceramic composite is prepared from oil shale fly ash and MSWI bottom ash. • A novel method for the production of glass ceramic composite is presented. • It provides simple route and lower energy consumption in terms of recycling waste. • The vitrified slag can promote the sintering densification process of glass ceramic. • The performances of products decrease with the increase of oil shale fly ash content. - Abstract: Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment.more » In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2 h) showed the properties of density of 1.92 ± 0.05 g/cm{sup 3}, weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was reduced compared to conventional vitrification and sintering method. Chemical resistance and heavy metals leaching results of glass ceramic composites further confirmed the possibility of its engineering applications.« less

Mercury release from fly ashes and hydrated fly ash cement pastes

NASA Astrophysics Data System (ADS)

Du, Wen; Zhang, Chao-yang; Kong, Xiang-ming; Zhuo, Yu-qun; Zhu, Zhen-wu

2018-04-01

The large-scale usage of fly ash in cement and concrete introduces mercury (Hg) into concrete structures and a risk of secondary emission of Hg from the structures during long-term service was evaluated. Three fly ashes were collected from coal-fired power plants and three blend cements were prepared by mixing Ordinary Portland cement (OPC) with the same amount of fly ash. The releasing behaviors of Hg0 from the fly ash and the powdered hydrated cement pastes (HCP) were measured by a self-developed Hg measurement system, where an air-blowing part and Hg collection part were involved. The Hg release of fly ashes at room temperature varied from 25.84 to 39.69 ng/g fly ash during 90-days period of air-blowing experiment. In contrast, the Hg release of the HCPs were in a range of 8.51-18.48 ng/g HCP. It is found that the Hg release ratios of HCPs were almost the same as those of the pure fly ashes, suggesting that the hydration products of the HCP have little immobilization effect on Hg0. Increasing temperature and moisture content markedly promote the Hg release.

Removal of fly-ash and dust particulate matters from syngas produced by gasification of coal by using a multi-stage dual-flow sieve plate wet scrubber.

PubMed

Kurella, Swamy; Meikap, Bhim Charan

2016-08-23

In this work, fly-ash water scrubbing experiments were conducted in a three-stage lab-scale dual-flow sieve plate scrubber to observe the performance of scrubber in fly-ash removal at different operating conditions by varying the liquid rate, gas rate and inlet fly-ash loading. The percentage of fly-ash removal efficiency increases with increase in inlet fly-ash loading, gas flow rate and liquid flow rate, and height of the scrubber; 98.55% maximum percentage of fly-ash removal efficiency (ηFA) is achieved at 19.36 × 10(-4) Nm(3)/s gas flow rate (QG) and 48.183 × 10(-6) m(3)/s liquid flow rate (QL) at 25 × 10(-3) kg/Nm(3) inlet fly-ash loading (CFA,i). A model has also been developed for the prediction of fly-ash removal efficiency of the column using the experimental results. The predicted values calculated using the correlation matched well with the experimental results. Deviations observed between the experimental and the predicted values were less than 20%.

Thermal co-treatment of combustible hazardous waste and waste incineration fly ash in a rotary kiln.

PubMed

Huber, Florian; Blasenbauer, Dominik; Mallow, Ole; Lederer, Jakob; Winter, Franz; Fellner, Johann

2016-12-01

As current disposal practices for municipal solid waste incineration (MSWI) fly ash are either associated with significant costs or negative environmental impacts, an alternative treatment was investigated in a field scale experiment. Thereto, two rotary kilns were fed with hazardous waste, and moistened MSWI fly ash (water content of 23%) was added to the fuel of one kiln with a ratio of 169kg/Mg hazardous waste for 54h and 300kg/Mg hazardous waste for 48h while the other kiln was used as a reference. It was shown that the vast majority (>90%) of the inserted MSWI fly ash was transferred to the bottom ash of the rotary kiln. This bottom ash complied with the legal limits for non-hazardous waste landfills, thereby demonstrating the potential of the investigated method to transfer hazardous waste (MSWI fly ash) into non-hazardous waste (bottom ash). The results of a simple mixing test (MSWI fly ash and rotary kiln bottom ash have been mixed accordingly without thermal treatment) revealed that the observed transformation of hazardous MSWI fly ash into non-hazardous bottom ash during thermal co-treatment cannot be referred to dilution, as the mixture did not comply with legal limits for non-hazardous waste landfills. For the newly generated fly ash of the kiln, an increase in the concentration of Cd, K and Pb by 54%, 57% and 22%, respectively, was observed. In general, the operation of the rotary kiln was not impaired by the MSWI fly ash addition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigation on the fly ash thermal treatment on the performance of Lithium Ferriphosphate (LiFePO{sub 4}) battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Febiolita, Bella; Khoirunnissak, Dewi; Purwanto, Agus, E-mail: aguspurw@gmail.com

Addition of the fly ash can be used to improve the capacity of LiFePO{sub 4} battery. Fly ash was added in Acethylene Black (AB) as 2% of the total weight of Acetylene Black (AB). The effects of temperature variation and fly ash characteristics were analyzed. Fly ash was prepared by heating at 50, 100, 150, and 250°C in muffle furnace for 5 hours and passed in 200 mesh screen prior to mixing it with other compounds. Lithium Ferriphospat (LiFePO{sub 4}), fly ash, Acethylene Black (AB), Polyvinylidene Fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed tomore » be slurry. The slurry were coated, dried and hot pressed to make a cathode film. The performance of battery lithium was examined by eight channel battery analyzer. The composition of the fly ash was examined by X-ray fluorescence spectrometry (XRF) and Fourier Tansform Infrared Spectroscopy (FTIR). The excellent performance was shown in the fly ash addition which were treated by heating at 150°C. The capacity of fly ash added LiFePO{sub 4} battery is 94.373 mAh/g, which is higher than that of without fly ash addition, i.e. 67.998 mAh/g.« less

Chemical and engineering properties of fired bricks containing 50 weight percent of class F fly ash

USGS Publications Warehouse

Chou, I.-Ming; Patel, V.; Laird, C.J.; Ho, K.K.

2001-01-01

The generation of fly ash during coal combustion represents a considerable solid waste disposal problem in the state of Illinois and nationwide. In fact, the majority of the three million tons of fly ash produced from burning Illinois bituminous coals is disposed of in landfills. The purpose of this study was to obtain a preliminary assessment of the technical feasibility of mitigating this solid waste problem by making fired bricks with the large volume of fly ash generated from burning Illinois coals. Test bricks were produced by the extrusion method with increasing amounts (20-50% by weight) of fly ash as a replacement for conventional raw materials. The chemical characteristics and engineering properties of the test bricks produced with and without 50 wt% of fly ash substitutions were analyzed and compared. The properties of the test bricks containing fly ash were at least comparable to, if not better than, those of standard test bricks made without fly ash and met the commercial specifications for fired bricks. The positive results of this study suggest that further study on test bricks with fly ash substitutions of greater than 50wt% is warranted. Successful results could have an important impact in reducing the waste disposal problem related to class F fly ash while providing the brick industry with a new low cost raw material. Copyright ?? 2001 Taylor & Francis.

Development and freeze-thaw durability of high flyash-content concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sajadi, J.

1987-01-01

Objectives were to investigate the effects on concrete strength, drying shrinkage, freeze-thaw durability, and air-void system parameters of replacing various amounts of portland cement with different types of fly ash and to compare selected characteristics of such fly-ash concretes and fly-ash concretes containing a high-range water-reducing admixture to those of a control mixture. It was concluded that concrete mixtures with 90-day compressive strengths equal to the control could be produced when large amounts of cement were replaced by fly ash. In addition, when the high-range water-reducing admixtures was employed, very large amounts of cement could be replaced by fly ashmore » to yield mixtures whose compressive strengths were equal to or greater than the strengths of the control mix at all ages. The maximum amount of cement that could be replaced for equal-strength mixtures depended upon the nature of the fly ash. Drying shrinkage of plain fly-ash concretes and fly-ash concretes containing the high-range water-reducing admixture were similar to those of the control mix. The optimum fly-ash content in a concrete is comparable in strength and durability to a conventional (control) concrete was influenced by the chemical and physical characteristics of the fly ash.« less

Differences in gasification behaviors and related properties between entrained gasifier fly ash and coal char

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jing Gu; Shiyong Wu; Youqing Wu

2008-11-15

In the study, two fly ash samples from Texaco gasifiers were compared to coal char and the physical and chemical properties and reactivity of samples were investigated by scanning electron microscopy (SEM), SEM-energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), N{sub 2} and CO{sub 2} adsorption method, and isothermal thermogravimetric analysis. The main results were obtained. The carbon content of gasified fly ashes exhibited 31-37%, which was less than the carbon content of 58-59% in the feed coal. The fly ashes exhibited higher Brunauer-Emmett-Teller (BET) surface area, richer meso- and micropores, more disordered carbon crystalline structure, and better CO{sub 2} gasification reactivitymore » than coal char. Ashes in fly ashes occurred to agglomerate into larger spherical grains, while those in coal char do not agglomerate. The minerals in fly ashes, especial alkali and alkaline-earth metals, had a catalytic effect on gasification reactivity of fly ash carbon. In the low-temperature range, the gasification process of fly ashes is mainly in chemical control, while in the high-temperature range, it is mainly in gas diffusion control, which was similar to coal char. In addition, the carbon in fly ashes was partially gasified and activated by water vapor and exhibited higher BET surface area and better gasification activity. Consequently, the fact that these carbons in fly ashes from entrained flow gasifiers are reclaimed and reused will be considered to be feasible. 15 refs., 7 figs., 5 tabs.« less

Intra- and inter-unit variation in fly ash petrography and mercury adsorption: Examples from a western Kentucky power station

USGS Publications Warehouse

Hower, J.C.; Finkelman, R.B.; Rathbone, R.F.; Goodman, J.

2000-01-01

Fly ash was collected from eight mechanical and 10 baghouse hoppers at each of the twin 150-MW wall-fired units in a western Kentucky power station. The fuel burned at that time was a blend of many low-sulfur, high-volatile bituminous Central Appalachian coals. The baghouse ash showed less variation between units than the mechanical hoppers. The mechanical fly ash, coarser than the baghouse ash, showed significant differences in the amount of total carbon and in the ratio of isotropic coke to both total carbon and total coke - the latter excluding inertinite and other unburned, uncoked coal. There was no significant variation in proportions of inorganic fly ash constituents. The inter-unit differences in the amount and forms of mechanical fly ash carbon appear to be related to differences in pulverizer efficiency, leading to greater amounts of coarse coal, therefore unburned carbon, in one of the units. Mercury capture is a function of both the total carbon content and the gas temperature at the point of fly ash separation, mercury content increasing with an increase in carbon for a specific collection system. Mercury adsorption on fly ash carbon increases at lower flue-gas temperatures. Baghouse fly ash, collected at a lower temperature than the higher-carbon mechanically separated fly ash, contains a significantly greater amount of Hg.

Assessing fly ash treatment: remediation and stabilization of heavy metals.

PubMed

Lima, A T; Ottosen, Lisbeth M; Ribeiro, Alexandra B

2012-03-01

Fly ashes from Municipal Solid Waste (MSW), straw (ST) and co-combustion of wood (CW) are here analyzed with the intent of reusing them. Two techniques are assessed, a remediation technique and a solidification/stabilization one. The removal of heavy metals from fly ashes through the electrodialytic process (EDR) has been tried out before. The goal of removing heavy metals has always been the reuse of fly ash, for instance in agricultural fields (BEK). The best removal rates are here summarized and some new results have been added. MSW fly ashes are still too hazardous after treatment to even consider application to the soil. ST ash is the only residue that gets concentrations low enough to be reused, but its fertilizing value might be questioned. An alternative reuse for the three ashes is here preliminary tested, the combination of fly ash with mortar. Fly ashes have been substituted by cement fraction or aggregate fraction. Surprisingly, better compressive strengths were obtained by replacing the aggregate fraction. CW ashes presented promising results for the substitution of aggregate in mortar and possibly in concrete. Copyright © 2010 Elsevier Ltd. All rights reserved.

Acceleration of Intended Pozzolanic Reaction under Initial Thermal Treatment for Developing Cementless Fly Ash Based Mortar.

PubMed

Kwon, Yang-Hee; Kang, Sung-Hoon; Hong, Sung-Gul; Moon, Juhyuk

2017-02-24

Without using strong alkaline solution or ordinary Portland cement, a new structural binder consisting of fly ash and hydrated lime was hardened through an intensified pozzolanic reaction. The main experimental variables are the addition of silica fume and initial thermal treatment (60 °C for 3 days). A series of experiments consisting of mechanical testing (compressive and flexural strength, modulus of elasticity), X-ray diffraction, and measurements of the heat of hydration, pore structure, and shrinkage were conducted. These tests show that this new fly ash-based mortar has a compressive strength of 15 MPa at 91 days without any silica fume addition or initial thermal treatment. The strength increased to over 50 MPa based on the acceleration of the intensified pozzolanic reaction from the silica fume addition and initial thermal treatment. This is explained by a significant synergistic effect induced by the silica fume. It intensifies the pozzolanic reaction under thermal treatment and provides a space filling effect. This improved material performance can open a new pathway to utilize the industrial by-product of fly ash in cementless construction materials.

Investigation on Leaching Behaviour of Fly Ash and Bottom Ash Replacement in Self-Compacting Concrete

NASA Astrophysics Data System (ADS)

Kadir, Aeslina Abdul; Ikhmal Haqeem Hassan, Mohd; Bakri Abdullah, Mohd Mustafa Al

2016-06-01

Fly ash and bottom ash are some of the waste generated by coal-fired power plants, which contains large quantities of toxic and heavy metals. In recent years, many researchers have been interested in studying on the properties of self-compacting concrete incorporated with fly ash and bottom ash but there was very limited research from the combination of fly ash and bottom ash towards the environmental needs. Therefore, this research was focused on investigating the leachability of heavy metals of SCC incorporated with fly ash and bottom ash by using Toxicity Characteristic Leaching Procedure, Synthetic Precipitation Leaching Procedure and Static Leaching Test. The samples obtained from the coal-fired power plant located at Peninsula, Malaysia. In this study, the potential heavy metals leached out from SCC that is produced with fly ash as a replacement for Ordinary Portland Cement and bottom ash as a substitute for sand with the ratios from 10% to 30% respectively were designated and cast. There are eight heavy metals of concern such as As, Cr, Pb, Zn, Cu, Ni, Mn and Fe. The results indicated that most of the heavy metals leached below the permissible limits from the United States Environmental Protection Agency and World Health Organization limit for drinking water. As a conclusion, the minimum leaching of the heavy metals from the incorporation of fly ash and bottom ash in self-compacting concrete was found in 20% of fly ash and 20% of bottom ash replacement. The results also indicate that this incorporation could minimize the potential of environmental problems.

Degradation of self-compacting concrete (SCC) due to sulfuric acid attack: Experiment investigation on the effect of high volume fly ash content

NASA Astrophysics Data System (ADS)

Kristiawan, S. A.; Sunarmasto; Tyas, G. P.

2016-02-01

Concrete is susceptible to a variety of chemical attacks. In the sulfuric acid environment, concrete is subjected to a combination of sulfuric and acid attack. This research is aimed to investigate the degradation of self-compacting concrete (SCC) due to sulfuric acid attack based on measurement of compressive strength loss and diameter change. Since the proportion of SCC contains higher cement than that of normal concrete, the vulnerability of this concrete to sulfuric acid attack could be reduced by partial replacement of cement with fly ash at high volume level. The effect of high volume fly ash at 50-70% cement replacement levels on the extent of degradation owing to sulfuric acid will be assessed in this study. It can be shown that an increase in the utilization of fly ash to partially replace cement tends to reduce the degradation as confirmed by less compressive strength loss and diameter change. The effect of fly ash to reduce the degradation of SCC is more pronounced at a later age.

Calcium phosphate stabilization of fly ash with chloride extraction.

PubMed

Nzihou, Ange; Sharrock, Patrick

2002-01-01

Municipal solid waste incinerator by products include fly ash and air pollution control residues. In order to transform these incinerator wastes into reusable mineral species, soluble alkali chlorides must be separated and toxic trace elements must be stabilized in insoluble form. We show that alkali chlorides can be extracted efficiently in an aqueous extraction step combining a calcium phosphate gel precipitation. In such a process, sodium and potassium chlorides are obtained free from calcium salts, and the trace metal ions are immobilized in the calcium phosphate matrix. Moderate calcination of the chemically treated fly ash leads to the formation of cristalline hydroxylapatite. Fly ash spiked with copper ions and treated by this process shows improved stability of metal ions. Leaching tests with water or EDTA reveal a significant drop in metal ion dissolution. Hydroxylapatite may trap toxic metals and also prevent their evaporation during thermal treatments. Incinerator fly ash together with air pollution control residues, treated by the combined chloride extraction and hydroxylapatite formation process may be considered safe to use as a mineral filler in value added products such as road base or cement blocks.

On the removal of hexavalent chromium from a Class F fly ash.

PubMed

Huggins, F E; Rezaee, M; Honaker, R Q; Hower, J C

2016-05-01

Coarse and fine samples of a Class F fly ash obtained from commercial combustion of Illinois bituminous coal have been exposed to two long-term leaching tests designed to simulate conditions in waste impoundments. ICP-AES analysis indicated that the coarse and fine fly ash samples contained 135 and 171mg/kg Cr, respectively. Measurements by XAFS spectroscopy showed that the ash samples originally contained 5 and 8% of the chromium, respectively, in the hexavalent oxidation state, Cr(VI). After exposure to water for more than four months, the percentage of chromium as Cr(VI) in the fly-ash decreased significantly for the coarse and fine fly-ash in both tests. Combining the XAFS data with ICP-AES data on the concentration of chromium in the leachates indicated that, after the nineteen-week-long, more aggressive, kinetic test on the coarse fly ash, approximately 60% of the Cr(VI) had been leached, 20% had been reduced to Cr(III) and retained in the ash, and 20% remained as Cr(VI) in the ash. In contrast, during the six-month-long baseline test, very little Cr was actually leached from either the coarse or the fine fly-ash (<0.1mg/kg); rather, about 66% and 20%, respectively, of the original Cr(VI) in the coarse and fine fly-ash was retained in the ash in that form, while the remainder, 34% and 80%, respectively, was reduced and retained in the ash as Cr(III). The results are interpreted as indicating that Cr(VI) present in Class F fly-ash can be reduced to Cr(III) when in contact with water and that such chemical reduction can compete with physical removal of Cr(VI) from the ash by aqueous leaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

Solidification/stabilization of fly ash from city refuse incinerator facility and heavy metal sludge with cement additives.

PubMed

Cerbo, Atlas Adonis V; Ballesteros, Florencio; Chen, Teng Chien; Lu, Ming-Chun

2017-01-01

Solidification and stabilization are well-known technologies used for treating hazardous waste. These technologies that use cementitious binder have been applied for decades as a final treatment procedure prior to the hazardous waste disposal. In the present work, hazardous waste like fly ash containing high concentrations of heavy metals such Zn (4715.56 mg/kg), Pb (1300.56 mg/kg), and Cu (534.72 mg/kg) and amounts of Ag, Cd, Co, Cr, Mn, and Ni was sampled from a city refuse incinerator facility. This fly ash was utilized in the solidification/stabilization of heavy metal sludge since fly ash has cement-like characteristics. Cement additives such as sodium sulfate, sodium carbonate, and ethylenediaminetetraacetic acid (EDTA) was incorporated to the solidified matrix in order to determine its effect on the solidification/stabilization performance. The solidified matrix was cured for 7, 14, 21, and 28 days prior for its physical and chemical characterizations. The results show that the solidified matrix containing 40% fly ash and 60% cement with heavy metal sludge was the formulation that has the highest fly ash content with a satisfactory strength. The solidified matrix was also able to immobilize the heavy metals both found in the fly ash and sludge based on the toxicity characteristic leaching procedure (TCLP) test. It also shows that the incorporation of sodium carbonate into the solidified matrix not only further improved the compressive strength from 0.36 MPa (without Na 2 CO 3 ) to 0.54 MPa (with Na 2 CO 3 ) but also increased its leaching resistance.

Magnetic susceptibility mapping of fly ash in soil samples near a coal-burning power plant in Pointe Coupee Parish, Louisiana.

NASA Astrophysics Data System (ADS)

Elhelou, O.; Richter, C.

2015-12-01

Atmospheric deposition of pollutants is a major health and environmental concern. In a 2010 study, the CATF attributed over 13,000 deaths each year to fly ash and other fine particles emitted by U.S. coal-burning power plants. The magnetic properties of fly ash allows for mapping an area suspect of PM pollution faster and more efficiently than by conducting chemical analysis as the former alternative. The objective of this study is to detect the presence of magnetic particles related to the migration of fly ash from a nearby coal power plant over parts of Pointe Coupee Parish, LA. This is based on the idea that the fly ash that is released into the atmosphere during the coal burning process contains heavy metals and magnetic particles in the form of ferrospheres, which can be used to trace back to the source. Maps of the top and sub soil were generated to differentiate the magnetic susceptibility values of the heavy metals potentially attributed to the migration and settling of fly ash onto the surface from any pre-existing or naturally occurring heavy metals in the sub soil. A 60 km2 area in Pointe Coupee Parish was investigated in approximately 0.5 km2 subsets. The area in Pointe Coupee Parish, LA was selected because land use is predominantly rural with the Big Cajun II power plant as the main contributor for air borne contaminants. Samples of fly ash obtained directly from the source below one of the power plant's precipitators were also analyzed to verify the field and laboratory analysis. Contour maps representing the spatial distribution of fly ash over Pointe Coupee, LA, along with histograms of magnetic susceptibility values, and chemical analysis all indicate a correlation between the proximity to the power plant and the predominant wind direction. Acquisition curves of the isothermal remnant magnetization demonstrate the presence of predominantly low coercivity minerals (magnetite) with a small amount of a high-coercivity phase. The microstructure of the magnetic fractions of the fly ash along with select top and sub soil samples were observed using a reflective light microscope for identifying and confirming the presence of ferrospheres associated with fly ash. Chemical analyses of select samples revealed their heavy metal composition and the correlation with their SIRM and low field mass susceptibility values.

Long-term effect of lime-fly ash treated soils.

DOT National Transportation Integrated Search

2003-12-01

In October of 2000 MDOT initiated State Study No. 147, entitled "Long-Term Effect of Lime-Fly Ash Treated Soils." The purpose of this study : was to evaluate the long-term performance of LFA stabilized soil as a base course material. Part of the impe...

Sulfate and acid resistant concrete and mortar

DOEpatents

Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

1998-01-01

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance.

Sulfate and acid resistant concrete and mortar

DOEpatents

Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

1998-06-30

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance. 6 figs.

Dehalogenation potential of municipal waste incineration fly ash. I. General principles.

PubMed

Pekárek, Vladimír; Karban, Jindrich; Fiserová, Eva; Bures, Michal; Pacáková, Vera; Vecerníková, Eva

2003-01-01

It is well known that the fly ash from filters of municipal waste incinerators (MWI-FA) shows dehalogenation properties after heating it to 240-450 degrees C. However, this property is not general, and fly ash samples do not possess dehalogenation ability at all in many cases. Fly ash has a very variable composition, and the state of the fly ash matter therefore plays the decisive role. In the present paper, the function of important components responsible for the dehalogenation activity of MWI-FA is analysed and compared with the model fly ash. With the aim of accounting for the dehalogenation activity of MWI-FA, the following studies of hexachlorobenzene (HCB) dechlorination were performed: The role of copper in dehalogenation experiments was evaluated for five types of metallic copper. The gasification of carbon in MWI-FA was studied in the 250-350 degrees C temperature range. Five different kinds of carbon were used, combined with conventional Cu(o) and activated nanosize copper powder. The dechlorination experiments were also carried out with Cu(II) compounds such as CuO, Cu(OH)2, CuCl2 and CuSO4. The results were discussed from the standpoint of thermodynamics of potential reactions. Based on these results, the model of fly ash was proposed, containing silica gel, metallic copper and carbon. The dechlorination ability of MWI-FA and the model fly ash are compared under oxygen-deficient atmosphere. The results show that, under given experimental conditions, copper acts in the dechlorination as a stoichiometric agent rather than as a catalyst. The increased surface activity of copper enhances its dechlorination activity. It was found further that the presence of copper leads to a decrease in the temperature of carbon gasification. The cyclic valence change from Cu(o) to Cu+ or Cu2+ is a prerequisite for the dehalogenation to take place. Thermodynamic analysis of the dechlorination effect, as well as the comparison of dechlorination pathways on MWI-FA and model fly ash, can provide a deeper understanding of the studied reaction.

Biochemical methane potential from sewage sludge: Effect of an aerobic pretreatment and fly ash addition as source of trace elements.

PubMed

Huiliñir, César; Pinto-Villegas, Paula; Castillo, Alejandra; Montalvo, Silvio; Guerrero, Lorna

2017-06-01

The effect of aerobic pretreatment and fly ash addition on the production of methane from mixed sludge is studied. Three assays with pretreated and not pretreated mixed sludge in the presence of fly ash (concentrations of 0, 10, 25, 50, 250 and 500mg/L) were run at mesophilic condition. It was found that the combined use of aerobic pretreatment and fly ash addition increases methane production up to 70% when the fly ash concentrations were lower than 50mg/L, while concentrations higher than 250mg/L cause up to 11% decrease of methane production. For the anaerobic treatment of mixed sludge without pretreatment, the fly ash improved methane generation at all the concentrations studied, with a maximum of 56%. The removal of volatile solids does not show an improvement compared to the separate use of an aerobic pre-treatment and fly ash addition. Therefore, the combined use of the aerobic pre-treatment and fly ash addition improves only the production of methane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recycling of municipal solid waste incinerator fly ash by using hydrocyclone separation.

PubMed

Ko, Ming-Sheng; Chen, Ying-Liang; Wei, Pei-Shou

2013-03-01

The municipal solid waste incinerators (MSWIs) in Taiwan generate about 300,000 tons of fly ash annually, which is mainly composed of calcium and silicon compounds, and has the potential for recycling. However, some heavy metals are present in the MSWI fly ash, and before recycling, they need to be removed or reduced to make the fly ash non-hazardous. Accordingly, the purpose of this study was to use a hydrocyclone for the separation of the components of the MSWI fly ash in order to obtain the recyclable portion. The results show that chloride salts can be removed from the fly ash during the hydrocyclone separation process. The presence of a dense medium (quartz sand in this study) is not only helpful for the removal of the salts, but also for the separation of the fly ash particles. After the dense-medium hydrocyclone separation process, heavy metals including Pb and Zn were concentrated in the fine particles so that the rest of the fly ash contained less heavy metal and became both non-hazardous and recyclable. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chemical Imaging Analysis of Environmental Particles Using the Focused Ion Beam/Scanning Electron Microscopy Technique. Microanalysis Insights into Atmospheric Chemistry of Fly Ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Haihan; Grassian, Vicki H.; Saraf, Laxmikant V.

2012-11-08

Airborne fly ash from coal combustion may represent a source of bioavailable iron (Fe) in the open ocean. However, few studies have been made focusing on Fe speciation and distribution in coal fly ash. In this study, chemical imaging of fly ash has been performed using a dual-beam FIB/SEM (focused ion beam/scanning electron microscope) system for a better understanding of how simulated atmospheric processing modify the morphology, chemical compositions and element distributions of individual particles. A novel approach has been applied for cross-sectioning of fly ash specimen with a FIB in order to explore element distribution within the interior ofmore » individual particles. Our results indicate that simulated atmospheric processing causes disintegration of aluminosilicate glass, a dominant material in fly ash particles. Aluminosilicate-phase Fe in the inner core of fly ash particles is more easily mobilized compared with oxide-phase Fe present as surface aggregates on fly ash spheres. Fe release behavior depends strongly on Fe speciation in aerosol particles. The approach for preparation of cross-sectioned specimen described here opens new opportunities for particle microanalysis, particular with respect to inorganic refractive materials like fly ash and mineral dust.« less

H2S adsorption by municipal solid waste incineration (MSWI) fly ash with heavy metals immobilization.

PubMed

Wu, Huanan; Zhu, Yu; Bian, Songwei; Ko, Jae Hac; Li, Sam Fong Yau; Xu, Qiyong

2018-03-01

As a byproduct of municipal solid waste incineration (MSWI) plant, fly ash is becoming a challenge for waste management in recent years. In this study, MSWI fly ash (FA) was evaluated for the potential capacity of odorous gas H 2 S removal. Results showed that fly ash demonstrated longer breakthrough time and higher H 2 S capacities than coal fly ash and sandy soil, due to its high content of alkali oxides of metals including heavy metals. H 2 S adsorption capacities of FA1 and FA2 were 15.89 and 12.59 mg H 2 S/g, respectively for 750 ppm H 2 S. The adsorption of H 2 S on fly ash led to formation of elemental sulfur and metal sulfide. More importantly, the formation of metal sulfide significantly reduced the leachability of heavy metals, such as Cr, Cu, Cd and Pb as shown by TCLP tests. The adsorption isotherms fit well with Langmuir model with the correlation coefficient over 0.99. The adsorption of H 2 S on fly ash features simultaneous H 2 S removal and stabilization and heavy metals found in most MSWI fly ash, making fly ash the potential low cost recycled sorbent material. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-volume fly ash concrete.

DOT National Transportation Integrated Search

2013-06-01

The objective of the proposed study is to design, test, and evaluate high-volume fly ash concrete mixtures. Traditional specifications : limit the amount of fly ash to 40% or less cement replacement. This program attempts to increase the ash content ...

Sintering of MSW fly ash for reuse as a concrete aggregate.

PubMed

Mangialardi, T

2001-10-12

The sintering process of municipal solid waste (MSW) fly ash was investigated in order to manufacture sintered products for reuse as concrete aggregates. Four types of fly ash resulting from different Italian MSW incineration plants were tested in this study. A modification of the chemical composition of MSW fly ash--through a preliminary four-stage washing treatment of this material with water--was attempted to improve the chemical and mechanical characteristics of sintered products.The sintering treatment of untreated or washed fly ash was performed on cylindrical compact specimens (15 mm in diameter and 20mm in height) at different compact pressures, sintering temperatures and times.The sintering process of untreated MSW fly ashes proved to be ineffective for manufacturing sintered products for reuse as a construction material, because of the adverse chemical characteristics of these fly ashes in terms of sulfate, chloride, and vitrifying oxide contents.A preliminary washing treatment of MSW fly ash with water greatly improved the chemical and mechanical characteristics of sintered products and, for all the types of fly ash tested, the sintered products satisfied the Italian requirements for normal weight aggregates for use in concretes having a specified strength not greater than 12 and 15N/mm(2), when measured on cylindrical and cubic specimens, respectively.A compact pressure of 28 N/mm(2), a sintering temperature of 1140 degrees C, and a sintering time of 60 min were the best operating conditions for manufacturing sintered products of washed MSW fly ash.

Retention of elemental mercury in fly ashes in different atmospheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

M.A. Lopez-Anton; M. Diaz-Somoano; M.R. Martinez-Tarazona

2007-01-15

Mercury is an extremely volatile element, which is emitted from coal combustion to the environment mostly in the vapor phase. To avoid the environmental problems that the toxic species of this element may cause, control technologies for the removal of mercury are necessary. Recent research has shown that certain fly ash materials have an affinity for mercury. Moreover, it has been observed that fly ashes may catalyze the oxidation of elemental mercury and facilitate its capture. However, the exact nature of Hg-fly ash interactions is still unknown, and mercury oxidation through fly ash needs to be investigated more thoroughly. Inmore » this work, the influence of a gas atmosphere on the retention of elemental mercury on fly ashes of different characteristics was evaluated. The retention capacity was estimated comparatively in inert and two gas atmospheres containing species present in coal gasification and coal combustion. Fly ashes produced in two pulverized coal combustion (PCC) plants, produced from coals of different rank (CTA and CTSR), and a fly ash (CTP) produced in a fluidized bed combustion (FBC) plant were used as raw materials. The mercury retention capacity of these fly ashes was compared to the retention obtained in different activated carbons. Although the capture of mercury is very similar in the gasification atmosphere and N{sub 2}, it is much more efficient in a coal combustion retention, being greater in fly ashes from PCC than those from FBC plants. 22 refs., 6 figs., 3 tabs.« less

Effects of different surface modification and contents on municipal solid waste incineration fly ash/epoxy composites.

PubMed

Goh, C K; Valavan, S E; Low, T K; Tang, L H

2016-12-01

Incineration fly ash, a waste from municipal solid waste incineration plant can be used to replace conventional filler as reinforcing filler to enhance the mechanical strength of a composite. Surface modification was performed on the incineration fly ash before mixing into the soft polymer matrix so as to improve interfacial bond of the filler and epoxy resin. In this study, detailed characterisation of mechanical, morphological and leaching behaviours of municipal solid waste incineration (MSWI) fly ash infused composite has been carried out. Flexural and tensile test was conducted to determine the effect on mechanical properties of the composite by varying the concentration of incineration fly ash filler added into polymer matrix and surface modification of incineration fly ash filler using silane coupling agent and colloidal mesoporous silica (CMS). The results indicated that composite infused with incineration fly ash filler surface treated with CMS shown improvement on the tensile and flexural strengths. In addition, SEM images showed that surface modification of incineration fly ash with colloidal mesoporous silica enhanced the interfacial bonding with polymer resin which explained the improvement of mechanical strength. Leaching test showed result of toxic metals such as Pb, Zn, Fe, Cu, Cr, Cd and Rb immobilised in the polymer matrix of the composite. Hence, the use of MSWI fly ash as reinforcing filler in the composite appears green and sustainable because this approach is a promising opportunity to substitute valuable raw material with MSWI fly ash. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of experimental installation of fly ash concrete in Louisa : Concrete case study number 32.

DOT National Transportation Integrated Search

1979-01-01

The objective of this study was to investigate the resistance of field concretes containing fly ash to damage from cycles of freezing and thawing as evidenced by scaling, based upon a reevaluation of a field project. In 1955 and 1956 an experimental ...

Recovery of gallium and vanadium from gasification fly ash.

PubMed

Font, Oriol; Querol, Xavier; Juan, Roberto; Casado, Raquel; Ruiz, Carmen R; López-Soler, Angel; Coca, Pilar; García Peña, Francisco

2007-01-31

The Puertollano Integrated Coal Gasification Combined Cycle (IGCC) Power Plant (Spain) fly ash is characterized by a relatively high content of Ga and V, which occurs mainly as Ga2O3 and as Ga3+ and V3+ substituting for Al3+ in the Al-Si fly ash glass matrix. Investigations focused on evaluating the potential recovery of Ga and V from these fly ashes. Several NaOH based extraction tests were performed on the IGCC fly ash, at different temperatures, NaOH/fly ash (NaOH/FA) ratios, NaOH concentrations and extraction times. The optimal Ga extraction conditions was determined as 25 degrees C, NaOH 0.7-1 M, NaOH/FA ratio of 5 L/kg and 6 h, attaining Ga extraction yields of 60-86%, equivalent to 197-275 mg of Ga/kg of fly ash. Re-circulation of leachates increased initial Ga concentrations (25-38 mg/L) to 188-215 mg/L, while reducing both content of impurities and NaOH consumption. Carbonation of concentrated Ga leachate demonstrated that 99% of the bulk Ga content in the leachate precipitates at pH 7.4. At pH 10.5 significant proportions of impurities, mainly Al (91%), co-precipitate while >98% of the bulk Ga remains in solution. A second carbonation of the remaining solution (at pH 7.5) recovers the 98.8% of the bulk Ga. Re-dissolution (at pH 0) of the precipitate increases Ga purity from 7 to 30%, this being a suitable Ga end product for further purification by electrolysis. This method produces higher recovery efficiency than currently applied for Ga on an industrial scale. In contrast, low V extraction yields (<64%) were obtained even when using extreme alkaline extraction conditions, which given the current marked price of this element, limits considerably the feasibility of V recovery from IGCC fly ash.

Effect of Bauxite addition on Adhesion Strength and Surface Roughness of Fly ash based Plasma Sprayed Coatings

NASA Astrophysics Data System (ADS)

Bhuyan, S. K.; Samal, S.; Pattnaik, D.; Sahu, A.; Swain, B.; Thiyagarajan, T. K.; Mishra, S. C.

2018-03-01

The environment is being contaminated with advancement of new technology, day by day. One of the primary sources for this contamination is the industrial waste. Industrialization is the prime reason behind the prosperity of any country to meet the materialistic demand. To run the industries, a huge amount of (electric) power is needed and hence need for thermal power plants to serve the purpose. In present scenario, coal fired thermal power plants are set up which generates a huge quantity of Fly ash. Consumption of industrial waste (Fly ash), continually a major concern for human race. In recent years, fly ash is being utilized for various purposes i.e. making bricks, mine reclamation, production of cements etc. The presence of Silica and Alumina in fly ash makes it useful for thermal barrier applications also. The plasma spray technology has the advantage of being able to process any types of metal/ceramic mineral, low-grade-ore minerals etc. to make value-added products and also to deposit ceramics, metals and a combination of these to deposit composite coatings with desired microstructure and required properties on a range of substrate materials. The present work focuses on utilization of fly ash mixing with bauxite (ore mineral) for a high valued application. Fly ash with 10 and 20% bauxite addition is used to deposit plasma spray overlay coatings at different power levels (10-20kW) on aluminum and mild steel substrates. Adhesion strength and surface roughness of the coatings are evaluated. Phase composition analysis of the coatings were done using X-ray diffraction analysis. Surface morphology of the coatings was studied using a scanning electron microscope (SEM). Maximum adhesion strength of 4.924 MPa is obtained for the composition fly ash and bauxite (10%), coated on mild steel at 16kW torch power level. The surface roughness (Ra) of the coatings is found to vary between 10.0102 to 17.2341 micron.

Rheology and Extrusion of Cement-Fly Ashes Pastes

NASA Astrophysics Data System (ADS)

Micaelli, F.; Lanos, C.; Levita, G.

2008-07-01

The addition of fly ashes in cement pastes is tested to optimize the forming of cement based material by extrusion. Two sizes of fly ashes grains are examinated. The rheology of concentrated suspensions of ashes mixes is studied with a parallel plates rheometer. In stationary flow state, tested suspensions viscosities are satisfactorily described by the Krieger-Dougherty model. An "overlapped grain" suspensions model able to describe the bimodal suspensions behaviour is proposed. For higher values of solid volume fraction, Bingham viscoplastic behaviour is identified. Results showed that the plastic viscosity and plastic yield values present minimal values for the same optimal formulation of bimodal mixes. The rheological study is extended to more concentrated systems using an extruder. Finally it is observed that the addition of 30% vol. of optimized ashes mix determined a significant reduction of required extrusion load.

Properties of ambient cured blended alkali activated cement concrete

NASA Astrophysics Data System (ADS)

Talha Junaid, M.

2017-11-01

This paper presents results of the development and strength properties of ambient-cured alkali activated geopolymer concrete (GPC). The study looks at the strength properties, such as compressive strength, splitting tensile strength, and elastic modulus of such concretes and its dependency on various parameters. The parameters studied in this work are the type and proportions of pre-cursor materials, type of activator and their respective ratios and the curing time. Two types of pre-cursor material; low calcium fly ash (FA) and ground granulated blast furnace slag (GGBFS) were activated using different proportions of sodium silicate and sodium hydroxide solutions. The results indicate that ambient cured geopolymer concrete can be manufactured to match strength properties of ordinary Portland cement concrete (OPC). The strength properties of GPC are dependent on the type and ratio of activator and the proportion of GGBFS used. Increasing the percentage of GGBFS increased the compressive and tensile strengths, while reducing the setting time of the mix. The effect of GGBFS on strength was more pronounced in mixes that contained sodium silicate as activator solution. Unlike OPC, ambient-cured GPC containing sodium silicate gain most of their strength in the first 7 days and there is no change in strength thereafter. However, GPC mixes not containing sodium silicate only achieve a fraction of their strength at 7 days and extended curing is required for such concretes to gain full strength. The results also indicate that the elastic modulus values of GPC mixes without sodium silicate are comparable to OPC while mixes with sodium silicate have elastic modulus values much lower than ordinary concrete.

COSMOS-rice technology abrogates the biotoxic effects of municipal solid waste incinerator residues.

PubMed

Guarienti, Michela; Cardozo, Sdenka Moscoso; Borgese, Laura; Lira, Gloria Rodrigo; Depero, Laura E; Bontempi, Elza; Presta, Marco

2016-07-01

Fly ashes generated by municipal solid waste incinerator (MSWI) are classified as hazardous waste and usually landfilled. For the sustainable reuse of these materials is necessary to reduce the resulting impact on human health and environment. The COSMOS-rice technology has been recently proposed for the treatment of fly ashes mixed with rice husk ash, to obtain a low-cost composite material with significant performances. Here, aquatic biotoxicity assays, including daphnidae and zebrafish embryo-based tests, were used to assess the biosafety efficacy of this technology. Exposure to lixiviated MSWI fly ash caused dose-dependent biotoxic effects on daphnidae and zebrafish embryos with alterations of embryonic development, teratogenous defects and apoptotic events. On the contrary, no biotoxic effects were observed in daphnidae and zebrafish embryos exposed to lixiviated COSMOS-rice material. Accordingly, whole-mount in situ hybridization analysis of the expression of various tissue-specific genes in zebrafish embryos provided genetic evidence about the ability of COSMOS-rice stabilization process to minimize the biotoxic effects of MSWI fly ash. These results demonstrate at the biological level that the newly developed COSMOS-rice technology is an efficient and cost-effective method to process MSWI fly ash, producing a biologically safe and reusable material. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of soil stabilization with class C fly ash.

DOT National Transportation Integrated Search

1987-01-01

Previous Iowa DOT sponsored research has shown that some Class : C fly ashes are cementitious (because calcium is combined as calcium : aluminates) while other Class C ashes containing similar amounts of : elemental calcium are not (1). Fly ashes fro...

The analysis of mechanical properties of non autoclaved aerated concrete with the substitution of fly ash and bottom ash

NASA Astrophysics Data System (ADS)

Karolina, R.; Muhammad, F.

2018-02-01

Based on PP. No.85 of 1999 on the management of hazardous and toxic (B3), fly ash and bottom ash wastes are categorized into B3 waste because there are heavy metal oxide contents that can pollute the environment. One form of environmental rescue that can be applied is to utilize waste fly ash and bottom ash in the manufacture of concrete. In this research, fly ash and bottom ash waste are used as substitution of cement and fine aggregate to make lightweight concrete. The purpose of this research is to know the mechanical properties of non-autoclaved aerated lightweight concrete (NAAC) with FA and BA substitution to cement and fine aggregate which is expected to improve the quality of concrete. The NAAC lightweight concrete in this study is divided into 4 categories: normal NAAC lightweight concrete, NAAC lightweight NAAC substituted concrete with FA, NAAC lightweight concrete substituted with BA, and NAAC combined light weight from FA and BA with variations of 10%, 20% And 30%. The test specimen used in cylindrical shape, which was tested at the age of 28 days, amounted to 90 pieces and consisted of 10 variations. Each variation amounted to 9 samples. Based on the test results with FA and BA substitutions of 10%, 20%, and 30%, the highest compressive strength was achieved in samples with FA 30% of 12.687 MPa, maximum tensile strength achieved in samples with FA 30% of 1,540 MPa, The highest absorption was achieved in normal NAAC of 5.66%. Based on the weight of the contents of all samples, samples can be categorized in lightweight concrete, since the weight of the contents is less than 1900 kg / m3.

Melting of municipal solid waste incinerator fly ash by waste-derived thermite reaction.

PubMed

Wang, Kuen-Sheng; Lin, Kae-Long; Lee, Ching-Hwa

2009-02-15

This work describes a novel approach for melting municipal solid waste incinerator (MSWI) fly ash, based on self-propagating reactions, by using energy-efficient simulated waste-derived thermite. The self-propagating characteristics, the properties of the recycled alloy and slag and the partitioning of heavy metals during the process are also studied. Experimental results demonstrate that the mix ratio of fly ash to the starting mixture of less than 30% supports the development of the self-propagating reaction with a melting temperature of 1350-2200 degrees C. Furthermore, metallic iron (or alloy) and the slag were retrieved after activation of the thermite reactions among the starting mixtures. It was noted that more than 91wt.% of iron was retrieved as alloy and the rest of non-reductive oxides as slag. During the thermite reactions, the partition of heavy metals to the SFA and flue gas varied with the characteristics of the target metals: Cd was mainly partitioned to flue gas (75-82%), and partition slightly increased with the increasing fly ash ratio; Pb and Zn, were mainly partitioned to the SFA, and the partition increased with increasing fly ash ratio; Cu was partitioned to the SFA (18-31%) and was not found in the flue gas; and moreover stable Cr and Ni were not identified in both the SFA and flue gas. On the other hand, the determined TCLP leaching concentrations were all well within the current regulatory thresholds, despite the various FA ratios. This suggests that the vitrified fly ash samples were environmental safe in heavy metal leaching. The results of this study suggested that melting of municipal solid waste incinerator fly ash by waste-derived thermite reactions was a feasible approach not only energy-beneficial but also environmental-safe.

Evaluation of fly ash pellets for phosphorus removal in a laboratory scale denitrifying bioreactor.

PubMed

Li, Shiyang; Cooke, Richard A; Huang, Xiangfeng; Christianson, Laura; Bhattarai, Rabin

2018-02-01

Nitrate and orthophosphate from agricultural activities contribute significantly to nutrient loading in surface water bodies around the world. This study evaluated the efficacy of woodchips and fly ash pellets in tandem to remove nitrate and orthophosphate from simulated agricultural runoff in flow-through tests. The fly ash pellets had previously been developed specifically for orthophosphate removal for this type of application, and the sorption bench testing showed a good promise for flow-through testing. The lab-scale horizontal-flow bioreactor used in this study consisted of an upstream column filled with woodchips followed by a downstream column filled with fly ash pellets (3 and 1 m lengths, respectively; both 0.15 m diameter). Using influent concentrations of 12 mg/L nitrate and 5 mg/L orthophosphate, the woodchip bioreactor section was able to remove 49-85% of the nitrate concentration at three hydraulic retention times ranging from 0.67 to 4.0 h. The nitrate removal rate for woodchips ranged from 40 to 49 g N/m 3 /d. Higher hydraulic retention times (i.e., smaller flow rates) corresponded with greater nitrate load reduction. The fly ash pellets showed relatively stable removal efficiency of 68-75% across all retention times. Total orthophosphate adsorption by the pellets was 0.059-0.114 mg P/g which was far less than the saturated capacity (1.69 mg/g; based on previous work). The fly ash pellets also removed some nitrate and the woodchips also removed some orthophosphate, but these reductions were not significant. Overall, woodchip denitrification followed by fly ash pellet P-sorption can be an effective treatment technology for nitrate and phosphate removal in subsurface drainage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stabilization of cesium in alkali-activated municipal solid waste incineration fly ash and a pyrophyllite-based system.

PubMed

Shiota, Kenji; Nakamura, Takafumi; Takaoka, Masaki; Aminuddin, Siti Fatimah; Oshita, Kazuyuki; Fujimori, Takashi

2017-11-01

Environmentally sound treatments are required to dispose of municipal solid waste incineration fly ash (MSWIFA) contaminated with radioactive cesium (Cs) from the Fukushima Daiichi nuclear power plant accident in Japan. This study focuses on the stabilization of Cs using an alkali-activated MSWIFA and pyophyllite-based system. Three composite solid products were synthesized after mixtures of raw materials (dehydrated pyrophyllite, MSWIFA, 14 mol/L aqueous sodium hydroxide, and sodium silicate solution) were cured at 105 °C for 24 h. Three types of MSWIFAs were prepared as raw fly ash, raw fly ash with 0.1% CsCl, and raw fly ash with 40% CsCl to understand the stabilization mechanism of Cs. Cs stabilization in two solid products was successful, with less than 6.9% leaching observed from two types tests, and was partly successful for the solid product with the highest concentration of Cs. X-ray diffraction showed that all of the solid products produced several crystalline phases, and that pollucite was formed in the highest Cs concentration product. The X-ray absorption fine structure and scanning electron microscopy with X-ray analysis suggested that most Cs species formed pollucite in the two solid products from MSWIFA with added CsCl. This system provides a technique for the direct stabilization of Cs in MSWIFA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of oxidative stress markers and concentrations of selected elements in the leaves of Cassia occidentalis growing wild on a coal fly ash basin.

PubMed

Love, Amit; Banerjee, B D; Babu, C R

2013-08-01

Assessment of oxidative stress levels and tissue concentrations of elements in plants growing wild on fly ash basins is critical for realistic hazard identification of fly ash disposal areas. Hitherto, levels of oxidative stress markers in plants growing wild on fly ash basins have not been adequately investigated. We report here concentrations of selected metal and metalloid elements and levels of oxidative stress markers in leaves of Cassia occidentalis growing wild on a fly ash basin (Badarpur Thermal Power Station site) and a reference site (Garhi Mandu Van site). Plants growing on the fly ash basin had significantly high foliar concentration of As, Ni, Pb and Se and low foliar concentration of Mn and Fe compared to the plants growing on the reference site. The plants inhabiting the fly ash basin showed signs of oxidative stress and had elevated levels of lipid peroxidation, electrolyte leakage from cells and low levels of chlorophyll a and total carotenoids compared to plants growing at the reference site. The levels of both protein thiols and nonprotein thiols were elevated in plants growing on the fly ash basin compared to plants growing on the reference site. However, no differences were observed in the levels of cysteine, reduced glutathione and oxidized glutathione in plants growing at both the sites. Our study suggests that: (1) fly ash triggers oxidative stress responses in plants growing wild on fly ash basin, and (2) elevated levels of protein thiols and nonprotein thiols may have a role in protecting the plants from environmental stress.

[Novel process utilizing alkalis assisted hydrothermal process to stabilize heavy metals both from municipal solid waste or medical waste incinerator fly ash and waste water].

PubMed

Wang, Lei; Jin, Jian; Li, Xiao-dong; Chi, Yong; Yan, Jian-hua

2010-08-01

An alkalis assisted hydrothermal process was induced to stabilize heavy metals both from municipal solid waste or medical waste incinerator fly ash and waste water. The results showed that alkalis assisted hydrothermal process removed the heavy metals effectively from the waste water, and reduced leachability of fly ash after process. The heavy metal leachabilities of fly ash studied in this paper were Mn 17,300 microg/L,Ni 1650 microg/L, Cu 2560 microg/L, Zn 189,000 microg/L, Cd 1970 microg/L, Pb 1560 microg/L for medical waste incinerator fly ash; Mn 17.2 microg/L, Ni 8.32 microg/L, Cu 235.2 microg/L, Zn 668.3 microg/L, Cd 2.81 microg/L, Pb 7200 microg/L for municipal solid waste incinerator fly ash. After hydrothermal process with experimental condition [Na2CO3 dosage (5 g Na2CO3/50 g fly ash), reaction time = 10 h, L/S ratio = 10/1], the heavy metal removal efficiencies of medical waste incinerator fly ash were 86.2%-97.3%, and 94.7%-99.6% for municipal solid waste incinerator fly ash. The leachabilities of both two kinds of fly ash were lower than that of the Chinese national limit. The mechanism of heavy metal stabilization can be concluded to the chemisorption and physically encapsulation effects of aluminosilicates during its formation, crystallization and aging process, the high pH value has some contribution to the heavy metal removal and stabilization.

Evaluation of physicochemical properties of radioactive cesium in municipal solid waste incineration fly ash by particle size classification and leaching tests.

PubMed

Fujii, Kengo; Ochi, Kotaro; Ohbuchi, Atsushi; Koike, Yuya

2018-07-01

After the Fukushima Daiichi-Nuclear Power Plant accident, environmental recovery was a major issue because a considerable amount of municipal solid waste incineration (MSWI) fly ash was highly contaminated with radioactive cesium. To the best of our knowledge, only a few studies have evaluated the detailed physicochemical properties of radioactive cesium in MSWI fly ash to propose an effective method for the solidification and reuse of MSWI fly ash. In this study, MSWI fly ash was sampled in Fukushima Prefecture. The physicochemical properties of radioactive cesium in MSWI fly ash were evaluated by particle size classification (less than 25, 25-45, 45-100, 100-300, 300-500, and greater than 500 μm) and the Japanese leaching test No. 13 called "JLT-13". These results obtained from the classification of fly ash indicated that the activity concentration of radioactive cesium and the content of the coexisting matter (i.e., chloride and potassium) temporarily change in response to the particle size of fly ash. X-ray diffraction results indicated that water-soluble radioactive cesium exists as CsCl because of the cooling process and that insoluble cesium is bound to the inner sphere of amorphous matter. These results indicated that the distribution of radioactive cesium depends on the characteristics of MSWI fly ash. Copyright © 2018 Elsevier Ltd. All rights reserved.

The measurement of unburned carbon in fly ash using infrared photoacoustics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waller, D.J.; Brown, R.C.

1995-12-31

Unburned carbon in fly ash yields valuable information on coal combustion efficiency in coal-fired boilers. The carbon content of fly ash is also an important parameters in the sale of fly ash for Portland cement. Unfortunately, a reliable and inexpensive instrument for measuring unburned carbon is not commercially available. The authors have developed an off-line instrument that detects carbon in fly ash via the photoacoustic effect. In this process, amplitude-modulated radiation is absorbed by a bulk sample of fly ash. The wavelength of the radiation is chosen such that mineral compounds and moisture in the fly ash are transparent tomore » the radiation but carbon is strongly absorbing. The modulated absorption generates a periodic pressure wave at the surface of the sample which propagates through the surrounding air as an acoustic wave. This wave is detected by a sensitive microphone, and is dependent on the carbon content of the sample. The resulting instrument has been used to measure fly ash carbon concentrations from less than 0.1% to nearly 7% by mass. The precision of these measurements is nominally within 4%, which is equivalent to the precision of the chemical analysis used to develop the calibration standards. The applicability of a theoretical model to the empirical results is discussed with respect to fly ash sample preparation.« less

Discussion on 'characteristics of fly ashes from full-scale coal-fired power plants and their relationship to mercury adsorption' by Lu et al.

DOE Office of Scientific and Technical Information (OSTI.GOV)

James C. Hower; Bruno Valentim; Irena J. Kostova

2008-03-15

Mercury capture by coal-combustion fly ash is a function of the amount of Hg in the feed coal, the amount of carbon in the fly ash, the type of carbon in the fly ash (including variables introduced by the rank of the feed coal), and the flue gas temperature at the point of ash collection. In their discussion of fly ash and Hg adsorption, Lu et al. (Energy Fuels 2007, 21, 2112-2120) had some fundamental flaws in their techniques, which, in turn, impact the validity of analyzed parameters. First, they used mechanical sieving to segregate fly ash size fractions. Mechanicalmore » sieving does not produce representative size fractions, particularly for the finest sizes. If the study samples were not obtained correctly, the subsequent analyses of fly ash carbon and Hg cannot accurately represent the size fractions. In the analysis of carbon forms, it is not possible to accurately determine the forms with scanning electron microscopy. The complexity of the whole particles is overlooked when just examining the outer particle surface. Examination of elements such as Hg, present in very trace quantities in most fly ashes, requires careful attention to the analytical techniques. 36 refs., 3 figs., 1 tab.« less

Characterization of fly ash from low-sulfur and high-sulfur coal sources: Partitioning of carbon and trace elements with particle size

USGS Publications Warehouse

Hower, J.C.; Trimble, A.S.; Eble, C.F.; Palmer, C.A.; Kolker, A.

1999-01-01

Fly ash samples were collected in November and December of 1994, from generating units at a Kentucky power station using high- and low-sulfur feed coals. The samples are part of a two-year study of the coal and coal combustion byproducts from the power station. The ashes were wet screened at 100, 200, 325, and 500 mesh (150, 75, 42, and 25 ??m, respectively). The size fractions were then dried, weighed, split for petrographic and chemical analysis, and analyzed for ash yield and carbon content. The low-sulfur "heavy side" and "light side" ashes each have a similar size distribution in the November samples. In contrast, the December fly ashes showed the trend observed in later months, the light-side ash being finer (over 20 % more ash in the -500 mesh [-25 ??m] fraction) than the heavy-side ash. Carbon tended to be concentrated in the coarse fractions in the December samples. The dominance of the -325 mesh (-42 ??m) fractions in the overall size analysis implies, though, that carbon in the fine sizes may be an important consideration in the utilization of the fly ash. Element partitioning follows several patterns. Volatile elements, such as Zn and As, are enriched in the finer sizes, particularly in fly ashes collected at cooler, light-side electrostatic precipitator (ESP) temperatures. The latter trend is a function of precipitation at the cooler-ESP temperatures and of increasing concentration with the increased surface area of the finest fraction. Mercury concentrations are higher in high-carbon fly ashes, suggesting Hg adsorption on the fly ash carbon. Ni and Cr are associated, in part, with the spinel minerals in the fly ash. Copyright ?? 1999 Taylor & Francis.

Elemental analyses of chars isolated from a biomass gasifier fly ash

Treesearch

Thomas L. Eberhardt; Hui Pan

2012-01-01

Processing of pine wood chips in a pilot-scale downdraft gasifier generated a carbon-rich fly ash as a byproduct. Studies on biomass-derived fly ashes have generally focused on their direct characterisation, as generated, to develop options for utilisation or disposal. Analogous to studies on coal-derived fly ashes, strategies were applied here to assess the...

Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite.

PubMed

Zhang, Zhikun; Zhang, Lei; Li, Aimin

2015-04-01

Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment. In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2h) showed the properties of density of 1.92 ± 0.05 g/cm(3), weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was reduced compared to conventional vitrification and sintering method. Chemical resistance and heavy metals leaching results of glass ceramic composites further confirmed the possibility of its engineering applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improvements of nano-SiO2 on sludge/fly ash mortar.

PubMed

Lin, D F; Lin, K L; Chang, W C; Luo, H L; Cai, M Q

2008-01-01

Sewage sludge ash has been widely applied to cementitious materials. In this study, in order to determine effects of nano-SiO(2) additives on properties of sludge/fly ash mortar, different amounts of nano-SiO(2) were added to sludge/fly ash mortar specimens to investigate their physical properties and micro-structures. A water-binding ratio of 0.7 was assigned to the mix. Substitution amounts of 0%, 10%, 20%, and 30% of sludge/fly ash (1:1 ratio) were proposed. Moreover, 0%, 1%, 2%, and 3% of nano-SiO(2) was added to the mix. Tests, including SEM and compressive strength, were carried out on mortar specimens cured at 3, 7, and 28 days. Results showed that sludge/fly ash can make the crystals of cement hydration product finer. Moreover, crystals increased after nano-SiO(2) was added. Hence, nano-SiO(2) can improve the effects of sludge/fly ash on the hydration of mortar. Further, due to the low pozzolanic reaction active index of sludge ash, early compressive strengths of sludge/fly ash mortar were decreased. Yet, nano-SiO(2) could help produce hydration crystals, which implies that the addition of nano-SiO(2) to mortar can improve the influence of sludge/fly ash on the development of the early strength of the mortar.

Reduction of carbon content in waste-tire combustion ashes by bio-thermal treatment.

PubMed

Chen, Chun-Chi; Lee, Wen-Jhy; Shih, Shun-I; Mou, Jin-Luh

2009-11-01

Application of bio-catalyst (NOE-7F) in thermal treatment can adequately dispose dark-black fly ashes from co-combustion of both waste tires and coal. After thermal treatment of fly ashes by adding 10% NOE-7F, the carbon contents reduced by 37.6% and the weight losses increased by 405%, compared with the fly ashes without mixing with NOE-7F. The combustion behaviors of wasted tires combustion fly ashes with NOE-7F were also investigated by both thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results verify that NOE-7F has positive effects on the combustion of residual carbon and toxic polycyclic aromatic hydrocarbons (PAHs) enhance the energy release and reduce the toxicity during the process of thermal treatment. Furthermore, using NOE-7F to dispose high-carbon content fly ashes did improve the compressive strength of fly ashes and concrete mixtures. Therefore, NOE-7F is a promising additive which could decrease treatment cost of high-carbon content fly ashes and reduce the amount of survival toxic PAHs.

Reduction of carbon content in waste-tire combustion ashes by bio-thermal treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C.C.; Lee, W.J.; Shih, S.I.

2009-07-01

Application of bio-catalyst (NOE-7F) in thermal treatment can adequately dispose dark-black fly ashes from co-combustion of both waste tires and coal. After thermal treatment of fly ashes by adding 10% NOE-7F, the carbon contents reduced by 37.6% and the weight losses increased by 405%, compared with the fly ashes without mixing with NOE-7F. The combustion behaviors of wasted tires combustion fly ashes with NOE-7F were also investigated by both thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results verify that NOE-7F has positive effects on the combustion of residual carbon and toxic polycyclic aromatic hydrocarbons (PAHs) enhance the energymore » release and reduce the toxicity during the process of thermal treatment. Furthermore, using NOE-7F to dispose high-carbon content fly ashes did improve the compressive strength of fly ashes and concrete mixtures. Therefore, NOE-7F is a promising additive which could decrease treatment cost of high-carbon content fly ashes and reduce the amount of survival toxic PAHs.« less

Surface mechanical behaviour of composite Ni-P-fly ash/zincate coated aluminium alloy

NASA Astrophysics Data System (ADS)

Panagopoulos, C. N.; Georgiou, E. P.

2009-04-01

Ni-P-fly ash coatings were produced on zincate coated 5083 wrought aluminium alloy substrates with the aid of an electroless deposition technique. Structural and chemical characterization of the produced coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-P-fly ash coating was found to consist of an amorphous Ni-P matrix with dispersed fly ash particles. The wear resistance of the Ni-P-fly ash coating on zincate treated aluminium alloy was observed to be higher than that of the bare aluminium alloy, when sliding against a stainless steel counterface. In addition, the adhesion between the Ni-P-fly ash/zincate coating and the aluminium alloy substrate was also studied with a scratch testing apparatus. The adhesion strength of Ni-P-fly ash/zincate coating on the aluminium alloy substrate was observed to be higher in comparison to the Ni-P/zincate coating on the same aluminium alloy.

Effectiveness of fly ash for strength and durability of concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ho, D.W.S.; Lewis, R.K.

1985-09-01

The effectiveness, K, of a fly ash can be defined as the ratio of the amount of cement replaced to the amount of fly ash added, provided the specified requirements of the concrete are maintained. It is generally assumed that the effectiveness of a fly ash can be treated as a constant. This paper presents results on concrete made with various mix proportions using three different cements and fly ash from three different sources. It was found that the K factor of each fly ash in achieving common 28-day compressive strength varies over a wide range depending on the amountmore » of fly ash used, the type of cement, the incorporation of chemical admixtures and the particular strength level chosen. Besides strength, K can also be calculated for other properties. For the materials used in this investigation, the K factors with respect to carbonation were found to be unequal to K factors for strength.« less

Selenium in fly ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gutenmann, W.H.; Bache, C.A.; Youngs, W.D.

1976-03-05

Selenium, at concentrations exceeding 200 parts per million (ppM) (dry weight), has been found in white sweet clover voluntarily growing on beds of fly ash in central New York State. Guinea pigs fed such clover concentrated selenium in their tissues. The contents of the honey stomachs of bees foraging on this seleniferous clover contained negligible selenium. Mature vegetables cultured on 10 percent (by weight) fly ash-amended soil absorbed up to 1 ppM of selenium. Fly ashes from 21 states contained total selenium contents ranging from 1.2 to 16.5 ppM. Cabbage grown on soil containing 10 percent (by weight) of thesemore » fly ashes absorbed selenium (up to 3.7 ppM) in direct proportion (correlation coefficient r = .89) to the selenium concentration in the respective fly ash. Water, aquatic weeds, algae, dragonfly nymphs, polliwogs, and tissues of bullheads and muskrats from a fly ash-contaminated pond contained concentrations of selenium markedly elevated over those of controls.« less

Case study of fly ash brick manufacturing units at Kota in Rajasthan

NASA Astrophysics Data System (ADS)

Sharma, Y.; Saxena, B. K.; Rao, K. V. S.

2018-03-01

Kota Super Thermal Power Station of 1240 MW is located at Kota in Rajasthan, India. The quantity of fly ash generated by it is about 1.64 to 2.03 million tonnes per year. This fly ash is being utilized for making bricks, tiles, portland pozzolana cement, construction of highways, and other purposes. 1.79 million tonnes of fly ash was utilized for different applications in one year duration from April 01st, 2015 to March 31st, 2016. Out of this total utilization, 0.6439 million tonnes (36.06 %) of fly ash was used for making bricks, blocks, and tiles. In this paper, a case study of two fly ash brick manufacturing units using fly ash produced from Kota Super Thermal Power Station is described. These units produce about 15,000 and 20,000 bricks respectively by employing 10 and 16 workers each and are making a profit of about Rs. 6,000 and Rs. 8,000 per day in one shift.

Preparation of Functionally Graded Materials (FGMs) Using Coal Fly Ash and NiCr-Based Alloy Powder by Spark Plasma Sintering (SPS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaneko, Gen-yo; Kitagawa, Hiroyuki; Hasezaki, Kazuhiro

2008-02-15

Functionally Graded Materials (FGMs) were prepared by spark plasma sintering (SPS) using coal fly ash and NiCr alloy powder. The coal fly ash was produced by the Misumi Coal Thermal Power Station (Chugoku Electric Power Co., Inc.), with 80 wt% nickel and 20 wt% chromium (Fukuda Metal Foil and Powder Co., Ltd.) used as source materials. The sintering temperature in the graphite die was 1000 deg. C. X-ray diffraction patterns of the sintered coal fly ash materials indicated that mullite (3Al{sub 2}O{sub 3}{center_dot}2SiO{sub 2}) and silica (SiO{sub 2}) phases were predominant. Direct joining of coal fly ash and NiCr causesmore » fracture at the interface. This is due to the mismatch in the thermal expansion coefficients (CTE). A crack in the FGM was observed between the two layers with a CTE difference of over 4.86x10{sup -6} K{sup -1}, while a crack in the FGM was difficult to detect when the CTE difference was less than 2.77x10{sup -6} K{sup -1}.« less

Activation of fly ash

DOEpatents

Corbin, David R.; Velenyi, Louis J.; Pepera, Marc A.; Dolhyj, Serge R.

1986-01-01

Fly ash is activated by heating a screened magnetic fraction of the ash in a steam atmosphere and then reducing, oxidizing and again reducing the hydrothermally treated fraction. The activated fly ash can be used as a carbon monoxide disproportionating catalyst useful in the production of hydrogen and methane.

Activation of fly ash

DOEpatents

Corbin, D.R.; Velenyi, L.J.; Pepera, M.A.; Dolhyj, S.R.

1986-08-19

Fly ash is activated by heating a screened magnetic fraction of the ash in a steam atmosphere and then reducing, oxidizing and again reducing the hydrothermally treated fraction. The activated fly ash can be used as a carbon monoxide disproportionating catalyst useful in the production of hydrogen and methane.

Utilization of western coal fly ash in construction of highways in the Midwest

DOT National Transportation Integrated Search

2000-03-01

Coal burning utilities in the Midwest are increasingly using sub-bituminous coal from Wyoming. These utilities typically produce fly ash, which, because of its high calcium oxide content, may be classified as Class C fly ash. These ashes are characte...

Combined disc pelletisation and thermal treatment of MSWI fly ash.

PubMed

Huber, Florian; Herzel, Hannes; Adam, Christian; Mallow, Ole; Blasenbauer, Dominik; Fellner, Johann

2018-03-01

An environmentally friendly and cost efficient way for the management of municipal solid waste incineration (MSWI) fly ash represents its thermal co-treatment together with combustible waste. However, the safe introduction and storage of MSWI fly ash in the waste bunker is challenging and associated with severe problems (e.g. dust emissions, generation of undefined lumps and heat in case of moistened MSWI fly ash). Therefore, the aim of this study is to investigate the suitability of pelletisation as a pretreatment of MSWI fly ash. In particular, MSWI fly ash was characterised after sampling, pelletisation and thermal treatment and the transfer of constituents to secondary fly ash and flue gas was investigated. For this purpose, MSWI fly ash pellets with a water content of about 0.15 kg/kg and a diameter of about 8 mm have been produced by disc pelletiser and treated in an electrically heated pilot-scale rotary kiln at different temperatures, ranging from 450 °C to 1050 °C. The total contents of selected elements in the MSWI fly ash before and after thermal treatment and in the generated secondary fly ash have been analysed in order to understand the fate of each element. Furthermore, leachable contents of selected elements and total content of persistent organic pollutants of the thermally treated MSWI fly ash were determined. Due to the low total content of Hg (0.7 mg/kg) and the low leachate content of Pb (<0.36 mg/kg), even at the lowest treatment temperature of 450 °C, thermally treated MSWI fly ash pellets can be classified as non-hazardous waste. However, temperatures of at least 650 °C are necessary to decrease the toxic equivalency of PCDD/F and DL-PCB. The removal of toxic heavy metals like Cd and Pb is significantly improved at temperatures of 850 °C, 950 °C or even 1050 °C. The observed metal removal led to relatively high contents of e.g. Cu (up to 11,000 mg/kg), Pb (up to 91,000 mg/kg) and Zn (up to 21,000 mg/kg) in the secondary fly ash. This metal enriched secondary fly ash might represent a potential raw material for metal recovery (e.g. via acidic leaching). Due to the high content of total dissolved solids observed in the leachate of thermally treated MSWI fly ash pellets, a wet extraction procedure is suggested to enable its safe disposal at non-hazardous waste landfills. Copyright © 2017 Elsevier Ltd. All rights reserved.

Wide-scale utilization of MSWI fly ashes in cement production and its impact on average heavy metal contents in cements: The case of Austria.

PubMed

Lederer, Jakob; Trinkel, Verena; Fellner, Johann

2017-02-01

A number of studies present the utilization of fly ashes from municipal solid waste incineration (MSWI) in cement production as a recycling alternative to landfilling. While there is a lot of research on the impact of MSWI fly ashes utilization in cement production on the quality of concrete or the leaching of heavy metals, only a few studies have determined the resulting heavy metal content in cements caused by this MSWI fly ashes utilization. Making use of the case of Austria, this study (1) determines the total content of selected heavy metals in cements currently produced in the country, (2) designs a scenario and calculates the resulting heavy metal contents in cements assuming that all MSWI fly ashes from Austrian grate incinerators were used as secondary raw materials for Portland cement clinker production and (3) evaluates the legal recyclability of demolished concretes produced from MSWI fly ash amended cements based on their total heavy metal contents. To do so, data from literature and statistics are combined in a material flow analysis model to calculate the average total contents of heavy metals in cements and in the resulting concretes according to the above scenario. The resulting heavy metal contents are then compared (i) to their respective limit values for cements as defined in a new technical guideline in Austria (BMLFUW, 2016), and (ii) to their respective limit values for recycling materials from demolished concrete. Results show that MSWI fly ashes utilization increases the raw material input in cement production by only +0.9%, but the total contents of Cd by +310%, and Hg, Pb, and Zn by +70% to +170%. However these and other heavy metal contents are still below their respective limit values for Austrian cements. The same legal conformity counts for recycling material derived from concretes produced from the MSWI fly ash cements. However, if the MSWI fly ash ratio in all raw materials used for cement production were increased from 0.9% to 22%, which is suggested by some studies, the limit values for cements as defined by the BMLFUW (2016) will be exceeded. Furthermore, the concrete produced from this cement will not be recyclable anymore due to its high total heavy metal contents. This and the comparatively high contribution of MSWI fly ashes to total heavy metal contents in cements indicate their relatively low resource potential if compared to other secondary raw materials in the cement industry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Human and Environmental Dangers Posed by Ongoing Global Tropospheric Aerosolized Particulates for Weather Modification.

PubMed

Herndon, J Marvin

2016-01-01

U.S. military perception of nuclear warfare led to countless unethical nuclear experiments performed on unsuspecting individuals without their informed consent. As evidenced here, subsequent perception of weather warfare has led to exposing millions of unsuspecting individuals to toxic coal fly ash with no public disclosure, no informed consent, and no health warnings. Three methods were used: (1) comparison of eight elements analyzed in rainwater samples, thought to have leached from aerosolized coal fly ash, with corresponding coal fly ash laboratory leachate; (2) comparison of 14 elements analyzed in air filter dust with corresponding elements in coal fly ash; and (3) comparison of 23 elements analyzed in fibrous mesh found after snow melted with corresponding elements in coal fly ash. The rainwater element ratios show that the aerial particulate matter has essentially the same water-leach characteristics as coal fly ash. The air filter dust element ratios occur in the same range of compositions as coal fly ash, as do element ratios in fibrous mesh found on grass after snow melted. The fibrous mesh provides an inferred direct connection with the aerosolizing jet aircraft via coal fly ash association with the jet combustion environment. Strong evidence for the correctness of the hypothesis: coal fly ash is likely the aerosolized particulate emplaced in the troposphere for geoengineering, weather modification, and/or climate alteration purposes. The documented public health associations for ≤2.5 μm particulate pollution are also applicable to aerosolized coal fly ash. The ability of coal fly ash to release aluminum in a chemically mobile form upon exposure to water or body moisture has potentially grave human and environmental consequences over a broad spectrum, including implications for neurological diseases and biota debilitation. The ability of coal fly ash to release heavy metals and radioactive elements upon exposure to body moisture has potentially grave human health implications including cancer, cardiovascular disease, diabetes, respiratory diseases, reduced male fertility, and stroke. The fibrous mesh data admit the possibility of environmentally disastrous formation of methylmercury and ozone-depleting chlorinated-fluorinated hydrocarbons in jet exhaust. Geophysical implications include atmospheric warming and rainfall retardation.

High volumes fly ash engineered cementitious composites with cost-effective PVA fiber

NASA Astrophysics Data System (ADS)

Yu, Dianyou; Xu, Zhichao; Liu, Yingchun

2018-03-01

A feasibility study of engineered cementitous composites (ECC) using the cost-effective PVA fiber (CEPVA-ECC) was developed based on the micromechanical design theory in order to reduce the cost of ECC. Different amounts of fly ash replacement (up to 83% replacement of cement) was utilized in CEPVA-ECC. The CEPVA-ECC using much cheaper Chinese domestic PVA fiber (1/4˜1/6 price of the imported fiber) maintained the tensile ductility characteristics (4%˜5%) with a moderate compressive strength (30˜40MPa). Moreover, the crack width was reduced with an increase of the fly ash amount.

MEASURE OF FLY ASH RESISTIVITY USING SIMULATED FLUE GAS ENVIRONMENTS

EPA Science Inventory

The report, describing the apparatus and laboratory procedures used to determine resistivity for a number of fly ashes under a variety of test conditions, supports research to develop a technique for predicting fly ash resistivity from chemical analyses of coal and coal ash. This...

Use of fly ash in diets of cage and floor broilers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pharr, C.L.; Andrews, L.D.

1980-09-01

Three experiments were conducted to compare limestone to fly ash from a coal-fired generator station as a calcium source for broilers. In experiment 1, 5 male and 5 female broiler chicks were placed in each of 32 cages. Sixteen cages of birds were fed a ration with limestone supplying 30% of the total calcium and 16 cages were fed a ration with 30% of the total calcium supplied by fly ash. The total calcium and phosphorus levels of the rations were 1.0% and .5%, respectively. In this experiment no significant difference was found for 8-week body weight between diets wheremore » the added calcium was from limestone or fly ash. In experiment 2 a group of 40 male and 40 female cage reared broilers and 40 male and 40 female floor reared broilers were fed a basal diet of limestone providing 33% of the total calcium. Three diets with increasing fly ash levels were fed to three cage groups of 40 male and 40 female broilers providing 33, 46, and 45% of the total calcium of .9, 1.1, and 1.8%, respectively. Broilers fed the highest fly ash level weighed significantly less at 8 weeks than the caged controls but did not differ from the other treatments. Bone breaking strength as measured by the Allo Kramer Shear Press was similar between the basal and low level fly ash group and increased with higher fly ash levels. In experiment 3 four groups of 40 male broilers in cages were fed limestone diets with graded levels of limestone for the calcium source. Another four groups of 40 caged male broilers were fed fly ash diets with equivalent graded levels of fly ash for the calcium source. Both limestone and fly ash diets provided .17, .34, .51, and .68% calcium of a total calcium content of .28, .45, .62, and .79%, respectively.« less

Combustion characteristics and retention-emission of selenium during co-firing of torrefied biomass and its blends with high ash coal.

PubMed

Ullah, Habib; Liu, Guijian; Yousaf, Balal; Ali, Muhammad Ubaid; Abbas, Qumber; Zhou, Chuncai

2017-12-01

The combustion characteristics, kinetic analysis and selenium retention-emission behavior during co-combustion of high ash coal (HAC) with pine wood (PW) biomass and torrefied pine wood (TPW) were investigated through a combination of thermogravimetric analysis (TGA) and laboratory-based circulating fluidized bed combustion experiment. Improved ignition behavior and thermal reactivity of HAC were observed through the addition of a suitable proportion of biomass and torrefied. During combustion of blends, higher values of relative enrichment factors in fly ash revealed the maximum content of condensing volatile selenium on fly ash particles, and depleted level in bottom ash. Selenium emission in blends decreased by the increasing ratio of both PW and TPW. Higher reductions in the total Se volatilization were found for HAC/TPW than individual HAC sample, recommending that TPW have the best potential of selenium retention. The interaction amongst selenium and fly ash particles may cause the retention of selenium. Copyright © 2017 Elsevier Ltd. All rights reserved.

The study of the burning possibilities of solid combustibles in the determined conditions for complete usage of caloric [energy] and ashes resulted

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voina, N.I.; Barca, F.; Mogos, D.

1995-12-31

In modern combustors, 95--98% of the organic mass of a solid combustible is converted into caloric energy; 2--4% remain in the fly ash captured in electrofilters and hydraulically removed in most cases. The 2--4% unburned materials in fly ash, together with the water from being hydraulically transported, make it difficult for the use of the fly ash for metal extraction or as a binder in the materials industry. This work presents the research results of a study in which the burning process was modified to result in fly ash without carbon content and fly ash removal by dry capture. Laboratorymore » fluidized-bed combustion of lignite with and without addition of limestone for sulfur capture was used to generate ashes for further study. The ashes were studied for their use as binders and as a cement substitute.« less

Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

PubMed Central

Liu, Jun; Qiu, Qiwen; Xing, Feng; Pan, Dong

2014-01-01

This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP) test and the scanning electron microscopy (SEM) images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days. PMID:28788677

Evaluation of interactions between soil and coal fly ash leachates using column percolation tests.

PubMed

Tsiridis, V; Petala, M; Samaras, P; Sakellaropoulos, G P

2015-09-01

The aim of this work was the assessment of the environmental impact of different origin fly ashes with regard to their final disposal. The experimental procedure included the performance of single column tests and column tests of fly ash and soil in series. The appraisal of the potential environmental hazards was implemented using physicochemical analyses and bioassays. Two different fly ash samples were examined, one fly ash produced from the combustion of sub-bituminous coal (CFA) and one fly ash produced from the combustion of lignite (LFA). Single column percolation tests were performed according to NEN 7343 protocol, while fly ash/soil experiments were conducted incorporating slight modifications to this protocol. The study focused on the release of metals Ba, Cr, Cu, Mo, Se and Zn and the ecotoxic behavior of leachates on crustacean Daphnia magna and bacteria Vibrio fischeri. The infiltration of the leachates of both fly ashes through soil affected considerably their leaching profile. The transport of Cu and Zn was facilitated by the dynamic leaching conditions and influenced by the pH of the leachates. Moreover, the release and bioavailability of Cr, Cu and Zn was probably altered during the infiltration experiments and organisms' response was not always correlated with the concentration of metals. Nevertheless, the results are signalling that possible manipulations and final disposal of fly ash should be considered when environmental threats are investigated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Predicting Water Quality Problems Associated with Coal Fly Ash Disposal Facilities Using a Trace Element Partitioning Study

NASA Astrophysics Data System (ADS)

Bhattacharyya, S.; Donahoe, R. J.; Graham, E. Y.

2006-12-01

For much of the U.S., coal-fired power plants are the most important source of electricity for domestic and industrial use. Large quantities of fly ash and other coal combustion by-products are produced every year, the majority of which is impounded in lagoons and landfills located throughout the country. Many older fly ash disposal facilities are unlined and have been closed for decades. Fly ash often contains high concentrations of toxic trace elements such as arsenic, boron, chromium, molybdenum, nickel, selenium, lead, strontium and vanadium. Trace elements present in coal fly ash are of potential concern due to their toxicity, high mobility in the environment and low drinking water MCL values. Concern about the potential release of these toxic elements into the environment due to leaching of fly ash by acid rain, groundwater or acid mine drainage has prompted the EPA to develop national standards under the subtitle D of the Resource Conservation and Recovery Act (RCRA) to regulate ash disposal in landfills and surface impoundments. An attempt is made to predict the leaching of toxic elements into the environment by studying trace element partitioning in coal fly ash. A seven step sequential chemical extraction procedure (SCEP) modified from Filgueiras et al. (2002) is used to determine the trace element partitioning in seven coal fly ash samples collected directly from electric power plants. Five fly ash samples were derived from Eastern Bituminous coal, one derived from Western Sub-bituminous coal and the other derived from Northern Lignite. The sequential chemical extraction procedure gives valuable information on the association of trace elements: 1) soluble fraction, 2) exchangeable fraction, 3) acid soluble fraction, 4) easily reducible fraction, 5) moderately reducible fraction, 6) poorly reducible fraction and 7) oxidizable organics/sulfide fraction. The trace element partitioning varies with the composition of coal fly ash which is influenced by the type of coal burned. Preliminary studies show that in some fly ash samples, significant amounts of As, B, Mo, Se, Sr and V are associated with the soluble and exchangeable fraction, and thus would be highly mobile in the environment. Lead, on the other hand, is mainly associated with the amorphous Fe and Mn oxide fractions and would be highly immobile in oxidizing conditions, but mobile in reducing conditions. Ni and Cr show different associations in different fly ash samples. In most fly ash samples, significant amounts of the trace elements are associated with more stable fractions that do not threaten the environment. The study of trace element partitioning in coal fly ash thus helps us to predict their leaching behavior under various conditions.

Leaching behaviour of coal-ash: a case study.

PubMed

Hajarnavis, M R; Bhide, A D

2003-10-01

Leaching of trace elements from fly ash dumps to subsoil layer due to the rain water results in contamination of ground water. The ground water pollution due to fly ash deposition on land so occurring was assessed by simulating the disposal site conditions using two lysimeter with two different soils. Leachate was collected and analysed daily to help understand the phenomenon of leaching of fly-ash constituents in the environment. The trace metals and physico-chemical parameters of fly ash and soil used were measured before and after the experiment. Results of analysis of soil and fly ash samples were then compared with the results of lysimeter-I and lysimeter-II. The study reveals that metals respond differently at dumping site while reacting with soil and water.

Clean up fly ash from coal burning plants by new isolated fungi Fusarium oxysporum and Penicillium glabrum.

PubMed

Ertit Taştan, Burcu

2017-09-15

In Turkey approximately 45 million tons of coals are burned in a year and 19.3 million tons of fly ash have emerged. The bioremediation of heavy metals or different elements from fly ash makes them bio-available. However, in previous studies, requiring of long operational time and failing to show tolerance to high pulp densities of fly ash of selected fungal species makes them impractical. In this work, bioremediation of fly ash by new isolated fungi Fusarium oxysporum and Penicillium glabrum were investigated in one step and two step bioremediation process. Ca, Si, Fe and S were found to be considerable amount in studied fly ashes by ED-XRF element analysis. The bioremediation yields of Mo (100%), S (64.36%) Ni (50%) and Cu (33.33%) by F. oxysporum were high. The remediated elements by P. glabrum in fly ash were Mo (100%), S (57.43%), Ni (25%), Si (24.66%), V (12.5%), Ti (5%) and Sr (3.2%). The isolation of high fly ash resistant fungi and reduction of the bioremediation time will allow the practical applications of the bioremediation technology when it is scaled up. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-performance self-compacting concrete with the use of coal burning waste

NASA Astrophysics Data System (ADS)

Bakhrakh, Anton; Solodov, Artyom; Naruts, Vitaly; Larsen, Oksana; Alimov, Lev; Voronin, Victor

2017-10-01

Today, thermal power plants are the main producers of energy in Russia. Most of thermal power plants use coal as fuel. The remaining waste of coal burning is ash, In Russia ash is usually kept at dumps. The amount of utilized ash is quite small, less than 13%. Meanwhile, each ash dump is a local ecological disaster. Ash dumps take a lot of place and destroy natural landscape. The use of fly ash in building materials can solve the problem of fly ash dumps in Russia. A lot of papers of scientists are devoted to the use of fly ash as filler in concrete. The main advantage of admixing fly ash in concrete is decrease of amount of used cement. This investigation was held to find out if it is possible to utilize fly ash by its use in high amounts in self-compacting concrete. During experiments three mixtures of SCC with different properties were obtained. The first one is experimental and shows the possibility of obtaining SCC with high compressive strength with 60% of fly ash from the mass of cement. Two other mixtures were optimized with the help of the math planning method to obtain high 7-day and 28-day high compressive strength.

Utilize Cementitious High Carbon Fly Ash (CHCFA) to Stabilize Cold In-Place Recycled (CIR) Asphalt Pavement as Base Coarse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wen, Haifang; Li, Xiaojun; Edil, Tuncer

The purpose of this study was to evaluate the performance of cementitious high carbon fly ash (CHCFA) stabilized recycled asphalt pavement as a base course material in a real world setting. Three test road cells were built at MnROAD facility in Minnesota. These cells have the same asphalt surface layers, subbases, and subgrades, but three different base courses: conventional crushed aggregates, untreated recycled pavement materials (RPM), and CHCFA stabilized RPM materials. During and after the construction of the three cells, laboratory and field tests were carried out to characterize the material properties. The test results were used in the mechanistic-empiricalmore » pavement design guide (MEPDG) to predict the pavement performance. Based on the performance prediction, the life cycle analyses of cost, energy consumption, and greenhouse gasses were performed. The leaching impacts of these three types of base materials were compared. The laboratory and field tests showed that fly ash stabilized RPM had higher modulus than crushed aggregate and RPM did. Based on the MEPDG performance prediction, the service life of the Cell 79 containing fly ash stabilized RPM, is 23.5 years, which is about twice the service life (11 years) of the Cell 77 with RPM base, and about three times the service life (7.5 years) of the Cell 78 with crushed aggregate base. The life cycle analysis indicated that the usage of the fly ash stabilized RPM as the base of the flexible pavement can significantly reduce the life cycle cost, the energy consumption, the greenhouse gases emission. Concentrations of many trace elements, particularly those with relatively low water quality standards, diminish over time as water flows through the pavement profile. For many elements, concentrations below US water drinking water quality standards are attained at the bottom of the pavement profile within 2-4 pore volumes of flow.« less

Destruction of inorganic municipal solid waste incinerator fly ash in a DC arc plasma furnace.

PubMed

Zhao, Peng; Ni, Guohua; Jiang, Yiman; Chen, Longwei; Chen, Mingzhou; Meng, Yuedong

2010-09-15

Due to the toxicity of dioxins, furans and heavy metals, there is a growing environmental concern on municipal solid waste incinerator (MSWI) fly ash in China. The purpose of this study is directed towards the volume-reduction of fly ash without any additive by thermal plasma and recycling of vitrified slag. This process uses extremely high-temperature in an oxygen-starved environment to completely decompose complex waste into very simple molecules. For developing the proper plasma processes to treat MSWI fly ash, a new crucible-type plasma furnace was built. The melting process metamorphosed fly ash to granulated slag that was less than 1/3 of the volume of the fly ash, and about 64% of the weight of the fly ash. The safety of the vitrified slag was tested. The properties of the slag were affected by the differences in the cooling methods. Water-cooled and composite-cooled slag showed more excellent resistance against the leaching of heavy metals and can be utilized as building material without toxicity problems. Copyright 2010 Elsevier B.V. All rights reserved.

Extraction of heavy metals from MSW incinerator fly ash using saponins.

PubMed

Hong, K J; Tokunaga, S; Ishigami, Y; Kajiuchi, T

2000-08-01

An extraction process with saponins was evaluated for removing heavy metals from MSW (municipal solid waste) incinerator fly ashes. Two different fly ashes, A and B, were treated on a laboratory scale with three triterpene-glycoside type of saponins, M, Q, and T, in the pH range 4-9. The results were compared with those of the HCI and EDTA treatment. The treatment with saponins extracted 20-45% of Cr from the fly ashes. Saponins were also effective in extracting Cu from fly ash A attaining 50-60% extraction. Saponin T extracted 100% of Pb from fly ash A at pH around 4. The extraction of Zn with the saponin treatment was similar to that of the HCl treatment. Further, Cr, Cu, Pb, and Zn were fractionated by sequential extraction to investigate the effect of saponins on each fraction. Extraction behavior of other elements during the saponin treatment was also studied. The leaching test on the residues received after the saponin treatment showed that the fly ashes were successfully detoxified to meet the landfilling guideline.

Fly ash reinforced thermoplastic vulcanizates obtained from waste tire powder.

PubMed

Sridhar, V; Xiu, Zhang Zhen; Xu, Deng; Lee, Sung Hyo; Kim, Jin Kuk; Kang, Dong Jin; Bang, Dae-Suk

2009-03-01

Novel thermoplastic composites made from two major industrial and consumer wastes, fly ash and waste tire powder, have been developed. The effect of increasing fly ash loadings on performance characteristics such as tensile strength, thermal, dynamic mechanical and magnetic properties has been investigated. The morphology of the blends shows that fly ash particles have more affinity and adhesion towards the rubbery phase when compared to the plastic phase. The fracture surface of the composites shows extensive debonding of fly ash particles. Thermal analysis of the composites shows a progressive increase in activation energy with increase in fly ash loadings. Additionally, morphological studies of the ash residue after 90% thermal degradation shows extensive changes occurring in both the polymer and filler phases. The processing ability of the thermoplastics has been carried out in a Monsanto processability testing machine as a function of shear rate and temperature. Shear thinning behavior, typical of particulate polymer systems, has been observed irrespective of the testing temperatures. Magnetic properties and percolation behavior of the composites have also been evaluated.

Leaching characteristics of selected South African fly ashes: Effect of pH on the release of major and trace species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gitari, W.M.; Fatoba, O.O.; Petrik, L.F.

2009-07-01

Fly ash samples from two South African coal-fired power stations were subjected to different leaching tests under alkaline and acidic conditions in an attempt to assess the effect of pH on the leachability of species from the fly ashes and also assess the potential impact of the fly ashes disposal on groundwater and the receiving environment. To achieve this, German Standard leaching (DIN-S4) and Acid Neutralization Capacity (ANC) tests were employed. Ca, Mg, Na, K and SO{sub 4} were significantly leached into solution under the two leaching conditions with the total amounts in ANC leachates higher than that of DIN-S4.more » This indicates that a large fraction of the soluble salts in unweathered fly ash are easily leached. These species represents the fraction that can be flushed off initially from the surface of ash particles on contacting the ash with water. The amounts of toxic trace elements such as As, Se, Cd, Cr and Pb leached out of the fly ashes when in contact with de-mineralized water (DIN-S4 test) were low and below the Target Water Quality Range (TWQR) of South Africa. This is explained by their low concentrations in the fly ashes and their solubility dependence on the pH of the leaching solution. However the amounts of some minor elements such as B, Mn, Fe, As and Se leached out at lower pH ranging between 10 to 4 (ANC test) were slightly higher than the TWQR, an indication that the pH of the leaching solution plays a significant role on the leaching of species in fly ash. The high concentrations of the toxic elements released from the fly ashes at lower pH gives an indication that the disposal of the fly ash could have adverse effects on the receiving environment if the pH of the solution contacting the ashes is not properly monitored.« less

Economical and Environmentally Benign Extraction of Rare Earth Elements (REES) from Coal & Coal Byproducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, Gary

This final report provides a complete summary of the activities, results, analytical discussion, and overall evaluation of the project titled “Economical and Environmentally Benign Extraction of Rare Earth Elements (REES) from Coal & Coal Byproducts” under DOE Award Number DE-FE-0027155 that started in March 2016 and ended December 2017. Fly ash was selected as the coal-byproduct source material due to fact that it is readily available with no need for extensive methods to obtain the material, it is produced in large quantities (>50 million tons per year) and had REE concentrations similar to other coal-byproducts. The selected fly ash usedmore » throughout this project was from the Mill Creek power generating facility operated by Louisville Gas and Electric located in Louisville, KY and was subjected to a variety of physical and chemical characterization tests. Results from fusion extractions showed that the selected fly-ash had a TREE+Y concentration of 480 ppm with critical REEs concentration of 200 ppm. The fly ash had an outlook ratio of 1.25 and an estimated value of $16-$18 worth of salable REEs per 1-tonne of fly ash. Additional characterizations by optical evaluation, QEMSCAN, XRD, size fractionation, and SEM analysis showed the fly ash consisted of small glassy spherules with a size range between 1 to 110 µm (ave. diam. of 13 um), was heterogeneous in chemical composition (main crystalline phases: aluminum oxides and iron oxides) and was primarily an amorphous material (75 to 80%). A simple stepped approach was completed to estimate the total REE resource quantity. The approach included REE characterization of the representative samples, evaluation of fly-ash availability, and final determination estimated resource availability with regards to REE grade on a regional and national scale. This data represents the best available information and is based upon the assumptions that the power generating facility where the fly-ash was obtained will use the same coal sources (actual mines were identified), the coal materials will have relatively consistent REE concentrations, and the REE extraction process developed during this project can achieve 42% REE recovery (validated and confirmed). Calculations indicated that the estimated REE resource is approximately 175,000 tonnes with a current estimated value of $3,330MM. The proposed REE extraction and production process developed during this project used four fundamental steps; 1) fly-ash pretreatment to enhance REE extraction, 2) REE extraction by acid digestion, 3) REE separation/concentration by carbon adsorption and column chromatography, and 4) REE oxide production. Secondary processing steps to manage process residuals and additional processing techniques to produce value-added products were incorporated into the process during the project. These secondary steps were not only necessary to manage residuals, but also provided additional revenue streams that offset operational and capital expenditures. The process produces one value product stream (production of zeolite Na-P1), a solids waste stream, and one liquid stream that met RCRA discharge requirements. Based upon final design criteria and operational parameters, the proposed system could produce approximately 200 grams of REOs from 1-tonne of fly-ash, thereby representing a TREE+Y recovery of 42% (project target of > 25%). A detailed economic model was developed to evaluate both CAPEX and OPEX estimates for systems with varying capacities between 100 kg to 200 tonnes of fly ash processed per day. Using a standard system capacity of 10 tonne/day system, capital costs were estimated at $88/kg fly ash while operating costs were estimated at approximately $450/kg fly ash. This operating cost estimate includes a revenue of $495/tonne of fly ash processed from the value-added product produced from the system (zeolite Na-P1). Although operating cost savings due to zeolite production were significant, the capital + operating cost for a 10 tonne system was more expensive than the total dollar value of REEs present in the fly ash material. Specifically, the estimated cost per 1-tonne of fly ash treated is approximately $540 while the estimated value of REEs in the fly ash is $18-$20/tonne. This is an excessive difference showing that the proposed process is not economically feasible strictly on the basis of REE revenue compared to extraction costs. Although the current proposed system does not produce sufficient quantities of REEs or additional revenue sources to offset operational and capital costs, supplementary factors including US strategic concerns, commercial demands, and defense department requirements must be factored. At this time, the process developed during this project provides foundational information for future development of simple processes that require low capital investment and one that will extract a valuable quality and quantity of REE oxides from industrial waste.« less

Sustainable asphalt pavement: Application of slaughterhouse waste oil and fly ash in asphalt binder

NASA Astrophysics Data System (ADS)

Sanchez Ramos, Jorge Luis

Increasing energy costs, lack of sufficient natural resources and the overwhelming demand for petroleum has stimulated the development of alternative binders to modify or replace petroleum-based asphalt binders. In the United States, the petroleum-based asphalt binder is mainly used to produce the Hot Mix Asphalt (HMA). There are approximately 4000 asphalt plants that make 500 million tons of asphalt binder valued at roughly 3 billion/year. The instability of the world's oil market has pushed oil prices to more than 80 per barrel in 2012, which increased the cost of asphalt binder up to $570 per ton. Therefore, there is a timely need to find alternative sustainable resources to the asphalt binder. This paper investigates the possibility of the partial replacement of the asphalt binder with slaughterhouse waste and/or fly ash. In order to achieve this objective, the asphalt binder is mixed with different percentages of waste oil and/or fly ash. In order to investigate the effect of these additives to the performance of the asphalt binder, a complete performance grade test performed on multiple samples. The results of the performance grade tests are compared with a control sample to observe how the addition of the waste oil and/or fly ash affects the sample. Considering the increasing cost and demand of asphalt, the use of slaughterhouse waste oil and/or fly ash as a partial replacement may result in environmental and monetary improvements in the transportation sector.

Influence of ignition process on mineral phase transformation in municipal solid waste incineration (MSWI) fly ash: Implications for estimating loss-on-ignition (LOI).

PubMed

Mu, Yue; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki

2017-01-01

This research focused on the mineral phase transformation under varied ignition conditions with the objective of estimating loss-on-ignition (LOI) parameter in municipal solid waste incineration (MSWI) fly ash residues. LOI is commonly used to measure the volatile species, unburned carbon and moisture in the solid materials. There are criteria for LOI measurement in some research fields, while there is no standard protocol for LOI measurement in MSWI fly ash. Using thermogravimetry technique, the ignition condition candidates were proposed at 440/700/900°C for 1 and 2h. Based on X-ray diffractometry results, obvious mineral phase transformation occurred as a function of ignition temperature variation rather than ignition time. Until 440°C, only some minor phases disappeared comparing with the original state. Significant mineral phase transformations of major phases (Ca- and Cl-based minerals) occurred between 440 and 700°C. The mineral phase transformation and the occurrence of newly-formed phases were determined not only by the ignition condition but also by the content of the co-existing components. Mineral phase components rarely changed when ignition temperature rose from 700 to 900°C. Consequently, in order to prevent critical damages to the original mineralogical composition of fly ash, the lowest ignition temperature (440°C) for 2h was suggested as an ideal measurement condition of LOI in MSWI fly ash. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recovery of aluminum and other metal values from fly ash

DOEpatents

McDowell, William J.; Seeley, Forest G.

1981-01-01

The invention described herein relates to a method for improving the acid leachability of aluminum and other metal values found in fly ash which comprises sintering the fly ash, prior to acid leaching, with a calcium sulfate-containing composition at a temperature at which the calcium sulfate is retained in said composition during sintering and for a time sufficient to quantitatively convert the aluminum in said fly ash into an acid-leachable form.

Recovery of aluminum and other metal values from fly ash

DOEpatents

McDowell, W.J.; Seeley, F.G.

1979-11-01

The invention relates to a method for improving the acid leachability of aluminum and other metal values found in fly ash which comprises sintering the fly ash, prior to acid leaching, with a calcium sulfate-containing composition at a temperature at which the calcium sulfate is retained in said composition during sintering and for a time sufficient to quantitatively convert the aluminum in said fly ash into an acid-leachable form.

Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

NASA Astrophysics Data System (ADS)

Panagopoulos, C. N.; Georgiou, E. P.; Tsopani, A.; Piperi, L.

2011-03-01

Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

Optical properties of fly ash. Volume 1, Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Self, S.A.

1994-12-01

Research performed under this contract was divided into four tasks under the following headings: Task 1, Characterization of fly ash; Task 2, Measurements of the optical constants of slags; Task 3, Calculations of the radiant properties of fly ash dispersions; and Task 4, Measurements of the radiant properties of fly ash dispersions. Tasks 1 and 4 constituted the Ph.D. research topic of Sarbajit Ghosal, while Tasks 2 and 3 constituted the Ph.D. research topic of Jon Ebert. Together their doctoral dissertations give a complete account of the work performed. This final report, issued in two volumes consists of an executivemore » summary of the whole program followed by the dissertation of Ghosal. Volume 1 contains the dissertation of Ghosal which covers the characterization of fly ash and the measurements of the radiant properties of fly ash dispersions. A list of publications and conference presentations resulting from the work is also included.« less

Using Cementitious Materials Such as Fly Ash to Replace a Part of Cement in Producing High Strength Concrete in Hot Weather

NASA Astrophysics Data System (ADS)

Turuallo, Gidion; Mallisa, Harun

2018-03-01

The use of waste materials in concrete gave many advantages to prove the properties of concrete such as its workability, strength and durability; as well to support sustaianable development programs. Fly ash was a waste material produced from coal combustion. This research was conducted to find out the effect of fly ash as a part replacement of cement to produce high strength concrete. The fly ash, which was used in this research, was taken from PLTU Mpanau Palu, Central Sulawesi. The water-binder ratio used in this research was 0.3 selected from trial mixes done before. The results of this research showed that the strength of fly ash concretes were higher than concrete with PCC only. The replacement of cement with fly ash concrete could be up to 20% to produce high strength concrete.

Geotechnical characterization of some Indian fly ashes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, S.K.; Yudhbir

2005-10-01

This paper reports the findings of experimental studies with regard to some common engineering properties (e.g., grain size, specific gravity, compaction characteristics, and unconfined compression strength) of both low and high calcium fly ashes, to evaluate their suitability as embankment materials and reclamation fills. In addition, morphology, chemistry, and mineralogy of fly ashes are studied using scanning electron microscope, electron dispersive x-ray analyzer, x-ray diffractometer, and infrared absorption spectroscopy. In high calcium fly ash, mineralogical and chemical differences are observed for particles, {gt}75 {mu} m and the particles of {lt} 45 {mu} m size. The mode and duration of curingmore » significantly affect the strength and stress-strain behavior of fly ashes. The geotechnical properties of fly ash are governed by factors like lime content (CaO), iron content (Fe{sub 2}O{sub 3}) and loss on ignition. The distinct difference between self-hardening and pozzolanic reactivity has been emphasized.« less

Use of rubber and bentonite added fly ash as a liner material.

PubMed

Cokca, Erdal; Yilmaz, Zeka

2004-01-01

In many countries regulations require all hazardous waste disposal facilities to be lined with suitable impermeable barriers to protect against contamination. In this study, a series of laboratory tests on rubber and bentonite added fly ash were conducted. The aim of the tests was to evaluate the feasibility of utilizing fly ash, rubber and bentonite as a low hydraulic conductivity liner material. Type C fly ash was obtained from Soma thermal power plant in Turkey; rubber in pulverized form was waste from the retreading industry. To investigate the properties of rubber and bentonite added fly ash, hydraulic conductivity, leachate analysis, unconfined compression, split tensile strength, one-dimensional consolidation, swell and freeze/thaw cycle tests were performed. The overall evaluation of results have revealed that rubber and bentonite added fly ash showed good promise and a candidate for construction of a liner.

Study of PCDD/Fs distribution in fly ash, ash deposits, and bottom ash from a medical waste incinerator in China.

PubMed

Du, Yingzhe; Jin, Yuqi; Lu, Shengyong; Peng, Zheng; Li, Xiaodong; Yan, Jianhua

2013-02-01

Over the past decades in China, the number of medical waste incinerators (MWIs) has been rising rapidly, causing emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). In this study, samples of fly ash, ash deposits, and bottom ash from typical MWIs were analyzed for PCDD/Fs and their distribution characteristics. Results showed international toxic equivalent (I-TEQ) values in the range of 6.9-67 ng I-TEQ/g in fly ash and ash deposits, whereas the concentration in bottom ash was extremely low (only 1.33 pg I-TEQ/g), yet the generation of PCDD/Fs was mostly de novo synthesis in fly ash and ash deposits according to the ratio of PCDFs to PCDDs; the major distribution differences of PCDD/Fs in fly ash was manifested by the content of toxic furan 2,3,7,8-TCDF but other toxic PCDD/Fs showed similar distribution. Other findings are that 2,3,4,7,8-PeCDF had the most contribution to TEQ concentration, and that the most abundant toxic furan congener is 1,2,3,4,6,7,8-HpCDF. Correlation analysis showed that there was no significant correlation between PCDD/Fs concentration and several other physical and chemical parameters. This paper is of interest because it presents the emission performances of PCDD/Fs in ash from medical waste incineration in China. PCDD/F contents in fly ash and ash deposits vary between 6.9 and 67.3 ng I-TEQ/g. However, the concentration in bottom ash was extremely low (only 1.33 x 10(-3) ng I-TEQ/g). The fingerprints of PCDD/Fs in fly ash are almost similar, except for 2,3,7,8-TCDF. There is no marked correlation between PCDD/Fs and other physicochemical properties.

Amelioration of soil PAH and heavy metals by combined application of fly ash and biochar

NASA Astrophysics Data System (ADS)

Masto, Reginald; George, Joshy; Ansari, Md; Ram, Lal

2016-04-01

Generation of electricity through coal combustion produces huge quantities of fly ash. Sustainable disposal and utilization of these fly ash is a major challenge. Fly ash along with other amendments like biochar could be used for amelioration of soil. In this study, fly ash and biochar were used together for amelioration of polycyclic aromatic hydrocarbon (PAH) contaminated soil. Field experiment was conducted to investigate the effects of fly ash and biochar on the amelioration of soil PAH, and the yield of Zea mays. The treatments were control, biochar (4 t/ha), fly ash (4 t/ha), ash + biochar ( 2 + 2 t/ha). Soil samples were collected after the harvest of maize crop and analysed for chemical and biological parameters. Thirteen PAHs were analysed in the postharvest soil samples. Soil PAHs were extracted in a microwave oven at 120 °C using hexane : acetone (1:1) mixture. The extracted solutions were concentrated, cleaned and the 13 PAHs [Acenaphthene (Ace), fluorene (Flr), phenanthrene (Phn), anthracene(Ant), pyrene(Pyr), benz(a)anthracene (BaA), chrysene (Chy), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene, benzo(g,h,i)perylene (BghiP), dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pyrene)(Inp)] were analysed using GC-MS. The mean pH increased from 6.09 in control to 6.64 and 6.58 at biochar and fly ash treated soils, respectively. N content was not affected, whereas addition of biochar alone and in combination with fly ash, has significantly increased the soil organic carbon content. P content was almost double in combined (9.06 mg/kg) treatment as compared to control (4.32 mg/kg). The increase in K due to biochar was 118%, whereas char + ash increased soil K by 64%. Soil heavy metals were decreased: Zn (-48.4%), Ni (-41.4%), Co (-36.9%), Cu (-35.7%), Mn (-34.3%), Cd (-33.2%), and Pb (-30.4%). Soil dehydrogenase activity was significantly increased by ash and biochar treatments and the maximum activity was observed for the combined treatment. Peroxidase, phenol oxidase, and catalase activities were not affected by these treatments. Acid phosphatase activity decreased, whereas alkaline phosphatase activity increased due to biochar and fly ash treatment. Microbial biomass carbon increased significantly (P < 0.05) with biochar (+27.9%), fly ash (19.8%), and char + ash (+27.9%) applications. Maize grain yield was increased by biochar (+11.4%) and char + ash (+28.1%) treatments. The total PAH concentration decreased from 4191 μg/kg in control to 1930 μg/kg in fly ash; 1509 μg/kg in biochar and 1011 μg/kg in ash + char treatments. Among the different PAHs the concentration was higher for BkF, which decreased from 713 μg/kg in control to 139 - 315 μg/kg under different treatments. Overall, combined application of fly ash and biochar was found to be effective in amelioration of soil quality parameters and improving crop yield.

Fabricaton of brick without burning process

NASA Astrophysics Data System (ADS)

Zultiniar; Fadli, A.; Yenti, S. R.; Drastinawati; Thariq, M. R. A.

2018-04-01

Brick is a material with many applications on building materials. The purpose of this research is to study the effect of fly ash addition and hardening time on mechanical properties of brick produced. Brick was formed by mixing cement, clay, water and fly ash with addition point was 0;0,3;0,6;0,9;1,2 kg weight. Brick was dried at room temperature for 7, 14 and 21 days. The result showed that compressive strength with addition 0,6 kg fly ash for 21 days was the the strongest where that’s value was 9,375 N/mm2. The highest porosity was get in on 21,34 % with 1,2 fly ash addition. The result of TCLP showed that for Pb, Cu, Cr content was still below the quality standards based on PP No.85 TH 1999 and still considered harmless. Leachate value for Pb of 3,10 mg/L, 1,213 mg/L for Cr and 4,374 mg/L for Cu.

Pervious concrete using fly ash aggregate as coarse aggregate-an experimental study

NASA Astrophysics Data System (ADS)

Dash, Subhakanta; Kar, Biswabandita; Mukherjee, Partha Sarathi

2018-05-01

The present study deals with the fabrication of pervious concrete from fly ash aggregates. The pervious concrete were obtained by the mixture of three different size fly ash aggregates (4.75 mm,9.5 mm,12.5 mm), Portland cement, water with little amount of sand or without sand. Admixtures like Silica fume(SF) and Super plasticizer are added to the mixture to enhance the strength of concrete. Trial being taken on preparation of Fly ash based pervious concrete (FPC) with different w/c ratio i.e. 0.30, 0.35 and 0.40 respectively. Tests such as porosity, permeability and compressive, strength are studied for this concrete material and the result concluded that the concrete when cured for 28 days its compressive strength falls in between 7.15 - 15.74 MPa and permeability 9.38 - 16.07 mm/s with porosity 27.59 - 34.05% and these are suited to be used as for use as an environment friendly concrete.

Belite cement clinker from coal fly ash of high Ca content. Optimization of synthesis parameters.

PubMed

Guerrero, A; Goñi, S; Campillo, I; Moragues, A

2004-06-01

The optimization of parameters of synthesis of belite cement clinker from coal fly ash of high Ca content is presented in this paper. The synthesis process is based on the hydrothermal-calcination-route of the fly ash without extra additions. The hydrothermal treatment was carried out in demineralized water and a 1 M NaOH solution for 4 h at the temperatures of 100 degrees C, 150 degrees C, and 200 degrees C. The precursors obtained during the hydrothermal treatmentwere heated at temperatures of 700 degrees C, 800 degrees C, 900 degrees C, and 1000 degrees C. The changes of fly ash composition after the different treatments were characterized by X-ray diffraction (XRD), FT infrared (FTIR) spectroscopy, surface area (BET-N2), and thermal analyses. From the results obtained we concluded that the optimum temperature of the hydrothermal treatment was 200 degrees C, and the optimum temperature for obtaining the belite cement clinker was 800 degrees C.

Fly ash in concrete : final report.

DOT National Transportation Integrated Search

1990-08-01

This study was initiated to develop information regarding the use of fly ash in portland cement concrete for state construction projects. : Concrete mixes containing 10%, 20%, 30%, 40% and 60% fly ash were evaluated in the laboratory in combination w...

Alkali content of fly ash : measuring and testing strategies for compliance : [tech transfer summary].

DOT National Transportation Integrated Search

2015-04-01

This study investigated the test methods used to determine the : alkali content of fly ash. It also evaluated if high-alkali fly ash : exacerbates alkali-silica reaction in laboratory tests and field : concrete.

Greatly increased use of fly ash in hydraulic cement concrete (HCC) for pavement layers and transportation structures - volume I.

DOT National Transportation Integrated Search

2012-03-01

The purpose of this phase is to evaluate the past, current and future trends of use of fly ash in concrete and restrictions to its use. The American Coal Ash Association (ACAA) conducts an annual survey of fly ash production and use. Typically on an ...

Suppression of phosphate liberation from eutrophic lake sediment by using fly ash and ordinary Portland cement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heng-Peng Ye; Fan-Zhong Chen; Yan-Qing Sheng

2006-08-15

In this study, the effect of suppression on phosphate liberation from eutrophic lake sediment by using fly ash and ordinary Portland cement (OPC) was investigated by small scale experiment. A system including sediment, lake water, and several kinds of capping materials was designed to clarify the suppression of phosphate liberation from sediment under the anaerobic condition. The suppression efficiencies of fly ash, OPC and glass bead used as control material were also determined, and these effects were discussed. The suppression efficiency of glass bead was 44.4%, and those of fly ash and OPC were 84.4%, 94.9%, respectively. The suppression bymore » fly ash and OPC was mainly carried out by the adsorption effect, in addition to the covering effect. The suppression efficiency depended on the amounts of the material used, and about 90% of liberated phosphate was suppressed by fly ash of 10.0 Kg m{sup -2}, and OPC of 6.0 Kg m{sup -2}. The concentrations of heavy metals, such as mercury, cadmium, lead, copper, zinc, chromium, silver, arsenic and nickel, in fly ash and OPC were lower than those in the environmental materials. And it was considered that the concentrations of heavy metals in fly ash and OPC were too low to influence the ecosystem in natural water region.« less

Recovery of lead from smelting fly ash of waste lead-acid battery by leaching and electrowinning.

PubMed

Chen, Chuh-Shun; Shih, Yu-Jen; Huang, Yao-Hui

2016-06-01

Fly ash that was enriched with lead (Pb), formed as an intermediate in waste lead-acid battery (WLAB) smelting, was recycled by the hydro-electrometallurgy. Characterization of fly ash thereof indicated that the Pb was in the forms of PbSO4 (anglesite) and Pb2OSO4 (lanarkite). Nitric acid and sodium hydroxide were firstly used to study the leaching of the fly ash sample, which was affected by leachant dosage and solid-to-liquid ratio (S/L). At an S/L of 60gL(-1), the leachability of Pb was 43% and 67% in 2M acidic and basic solutions, respectively, based on an average 70wt% of Pb in the original fly ash. Anglesite was completely soluble in NaOH and lanarkite was mildly soluble in HNO3. Pb was recovered from the pregnant leach solution within an electrolytic cell constructed with graphite or RuO2/IrO2-coated titanium (Ti-DSA) anodes and a stainless steel cathode. Properties of anodes deposited with lead dioxides were analyzed by cyclic voltammetry. The optimized parameters of electrowinning were 2M NaOH leachant, a current density of 0.75Adm(-2) and an electrolytic process duration of 120min, which yielded a Pb removal of higher than 99% and a specific energy consumption of 0.57Whg(-1). This process constitutes an eco-friendly and economic alternative to the presently utilized secondary pyrometallurgy for treating lead-containing fly ash. Copyright © 2016 Elsevier Ltd. All rights reserved.

Innovative prediction of fly ash performance in concrete.

DOT National Transportation Integrated Search

2013-02-01

In the last half century much research has been conducted to find an acceptable cement substitute; the : most intriguing and interesting of those materials is fly ash. Fly ash consists of almost perfectly spherical : particles that are rich in calciu...

40 CFR 302.6 - Notification requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... transportation of coal and coal ash (including fly ash, bottom ash, and boiler slags), including the dumping and... coal and coal ash, including fly ash, bottom ash, and boiler slags. (d) Except for releases of..., chromium, copper, lead, nickel, selenium, silver, thallium, or zinc is not required if the mean diameter of...

Physical factors affecting the mutagenicity of fly ash from a coal-fired power plant.

PubMed

Fisher, G L; Chrisp, C E; Raabe, O G

1979-05-25

The two finest, most respirable coal fly ash fractions collected from the smokestack of a power plant were more mutagenic than two coarser fractions. Mutagenicity was evaluated in the histidine-requiring bacterial strains TA 1538, TA 98, and TA 100 of Salmonella typhimurium. Ash samples collected from the hoppers of an electrostatic precipitator in the plant were not mutagenic. The mutagens in coal fly ash were resistant to x-ray or ultraviolet irradiation, possibly as a result of stabilization by fly ash surfaces. All mutagenic activity is lost with heating to 350 degrees C.

Sustainability of an in situ aided phytostabilisation on highly contaminated soils using fly ashes: Effects on the vertical distribution of physicochemical parameters and trace elements.

PubMed

Bidar, Géraldine; Waterlot, Christophe; Verdin, Anthony; Proix, Nicolas; Courcot, Dominique; Détriché, Sébastien; Fourrier, Hervé; Richard, Antoine; Douay, Francis

2016-04-15

Aided phytostabilisation using trees and fly ashes is a promising technique which has shown its effectiveness in the management of highly metal-contaminated soils. However, this success is generally established based on topsoil physicochemical analysis and short-term experiments. This paper focuses on the long-term effects of the afforestation and two fly ashes (silico-aluminous and sulfo-calcic called FA1 and FA2, respectively) by assessing the integrity of fly ashes 10 years after their incorporation into the soil as well as the vertical distribution of the physicochemical parameters and trace elements (TEs) in the amended soils (F1 and F2) in comparison with a non-amended soil (R). Ten years after the soil treatment, the particle size distribution analysis between fly ashes and their corresponding masses (fly ash + soil particles) showed a loss or an agglomeration of finer particles. This evolution matches with the appearance of gypsum (CaSO4 2H2O) in FA2m instead of anhydrite (CaSO4), which is the major compound of FA2. This finding corresponds well with the dissolution and the lixiviation of Ca, S and P included in FA2 along the F2 soil profile, generating an accumulation of these elements at 30 cm depth. However, no variation of TE contamination was found between 0 and 25 cm depth in F2 soil except for Cd. Conversely, Cd, Pb, Zn and Hg enrichment was observed at 25 cm depth in the F1 soil, whereas no enrichment was observed for As. The fly ashes studied, and notably FA2, were able to reduce Cd, Pb and Zn availability in soil and this capacity persists over the time despite their structural and chemical changes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Irradiation effect on leaching behavior and form of heavy metals in fly ash of municipal solid waste incinerator.

PubMed

Nam, Sangchul; Namkoong, Wan

2012-01-15

Fly ash from a municipal solid waste incinerator (MSWI) is commonly classified as hazardous waste. High-energy electron beam irradiation systems have gained popularity recently as a clean and promising technology to remove environmental pollutants. Irradiation effects on leaching behavior and form of heavy metals in MSWI fly ash have not been investigated in any significant detail. An electron beam accelerator was used in this research. Electron beam irradiation on fly ash significantly increased the leaching potential of heavy metals from fly ash. The amount of absorbed dose and the metal species affected leaching behavior. When electron beam irradiation intensity increased gradually up to 210 kGy, concentration of Pb and Zn in the leachate increased linearly as absorbed dose increased, while that of Cu underwent no significant change. Concentration of Pb and Zn in the leachate increased up to 15.5% (10.7 mg/kg), and 35.6% (9.6 mg/kg) respectively. However, only 4.8% (0.3mg/kg) increase was observed in the case of Cu. The results imply that irradiation has significant effect on the leaching behavior of heavy metals in fly ash, and the effect is quite different among the metal species tested in this study. A commonly used sequential extraction analysis which can classify a metal species into five forms was conducted to examine any change in metal form in the irradiated fly ash. Notable change in metal form in fly ash was observed when fly ash was irradiated. Change in Pb form was much greater than that of Cu form. Change in metal form was related to leaching potential of the metals. Concentration of heavy metal in leachate was positively related to the exchangeable form which is the most mobile. It may be feasible to treat fly ash by electron beam irradiation for selective recovery of valuable metals or for pretreatment prior to conventional processes. Copyright © 2011 Elsevier B.V. All rights reserved.

Heavy metals in MSW incineration fly ashes

NASA Astrophysics Data System (ADS)

Ferreira, C.; Ribeiro, A.; Ottosen, L.

2003-05-01

Incineration is a common solution for dealing with the increasing amount of municipal solid waste (MSW). During the process, the heavy metals initially present in the waste go through several transformations, ending up in combustion products, such as fly ash. This article deals with some issues related to the combustion of MSW and the formation of fly ash, especially in what concerns heavy metals. Treatment of the flue gas in air pollution control equipment plays an important role and the basic processes to accomplish this are explained. Fly ash from a semi-dry flue gas treatment system is characterized regarding its physical-chemical properties: pH, solubility, chemical composition, and leaching, amongst others. Results indicate a high alkalinity and the presence of large amounts of calcium, chlorides, sulfates, carbonates, sodium and potassium. Metal concentrations in fly ash are: 6,2g/kg for zinc, 2,4g/kg for lead, 1,7g/kg for iron, and 7,9g/kg for magnesium. Copper, manganese, chromium and cadmium are also present with 546, 338, 104 and 91mg/kg of fly ash, respectively. These results are extremely important in subsequent studies on the treatment of fly ash.

Risk assessment of heavy metals from combustion of pelletized municipal sewage sludge.

PubMed

Xiao, Zhihua; Yuan, Xingzhong; Leng, Lijian; Jiang, Longbo; Chen, Xiaohong; Zhibin, Wu; Xin, Peng; Jiachao, Zhang; Zeng, Guangming

2016-02-01

Fly ash and slag are important by-products obtained from combustion of municipal sewage sludge (MSS) after pelletization. The quantitative environmental impact assessment of heavy metals in fly ash and slag, compared to MSS, were performed in accordance with bioavailability and eco-toxicity, geo-accumulation index (GAI), risk assessment code (RAC), and potential ecological risk index (PERI). The results demonstrated that not only direct but also long-term bioavailability and eco-toxicity of heavy metals in fly ash and slag decreased except direct bioavailability and eco-toxicity of Pb in fly ash. The GAI demonstrated that combustion significantly weakened (P < 0.05) the pollution levels of heavy metals. PERI indicated that all risks attributed to heavy metals were significantly lowered (P < 0.05) from 777.07 (very high risk) in MSS to 288.72 (moderate risk) and 64.55 (low risk) in fly ash and slag, respectively. In terms of the RAC, seven heavy metals had low even no risk to the environments after combustion besides As in slag. The environmental risk of heavy metals in fly ash and slag was decreased compared with MSS. However, the results of PERI showed that fly ash had a moderate risk.

Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures.

PubMed

Glinicki, Michał A; Jóźwiak-Niedźwiedzka, Daria; Gibas, Karolina; Dąbrowski, Mariusz

2016-01-02

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement-ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash.

Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures

PubMed Central

Glinicki, Michał A.; Jóźwiak-Niedźwiedzka, Daria; Gibas, Karolina; Dąbrowski, Mariusz

2016-01-01

The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement—ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash. PMID:28787821

Characterization of typical heavy metals in pyrolysis MSWI fly ash.

PubMed

Xu, Tengtun; Wang, Li'ao; Zeng, Yunmin; Zhao, Xue; Wang, Lei; Zhan, Xinyuan; Li, Tong; Yang, Lu

2018-06-07

Thermal treatment methods are used extensively in the process of municipal solid waste incineration fly ash. However, the characterization of heavy metals during this process should be understood more clearly in order to control secondary pollution. In this paper, the content, speciation and leaching toxicity of mercury (Hg), plumbum (Pb), cadmium (Cd) and zinc (Zn) in fly ash treated under different temperatures and time were firstly analysed as pre-tests. Later, pilot-scale pyrolysis equipment was used to explore the concentration and speciation changes in the heavy metals of fly ash. Finally, the phase constitution and microstructure changes in fly ash were compared before and after pyrolysis using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The results showed that (a) The appropriate processing temperature was between 400°C and 450°C, and the processing time should be 1 h. (b) The stability of heavy metals in fly ash increased after pyrolysis. (c) XRD and SEM results indicated that phase constitution changed a little, but the microstructure varied to a porous structure similar to that of a coral reef after pyrolysis. These results suggest that pyrolysis could be an effective method in controlling heavy metal pollution in fly ash.

Use of solid residue from thermal power plant (fly ash) for enhancing sewage sludge anaerobic digestion: Influence of fly ash particle size.

PubMed

Montalvo, S; Cahn, I; Borja, R; Huiliñir, C; Guerrero, L

2017-11-01

The influence of fly ash particle size on methane production and anaerobic biodegradability was evaluated. Assays with different fly ash particle sizes (0.8-2.36mm) at a concentration of 50mg/L were ran under mesophilic conditions. In anaerobic processes operating with fly ash, greater removal of both volatile total and suspended solids, chemical oxygen demand (total and soluble) was achieved, with an increase of methane production between 28% and 96% compared to the control reactors. The highest increase occurred at ash particles sizes of 1.0-1.4mm. The metal concentrations in the digestates obtained after anaerobic digestion of sewage sludge are far below those considered as limiting for the use of sludge in soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reclaimed fly ash as select fill under PCC pavement.

DOT National Transportation Integrated Search

1999-11-01

With the support of the Iowa Fly Ash Affiliates, research on reclaimed fly ash for use as a : construction material has been ongoing since 1991. The material exhibits engineering : properties similar to those of soft limestone or sandstone and a ligh...

Size distribution of rare earth elements in coal ash

USGS Publications Warehouse

Scott, Clinton T.; Deonarine, Amrika; Kolker, Allan; Adams, Monique; Holland, James F.

2015-01-01

Rare earth elements (REEs) are utilized in various applications that are vital to the automotive, petrochemical, medical, and information technology industries. As world demand for REEs increases, critical shortages are expected. Due to the retention of REEs during coal combustion, coal fly ash is increasingly considered a potential resource. Previous studies have demonstrated that coal fly ash is variably enriched in REEs relative to feed coal (e.g, Seredin and Dai, 2012) and that enrichment increases with decreasing size fractions (Blissett et al., 2014). In order to further explore the REE resource potential of coal ash, and determine the partitioning behavior of REE as a function of grain size, we studied whole coal and fly ash size-fractions collected from three U.S commercial-scale coal-fired generating stations burning Appalachian or Powder River Basin coal. Whole fly ash was separated into , 5 um, to 5 to 10 um and 10 to 100 um particle size fractions by mechanical shaking using trace-metal clean procedures. In these samples REE enrichments in whole fly ash ranges 5.6 to 18.5 times that of feedcoals. Partitioning results for size separates relative to whole coal and whole fly ash will also be reported. 

40 CFR 240.211-3 - Recommended procedures: Operations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... every 60 minutes and as changes are made. (5) Weights of bottom ash, grate siftings, and fly ash.... (10) Gross calorific value of daily representative samples of bottom ash, grate siftings, and fly ash...

Removal of cadmium from aqueous solutions using industrial coal fly ash-nZVI.

PubMed

Ma, Lixia; Wei, Qi; Chen, Yueqin; Song, Qiuyang; Sun, Conghui; Wang, Zhiqiang; Wu, Guanghong

2018-02-01

Batch experiments were conducted to test the effects of various solution properties, such as pH, temperature, initial concentration and anoxic and aerobic atmosphere, on Cd removal by nanoscale zerovalent iron (nZVI) supported on industrial coal fly ash. Cd (II) could be removed by adsorption on fly ash-nZVI in a very short time (5 min) with high removal rates (greater than 99.9%) over a wide range of concentration (5-100 mg l -1 ). Cd (II) was physically adsorbed on the surface of fly ash-nZVI. The preparation of fly ash-nZVI can incorporate the use of waste media, making the overall adsorbent more removal efficient and low cost.

Removal of cadmium from aqueous solutions using industrial coal fly ash-nZVI

PubMed Central

Ma, Lixia; Wei, Qi; Chen, Yueqin; Song, Qiuyang; Sun, Conghui; Wang, Zhiqiang

2018-01-01

Batch experiments were conducted to test the effects of various solution properties, such as pH, temperature, initial concentration and anoxic and aerobic atmosphere, on Cd removal by nanoscale zerovalent iron (nZVI) supported on industrial coal fly ash. Cd (II) could be removed by adsorption on fly ash-nZVI in a very short time (5 min) with high removal rates (greater than 99.9%) over a wide range of concentration (5–100 mg l−1). Cd (II) was physically adsorbed on the surface of fly ash-nZVI. The preparation of fly ash-nZVI can incorporate the use of waste media, making the overall adsorbent more removal efficient and low cost. PMID:29515830

Relationship between textural properties, fly ash carbons, and Hg capture in fly ashes derived from the combustion of anthracitic pulverized feed blends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isabel Surez-Ruiz; Jose B. Parra

2007-08-15

In this work, the textural properties of a series of whole anthracitic-derived fly ashes sampled in eight hoppers from the electrostatic precipitators and their sized fractions (from {gt}150 to {lt}25 {mu}m) are investigated. Data from N{sub 2} adsorption isotherms at 77 K, helium density, and mercury porosimetry have contributed to establish a relationship between the Brunauer-Emmett-Teller (BET) surface areas, VTOT, porosity, carbon content (the type of fly ash carbons), and Hg retention in these fly ashes. The unburned carbons in these ashes are macroporous materials, and they are different from the carbons in fly ashes from classes C and Fmore » (the latter derived from the combustion of bituminous coals) and show different textural properties. These ashes represent the end member of the fly ash classes C and F with respect to certain textural properties. Although the BET surface area and VTOT values for the studied samples are the lowest reported, they increase with the increase in carbon content, anisotropic carbon content, and particle size of the ashes. Thus, a positive relationship between all these parameters and Hg capture by the coarser ash fractions was found. The finest fraction of carbons ({lt}25 {mu}m) represented an exception. Although it makes a significant contribution to the total carbon of the whole fly ashes and shows relatively higher surface areas and VTOT values, its Hg concentration was found to be the lowest. This suggests that the type of unburned carbons in the finest fraction and/or other adsorption mechanisms may play a role in Hg concentration. Because the textural properties of anisotropic carbons depend on their subtype and on their origin, the need for its differentiation has been evidenced. 54 refs., 8 figs., 3 tabs.« less

Fly ash carbon burn-out at TVA`s Colbert and Shawnee Stations: Site specific application study. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cochran, J.W.; Kirkconnell, S.F.

1996-04-01

Many power plants, particularly after conversion to low-NOx burners, produce fly ash that is too high in carbon content to be successfully marketed as a concrete admixture. Fly ash beneficiation using Carbon Burn-Out (CBO) technology offers the opportunity to market fly ash that was previously landfilled. This site application study of beneficiating pulverized coal boiler fly ash at Tennessee Valley Authority`s Colbert and Shawnee Stations indicates this process is a cost effective solution for decreasing solid waste disposal, increasing landfill life, improving boiler heat rate, and generating a positive revenue stream. Results indicate that the Colbert Station has the flymore » ash market, site integration potential, and positive economics to support construction and operation of a CBO plant with an annual production rate of approximately 150,000 tons. As the market for fly ash increases, this capacity may be expanded to handle the majority of fly ash generated at Colbert. Results of the Shawnee Station analysis indicate that site integration constraints combined with the lack of near term local area fly ash market growth do not support construction and operation of a CBO plant. CBO commercial process design work in developing a generic commercial design resulted in a major improvement to the heat recovery portion of the process. This development resulted in the elimination of five major equipment items, with a corresponding reduction in plant complexity and costs. The design change is now considered part of the commercial offering.« less

Mercury capture by selected Bulgarian fly ashes: Influence of coal rank and fly ash carbon pore structure on capture efficiency

USGS Publications Warehouse

Kostova, I.J.; Hower, J.C.; Mastalerz, Maria; Vassilev, S.V.

2011-01-01

Mercury capture by fly ash C was investigated at five lignite- and subbituminous-coal-burning Bulgarian power plants (Republika, Bobov Dol, Maritza East 2, Maritza East 3, and Sliven). Although the C content of the ashes is low, never exceeding 1.6%, the Hg capture on a unit C basis demonstrates that the low-rank-coal-derived fly ash carbons are more efficient in capturing Hg than fly ash carbons from bituminous-fired power plants. While some low-C and low-Hg fly ashes do not reveal any trends of Hg versus C, the 2nd and, in particular, the 3rd electrostatic precipitator (ESP) rows at the Republika power plant do have sufficient fly ash C range and experience flue gas sufficiently cool to capture measurable amounts of Hg. The Republika 3rd ESP row exhibits an increase in Hg with increasing C, as observed in other power plants, for example, in Kentucky power plants burning Appalachian-sourced bituminous coals. Mercury/C decreases with an increase in fly ash C, suggesting that some of the C is isolated from the flue gas stream and does not contribute to Hg capture. Mercury capture increases with an increase in Brunauer-Emmett-Teller (BET) surface area and micropore surface area. The differences in Hg capture between the Bulgarian plants burning low-rank coal and high volatile bituminous-fed Kentucky power plants suggests that the variations in C forms resulting from the combustion of the different ranks also influence the efficiency of Hg capture. ?? 2010 Elsevier Ltd.

Field evaluation of fly ash in aggregate shoulder materials : final report.

DOT National Transportation Integrated Search

1985-06-01

This study consisted of an evaluation of self-hardening fly ash (Class C) used as an additive in the treatment of shoulders surfaced with sand clay gravel and/or shell (oyster). This was accomplished through construction of fly ash treated aggregate ...

Process for the recovery of alumina from fly ash

DOEpatents

Murtha, M.J.

1983-08-09

An improvement in the lime-sinter process for recovering alumina from pulverized coal fly ash is disclosed. The addition of from 2 to 10 weight percent carbon and sulfur to the fly ash-calcium carbonate mixture increase alumina recovery at lower sintering temperatures.

Alkaline hydrothermal conversion of fly ash filtrates into zeolites 2: utilization in wastewater treatment.

PubMed

Somerset, Vernon; Petrik, Leslie; Iwuoha, Emmanuel

2005-01-01

Filtrates were collected using a codisposal reaction wherein fly ash was reacted with acid mine drainage. These codisposal filtrates were then analyzed by X-ray Fluorescence spectrometry for quantitative determination of the SiO2 and Al2O3 content. Alkaline hydrothermal zeolite synthesis was then applied to the filtrates to convert the fly ash material into zeolites. The zeolites formed under the experimental conditions were faujasite, sodalite, and zeolite A. The use of the fly ash-derived zeolites and a commercial zeolite was explored in wastewater decontamination experiments as it was applied to acid mine drainage in different dosages. The concentrations of Ni, Zn, Cd, As, and Pb metal ions in the treated wastewater were investigated. The results of the treatment of the acid mine drainage with the prepared fly ash zeolites showed that the concentrations of Ni, Zn, Cd, and Hg were decreased as the zeolite dosages of the fly ash zeolite (FAZ1) increased.

Mercury retention by fly ashes from coal combustion: Influence of the unburned carbon content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez-Anton, M.A.; Diaz-Somoano, M.; Martinez-Tarazona, M.R.

2007-01-31

The objective of this study was to evaluate the effect of unburned carbon particles present in fly ashes produced by coal combustion on mercury retention. To achieve this objective, the work was divided into two parts. The aim of the first part of the study was to estimate the amount of mercury captured by the fly ashes during combustion in power stations and the relationship of this retention to the unburned carbon content. The second part was a laboratory-scale study aimed at evaluating the retention of mercury concentrations greater than those produced in power stations by fly ashes of differentmore » characteristics and by unburned carbon particles. From the results obtained it can be inferred that the unburned carbon content is not the only variable that controls mercury capture in fly ashes. The textural characteristics of these unburned particles and of other components of fly ashes also influence retention.« less

Characterization of morphology and hydration products of high-volume fly ash paste by monochromatic scanning x-ray micro-diffraction (μ-SXRD)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bae, Sungchul; Meral, Cagla; Department of Civil Engineering, Middle East Technical University, 06800 Ankara

2014-05-01

The present study focuses on identification and micro-structural characterization of the hydration products formed in high-volume fly ash (HVFA)/portland cement (PC) systems using monochromatic scanning x-ray micro-diffraction (μ-SXRD) and SEM-EDS. Pastes with up to 80% fly ash replacement were studied. Phase maps for HVFA samples using μ-SXRD patterns prove that μ-SXRD is an effective method to identify and visualize the distribution of phases in the matrix. μ-SXRD and SEM-EDS analysis shows that the C-S-H formed in HVFA system containing 50% or more of fly ash has a similar structure as C-S-H(I) with comparatively lower Ca/Si ratio than the one producedmore » in PC system. Moreover, coexistence of C-S-H(I) and strätlingite is observed in the system containing 80% of fly ash, confirming that the amount of alumina and silicate phases provided by the fly ash is a major factor for the formation of C-S-H(I) and strätlingite in HVFA system. - Highlights: • High-volume fly ash (HVFA) paste was studied by scanning x-ray micro-diffraction. • Coexistence of C-S-H(I) and strätlingite in the HVFA system is clearly shown. • The distribution of minor phases in the HVFA system is shown. • Differences between inner and outer products of fly ash are observed by SEM-EDS.« less

Interaction of planar and nonplanar organic contaminants with coal fly ash: effects of polar and nonpolar solvent solutions.

PubMed

Burgess, Robert M; Ryba, Stephan A; Cantwell, Mark G; Gundersen, Jennifer L; Tien, Rex; Perron, Monique M

2006-08-01

Coal fly ash has a very high sorption capacity for a variety of anthropogenic contaminants and has been used to cleanse wastewater of pollutants for approximately 40 years. Like other black carbons, the planar structure of the residual carbon in fly ash results in elevated affinities for planar organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and some polychlorinated biphenyls (PCBs). The present study was performed to understand better the mechanisms affecting the strong interaction between planar contaminants and coal fly ash. The removal of 10 PCBs and 10 PAHs by several fly ashes and other sorbents was evaluated under different experimental conditions to highlight the intermolecular forces influencing adsorption. Varying fly ash concentration and solvent system composition indicated that dispersive interactions were most prevalent. For the PCBs, empirical results also were compared to molecular modeling estimates of the energy necessary for the PCB molecule to assume a planar conformation (PCe). The PCe levels ranged from 8 to 25 kcal/mol, depending on the degree of ortho-substituted chlorination of the PCB. A significant correlation between PCe and PCB removal from solution was observed for the fly ashes and activated carbon, whereas the nonplanar sorbent octadecyl (C18) indicated no relationship. These findings demonstrate the strong interaction between black carbon fly ash and planar organic contaminants. Furthermore, as exemplified by the PCBs, these results show how this interaction is a function of a contaminant's ability to assume a planar conformation.

A pilot study of mercury liberation and capture from coal-fired power plant fly ash.

PubMed

Li, Jin; Gao, Xiaobing; Goeckner, Bryna; Kollakowsky, Dave; Ramme, Bruce

2005-03-01

The coal-fired electric utility generation industry has been identified as the largest anthropogenic source of mercury (Hg) emissions in the United States. One of the promising techniques for Hg removal from flue gas is activated carbon injection (ACI). The aim of this project was to liberate Hg bound to fly ash and activated carbon after ACI and provide high-quality coal combustion products for use in construction materials. Both bench- and pilot-scale tests were conducted to liberate Hg using a thermal desorption process. The results indicated that up to 90% of the Hg could be liberated from the fly ash or fly-ash-and-activated-carbon mixture using a pilot-scale apparatus (air slide) at 538 degrees C with a very short retention time (less than 1 min). Scanning electron microscope (SEM) evaluation indicated no significant change in fly ash carbon particle morphology following the thermal treatment. Fly ash particles collected in the baghouse of the pilot-scale apparatus were smaller in size than those collected at the exit of the air slide. A similar trend was observed in carbon particles separated from the fly ash using froth flotation. The results of this study suggest a means for power plants to reduce the level of Hg in coal-combustion products and potentially recycle activated carbon while maintaining the resale value of fly ash. This technology is in the process of being patented.

Removal of chloride from MSWI fly ash.

PubMed

Chen, Wei-Sheng; Chang, Fang-Chih; Shen, Yun-Hwei; Tsai, Min-Shing; Ko, Chun-Han

2012-10-30

The high levels of alkali chloride and soluble metal salts present in MSWI fly ash is worth noting for their impact on the environment. In addition, the recycling or reuse of fly ash has become an issue because of limited landfill space. The chloride content in fly ash limits its application as basis for construction materials. Water-soluble chlorides such as potassium chloride (KCl), sodium chloride (NaCl), and calcium chloride hydrate (CaCl(2) · 2H(2)O) in fly ash are easily washed away. However, calcium chloride hydroxide (Ca(OH)Cl) might not be easy to leach away at room temperature. The roasting and washing-flushing processes were applied to remove chloride content in this study. Additionally, air and CO(2) were introduced into the washing process to neutralize the hazardous nature of chlorides. In comparison with the water flushing process, the roasting process is more efficient in reducing the process of solid-liquid separation and drying for the reuse of Cl-removed fly ash particles. In several roasting experiments, the removal of chloride content from fly ash at 1050°C for 3h showed the best results (83% chloride removal efficiency). At a solid to liquid ratio of 1:10 the water-flushing process can almost totally remove water-soluble chloride (97% chloride removal efficiency). Analyses of mineralogical change also prove the efficiency of the fly ash roasting and washing mechanisms for chloride removal. Copyright © 2012 Elsevier B.V. All rights reserved.

Characterization of fly ashes from circulating fluidized bed combustion (CFBC) boilers cofiring coal and petroleum coke

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feihu Li; Jianping Zhai; Xiaoru Fu

2006-08-15

The chemistry, mineralogy, morphology, and particle size distribution were investigated in fly ashes from the burning of Datong (ShanXi, China) bituminous coal and the cofiring of Mideast high-sulfur petroleum coke (PC) with 30:70 (cal %) and 50:50 (cal %) blends of Datong bituminous coal in two commercial CFBC boilers. With the exception of CaO, the amounts of major oxides in the fly ashes from cofiring PC and coal were close to those of the common coal fly ashes. The PC-coal fly ashes were enriched in Ni, V, and Mo, implying these trace elements were mainly derived from PC. Ni andmore » V, along with several other elements, such as Cr, Cu, Se, Pb, U, Th, and possibly As and Cd, increased in content with a decrease in temperature of the electrostatic precipitator (ESP). The results of chemistry, mineralogy, and morphology studies suggested that the desulfurization rate of the CFBC boilers at current conditions was low, and the PC tends to coarsen the fly ash particles and increase the loss on ignition (LOI) values, making these fly ashes unsuitable for use as a cement additive or a mineral admixture in concrete. Further studies on the combustion status of the CFBC boilers are needed if we want to be able to increase the desulfurization rate and produce high-quality fly ashes for broader and full utilization. 22 refs., 4 figs., 4 tabs.« less

Mechanism of unintentionally produced persistent organic pollutant formation in iron ore sintering.

PubMed

Sun, Yifei; Liu, Lina; Fu, Xin; Zhu, Tianle; Buekens, Alfons; Yang, Xiaoyi; Wang, Qiang

2016-04-05

Effects of temperature, carbon content and copper additive on formation of chlorobenzenes (CBzs) and polychlorinated biphenyls (PCBs) in iron ore sintering were investigated. By heating simulated fly ash (SFA) at a temperature range of 250-500°C, the yield of both CBzs and PCBs presented two peaks of 637ng/g-fly ash at 350°C and 1.5×10(5)ng/g-fly ash at 450°C for CBzs, and 74ng/g-fly ash at 300°C and 53ng/g-fly ash at 500°C. Additionally, in the thermal treatment of real fly ash (RFA), yield of PCBs displayed two peak values at 350°C and 500°C, however, yield of CBzs showed only one peak at 400°C. In the thermal treatment of SFA with a carbon content range of 0-20wt% at 300°C, both CBzs and PCBs obtained the maximum productions of 883ng/g-fly ash for CBzs and 127ng/g-fly ash for PCBs at a 5wt% carbon content. Copper additives also affected chlorinated aromatic formation. The catalytic activity of different copper additives followed the orders: CuCl2∙2H2O>Cu2O>Cu>CuSO4>CuO for CBzs, and CuCl2∙2H2O>Cu2O>CuO>Cu>CuSO4 for PCBs. Copyright © 2015 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. Mercedes Maroto-Valer; John M. Andresen; Yinzhi Zhang

This research program focused on the development of fly ash derived sorbents to capture CO{sub 2} from power plant flue gas emissions. The fly ash derived sorbents developed represent an affordable alternative to existing methods using specialized activated carbons and molecular sieves, that tend to be very expensive and hinder the viability of the CO{sub 2} sorption process due to economic constraints. Under Task 1 'Procurement and characterization of a suite of fly ashes', 10 fly ash samples, named FAS-1 to -10, were collected from different combustors with different feedstocks, including bituminous coal, PRB coal and biomass. These samples presentedmore » a wide range of LOI value from 0.66-84.0%, and different burn-off profiles. The samples also spanned a wide range of total specific surface area and pore volume. These variations reflect the difference in the feedstock, types of combustors, collection hopper, and the beneficiation technologies the different fly ashes underwent. Under Task 2 'Preparation of fly ash derived sorbents', the fly ash samples were activated by steam. Nitrogen adsorption isotherms were used to characterize the resultant activated samples. The cost-saving one-step activation process applied was successfully used to increase the surface area and pore volume of all the fly ash samples. The activated samples present very different surface areas and pore volumes due to the range in physical and chemical properties of their precursors. Furthermore, one activated fly ash sample, FAS-4, was loaded with amine-containing chemicals (MEA, DEA, AMP, and MDEA). The impregnation significantly decreased the surface area and pore volume of the parent activated fly ash sample. Under Task 3 'Capture of CO{sub 2} by fly ash derived sorbents', sample FAS-10 and its deashed counterpart before and after impregnation of chemical PEI were used for the CO{sub 2} adsorption at different temperatures. The sample FAS-10 exhibited a CO{sub 2} adsorption capacity of 17.5mg/g at 30 C, and decreases to 10.25mg/g at 75 C, while those for de-ashed counterpart are 43.5mg/g and 22.0 mg/g at 30 C and 75 C, respectively. After loading PEI, the CO{sub 2} adsorption capacity increased to 93.6 mg/g at 75 C for de-ashed sample and 62.1 mg/g at 75 C for raw fly ash sample. The activated fly ash, FAS-4, and its chemical loaded counterparts were tested for CO{sub 2} capture capacity. The activated carbon exhibited a CO{sub 2} adsorption capacity of 40.3mg/g at 30 C that decreased to 18.5mg/g at 70 C and 7.7mg/g at 120 C. The CO{sub 2} adsorption capacity profiles changed significantly after impregnation. For the MEA loaded sample the capacity increased to 68.6mg/g at 30 C. The loading of MDEA and DEA initially decreased the CO{sub 2} adsorption capacity at 30 C compared to the parent sample but increased to 40.6 and 37.1mg/g, respectively, when the temperature increased to 70 C. The loading of AMP decrease the CO{sub 2} adsorption capacity compared to the parent sample under all the studied temperatures. Under Task 4 'Comparison of the CO{sub 2} capture by fly ash derived sorbents with commercial sorbents', the CO{sub 2} adsorption capacities of selected activated fly ash carbons were compared to commercial activated carbons. The CO{sub 2} adsorption capacity of fly ash derived activated carbon, FAS-4, and its chemical loaded counterpart presented CO{sub 2} capture capacities close to 7 wt%, which are comparable to, and even better than, the published values of 3-4%.« less

Preparation and Properties of Alkali Activated Metakaolin-Based Geopolymer.

PubMed

Chen, Liang; Wang, Zaiqin; Wang, Yuanyi; Feng, Jing

2016-09-08

The effective activation and utilization of metakaolin as an alkali activated geopolymer precursor and its use in concrete surface protection is of great interest. In this paper, the formula of alkali activated metakaolin-based geopolymers was studied using an orthogonal experimental design. It was found that the optimal geopolymer was prepared with metakaolin, sodium hydroxide, sodium silicate and water, with the molar ratio of SiO₂:Al₂O₃:Na₂O:NaOH:H₂O being 3.4:1.1:0.5:1.0:11.8. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were adopted to investigate the influence of curing conditions on the mechanical properties and microstructures of the geopolymers. The best curing condition was 60 °C for 168 h, and this alkali activated metakaolin-based geopolymer showed the highest compression strength at 52.26 MPa. In addition, hollow micro-sphere glass beads were mixed with metakaolin particles to improve the thermal insulation properties of the alkali activated metakaolin-based geopolymer. These results suggest that a suitable volume ratio of metakaolin to hollow micro-sphere glass beads in alkali activated metakaolin-based geopolymers was 6:1, which achieved a thermal conductivity of 0.37 W/mK and compressive strength of 50 MPa. By adjusting to a milder curing condition, as-prepared alkali activated metakaolin-based geopolymers could find widespread applications in concrete thermal protection.

Preparation and Properties of Alkali Activated Metakaolin-Based Geopolymer

PubMed Central

Chen, Liang; Wang, Zaiqin; Wang, Yuanyi; Feng, Jing

2016-01-01

The effective activation and utilization of metakaolin as an alkali activated geopolymer precursor and its use in concrete surface protection is of great interest. In this paper, the formula of alkali activated metakaolin-based geopolymers was studied using an orthogonal experimental design. It was found that the optimal geopolymer was prepared with metakaolin, sodium hydroxide, sodium silicate and water, with the molar ratio of SiO2:Al2O3:Na2O:NaOH:H2O being 3.4:1.1:0.5:1.0:11.8. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were adopted to investigate the influence of curing conditions on the mechanical properties and microstructures of the geopolymers. The best curing condition was 60 °C for 168 h, and this alkali activated metakaolin-based geopolymer showed the highest compression strength at 52.26 MPa. In addition, hollow micro-sphere glass beads were mixed with metakaolin particles to improve the thermal insulation properties of the alkali activated metakaolin-based geopolymer. These results suggest that a suitable volume ratio of metakaolin to hollow micro-sphere glass beads in alkali activated metakaolin-based geopolymers was 6:1, which achieved a thermal conductivity of 0.37 W/mK and compressive strength of 50 MPa. By adjusting to a milder curing condition, as-prepared alkali activated metakaolin-based geopolymers could find widespread applications in concrete thermal protection. PMID:28773888

Geoenvironmental impacts of using high carbon fly ash in structural fill applications : [research summary].

DOT National Transportation Integrated Search

2013-03-01

Coal power plants generate approximately 50% of the electricity in the : United States. As a result, large amounts of coal combustion byproducts, : especially fly ash, are produced annually. Only 40% of the fly ash : (mainly C and F-type classificati...

The application of electrocoagulation for the conversion of MSWI fly ash into nonhazardous materials.

PubMed

Liao, Wing-Ping; Yang, Renbo; Kuo, Wei-Ting; Huang, Jui-Yuan

2014-05-01

This research investigated the electrocoagulation of municipal solid waste incineration (MSWI) fly ash at a liquid-to-solid ratio (L/S) of 20:1. The leachate that was obtained from this treatment was recovered for reutilization. Two different anodic electrodes were investigated, and two unit runs were conducted. In Unit I, the optimum anode was chosen, and in Unit II, the optimum anode and the recovered leachate were used to replace deionized water for repeating the same electrocoagulation experiments. The results indicate that the aluminum (Al) anode performed better than the iridium oxide (IrO2) anode. The electrocoagulation technique includes washing with water, changing the composition of the fly ash, and stabilizing the heavy metals in the ash. Washing with water can remove the soluble salts from fly ash, and the fly ash can be converted into Friedel's salt (3CaO·Al2O3·CaCl2·10H2O) under an uniform electric field and the sacrificial release of Al(+3) ions, which stabilizes the toxic heavy metals and brings the composition of the fly ash to within the regulatory limits of the toxicity characteristic leaching procedure (TCLP). Use of the Al anode to manage the MSWI fly ash and the leachate obtained from the electrocoagulation treatment is therefore feasible. Copyright © 2014 Elsevier Ltd. All rights reserved.

Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies.

PubMed

Saqib, Naeem; Bäckström, Mattias

2015-10-01

Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn>Cu>Pb>Cr>Sb>As>Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in >50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths. Copyright © 2015. Published by Elsevier B.V.

Effective use of fly ash slurry as fill material.

PubMed

Horiuchi, S; Kawaguchi, M; Yasuhara, K

2000-09-15

A lot of effort has been put into increasing coal ash utilization; however, 50% of total amount is disposed of on land and in the sea. Several attempts have been reported recently concerning slurried coal fly ash use for civil engineering materials, such as for structural fill and backfill. The authors have studied this issue for more than 15 years and reported its potential for (1) underwater fills, (2) light weight backfills, and (3) light weight structural fills, through both laboratory tests and construction works. This paper is an overview of the results obtained for slurry, focusing on the following. (1) Coal fly ash reclaimed by slurry placement shows lower compressibility, higher ground density, and higher strength than by the other methods. This higher strength increases stability against liquefaction during earthquake. (2) Higher stability of the fly ash ground formed by slurry placement is caused by higher density and its self-hardening property. (3) Stability of fly ash reclaimed ground can be increased by increasing density and also by strength enhancement by cement addition. (4) Technical data obtained through a man-made island construction project shows the advantages of fly ash slurry in terms of mechanical properties such as higher stability against sliding failure, sufficient ground strength, and also in terms of cost saving. (5) Concentration in leachates from the placed slurry is lower than the Japanese environmental law. (6) In order to enlarge the fly ash slurry application toward a lightweight fill, mixtures of air foam, cement and fly ash were examined. Test results shows sufficient durability of this material against creep failure. This material was then used as lightweight structural fill around a high-rise building, and showed sufficient quality. From the above data, it can be concluded that coal fly ash slurry can be effectively utilized in civil engineering projects.

RARE EARTH ELEMENTS IN FLY ASHES AS POTENTIAL INDICATORS OF ANTHROPOGENIC SOIL CONTAMINATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattigod, Shas V.

2003-08-01

Studies of rare earth element (REE) content of disposed fly ashes and their potential mobility were neglected for decades because these elements were believed to be environmentally benign. A number of recent studies have now shown that REE may pose a long-term risk to the biosphere. Therefore, there is a critical need to study the REE concentrations in fly ash and their potential mobilization and dispersal upon disposal in the environment. We analyzed the REE content of bulk, size fractionated, and density separated fractions of three fly ash samples derived from combustion of sub bituminous coals from the western Unitedmore » States and found that the concentrations of these elements in bulk ashes were within the range typical of fly ashes derived from coals from the North American continent. The concentrations of light rare earth elements (LREE) such as La, Ce, and Nd, however, tended towards the higher end of the concentration range whereas, the concentrations of middle rare earth elements (MREE) (Sm and Eu) and heavy rare earth elements (HREE) (Lu) were closer to the lower end of the observed range for North American fly ashes. The concentrations of REE did not show any significant enrichment with decreasing particle size, this is typical of nonvolatile lithophilic element behavior during the combustion process. The lithophilic nature of REE was also confirmed by their concentrations in heavy density fractions of these fly ashes being on average about two times more enriched than the concentrations in the light density fractions. Shale normalized average of REE concentrations of fly ashes and coals revealed significant positive anomalies for Eu and Dy. Because of these distinctive positive anomalies of Eu and Dy, we believe that fly ash contamination of soils can be fingerprinted and distinguished from other sources of anthropogenic REE inputs in to the environment.« less

Impact assessment of fly ash on ground water quality: An experimental study using batch leaching tests.

PubMed

Dandautiya, Rahul; Singh, Ajit Pratap; Kundu, Sanghamitra

2018-05-01

The fly ash, generated at the coal-based thermal power plant, is always a cause of concern to environmentalists owing to its adverse impact on air, water and land. There exists a high environmental risk when it is disposed to the environment. Thus, two different type of fly ash samples (FA-1 and FA-2) have been considered in this study to examine the leaching potential of the elements magnesium, aluminium, silicon, calcium, titanium, vanadium, chromium, manganese, iron, nickel, cobalt, copper, zinc, arsenic, selenium, strontium, cadmium, barium and lead for different types of leachant. Toxicity characteristics leaching procedure and ASTM tests have been performed in the laboratory to simulate different natural leaching scenarios. Characterisation of samples have been done through X-ray diffraction and field emission gun scanning electron microscope. The effect of different liquid to solid ratios (i.e. 5, 10, 20 and 50) on the mobilisation of elements has been analysed. The results indicated that the maximum leaching of all elements occurred at a liquid to solid ratio of 5 except for arsenic, barium and silicon. The groundwater analysis has also been done to understand the actual effects of leachate. The elements presenting the highest leachability in the two fly ash samples under all tested conditions were magnesium, aluminium, silicon and calcium. It has been observed that calcium exhibits greater leaching effects than all other constituents. The study presented here has been found very useful for assessing contamination levels in groundwater owing to leaching effects of fly ash under different scenarios, which can be helpful to prevent spreading of the contaminants by efficient management of fly ash.

Synthesis of fly ash based core-shell composites for use as functional pigment in paints

NASA Astrophysics Data System (ADS)

Sharma, Richa; Tiwari, Sangeeta

2016-04-01

Fly ash is a combustion residue, mainly composed of silica, alumina and iron oxides. It is produced by the power industries in very large amounts and usually disposed in landfills, which have represented an environmental problem in recent years1. The need to generate a market for fly ash consumption is the main reason why alternative applications have been studied. It has been applied as an additive in construction materials like cement and pavements2. The present work describes the synthesis of Flyash-Titania core-shell particles by precipitation technique using Titanium tetra isopropoxide (TTIP) which can be used for variety of applications such as NIR reflecting materials for cool coatings, Photocatalysis etc. In this work, Fly ash is used in core and Nano -TiO2 is coated as shell on it. Surfactants are used to improve the adhesion of Nano Titania shell on fly ash core. Effect on adhesion of TiO2 on Fly ash is studied by using different types of surfactant. The preparation of core shells was carried out in absence of surfactant as well as using anionic and non-ionic surfactants. The percentage of surfactant was varied to study the effect of amount of surfactant on the uniformity and size of particles in the shell using Kubelka-Munk transformed reflectance spectra. The morphology of core shell structures was studied using SEM technique. Use of anionic surfactant results in more uniform coating with reduced particle size of the shell material. The composite particles prepared by using anionic surfactant are having good pigment properties and also shows good reflectance in Near Infrared region and hence can be used as a pigment in cool coatings.

Development of Fly Ash-Based Sorbent to Capture CO2 from Flue Gas

NASA Astrophysics Data System (ADS)

Majchrzak-Kucęba, I.; Nowak, W.

In the present work the thermogravimetric characterization of the sorption of carbon dioxide on polymer-modifiedmesoporous materials (MCM-41) from fly ashes is described. In order to obtain MCM-41 materials from three different types fly ashes,(including CFB fly ash) hydrothermal processesusing the supernatantsof coal fly ashes and surfactantsas the structure-directing agents,have been carried out. The obtained mesoporous materials were subjected to polyethylenimine (PEI) modification by their impregnation to obtain samples with PEl contents of 30, 50 and 70%, respectively. CO2 sorption/desorption tests on loaded PEl samples were carried out in a flow of a mixture of gasses (CO2-1O%, O2-10%, N2-80%) at different temperatures: 25 and 75°C. The highest CO2 sorption value was obtained for the sample that contained the best-quality MCM-41 and was impregnatedwith PEI in the amount of 50%. This sample at a temperatureof 75°C can take CO2 in an amount equivalent to 111.7 mgCO2/g sample weight. Under the same conditions, but without PEI impregnation, this sample can take CO2 in an amount equivalent to 3.2 mgCO2/g sample weight, thus 35 times less. The research of CO2 adsorption on polymer-modified mesoporous materials from fly ashes carried out within this work has shown that these materials are characterized by high CO2 adsorption capacity under conditions typical of coal combustionboiler flue gas and have the chance of becoming an efficient adsorbent for application to post-combustion CO2 separation. For PEI impregnated samples, a different behaviour of adsorption/desorption profiles has also been observed (both sorption and desorptionprogressesvery rapidly).

Estimates of increased black carbon emissions from electrostatic precipitators during powdered activated carbon injection for mercury emissions control.

PubMed

Clack, Herek L

2012-07-03

The behavior of mercury sorbents within electrostatic precipitators (ESPs) is not well-understood, despite a decade or more of full-scale testing. Recent laboratory results suggest that powdered activated carbon exhibits somewhat different collection behavior than fly ash in an ESP and particulate filters located at the outlet of ESPs have shown evidence of powdered activated carbon penetration during full-scale tests of sorbent injection for mercury emissions control. The present analysis considers a range of assumed differential ESP collection efficiencies for powdered activated carbon as compared to fly ash. Estimated emission rates of submicrometer powdered activated carbon are compared to estimated emission rates of particulate carbon on submicrometer fly ash, each corresponding to its respective collection efficiency. To the extent that any emitted powdered activated carbon exhibits size and optical characteristics similar to black carbon, such emissions could effectively constitute an increase in black carbon emissions from coal-based stationary power generation. The results reveal that even for the low injection rates associated with chemically impregnated carbons, submicrometer particulate carbon emissions can easily double if the submicrometer fraction of the native fly ash has a low carbon content. Increasing sorbent injection rates, larger collection efficiency differentials as compared to fly ash, and decreasing sorbent particle size all lead to increases in the estimated submicrometer particulate carbon emissions.

KINETIC STUDY OF ADSORPTION AND TRANSFORMATION OF MERCURY ON FLY ASH PARTICLES IN AN ENTRAINED FLOW REACTOR

EPA Science Inventory

Experimental studies were performed to investigate the interactions of elemental mercury vapor with entrained fly ash particles from coal combustion in a flow reactor. The rate of transformation of elemental mercury on fly ash particles was evauated over the temperature range fro...

Development of a standard operating procedure for analysis of ammonia concentrations in coal fly ash : [summary].

DOT National Transportation Integrated Search

2015-04-01

Fly ash produced when pulverized coal is burned in electrical generators can be used as a : concrete additive with many benefits. However, fly ash can have a high ammonia content, : which is released when used in concrete, potentially exposing worker...

Influence Of Trace Metal Distribution On Its Leachability From Coal Fly Ash

EPA Science Inventory

The risks associated with the reuse of coal fly ash in natural environmental settings in terms of their mobility and ecotoxicological significance is largely determined by: (1) the physicochemical conditions the fly ash is placed under; (2) the total leachable metal content in fl...

Salt-soda sinter process for recovering aluminum from fly ash

DOEpatents

McDowell, William J.; Seeley, Forest G.

1981-01-01

A method for recovering aluminum values from fly ash comprises sintering the fly ash with a mixture of NaCl and Na.sub.2 CO.sub.3 to a temperature in the range 700.degree.-900.degree. C. for a period of time sufficient to convert greater than 90% of the aluminum content of the fly ash into an acid-soluble fraction and then contacting the thus-treated fraction with an aqueous solution of nitric or sulfuric acid to effect dissolution of aluminum and other metal values in said solution.

Salt-soda sinter process for recovering aluminum from fly ash

DOEpatents

McDowell, W.J.; Seeley, F.G.

A method for recovering aluminum values from fly ash comprises sintering the fly ash with a mixture of NaCl and Na/sub 2/CO/sub 3/ to a temperature in the range 700/sup 0/ to 900/sup 0/C for a period of time sufficient to convert greater than 90% of the aluminum content of the fly ash into an acidsoluble fraction and then contacting the thus-treated fraction with an aqueous solution of nitric or sulfuric acid to effect dissolution of aluminum and other metal values in said solution.

The Effect of Fly Ash on the Corrosion Behaviour of Galvanised Steel Rebarsin Concrete

NASA Astrophysics Data System (ADS)

Tittarelli, Francesca; Mobili, Alessandra; Bellezze, Tiziano

2017-08-01

The effect of fly ash on the corrosion behaviour of galvanised steel rebars in cracked concrete specimens exposed to wet-dry cycles in a chloride solution has been investigated. The obtained results show that the use of fly ash, replacing either cement or aggregate, always improves the corrosion behaviour of galvanised steel reinforcements. In particular, the addition of fly ash, even in the presence of concrete cracks, decreases the corrosion rate monitored in very porous concretes, as those with w/c = 0.80, to values comparable with those obtained in good quality concretes, as those with w/c = 0.45. Therefore, fly ash cancels the negative effect, at least from the corrosion point of view, of a great porosity of the cement matrix.

Particle size distribution of fly ash from co-incineration of bituminous coal with municipal solid waste

NASA Astrophysics Data System (ADS)

Cieślik, Ewelina; Konieczny, Tomasz; Bobik, Bartłomiej

2018-01-01

One of the source of air pollutants is emission from local coal-fired boiler-houses and domestic heating boilers. The consequence of incineration of municipal waste is the introduction of additional pollutants into the atmosphere, including fly ash. The aim of this work was to evaluate the particle size distribution of fly ash emitted by coal combustion and co-incineration of coal with municipal waste in a domestic 18 kW central heating boiler equipped with an automatic fuel feeder. Mixtures of bituminous coal with different types of solid waste (5, 10 and 15% of mass fraction) were used. Solid waste types consisted of: printed, colored PE caps, fragmented cable trunking, fragmented car gaskets and shredded tires from trucks. During the incineration of a given mixture of municipal waste with bituminous coal, the velocity of exhaust gas was specified, the concentration and mass flow of fly ash were determined together with the physico-chemical parameters of the exhaust gas, the samples of emitted fly ash were taken as the test material. Particle size analysis of fly ash was performed using laser particle sizer Fritch Analysette 22. The PM10 share from all fly ashes from incineration of mixtures was about 100%. Differences were noted between PM2.5 and PM1.

Removal of trivalent chromium from aqueous solution by zeolite synthesized from coal fly ash.

PubMed

Wu, Deyi; Sui, Yanming; He, Shengbing; Wang, Xinze; Li, Chunjie; Kong, Hainan

2008-07-15

The capability of 14 zeolites synthesized from different fly ashes (ZFAs) to sequestrate Cr(III) from aqueous solutions was investigated in a batch mode. The influence of pH on the sorption of Cr(III) was examined. ZFAs had a much greater ability than fly ash to remove Cr(III), due to the high cation exchange capacity (CEC) and the high acid neutralizing capacity (ANC) of ZFAs. The mechanism of Cr(III) removal by ZFAs involved ion exchange and precipitation. A high-calcium content in both the fly ashes and ZFAs resulted in a high ANC value and, as a result, a high immobilization capacity for Cr(III). The pH strongly influenced Cr(III) removal by ZFAs. Inside the solubility range, removal of chromium increased with increasing pH. Hydroxysodalite made from a high-calcium fly ash had a higher sorptive capacity for Cr(III) than the NaP1 zeolite from medium- and low-calcium fly ashes. On the other hand, at pH values above the solubility range, the efficiency of chromium removal by the ZFAs approached 100% due to the precipitation of Cr(OH)3 on the sorbent surfaces. It is concluded that ZFAs and high-calcium fly ashes may be promising materials for the purification of Cr(III) from water/wastewater.

Analysis of metal Bioleaching from thermal power plant fly ash by Aspergillus niger 34770 culture supernatant and reduction of phytotoxicity during the process.

PubMed

Jadhav, Umesh U; Hocheng, Hong

2015-01-01

Aspergillus niger culture supernatant is used for bioleaching process. Before starting bioleaching process, fly ash was washed with distilled water. This removed 100 % sodium, 47 % (±0.45) boron, 38.07 % (±0.12) calcium, 29.89 % (±0.78) magnesium, and 11.8 % (±0.05) potassium. The pH was reduced from 10.5 to 8.5 after water washing. During bioleaching process, around 100 % metal removal was achieved in 4 h for all metals except chromium 93 % (±1.18), nickel 83 % (±0.32), arsenic 78 % (±0.52), and lead 70 % (±0.20). The process parameters including temperature, shaking speed, and solid/liquid ratio were optimized for bioleaching process. Experiments were conducted to evaluate effect of fly ash on growth of mung bean (Vigna radiata). At 20 g/100 ml fly ash concentration no germination of V. radiata seeds was observed. With an increasing concentration of untreated fly ash, a gradual decrease in root/shoot length was observed. After bioleaching process 78 % (±0.19) germination of V. radiata was observed with 20 g/100 ml fly ash. This study will help to develop an efficient process to remove the toxic metals from fly ash.

Thermal and hydrometallurgical recovery methods of heavy metals from municipal solid waste fly ash.

PubMed

Kuboňová, L; Langová, Š; Nowak, B; Winter, F

2013-11-01

Heavy metals in fly ash from municipal solid waste incinerators are present in high concentrations. Therefore fly ash must be treated as a hazardous material. On the other hand, it may be a potential source of heavy metals. Zinc, lead, cadmium, and copper can be relatively easily removed during the thermal treatment of fly ash, e.g. in the form of chlorides. In return, wet extraction methods could provide promising results for these elements including chromium and nickel. The aim of this study was to investigate and compare thermal and hydrometallurgical treatment of municipal solid waste fly ash. Thermal treatment of fly ash was performed in a rotary reactor at temperatures between 950 and 1050°C and in a muffle oven at temperatures from 500 to 1200°C. The removal more than 90% was reached by easy volatile heavy metals such as cadmium and lead and also by copper, however at higher temperature in the muffle oven. The alkaline (sodium hydroxide) and acid (sulphuric acid) leaching of the fly ash was carried out while the influence of temperature, time, concentration, and liquid/solid ratio were investigated. The combination of alkaline-acidic leaching enhanced the removal of, namely, zinc, chromium and nickel. Copyright © 2013 Elsevier Ltd. All rights reserved.

Design and fabrication of advanced materials from Illinois coal wastes. Quarterly report, 1 December 1994--28 February 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malhotra, V.M.; Wright, M.A.

1995-12-31

The main goal of this project is to develop a bench-scale procedure to design and fabricate advanced brake and structural composite materials from Illinois coal combustion residues. During the first two quarters of the project, the thrust of the work directed towards characterizing the various coal combustion residues and FGD residue, i.e., scrubber sludge. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), differential thermal analysis (DTA), and transmission-Fourier transform infrared (FTIR) were conducted on PCC fly ash (Baldwin), FBC fly ash (ADK unit l-6), FBC fly ash (S.I. coal), FBC spent bed ash (ADM, unit l-6), bottom ash, and scrubbermore » sludge (CWLP) residues to characterize their geometrical shapes, mineral phases, and thermal stability. Our spectroscopic results indicate that the scrubber sludge is mainly composed of a gypsum-like phase whose lattice structure is different from the lattice structure of conventional gypsum, and sludge does not contain hannebachite (CaSO{sub 3}.0.5H{sub 2}O) phase. Our attempts to fabricate brake frictional shoes, in the form of 1.25 inch disks, from PCC fly ash, FBC spent bed ash, scrubber sludge, coal char, iron particles, and coal tar were successful. Based on the experience gained and microscopic analyses, we have now upscaled our procedures to fabricate 2.5 inch diameter disk,- from coal combustion residues. This has been achieved. The SEM and Young`s modulus analyses of brake composites fabricated at 400 psi < Pressure < 2200 psi suggest pressure has a strong influence on the particle packing and the filling of interstices in our composites. Also, these results along with mechanical behavior of the fabricated disks lead us to believe that the combination of surface altered PCC fly ash and scrubber sludge particles, together ed ash particles are ideal for our composite materials.« less

Effects of chemical composition of fly ash on efficiency of metal separation in ash-melting of municipal solid waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Tomikawa, Hiroki

2013-03-15

Highlights: ► Separation of Pb and Zn from Fe and Cu in ash-melting of municipal solid waste. ► Molar ratio of Cl to Na and K in fly ash affected the metal-separation efficiency. ► The low molar ratio and a non-oxidative atmosphere were better for the separation. - Abstract: In the process of metal separation by ash-melting, Fe and Cu in the incineration residue remain in the melting furnace as molten metal, whereas Pb and Zn in the residue are volatilized. This study investigated the effects of the chemical composition of incineration fly ash on the metal-separation efficiency of themore » ash-melting process. Incineration fly ash with different chemical compositions was melted with bottom ash in a lab-scale reactor, and the efficiency with which Pb and Zn were volatilized preventing the volatilization of Fe and Cu was evaluated. In addition, the behavior of these metals was simulated by thermodynamic equilibrium calculations. Depending on the exhaust gas treatment system used in the incinerator, the relationships among Na, K, and Cl concentrations in the incineration fly ash differed, which affected the efficiency of the metal separation. The amounts of Fe and Cu volatilized decreased by the decrease in the molar ratio of Cl to Na and K in the ash, promoting metal separation. The thermodynamic simulation predicted that the chlorination volatilization of Fe and Cu was prevented by the decrease in the molar ratio, as mentioned before. By melting incineration fly ash with the low molar ratio in a non-oxidative atmosphere, most of the Pb and Zn in the ash were volatilized leaving behind Fe and Cu.« less

Coal fly ash based carbons for SO2 removal from flue gases.

PubMed

Rubio, B; Izquierdo, M T

2010-07-01

Two different coal fly ashes coming from the burning of two coals of different rank have been used as a precursor for the preparation of steam activated carbons. The performance of these activated carbons in the SO(2) removal was evaluated at flue gas conditions (100 degrees C, 1000 ppmv SO(2), 5% O(2), 6% H(2)O). Different techniques were used to determine the physical and chemical characteristics of the samples in order to explain the differences found in their behaviour. A superior SO(2) removal capacity was shown by the activated carbon obtained using the fly ash coming from a sub-bituminous-lignite blend. Experimental results indicated that the presence of higher amount of certain metallic oxides (Ca, Fe) in the carbon-rich fraction of this fly ash probably has promoted a deeper gasification in the activation with steam. A more suitable surface chemistry and textural properties have been obtained in this case which explains the higher efficiency shown by this sample in the SO(2) removal. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Very high volume fly ash green concrete for applications in India.

PubMed

Yu, Jing; Mishra, Dhanada K; Wu, Chang; Leung, Christopher Ky

2018-06-01

Safe disposal of fly ash generated by coal-based thermal power plants continues to pose significant challenges around the world and in India in particular. Green structural concrete with 80% cement replaced by local Chinese fly ash has been recently developed to achieve a target characteristic compressive strength of 45 MPa. Such green concrete mixes are not only cheaper in cost, but also embody lower energy and carbon footprint, compared with conventional mixes. This study aims to adopt such materials using no less than 80% fly ash as binder in routine concrete works in countries like India with the commonly used lower target characteristic compressive strength of 30 MPa. It is achieved by the simple and practical method of adjusting the water/binder ratio and/or superplasticiser dosage. The proposed green concrete shows encouraging mechanical properties at 7 days and 28 days, as well as much lower material cost and environmental impact compared with commercial Grade 30 concrete. This technology can play an important role in meeting the huge infrastructure demands in India in a sustainable manner.

Assessment of copper and zinc recovery from MSWI fly ash in Guangzhou based on a hydrometallurgical process.

PubMed

Tang, Jinfeng; Su, Minhua; Zhang, Hongguo; Xiao, Tangfu; Liu, Yu; Liu, Yifan; Wei, Lezhang; Ekberg, Christian; Steenari, Britt-Marie

2018-06-01

Fly ash commonly accumulates a significant amount of heavy metals and most of these heavy metals are toxic and easily leached out to the environment, posing risks to human health. Thus, fly ash has been classified as a type of hazardous waste and requires proper treatment before disposal in specific landfill sites for hazardous waste. In this study, a hydrometallurgical process developed to recover copper and zinc performed in pilot scale close to industrial scale followed by a landfill compliance leaching test of the ash residue is evaluated. LIX860N-I and Cyanex 572 gave high selectively for extractions, a yield efficiency of 95% and 61% was achieved for copper and zinc respectively. Results of pilot experiments reveals that the combining metal recovery/recycling and landfill disposal of the ash residue in a local regular landfill was demonstrated to be a technically and economically effective strategy. Specifically, the economic and environmental aspects of a scenario, in which the fly ash generated in Guangzhou is processed were systematically assessed. the assessment results show that a 7.15 million US$ of total expense reduction, a less energy cost of 19k GJ as well as 2100 tons less CO 2 emissions could be achieved annually comparing to the current alternative, direct disposal of the fly ash as hazardous waste. The results reveal that the hydrometallurgical process has industrial application potential on both economic and environmental aspects and further optimization of the process can give more accurate assessment of the cost and environment effect. In addition, leaching tests and evaluation of solid residue according to the regulations specific to the country should be studied in future. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cellular Mutagenicity and Heavy Metal Concentrations of Leachates Extracted from the Fly and Bottom Ash Derived from Municipal Solid Waste Incineration

PubMed Central

Chen, Po-Wen; Liu, Zhen-Shu; Wun, Min-Jie; Kuo, Tai-Chen

2016-01-01

Two incinerators in Taiwan have recently attempted to reuse the fly and bottom ash that they produce, but the mutagenicity of these types of ash has not yet been assessed. Therefore, we evaluated the mutagenicity of the ash with the Ames mutagenicity assay using the TA98, TA100, and TA1535 bacterial strains. We obtained three leachates from three leachants of varying pH values using the toxicity characteristic leaching procedure test recommended by the Taiwan Environmental Protection Agency (Taiwan EPA). We then performed the Ames assay on the harvested leachates. To evaluate the possible relationship between the presence of heavy metals and mutagenicity, the concentrations of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in the leachates were also determined. The concentrations of Cd and Cr in the most acidic leachate from the precipitator fly ash and the Cd concentration in the most acidic leachate from the boiler fly ash exceeded the recommended limits. Notably, none of the nine leachates extracted from the boiler, precipitator, or bottom ashes displayed mutagenic activity. This data partially affirms the safety of the fly and bottom ash produced by certain incinerators. Therefore, the biotoxicity of leachates from recycled ash should be routinely monitored before reusing the ash. PMID:27827867

Properties and Leachability of Self-Compacting Concrete Incorporated with Fly Ash and Bottom Ash

NASA Astrophysics Data System (ADS)

Kadir, Aeslina Abdul; Ikhmal Haqeem Hassan, Mohd; Jamaluddin, Norwati; Bakri Abdullah, Mohd Mustafa Al

2016-06-01

The process of combustion in coal-fired power plant generates ashes, namely fly ash and bottom ash. Besides, coal ash produced from coal combustion contains heavy metals within their compositions. These metals are toxic to the environment as well as to human health. Fortunately, treatment methods are available for these ashes, and the use of fly ash and bottom ash in the concrete mix is one of the few. Therefore, an experimental program was carried out to study the properties and determine the leachability of selfcompacting concrete incorporated with fly ash and bottom ash. For experimental study, self-compacting concrete was produced with fly ash as a replacement for Ordinary Portland Cement and bottom ash as a replacement for sand with the ratios of 10%, 20%, and 30% respectively. The fresh properties tests conducted were slump flow, t500, sieve segregation and J-ring. Meanwhile for the hardened properties, density, compressive strength and water absorption test were performed. The samples were then crushed to be extracted using Toxicity Characteristic Leaching Procedure and heavy metals content within the samples were identified accordingly using Atomic Absorption Spectrometry. The results demonstrated that both fresh and hardened properties were qualified to categorize as self-compacting concrete. Improvements in compressive strength were observed, and densities for all the samples were identified as a normal weight concrete with ranges between 2000 kg/m3 to 2600 kg/m3. Other than that, it was found that incorporation up to 30% of the ashes was safe as the leached heavy metals concentration did not exceed the regulatory levels, except for arsenic. In conclusion, this study will serve as a reference which suggests that fly ash and bottom ash are widely applicable in concrete technology, and its incorporation in self-compacting concrete constitutes a potential means of adding value to appropriate mix and design.

Hierarchical zeolites from class F coal fly ash

NASA Astrophysics Data System (ADS)

Chitta, Pallavi

Fly ash, a coal combustion byproduct is classified as types class C and class F. Class C fly ash is traditionally recycled for concrete applications and Class F fly ash often disposed in landfills. Class F poses an environmental hazard due to disposal and leaching of heavy metals into ground water and is important to be recycled in order to mitigate the environmental challenges. A major recycling option is to reuse the fly ash as a low-cost raw material for the production of crystalline zeolites, which serve as catalysts, detergents and adsorbents in the chemical industry. Most of the prior literature of fly ash conversion to zeolites does not focus on creating high zeolite surface area zeolites specifically with hierarchical pore structure, which are very important properties in developing a heterogeneous catalyst for catalysis applications. This research work aids in the development of an economical process for the synthesis of high surface area hierarchical zeolites from class F coal fly ash. In this work, synthesis of zeolites from fly ash using classic hydrothermal treatment approach and fusion pretreatment approach were examined. The fusion pretreatment method led to higher extent of dissolution of silica from quartz and mullite phases, which in turn led to higher surface area and pore size of the zeolite. A qualitative kinetic model developed here attributes the difference in silica content to Si/Al ratio of the beginning fraction of fly ash. At near ambient crystallization temperatures and longer crystallization times, the zeolite formed is a hierarchical faujasite with high surface area of at least 360 m2/g. This work enables the large scale recycling of class F coal fly ash to produce zeolites and mitigate environmental concerns. Design of experiments was used to predict surface area and pore sizes of zeolites - thus obviating the need for intense experimentation. The hierarchical zeolite catalyst supports tested for CO2 conversion, yielded hydrocarbons up to C9, a performance attesting the hierarchal pore structure. The preliminary techno-economic feasibility assessment demonstrates a net energy saving of 75% and cost saving of 63% compared to the commercial zeolite manufacturing process.

Impedance Spectroscopy Study of the Effect of Environmental Conditions on the Microstructure Development of Sustainable Fly Ash Cement Mortars.

PubMed

Ortega, José Marcos; Sánchez, Isidro; Climent, Miguel Ángel

2017-09-25

Today, the characterisation of the microstructure of cement-based materials using non-destructive techniques has become an important topic of study, and among them, the impedance spectroscopy has recently experienced great progress. In this research, mortars with two different contents of fly ash were exposed to four different constant temperature and relative humidity environments during a 180-day period. The evolution of their microstructure was studied using impedance spectroscopy, whose results were contrasted with mercury intrusion porosimetry. The hardening environment has an influence on the microstructure of fly ash cement mortars. On one hand, the impedance resistances R₁ and R₂ are more influenced by the drying of the materials than by microstructure development, so they are not suitable for following the evolution of the porous network under non-optimum conditions. On the other hand, the impedance spectroscopy capacitances C₁ and C₂ allow studying the microstructure development of fly ash cement mortars exposed to those conditions, and their results are in accordance with mercury intrusion porosimetry ones. Finally, it has been observed that the combined analysis of the abovementioned capacitances could be very useful for studying shrinkage processes in cement-based materials kept in low relative humidity environments.

Evaluation of genotoxicity of coal fly ash in Allium cepa root cells by combining comet assay with the Allium test.

PubMed

Chakraborty, Rajarshi; Mukherjee, Ashit Kumar; Mukherjee, Anita

2009-06-01

Fly ash is a by-product of coal-fired electricity generation plants. Its utilization and disposal is of utmost importance. Using onion (Allium cepa) root tip system, the present study was carried out to evaluate the potential toxic and genotoxic effects of fly ash, collected from a thermal power plant in West Bengal, India. Prior to testing, the collected fly ash sample was mixed with sand in different proportions. Allium bulbs were allowed to germinate directly in fly ash and after five days the germinating roots were processed for the Allium test. Additionally, the Allium test was adapted for detecting DNA damage through comet assay. The results from the Allium test indicate that fly ash at 100% concentration inhibits root growth and mitotic indices; induces binucleated cells as a function of the proportion, but is not toxic at very low concentration. In the comet assay, a statistical increase for DNA strand breaks was found only at higher concentrations. The sample was analyzed by flame atomic absorption spectrometer for Zn, Pb, Cu, Ni, Cd and As, whose presence could partly be responsible for the toxicity of fly ash. The study concludes that the classical Allium test can give a more comprehensive data when done in combination with the comet assay, which is faster, simpler and independent of mitosis. Also when fly ash is used for other purposes in combination with soils, it should be judiciously used at very low concentrations in order to protect the ecosystem health from any potential adverse effects.

Mode of occurrence of arsenic in feed coal and its derivative fly ash, Black Warrior Basin, Alabama

USGS Publications Warehouse

Zielinski, R.A.; Foster, A.L.; Meeker, G.P.; Brownfield, I.K.

2007-01-01

An arsenic-rich (As = 55 ppm) bituminous feed coal from the Black Warrior Basin, Alabama and its derivative fly ash (As = 230 ppm) were selected for detailed investigation of arsenic residence and chemical forms. Analytical techniques included microbeam analysis, selective extraction, and As K-edge X-ray absorption fine-structure (XAFS) spectroscopy. Most As in the coal is contained in a generation of As-bearing pyrite (FeS2) that formed in response to epigenetic introduction of hydrothermal fluids. XAFS results indicate that approximately 50% of the As in the coal sample occurs as the oxidized As(V) species, possibly the result of incipient oxidation of coal and pyrite prior to our analysis. Combustion of pyrite and host coal produced fly ash in which 95% of As is present as As(V). Selective extraction of the fly ash with a carbonate buffer solution (pH = 10) removed 49% of the As. A different extraction with an HCl-NH2OH mixture, which targets amorphous and poorly crystalline iron oxides, dissolved 79% of the As. XAFS spectroscopy of this highly acidic (pH = 3.0) fly ash indicated that As is associated with some combination of iron oxide, oxyhydroxide, or sulfate. In contrast, a highly alkaline (pH = 12.7) fly ash from Turkey shows most As associated with a phase similar to calcium orthoarsenate (Ca3(AsO4)2). The combined XAFS results indicate that fly ash acidity, which is determined by coal composition and combustion conditions, may serve to predict arsenic speciation in fly ash.

Geotechnical applications of CCPs in Wisconsin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edil, T.C.; Benson, C.H.

2006-07-01

The article reports research case histories on applications of coal combustion products (CCPs) in Wisconsin developed by the University of Wisconsin Consortium for Fly Ash Use in Geotechnical Applications (FAUGA). Fly ash was used to stabilize poor soils during construction of Wisconsin State Highway (STH) 60, and bottom ash was used as a granular working platform. Long term performance is proving good. Nearly all Class C fly ash in Wisconsin is now used in construction. Leaching characteristics of pavements incorporating fly ash are being monitored by pan lysimeters underneath. A computer model, WiscLEACH has been developed to predict the maximummore » concentration of chemicals in ground water adjacent to roadways using CCPs. 1 photo.« less

ULTRAFINE ASH AEROSOLS FROM COAL COMBUSTION: CHARACTERIZATION AND HEALTH EFFECTS

EPA Science Inventory

Ultrafine coal fly ash particles, defined here as those with diameters less than 0.5 micrometer, typically comprise less than 1% of the total fly ash mass. These particles are formed almost exclusively through ash vaporization, nucleation, and coagulation/condensation mechanisms,...

Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature.

PubMed

Saqib, Naeem; Bäckström, Mattias

2014-12-01

Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of fly ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature. Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature. Copyright © 2014 Elsevier Ltd. All rights reserved.

SPECIATION OF MERCURY IN THE PRESENCE OF COAL AND WASTE COMBUSTION FLY ASHES

EPA Science Inventory

The paper gives results of a study that focused on the oxidation of elemental mercury (Hgo) in the presence of both complex, four-component, model fly ashes, and actual coal combustion fly ashes collected from a pilot plant. Steady-state oxidation of Hgo promoted by the four-com...

Beneficial use of off-specification fly ashes to increase the shear strength and stiffness of expansive soil-rubber (ESR) mixtures.

DOT National Transportation Integrated Search

2011-07-01

The use of off-specification fly ashes to increase the shear strength and stiffness of an expansive soil-rubber (ESR) mixture is investigated systematically in this study. The off-specification fly ashes used include a high-sulfur content and a high-...

Design and evaluation of high-volume fly ash (HVFA) concrete mixes, report E : hardened mechanical properties and durability performance of HVFA concrete.

DOT National Transportation Integrated Search

2012-10-01

A rising concern in todays construction industry is environmental responsibility. : The addition of fly ash is a leading innovation in sustainable design of concrete. Fly ash, : a waste by-product of coal burning power plants, can be used to repla...

An Experimental Study of High Strength-High Volume Fly Ash Concrete for Sustainable Construction Industry

NASA Astrophysics Data System (ADS)

Kate, Gunavant K.; Thakare, Sunil B., Dr.

2017-08-01

Concrete is the most widely used building material in the construction of infrastructures such as buildings, bridges, highways, dams, and many other facilities. This paper reports the development, the basic idea, the main properties of high strength-high volume fly ash with application in concrete associated with the development and implementation of Sustainable Properties of High Volume Fly Ash Concrete (HVFAC) Mixtures and Early Age Shrinkage and mechanical properties of concrete for 7,28,56 and 90days. Another alternative to make environment-friendly concrete is the development of high strength-high-volume fly ash concrete which is an synthesized from materials of geological origin or by-product materials such as fly ash which is rich in silicon and aluminum. In this paper 6 concrete mixtures were produced to evaluate the effect of key parameters on the mechanical properties of concrete and its behavior. The study key parameters are; binder material content, cement replacement ratios, and the steel fibers used to High Volume Fly Ash mixtures for increasing performance of concrete.

[MSW incineration fly ash melting by DSC-DTA].

PubMed

Li, Rundong; Chi, Yong; Li, Shuiqing; Wang, Lei; Yan, Jianhua; Cen, Kefa

2002-07-01

Melting characteristics of two kinds of municipal solid waste incineration(MSWI) fly ash were studied in this paper by high temperature differential scanning calorimetry and differential temperature analysis. MSWI fly ash was considered as hazardous waste because it contains heavy metals and dioxins. The experiments were performed in either N2 or O2 atmosphere in temperature range of 20 degrees C-1450 degrees C at various heating rates. Two different MSW incineration fly ashes used in the experiments were collected from our country and France respectively. The process of fly ash melting exhibits two reactions occurring at temperature ranges of about 480 degrees C-670 degrees C and 1136 degrees C-1231 degrees C, respectively. The latent heat of polymorphic transformation and fusion were approximately 20 kJ/kg and 700 kJ/kg, while the total heat required for melting process was about 1800 kJ/kg. The paper also studied effect of CaO to melting. A heat flux thermodynamic model for fly ash melting was put forward and it agrees well with experimental data.

Evaluating the Effects of the Kingston Fly Ash Release on Fish Reproduction: Spring 2009 - 2010 Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greeley Jr, Mark Stephen; Adams, Marshall; McCracken, Kitty

2012-05-01

On December 22, 2008, a dike containing fly ash and bottom ash at the Tennessee Valley Authority's (TVA) Kingston Fossil Plant in East Tennessee failed and released a large quantity of ash into the adjacent Emory River. Ash deposits from the spill extended 4 miles upstream of the facility to Emory River mile 6 and downstream to Tennessee River mile 564 ({approx}8.5 miles downstream of the confluence of the Emory River with the Clinch River, and {approx}4 miles downstream of the confluence of the Clinch River with the Tennessee River). A byproduct of coal combustion, fly ash contains a varietymore » of metals and other elements which, at sufficient concentrations and in specific forms, can be harmful to biological systems. The ecological effects of fly ash contamination on exposed fish populations depend on the magnitude and duration of exposure, with the most significant risk considered to come from elevated levels of certain metals in the ash, particularly selenium, on fish reproduction and fish early life stages (Lemly 1993; Besser and others 1996). The ovaries of adult female fish in a lake contaminated by coal ash were reported to have an increased frequency of atretic oocytes (dead or damaged immature eggs) and reductions in the overall numbers of developing oocytes (Sorensen 1988) associated with elevated body burdens of selenium. Larval fish exposed to selenium through maternal transfer of contaminants to developing eggs in either contaminated bodies of water (Lemly 1999) or in experimental laboratory exposures (Woock and others 1987, Jezierska and others 2009) have significantly increased incidences of developmental abnormalities. Contact of fertilized eggs and developing embryos to ash in water and sediments may also pose an additional risk to the early life stages of exposed fish populations through direct uptake of metals and other ash constituents (Jezierska and others 2009). The establishment and maintenance of fish populations is intimately associated with the ability of individuals within a population to reproduce. Reproduction is thus generally considered to be the most critical life function affected by environmental contamination. From a regulatory perspective, the issue of potential contaminant-related effects on fish reproduction from the Kingston fly ash spill has particular significance because the growth and propagation of fish and other aquatic life is a specific classified use of the affected river systems. To address the potential effects of fly ash from the Kingston spill on the reproductive health of exposed fish populations, ORNL has undertaken a series of studies in collaboration with TVA that include: (1) a combined field study of metal bioaccumulation in ovaries and other fish tissues (Adams and others 2012) and the reproductive condition of sentinel fish species in reaches of the Emory and Clinch Rivers affected by the fly ash spill (the current report); (2) laboratory tests of the potential toxicity of fly ash from the spill area on fish embryonic and larval development (Greeley and others 2012); (3) additional laboratory experimentation focused on the potential effects of long-term exposures to fly ash on fish survival and reproductive competence (unpublished); and (4) a combined field and laboratory study examining the in vitro developmental success of embryos and larvae obtained from fish exposed in vivo for over two years to fly ash in the Emory and Clinch Rivers (unpublished). The current report focuses on the reproductive condition of adult female fish in reaches of the Emory and Clinch Rivers influenced by the fly ash spill at the beginning of the spring 2009 breeding season - the first breeding season immediately following the fly ash release - and during the subsequent spring 2010 breeding season. Data generated from this and related reproductive/early life stage studies provide direct input to ecological risk assessment efforts and complement and support other phases of the overall biomonitoring program associated with the fly ash spill.« less

Compressive strength of concrete and mortar containing fly ash

DOEpatents

Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

1997-04-29

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specifications required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs. 33 figs.

Compressive strength of concrete and mortar containing fly ash

DOEpatents

Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

1998-12-29

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specification required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs. 33 figs.

Compressive strength of concrete and mortar containing fly ash

DOEpatents

Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

1997-01-01

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specifications required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs.

Compressive strength of concrete and mortar containing fly ash

DOEpatents

Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

1998-01-01

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specification required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs.

SHS synthesis of Si-SiC composite powders using Mg and reactants from industrial waste

NASA Astrophysics Data System (ADS)

Chanadee, Tawat

2017-11-01

Si-SiC composite powders were synthesized by self-propagating high-temperature synthesis (SHS) using reactants of fly ash-based silica, sawdust-based activated carbon, and magnesium. Fly ash-based silica and sawdust-based activated carbon were prepared from coal mining fly ash and Para rubber-wood sawdust, respectively. The work investigated the effects of the synthesis atmosphere (air and Ar) on the phase and morphology of the SHS products. The SHS product was leached by a two-step acid leaching processes, to obtain the Si-SiC composite powder. The SHS product and SHS product after leaching were characterized by X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The results indicated that the SHS product synthesized in air consisted of Si, SiC, MgO, and intermediate phases (SiO2, Mg, Mg2SiO4, Mg2Si), whereas the SHS product synthesized in Ar consisted of Si, SiC, MgO and a little Mg2SiO4. The SiC content in the leached-SHS product was higher when Ar was used as the synthesis atmosphere. As well as affecting the purity, the synthesis atmospheres also affected the average crystalline sizes of the products. The crystalline size of the product synthesized in Ar was smaller than that of the product synthesized in air. All of the results showed that fly ash and sawdust could be effective waste-material reactants for the synthesis of Si-SiC composite powders.

Leaching characteristics of arsenic and selenium from coal fly ash: role of calcium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian Wang; Jianmin Wang; Yulin Tang

2009-05-15

Understanding the leaching behavior of arsenic (As) and selenium (Se) in coal fly ash is important in evaluating the potential environmental impact of coal fly ash. Batch experiments were employed to systematically investigate the leaching behavior of As and Se in two major types of coal fly ashes, bituminous coal ash and sub-bituminous coal ash, and to determine the underlying processes that control As and Se leaching. The effects of pH, solid/liquid (S/L) ratio, calcium addition, and leaching time on the release of As and Se were studied. Overall, bituminous coal ash leached significantly more As and Se than sub-bituminousmore » coal ash, and Se was more readily leachable, in both absolute concentration and relative fraction, than As for both types of fly ashes. Adsorption/desorption played a major role on As and Se leaching from bituminous coal ashes. However, calcium precipitation played the most important role in reducing As and Se leaching from sub-bituminous coal ashes in the entire experimental pH range. The leaching of As and Se from bituminous coal ashes generally increased with increases in the S/L ratio and leaching time. However, for sub-bituminous coal ashes, the leaching of As was not detected under most experimental conditions, while the leaching of Se increased with increases in the S/L ratio and leaching time. As{sup V} and Se{sup IV} were found to be the major species in all ash leachates in this study. 46 refs., 7 figs., 1 tab.« less

Trace element partitioning in ashes from boilers firing pure wood or mixtures of solid waste with respect to fuel composition, chlorine content and temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saqib, Naeem, E-mail: naeem.saqib@oru.se; Bäckström, Mattias, E-mail: mattias.backstrom@oru.se

Highlights: • Different solids waste incineration is discussed in grate fired and fluidized bed boilers. • We explained waste composition, temperature and chlorine effects on metal partitioning. • Excessive chlorine content can change oxide to chloride equilibrium partitioning the trace elements in fly ash. • Volatility increases with temperature due to increase in vapor pressure of metals and compounds. • In Fluidized bed boiler, most metals find themselves in fly ash, especially for wood incineration. - Abstract: Trace element partitioning in solid waste (household waste, industrial waste, waste wood chips and waste mixtures) incineration residues was investigated. Samples of flymore » ash and bottom ash were collected from six incineration facilities across Sweden including two grate fired and four fluidized bed incinerators, to have a variation in the input fuel composition (from pure biofuel to mixture of waste) and different temperature boiler conditions. As trace element concentrations in the input waste at the same facilities have already been analyzed, the present study focuses on the concentration of trace elements in the waste fuel, their distribution in the incineration residues with respect to chlorine content of waste and combustion temperature. Results indicate that Zn, Cu and Pb are dominating trace elements in the waste fuel. Highly volatile elements mercury and cadmium are mainly found in fly ash in all cases; 2/3 of lead also end up in fly ash while Zn, As and Sb show a large variation in distribution with most of them residing in the fly ash. Lithophilic elements such as copper and chromium are mainly found in bottom ash from grate fired facilities while partition mostly into fly ash from fluidized bed incinerators, especially for plants fuelled by waste wood or ordinary wood chips. There is no specific correlation between input concentration of an element in the waste fuel and fraction partitioned to fly ash. Temperature and chlorine content have significant effects on partitioning characteristics by increasing the formation and vaporization of highly volatile metal chlorides. Zinc and cadmium concentrations in fly ash increase with the incineration temperature.« less

Trace elements in coal ash

USGS Publications Warehouse

Deonarine, Amrika; Kolker, Allan; Doughten, Michael W.

2015-01-01

In this fact sheet, the form, distribution, and behavior of trace elements of environmental interest in samples of coal fly ash were investigated in response to concerns about element mobility in the event of an ash spill. The study includes laboratory-based leaching experiments to examine the behavior of trace elements, such as arsenic (As) and chromium (Cr), in response to key environmental factors including redox conditions (degree of oxygenation), which are known to vary with depth within coal ash impoundments and in natural ecosystems. The experiments show that As dissolves from samples of coal fly ash into simulated freshwater under both oxic (highly oxygenated) and anoxic (poorly oxygenated) conditions, whereas dissolved Cr concentrations are very redox dependent. This U.S. Geological Survey research helps define the distribution of elements such as As in coal ash and shows that element mobility can vary considerably under different conditions expected in the environment.

Recovery of iron oxide from coal fly ash

DOEpatents

Dobbins, Michael S.; Murtha, Marlyn J.

1983-05-31

A high quality iron oxide concentrate, suitable as a feed for blast and electric reduction furnaces is recovered from pulverized coal fly ash. The magnetic portion of the fly ash is separated and treated with a hot strong alkali solution which dissolves most of the silica and alumina in the fly ash, leaving a solid residue and forming a precipitate which is an acid soluble salt of aluminosilicate hydrate. The residue and precipitate are then treated with a strong mineral acid to dissolve the precipitate leaving a solid residue containing at least 90 weight percent iron oxide.

Fly ash particles spheroidization using low temperature plasma energy

NASA Astrophysics Data System (ADS)

Shekhovtsov, V. V.; Volokitin, O. G.; Kondratyuk, A. A.; Vitske, R. E.

2016-11-01

The paper presents the investigations on producing spherical particles 65-110 μm in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition of fly ash particles to a state of viscous flow occurs at 20 mm distance from the plasma jet. The X-ray phase analysis is carried out for the both original state of fly ash powders and the particles obtained. This analysis shows that fly ash contains 56.23 wt.% SiO2; 20.61 wt.% Al2O3 and 17.55 wt.% Fe2O3 phases that mostly contribute to the integral (experimental) intensity of the diffraction maximum. The LTP treatment results in a complex redistribution of the amorphous phase amount in the obtained spherical particles, including the reduction of O2Si, phase, increase of O22Al20 and Fe2O3 phases and change in Al, O density of O22Al20 chemical unit cell.

Leaching kinetics of As, Mo, and Se from acidic coal fly ash samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neupane, Ghanashyam; Donahoe, Rona J.; Bhattacharyya, Siddhartha

Annually, coal-fired electric power plants produce large volumes potentially hazardous coal combustion products (CCPs) including fly ash. Since majority of the coal fly ash and other CCPs deposited in dry land fills or wet lagoons, they pose risk of contamination to local environment and hydrogeology. In this study, we present results of leaching kinetics for As, Mo, and Se from three acidic fly ash samples. This study shows that the leachate concentrations of As, Mo, and Se increase over time. Three kinetics equations, pseudo-second order, Elovich, and power-function, are able to adequately describe the experimental leaching kinetics data. Experimental leachingmore » data and modeling results indicate that the rate limiting leaching of As, Mo, and Se is largely controlled by the dissolution of the fly ash particles. Furthermore, it is important to adopt effective containment/treatment schemes to avoid potential and persistent dispersion of trace elements from ash disposal facilities to surrounding environment for a long time.« less

Leaching kinetics of As, Mo, and Se from acidic coal fly ash samples

DOE PAGES

Neupane, Ghanashyam; Donahoe, Rona J.; Bhattacharyya, Siddhartha; ...

2017-07-03

Annually, coal-fired electric power plants produce large volumes potentially hazardous coal combustion products (CCPs) including fly ash. Since majority of the coal fly ash and other CCPs deposited in dry land fills or wet lagoons, they pose risk of contamination to local environment and hydrogeology. In this study, we present results of leaching kinetics for As, Mo, and Se from three acidic fly ash samples. This study shows that the leachate concentrations of As, Mo, and Se increase over time. Three kinetics equations, pseudo-second order, Elovich, and power-function, are able to adequately describe the experimental leaching kinetics data. Experimental leachingmore » data and modeling results indicate that the rate limiting leaching of As, Mo, and Se is largely controlled by the dissolution of the fly ash particles. Furthermore, it is important to adopt effective containment/treatment schemes to avoid potential and persistent dispersion of trace elements from ash disposal facilities to surrounding environment for a long time.« less

Assessment of contamination by percolation of septic tank effluent through natural and amended soils.

PubMed

Cheung, K C; Venkitachalam, T H

2004-01-01

Fly ash has been found to be a potential material for the treatment of municipal and industrial wastewater, and may be useful in the treatment of septic tank effluent. Laboratory columns (30 cm) were used to determine the sorption capacity and hydraulic properties of lagoon fly ash, loamy sand, sand, and sand amended by lagoon fly ash (30 and 60%) and red mud gypsum (20%). The removal of chemical oxygen demand (COD) was high in all column effluents (71-93%). Extent of nitrification was high in Spearwood sand, Merribrook loamy sand and 20% red mud gypsum amended Spearwood sand. However, actual removal of nitrogen (N) was high in columns containing lagoon fly ash. Unamended Spearwood sand possessed only minimal capacity for P sorption. Merribrook loamy sand and red mud gypsum amended sand affected complete P removal throughout the study period of 12 weeks. Significant P leakage occurred from lagoon fly ash amended sand columns following 6-10 weeks of operation. Neither lagoon fly ash nor red mud gypsum caused any studied heavy metal contamination including manganese (Mn), lead (Pb), zinc (Zn), cadmium (Cd) and chromium (Cr) of effluent. It can be concluded that Merribrook loamy sand is better natural soil than Spearwood sand as a filter medium. The addition of lagoon fly ash enhanced the removal of P in Spearwood sand but the efficiency was lower than with red mud gypsum amendment.

Flue gas desulfurization gypsum and fly ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-05-01

The Cumberland Fossil Plant (CUF) is located in Stewart County, Tennessee, and began commercial operation in 1972. This is the Tennessee Valley Authority`s newest fossil (coal-burning) steam electric generating plant. Under current operating conditions, the plant burns approximately seven million tons of coal annually. By-products from the combustion of coal are fly ash, approximately 428,000 tons annually, and bottom ash, approximately 115,000 tons annually. Based on historical load and projected ash production rates, a study was initially undertaken to identify feasible alternatives for marketing, utilization and disposal of ash by-products. The preferred alternative to ensure that facilities are planned formore » all by-products which will potentially be generated at CUF is to plan facilities to handle wet FGD gypsum and dry fly ash. A number of different sites were evaluated for their suitability for development as FGD gypsum and ash storage facilities. LAW Engineering was contracted to conduct onsite explorations of sites to develop information on the general mature of subsurface soil, rock and groundwater conditions in the site areas. Surveys were also conducted on each site to assess the presence of endangered and threatened species, wetlands and floodplains, archaeological and cultural resources, prime farmland and other site characteristics which must be considered from an environmental perspective.« less

Kinetics of fly ash beneficiation by carbon burnout: Quarterly report, October 1-December 31, 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

To investigate the kinetics of beneficiation of fly ash by carbon burnout The project is a joint venture between Delmarva Power, a power generating company on the eastern shore of Maryland, and the University of Maryland Eastern Shore. The studies have focused on the beneficiation of fly ash by carbon burnout.

Analysis of the fly ash from the processing of wood chips in a pilot-scale downdraft gasifier: Comparison of inorganic constituents determined by PIXE and ICP-AES

Treesearch

Thomas L Eberhardt; Hui Pan

2013-01-01

Gasification of biomass ultimately generates at least one solid byproduct in which the inorganic constituents of the biomass are concentrated. Given the potential for utilization, or issues with disposal, facile methods are needed for determining the compositions of the fly ashes from recently-available gasifier-based bioenergy systems. Proton induced x-ray emission...

Leaching of Mixtures of Biochar and Fly Ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palumbo, Anthony Vito; Porat, Iris; Phillips, Jana Randolph

2009-01-01

Increasing atmospheric levels of greenhouse gases, especially CO2, and their effects on global temperature have led to interest in the possibility of carbon storage in terrestrial environments.2, 5, 6 Both the residual char from biomass pyrolysis7-9, 12 (biochar) and fly ash from coal combustion1, 13, 14 have the potential to significantly expand terrestrial sequestration options. Both biochar and fly ash also have potentially beneficial effects on soil properties. Fly ash has been shown to increase porosity, water-holding capacity, pH, conductivity, and dissolved SO42-, CO32-, Cl- and basic cations.10, 11, 16 Adding biochar to soil generally raises pH, increases total nitrogenmore » and total phosphorous, encourages greater root development, improves cation exchange capacity and reduces available aluminum.3, 17 Combinations of these benefits likely lead to the observed increased yields for crops including corn and sugarcane.17 with biochar addition to soil. In addition, it has been found that soils with added biochar emit lower amounts of other greenhouse gases (methane and nitrous oxide) 8, 17 than do unammended soils. Biochar and fly ash amendments may be useful in promoting terrestrial carbon sequestration on currently underutilized and degraded lands. For example, about 1% of the US surface lands consist of previously mined lands or highway rights-of-way.18 Poorly managed lands could count for another 15% of US area. Biochar and fly ash amendments could increase productivity of these lands and increase carbon storage in the soil Previous results showed minimal leaching of organic carbon and metals from a variety of fly ashes.15 Here, we are examining the properties of mixtures of biochar, fly ash, and soil and evaluating leaching of organic carbon and metals from the mixtures.« less

Thermal and hydrometallurgical recovery methods of heavy metals from municipal solid waste fly ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuboňová, L., E-mail: lenka.kubonova@vsb.cz; Langová, Š.; Nowak, B.

2013-11-15

Highlights: • MSW fly ash was thermally and hydrometallurgically treated to remove heavy metals. • More than 90% of easy volatile heavy metals (Cd and Pb) were removed thermally. • More than 90% of Cd, Cr, Cu an Zn were removed by alkaline – acid leaching. • The best results were obtained for the solution of 3 M NaOH and 2 M H{sub 2}SO{sub 4}. - Abstract: Heavy metals in fly ash from municipal solid waste incinerators are present in high concentrations. Therefore fly ash must be treated as a hazardous material. On the other hand, it may be amore » potential source of heavy metals. Zinc, lead, cadmium, and copper can be relatively easily removed during the thermal treatment of fly ash, e.g. in the form of chlorides. In return, wet extraction methods could provide promising results for these elements including chromium and nickel. The aim of this study was to investigate and compare thermal and hydrometallurgical treatment of municipal solid waste fly ash. Thermal treatment of fly ash was performed in a rotary reactor at temperatures between 950 and 1050 °C and in a muffle oven at temperatures from 500 to 1200 °C. The removal more than 90% was reached by easy volatile heavy metals such as cadmium and lead and also by copper, however at higher temperature in the muffle oven. The alkaline (sodium hydroxide) and acid (sulphuric acid) leaching of the fly ash was carried out while the influence of temperature, time, concentration, and liquid/solid ratio were investigated. The combination of alkaline-acidic leaching enhanced the removal of, namely, zinc, chromium and nickel.« less

Application of large volume injection GC-MS to analysis of organic compounds in the extracts and leachates of municipal solid waste incineration fly ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korenkova, Eva; Matisova, Eva; Slobodnik, Jaroslav

2006-07-01

Organic solvent and water extracts of fly ash from a Milan (Italy) municipal solid waste incinerator (MSWI) were analyzed by large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) with programmable temperature vaporizer (PTV). Using injection volumes of 10-100 {mu}l, typically over a hundred compounds were detected in organic solvent extracts and ca. 35% of them could be tentatively identified from their electron impact ionization mass spectra. A protocol for the determination of the maximum amount of a potential environmental pollutant available for leaching (availability test) was developed for four selected target compounds: pentachlorobenzene (PeCB), hexachlorobenzene (HxCB), o-terphenyl (o-TPH) and m-terphenyl (m-TPH). Keymore » parameters, extraction time and liquid-to-solid ratio (L/S), were studied in more detail. Recoveries of PeCB, HxCB and o-TPH spiked into the fly ash samples at two concentration levels ranged from 38% to 53% for freshly spiked and from 14% to 40% for 40-day aged fly ash. Recoveries of m-TPH were 8% to 11% from freshly spiked and less than 3% from aged spiked fly ash. The native amounts in Milan MSWI fly ash, determined in an interlaboratory exercise using the developed protocol, were 31 ng/g PeCB, 34 ng/g HxCB, 72 ng/g o-TPH and 4.4 ng/g m-TPH. A separate methodology was developed for the determination of compounds extracted from fly ash by water (leaching test). Following 8-h sonication at L/S 20, the leached amounts of PeCB, HxCB and o-TPH were 1.1, 3.1 and 6.0 ng/g fly ash, respectively.« less

Fate of the naturally occurring radioactive materials during treatment of acid mine drainage with coal fly ash and aluminium hydroxide.

PubMed

Madzivire, Godfrey; Maleka, Peane P; Vadapalli, Viswanath R K; Gitari, Wilson M; Lindsay, Robert; Petrik, Leslie F

2014-01-15

Mining of coal is very extensive and coal is mainly used to produce electricity. Coal power stations generate huge amounts of coal fly ash of which a small amount is used in the construction industry. Mining exposes pyrite containing rocks to H2O and O2. This results in the oxidation of FeS2 to form H2SO4. The acidic water, often termed acid mine drainage (AMD), causes dissolution of potentially toxic elements such as, Fe, Al, Mn and naturally occurring radioactive materials such as U and Th from the associated bedrock. This results in an outflow of AMD with high concentrations of sulphate ions, Fe, Al, Mn and naturally occurring radioactive materials. Treatment of AMD with coal fly ash has shown that good quality water can be produced which is suitable for irrigation purposes. Most of the potentially toxic elements (Fe, Al, Mn, etc) and substantial amounts of sulphate ions are removed during treatment with coal fly ash. This research endeavours to establish the fate of the radioactive materials in mine water with coal fly ash containing radioactive materials. It was established that coal fly ash treatment method was capable of removing radioactive materials from mine water to within the target water quality range for drinking water standards. The alpha and beta radioactivity of the mine water was reduced by 88% and 75% respectively. The reduced radioactivity in the mine water was due to greater than 90% removal of U and Th radioactive materials from the mine water after treatment with coal fly ash as ThO2 and UO2. No radioisotopes were found to leach from the coal fly ash into the mine water. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chemical associations and mobilization of heavy metals in fly ash from municipal solid waste incineration.

PubMed

Weibel, Gisela; Eggenberger, Urs; Schlumberger, Stefan; Mäder, Urs K

2017-04-01

This study focusses on chemical and mineralogical characterization of fly ash and leached filter cake and on the determination of parameters influencing metal mobilization by leaching. Three different leaching processes of fly ash from municipal solid waste incineration (MSWI) plants in Switzerland comprise neutral, acidic and optimized acidic (+ oxidizing agent) fly ash leaching have been investigated. Fly ash is characterized by refractory particles (Al-foil, unburnt carbon, quartz, feldspar) and newly formed high-temperature phases (glass, gehlenite, wollastonite) surrounded by characteristic dust rims. Metals are carried along with the flue gas (Fe-oxides, brass) and are enriched in mineral aggregates (quartz, feldspar, wollastonite, glass) or vaporized and condensed as chlorides or sulphates. Parameters controlling the mobilization of neutral and acidic fly ash leaching are pH and redox conditions, liquid to solid ratio, extraction time and temperature. Almost no depletion for Zn, Pb, Cu and Cd is achieved by performing neutral leaching. Acidic fly ash leaching results in depletion factors of 40% for Zn, 53% for Cd, 8% for Pb and 6% for Cu. The extraction of Pb and Cu are mainly limited due to a cementation process and the formation of a PbCu 0 -alloy-phase and to a minor degree due to secondary precipitation (PbCl 2 ). The addition of hydrogen peroxide during acidic fly ash leaching (optimized acidic leaching) prevents this reduction through oxidation of metallic components and thus significantly higher depletion factors for Pb (57%), Cu (30%) and Cd (92%) are achieved. The elevated metal depletion using acidic leaching in combination with hydrogen peroxide justifies the extra effort not only by reduced metal loads to the environment but also by reduced deposition costs. Copyright © 2016 Elsevier Ltd. All rights reserved.

In search for a compromise between biodiversity conservation and human health protection in restoration of fly ash deposits: effect of anti-dust treatments on five groups of arthropods.

PubMed

Tropek, Robert; Cerna, Ilona; Straka, Jakub; Kocarek, Petr; Malenovsky, Igor; Tichanek, Filip; Sebek, Pavel

2016-07-01

Recently, fly ash deposits have been revealed as a secondary refuge of critically endangered arthropods specialised on aeolian sands in Central Europe. Simultaneously, these anthropogenic habitats are well known for their negative impact on human health and the surrounding environment. The overwhelming majority of these risks are caused by wind erosion, the substantial decreasing of which is thus necessary. But, any effects of anti-dust treatments on endangered arthropods have never been studied. We surveyed communities of five arthropod groups (wild bees and wasps, leafhoppers, spiders, hoverflies and orthopteroid insects) colonising three fly ash deposits in the western Czech Republic. We focused on two different anti-dust treatments (~70 and 100 % cover of fly ash by barren soil) and their comparison with a control of bare fly ash. Altogether, we recorded 495 species, including 132 nationally threatened species (eight of them were considered to be extinct in the country) and/or 30 species strictly specialised to drift sands. Bees and wasps and leafhoppers contained the overwhelming majority of species of the highest conservation interest; a few other important records were also in spiders and orthopteroids. Total soil cover depleted the unique environment of fly ash and thus destroyed the high conservation potential of the deposits. On the other hand, partial coverage (with ~30 % of bare fly ash) still offered habitats for many of the most threatened species, as we showed by both regression and multivariate analyses, with a decrease of wind erosion. This topic still needs much more research interest, but we consider mosaic-like preservation of smaller spots of fly ash as one of the possible compromises between biodiversity and human health.

Synergistic effect of fly ash in in-vessel composting of biomass and kitchen waste.

PubMed

Manyapu, Vivek; Mandpe, Ashootosh; Kumar, Sunil

2018-03-01

The present study aims to utilize coal fly ash for its property to adsorb heavy metals and thus reducing the bioavailability of the metals for plant uptake. Fly ash was incorporated into the in-vessel composting system along with organic waste. The in-vessel composting experiments were conducted in ten plastic vessels of 15 L capacity comprising varying proportions of biomass waste, kitchen waste and fly ash. In this study, maximum degradation of organic matter was observed in Vessel 3 having k value of 0.550 d -1 . In vessel 10, 20% fly ash with a combination of 50% biomass waste and 30% kitchen waste along with the addition of 5% jaggery as an additive produced the best outcome with least organic matter (%C) loss and lowest value of rate constant (k). Copyright © 2017 Elsevier Ltd. All rights reserved.

Modified fly ash from municipal solid waste incineration as catalyst support for Mn-Ce composite oxides

NASA Astrophysics Data System (ADS)

Chen, Xiongbo; Liu, Ying; Yang, Ying; Ren, Tingyan; Pan, Lang; Fang, Ping; Chen, Dingsheng; Cen, Chaoping

2017-08-01

Fly ash from municipal solid waste incineration was modified by hydrothermal treatment and used as catalyst support for Mn-Ce composite oxides. The prepared catalyst showed good activity for the selective catalytic reduction (SCR) of NO by NH3. A NO conversion of 93% could be achieved at 300 °C under a GHSV of 32857 h-1. With the help of characterizations including XRD, BET, SEM, TEM, XPS and TPR, it was found that hydrothermal treatment brought a large surface area and abundant mesoporous to the modified fly ash, and Mn-Ce composite oxides were highly dispersed on the surface of the support. These physical and chemical properties were the intrinsic reasons for the good SCR activity. This work transformed fly ash into high value-added products, providing a new approach to the resource utilization and pollution control of fly ash.

The geochemistry and bioreactivity of fly-ash from coal-burning power stations.

PubMed

Jones, Timothy; Wlodarczyk, Anna; Koshy, Lata; Brown, Patrick; Shao, Longyi; BéruBé, Kelly

2009-07-01

Fly-ash is a byproduct of the combustion of coal in power stations for the generation of electricity. The fly-ash forms from the melting of incombustible minerals found naturally in the coal. The very high coal combustion temperatures result in the formation of microscopic glass particles from which minerals such as quartz, haematite and mullite can later recrystallize. In addition to these minerals, the glassy fly-ash contains a number of leachable metals. Mullite is a well-known material in the ceramics industry and a known respiratory hazard. Macroscopically mullite can be found in a large range of morphologies; however microscopic crystals appear to favour a fibrous habit. Fly-ash is a recognized bioreactive material in rat lung, generating hydroxyl radicals, releasing iron, and causing DNA damage. However, the mechanisms of the bioreactivity are still unclear and the relative contributions of the minerals and leachable metals to that toxicity are not well known.

Adsorption of 2,4-Dichlorophenoxyacetic Acid from an Aqueous Solution on Fly Ash.

PubMed

Kuśmierek, Krzysztof; Świątkowski, Andrzej

2016-03-01

The adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on fly ash was studied. The effects of adsorbent dose, contact time, pH, ionic strength, and temperature on the adsorption were investigated. Adsorption kinetic data were analyzed using pseudo-first and pseudo-second order models, and results showed that adsorption kinetics were better represented by the pseudo-second order model. Adsorption isotherms of 2,4-D on fly ash were analyzed using the Freundlich and Langmuir models. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicated that the adsorption process was spontaneous and endothermic. The negative values of ΔG° and the positive value of ΔH° indicate the spontaneous nature of 2,4-D adsorption on fly ash, and that the adsorption process was endothermic. Results showed that fly ash is an efficient, low-cost adsorbent for removal of 2,4-D from water.

The Effect of Silane Addition on Chitosan-Fly Ash/CTAB as Electrolyte Membrane

NASA Astrophysics Data System (ADS)

Kusumastuti, E.; Isnaeni, D.; Sulistyaningsih, T.; Mahatmanti, F. W.; Jumaeri; Atmaja, L.; Widiastuti, N.

2017-02-01

Electrolyte membrane is an important component in fuel cell system, because it may influence fuel cell performance. Many efforts have been done to produce electrolyte membrane to replace comercial membrane. In this research, electrolyte membrane is composed of chitosan as an organic matrix and fly ash modified with CTAB and silane as inorganic filler. Fly ash is modified using silane as coupling agent to improve interfacial morphology between organic matrix and inorganic filler. This research aims to determine the best membrane performance based on its characteristics such as water uptake, mechanical properties, proton conductivity, and methanol permeability. The steps that have been done include silica preparation from fly ash, modification of silica surface with CTAB, silica coupling process with silane, synthesis of membranes with inversion phase method, and membrane characterization. The result shows that membrane C-FA/CTAB-Silane 10% (w/w) has the best performance with proton conductivity 8.00 x 10-4 S.cm-1, methanol permeability 3.37 x 10-7 cm.s-1, and selectivity 2.12 x 103 S.s.cm-3. The result of FTIR analysis on membrane C-FA/CTAB-Silane 10% shows that there is only physical interaction occured between chitosan, fly ash and silane, because there is no peak differences significantly at wave number 1000-1250 cm-1, while morphology analysis on membrane with Scanning Electron Microscopy (SEM) shows good dispersion and there is no agglomeration on chitosan matrix.

A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate

PubMed Central

Sekaran, Alan; Palaniswamy, Murthi; Balaraju, Sivagnanaprakash

2015-01-01

Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i) Mix A, conventional concrete mix with no material substitution, (ii) Mix B, 30% replacement of cement with fly ash, and (iii) Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C) had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications. PMID:26421315

A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate.

PubMed

Sekaran, Alan; Palaniswamy, Murthi; Balaraju, Sivagnanaprakash

2015-01-01

Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i) Mix A, conventional concrete mix with no material substitution, (ii) Mix B, 30% replacement of cement with fly ash, and (iii) Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C) had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications.

Photosynthetic pigment concentrations, gas exchange and vegetative growth for selected monocots and dicots treated with two contrasting coal fly ashes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yunusa, I.A.M.; Burchett, M.D.; Manoharan, V.

2009-07-15

There is uncertainty as to the rates of coal fly ash needed for optimum physiological processes and growth. In the current study we tested the hyothesis that photosynthetic pigments concentrations and CO{sub 2} assimilation (A) are more sensitive than dry weights in plants grown on media amended with coal fly ash. We applied the Terrestrial Plant Growth Test (Guideline 208) protocols of the Organization for Economic Cooperation and Development (OECD) to monocots (barley (Hordeum vulgare) and ryegrass (Secale cereale)) and dicots (canola (Brasica napus), radish (Raphanus sativus), field peas (Pisum sativum), and lucerne (Medicago sativa)) on media amended with flymore » ashes derived from semi-bituminous (gray ash) or lignite (red ash) coals at rates of 0, 2.5, 5.0, 10, or 20 Mg ha(-1). The red ash had higher elemental concentrations and salinity than the gray ash. Fly ash addition had no significant effect on germination by any of the six species. At moderate rates ({<=}10 Mg ha{sup -1}) both ashes increased (P < 0.05) growth rates and concentrations of chlorophylls a and b, but reduced carotenoid concentrations. Addition of either ash increased A in radish and transpiration in barley. Growth rates and final dry weights were reduced for all of the six test species when addition rates exceeded 10 Mg ha{sup -1} for gray ash and 5 Mg ha{sup -1} for red ash. We concluded that plant dry weights, rather than pigment concentrations and/or instantaneous rates of photosynthesis, are more consistent for assessing subsequent growth in plants supplied with fly ash.« less

Design and fabrication of advanced materials from Illinois coal wastes. Quarterly report, 1 March 1995--31 May 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malhotra, V.M.; Wright, M.A.

1995-12-31

The main goal of this project is to develop a bench-scale procedure to design and fabricate advanced brake and structural composite materials from Illinois coal combustion residues. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), differential thermal analysis (DTA), and transmission-Fourier transform infrared (FTIR) were conducted on PCC fly ash (Baldwin), FBC fly ash (ADM unit1-6), FBC fly ash (S.I. coal), FBC spent bed ash (ADM unit1-6), bottom ash, and scrubber sludge (CWLP) residues to characterize their geometrical shapes, mineral phases, and thermal stability. Our spectroscopic results indicate that the scrubber sludge is mainly composed of a gypsum-like phase whosemore » lattice structure is different from the lattice structure of conventional gypsum, and sludge does not contain hannebachite (CaSO{sub 3}0.5H{sub 2}O) phase. In the second and third quarters the focus of research has been on developing protocols for the formation of advanced brake composites and structural composites. Our attempts to fabricate brake frictional shoes, in the form of 1.25 inch disks, from PCC fly ash, FBC spent bed ash, scrubber sludge, coal char, iron particles, and coal tar were successful. Based on the experience gained and microscopic analyses, we have now upscaled our procedures to fabricate 2.5 inch diameter disks from coal combustion residues. The SEM and Young`s modulus analyses of brake composites fabricated at 400 psi < Pressure < 2200 psi suggest pressure has a strong influence on the particle packing and the filling of interstices in our composites.« less

Removal of chloride from fly ash produced in hazardous waste incineration by leaching and displacement washing in a vertical filter press.

PubMed

Kinnarinen, Teemu; Huhtanen, Mikko; Penttilä, Mika; Häkkinen, Antti

2013-02-01

Fly ash is generated in large quantities by waste incineration processes. Chloride is commonly present in the fly ash produced by the incineration of hazardous materials, such as polyvinylchloride plastic. Major difficulties related to the disposal and handling of fly ash include the high concentration of easily leachable chlorides, heavy metals and toxic compounds. In order to avoid adverse environmental effects from the disposal of fly ash, the content of soluble chlorides must be reduced. One of the most effective options for chloride removal is leaching and displacement washing in a filter press. The primary aim of this study was to obtain efficient removal of chloride from fly ash by utilizing a leaching and displacement washing process, carried out in a filter press. The secondary objective was to obtain high filtration capacities and low filter cake moisture contents. The slurry was prepared by mixing fly ash with water at an ash:water ratio of 1:2 and filtered to separate the solids from the liquid. After solid-liquid separation, most of the dissolved residual chloride was removed from the filter cake by washing the cake with fresh water in the second stage of separation. It was possible to remove up to 98% of the total chloride and to obtain sufficient filtration capacities. The residual moisture content of the filter cakes varied from 22 to 35 wt%, which meant that the cakes could be disposed of in landfill, or possibly utilized as a construction material.

INTERACTION OF PLANAR AND NONPLANAR ORGANIC CONTAMINANTS WITH COAL FLY ASH: EFFECTS OF POLAR AND NONPOLAR SOLVENT SOLUTIONS

EPA Science Inventory

Coal fly ash has several uses but much of the material is treated as waste and disposed of in various ways including land filling. Coal fly ash also has a very high sorption capacity for a variety of anthropogenic contaminants and has been used to cleanse wastewater of such poll...

Selenium in particulates and gaseous fractions of smoke from cigarettes prepared from tobacco grown on fly-ash-amended soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gutemann, W.H.; Lisk, D.J.; Hoffman, D.

Cigarettes prepared from tobacco grown in pots of soils amended with soft coal fly ash were smoked, and the mainstream and gaseous fractions were analyzed for total selenium concentration. Fly-ash-grown and control (soil-grown) tobaccos contained, respectively, 0.79 and 0.03 ppm selenium. The quantities of selenium (ng per cigarette) found in the mainstream particulate and gaseous fractions were, respectively, 62.4 and 246.0 for the fly-ash-grown and 8.6 and 12.0 for the control treatments. Studies of the absorption, retention, effects, metabolism, and excretion of selenium in the body are reviewed.

The application of waste fly ash and construction-waste in cement filling material in goaf

NASA Astrophysics Data System (ADS)

Chen, W. X.; Xiao, F. K.; Guan, X. H.; Cheng, Y.; Shi, X. P.; Liu, S. M.; Wang, W. W.

2018-01-01

As the process of urbanization accelerated, resulting in a large number of abandoned fly ash and construction waste, which have occupied the farmland and polluted the environment. In this paper, a large number of construction waste and abandoned fly ash are mixed into the filling material in goaf, the best formula of the filling material which containing a large amount of abandoned fly ash and construction waste is obtained, and the performance of the filling material is analyzed. The experimental results show that the cost of filling material is very low while the performance is very good, which have a good prospect in goaf.

Comparison of Glass Powder and Fly Ash Effect on the Fresh Properties of Self-Compacting Mortars

NASA Astrophysics Data System (ADS)

Öznur Öz, Hatice; Erhan Yücel, Hasan; Güneş, Muhammet

2017-10-01

This study is aimed to determine effects of glass powder on fresh properties of self-compacting mortars. Self-compacting mortars incorporating glass powder (SCMGPs) were designed with a water/binder ratio of 0.40 and a total binder content of 550 kg/m3. At first, the control mixture was produced with 20% fly ash and % 80 cement of the total binder content without using the glass powder. Then, glass powder was used in the proportions 5%, 10%, 15% and 20% instead of fly ash in the mortars. Mini-slump flow and mini-v funnel tests experimentally investigated on SCMGPs to compare the effect of fly ash and glass powder. With increasing the amount of glass powder used in SCMGPs increased the amount of superplasticizer used to obtain the desired mini-slump flow diameter. So, the use of glass powder reduced the flow ability of SCMGPs in comparison to fly ash. Additionally, the compressive strength and flexural strength of the mortar mixtures were determined at the 28th day. The test results indicated that the mechanical characteristics of SCMGPs improved when the fly ash was replaced with glass powder in SCMGPs.

Preparation of poly-o-phenylenediamine/TiO 2/fly-ash cenospheres and its photo-degradation property on antibiotics

NASA Astrophysics Data System (ADS)

Huo, Pengwei; Yan, Yongsheng; Li, Songtian; Li, Huaming; Huang, Weihong

2010-03-01

A series of poly-o-phenylenediamine/TiO 2/fly-ash cenospheres(POPD/TiO 2/fly-ash cenospheres) composites have been prepared from o-phenylenediamine and TiO 2/fly-ash cenospheres under various polymerization conditions. The properties of the samples were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), specific surface area (BET), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance spectrum (UV-vis DRS). Photocatalytic activity was studied by degradation of antibiotics waste water under visible light. The results indicate that the photo-induced method is viable for preparing modified photocatalysts, and the modified photocatalysts have good absorption in visible light range. The photocatalysts of POPD/TiO 2/fly-ash cenospheres which have good performance are prepared at pH 3 and 4, and the polymerized time around 40 min. When the photocatalysts are prepared under the conditions of pH 3 and polymerized time 40 min, the degradation rate of roxithromycin waste water could reach near 60%, and it indicates that the way of POPD modified TiO 2/fly-ash cenospheres to degrade the antibiotics waste water is viable.

Chromium behavior during thermal treatment of MSW fly ash.

PubMed

Kirk, Donald W; Chan, Chris C Y; Marsh, Hilary

2002-02-14

Energy-from-waste incineration has been promoted as an environmentally responsible method for handling non-recyclable waste from households. Despite the benefits of energy production, elimination of organic residues and reduction of volume of waste to be landfilled, there is concern about fly ash disposal. Fly ash from an incinerator contains toxic species such as Pb, Zn, Cd and Cr which may leach into soil and ground water if landfilled. Thermal treatment of the fly ash from municipal solid waste has been tested and proposed as a treatment option for removal of metal species such as Pb, Cd and Zn, via thermal re-volatilization. However, Cr is an element that remains in the residue of the heat treated fly ash and appears to become more soluble. This Cr solubilization is of concern if it exceeds the regulatory limit for hazardous waste. Hence, this unexpected behavior of Cr was investigated. The initial work involved microscopic characterization of Cr in untreated and thermally-treated MSW fly ash. This was followed by determining leaching characteristics using standard protocol leaching tests and characterization leaching methods (sequential extraction). Finally, a mechanism explaining the increased solubilization was proposed and tested by reactions of synthetic chemicals.

Effects of different treatments of fly ash and mining soil on growth and antioxidant protection of Indian wild rice.

PubMed

Bisoi, Sidhanta Sekhar; Mishra, Swati S; Barik, Jijnasa; Panda, Debabrata

2017-05-04

The aim of the present study was investigation of the effects of fly ash and mining soil on growth and antioxidant protection of two cultivars of Indian wild rice (Oryza nivara and Oryza rufipogon) for possible phytoremediation and restoration of metal-contaminated site. In this study, Indian wild rice showed significant changes in germination, growth, and biochemical parameters after exposure to different ratio of fly ash and mining soil with garden soil. There was significant reduction of germination, fresh weight, dry weight, leaf chlorophyll content, leaf area, Special Analysis Device Chlorophyll (SPAD) Index, proteins, and activities of antioxidant enzymes in both cultivars of the wild rice grown in 100% fly ash and mining soil compared to the plants grown in 100% garden soil. Results from this study showed that in both cultivars of wild rice, all growth and antioxidant parameters increased when grown in 50% fly ash and mining soil. Taken together, Indian wild rice has the capacity to tolerate 50% of fly ash and mining soil, and can be considered as a good candidate for possible phytoremediation of contaminated soils.

Utilization of fly ash as partial sand replacement in oil palm shell lightweight aggregate concrete

NASA Astrophysics Data System (ADS)

Nazrin Akmal, A. Z. Muhammad; Muthusamy, K.; Mat Yahaya, F.; Hanafi, H. Mohd; Nur Azzimah, Z.

2017-11-01

Realization on the increasing demand for river sand supply in construction sector has inspired the current research to find alternative material to reduce the use of natural sand in oil palm shell lightweight aggregate concrete (OPS LWAC) production. The existence of fly ash, a by-product generated from coal power plant, which pose negative impact to the environment when it is disposed as waste, were used in this research. The effect of fly ash content as partial sand replacement towards workability and compressive strength of OPS lightweight aggregate concrete were investigated. Four concrete mixes containing various percentage of fly ash that are 0%, 10%, 20% and 30% by weight of sand were used in the experimental work. All mixes were cast in form of cubes before subjected to water curing until the testing age. Compressive strength test were conducted at 1, 3, 7 and 28 days. The finding shows that the workability of the OPS LWAC decreases when more fly ash are used as sand replacement. It was found that adding of 10% fly ash as sand replacement content resulted in better compressive strength of OPS LWAC, which is higher than the control mix.

Removal of heavy metals from fly ash leachate using combined bioelectrochemical systems and electrolysis.

PubMed

Tao, Hu-Chun; Lei, Tao; Shi, Gang; Sun, Xiao-Nan; Wei, Xue-Yan; Zhang, Li-Juan; Wu, Wei-Min

2014-01-15

Based on environmental and energetic analysis, a novel combined approach using bioelectrochemical systems (BES) followed by electrolysis reactors (ER) was tested for heavy metals removal from fly ash leachate, which contained high detectable levels of Zn, Pb and Cu according to X-ray diffraction analysis. Acetic acid was used as the fly ash leaching agent and tested under various leaching conditions. A favorable condition for the leaching process was identified to be liquid/solid ratio of 14:1 (w/w) and leaching duration 10h at initial pH 1.0. It was confirmed that the removal of heavy metals from fly ash leachate with the combination of BESs and ER is feasible. The metal removal efficiency was achieved at 98.5%, 95.4% and 98.1% for Cu(II), Zn(II), and Pb(II), respectively. Results of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) indicated that Cu(II) was reduced and recovered mainly as metal Cu on cathodes related to power production, while Zn(II) and Pb(II) were not spontaneously reduced in BESs without applied voltage and basically electrolyzed in the electrolysis reactors. Copyright © 2013 Elsevier B.V. All rights reserved.

Can washing-pretreatment eliminate the health risk of municipal solid waste incineration fly ash reuse?

PubMed

Wang, Yao; Pan, Yun; Zhang, Lingen; Yue, Yang; Zhou, Jizhi; Xu, Yunfeng; Qian, Guangren

2015-01-01

Although the reuse of washing-pretreated MSWI fly ash bas been a hot topic, the associated risk is still an issue of great concern. The present study investigated the influence of washing-pretreatment on the total contents and bioaccessibility of heavy metals in MSWI fly ash. Furthermore, the study incorporated bioaccessibility adjustment into probabilistic risk assessment, to quantify the health risk from multi-pathway exposure to the concerned chemicals as a result of reusing washed MSWI fly ash. The results revealed that both water-washing and acid-washing process have resulted in the concentrated heavy metal content, and have reduced the bioaccessibility of heavy metals. Besides, the acid-washing process increased the cancer risk in most cases, while the effect of water-washing process was uncertain. However, both water-washing and acid-washing pretreatment could decrease the hazard index based on bioaccesilbility. Despite the uncertainties accompanying these procedures, the results indicated that, in this application scenario, only water-washing or acid-washing process cannot reduce the actual risk from all samples to acceptable level, especially for cancer risk. Copyright © 2014. Published by Elsevier Inc.

Effect of temperature on the hydration of Portland cement blended with siliceous fly ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deschner, Florian, E-mail: florian.deschner@gmail.com; Lothenbach, Barbara; Winnefeld, Frank

2013-10-15

The effect of temperature on the hydration of Portland cement pastes blended with 50 wt.% of siliceous fly ash is investigated within a temperature range of 7 to 80 °C. The elevation of temperature accelerates both the hydration of OPC and fly ash. Due to the enhanced pozzolanic reaction of the fly ash, the change of the composition of the C–S–H and the pore solution towards lower Ca and higher Al and Si concentrations is shifted towards earlier hydration times. Above 50 °C, the reaction of fly ash also contributes to the formation of siliceous hydrogarnet. At 80 °C, ettringitemore » and AFm are destabilised and the released sulphate is partially incorporated into the C–S–H. The observed changes of the phase assemblage in dependence of the temperature are confirmed by thermodynamic modelling. The increasingly heterogeneous microstructure at elevated temperatures shows an increased density of the C–S–H and a higher coarse porosity. -- Highlights: •The reaction of quartz powder at 80 °C strongly enhances the compressive strength. •Almost no strength increase of fly ash blended OPC at 80 °C was found after 2 days. •Siliceous hydrogarnet is formed upon the reaction of fly ash at high temperatures. •Temperature dependent change of the system was simulated by thermodynamic modelling. •Destabilisation of ettringite above 50 °C correlates with sulphate content of C–S–H.« less

Microstructure and wear characterization of aluminum matrix composites reinforced with industrial waste fly ash particulates synthesized by friction stir processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinaharan, I., E-mail: dinaweld2009@gmail.com

Fly ash (FA) is a waste product of coal combustion in thermal power plants which is available in massive quantities all over the world causing land pollution. This paper reports the characterization of AA6061 aluminum matrix composites (AMCs) reinforced with FA particles synthesized using friction stir processing (FSP). The volume fraction of FA particles was varied from 0 to 18 in steps of 6. The prepared AMCs were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and electron backscattered diagram (EBSD). The wear rate was estimated using a pin-on-disc wear apparatus. FA particles were observed to be distributed homogeneouslymore » in the AMC irrespective of the location within the stir zone. The EBSD micrographs revealed remarkable grain refinement in the AMC. The incorporation of FA particles enhanced the microhardness and wear resistance of the AMC. The strengthening mechanisms of the AMC were discussed and correlated to the observed microstructures. The wear mechanisms were identified by characterizing the wear debris and worn surfaces. - Highlights: •Industrial waste fly ash was used to produce aluminum matrix composites. •Friction stir processing was used to produce AA6061/Fly Ash composite. •Fly ash particles refined the grains of aluminum matrix. •Fly ash particles enhanced the hardness and wear resistance. •Successful utilization of fly ash to make aluminum composites reduces land pollution.« less

Heavy metals and PCDD/Fs in solid waste incinerator fly ash in Zhejiang province, China: chemical and bio-analytical characterization.

PubMed

Yao, Jun; Li, Wenbing; Xia, Fangfang; Zheng, Yuange; Fang, Chengran; Shen, Dongsheng

2012-06-01

Fly ash samples were taken from solid waste incinerators with different feeding waste, furnace type, and air pollution control device in six cities of Zhejiang province. The solid waste incinerators there constitute one fifth of incinerators in China. Heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in the fly ash. Moreover, the fly ash samples were extracted by toxicity characteristic leaching procedure (TCLP). The biotoxicity of the leachate was evaluated by Chlorella pyrenoidosa. High variation and contents were found for both the heavy metals and PCDD/Fs. The contents of Zn, Cu, As, Pb, Cd, Cr, Ni, and Hg in the fly ash samples varied from 300 to 32,100, 62.1-1175, 1.1-57, 61.6-620, 0.4-223, 16.6-4380, 1.2-94.7, and 0.03-1.4 μg g(-1) dw, respectively. The total contents of 17 PCDD/Fs varied from 0.1128 to 127.7939 μg g(-1) dw, and the 2,3,7,8-TeCDD toxic equivalents (TEQ) of PCDD/Fs ranged from 0.009 to 6.177 μg g(-1) dw. PCDF congeners were the main contributor to the TEQ. The leachate of the fly ash showed biotoxicity to C. pyrenoidosa. A significant correlation was found between the Cd and EC(50) values. Further research is required to investigate the environmental impact of the various pollutants in the fly ash.

Preparation of fly ash-granulated blast furnace slag-carbide slag binder and application in total tailings paste backfill

NASA Astrophysics Data System (ADS)

Li, Chao; Hao, Ya-fei; Zhao, Feng-qing

2018-03-01

Based on activation and synergistic effect among various materials, a low-cost mine backfill cementing material, FGC binder, was prepared by using fly ash, granulated blast-furnace slag (GBFS), carbide slag and composite activator. The proper proportioning of FGC binder is obtained by response surface experiment optimization method: fly ash 62 %, GBFS 20 %, carbide slag 8 % and compound activators 10 %. Adjusting the material ratio obtains different cementing material which could satisfy requirements of different mined-out areas. With the mass ratio of cementing material and tailings 1:4∼1:8, the concentration of total solid 70 %, the compressive strength values of total tailings filling body at 28 d reaches 1.64∼4.14 MPa, and the backfilling cost is 20 % lower than using OPC cement.

Critical Elements in Fly Ash from the Combustion of Bituminous Coal in Major Polish Power Plants

NASA Astrophysics Data System (ADS)

Bielowicz, Barbara; Botor, Dariusz; Misiak, Jacek; Wagner, Marian

2018-03-01

The concentration of critical elements, including such REE as Fe, Co, W, Zn, Cr, Ni, V, Mn, Ti, Ag, Ga, Ta, Sr, Li, and Cu, in the so-called fly ash obtained from the 9 Polish power plants and 1 thermal power station has been determined. The obtained values, compared with the global average concentration in bituminous coal ash and sedimentary rocks (Clarke values), have shown that the enrichment of fly ash in the specified elements takes place in only a few bituminous coal processing sites in Poland. The enrichment factor (EF) is only slightly higher (the same order of magnitude) than the Clarke values. The enrichment factor in relation to the Clarke value in the Earth's crust reached values above 10 in all of the examined ashes for the following elements: Cr, Ni, V, W, and, in some ash samples, also Cu and Zn. The obtained values are low, only slightly higher than the global average concentrations in sedimentary rocks and bituminous coal ashes. The ferromagnetic grains (microspheres) found in bituminous coal fly ashes seem to be the most economically prospective in recovery of selected critical elements. The microanalysis has shown that iron cenospheres and plerospheres in fly ash contain, in addition to enamel and iron oxides (magnetite and hematite), iron spinels enriched in Co, Cr, Cu, Mn, Ni, W, and Zn.

Evaluation of fly ash in water reduced paving mixtures.

DOT National Transportation Integrated Search

1985-06-01

Fly ash was used to replace 15% of the cement in C3WR and C6WR concrete : paving mixes containing ASTM C494 Type A water reducin9 admixtures. Two Class : C ashes and one Class F ash from Iowa approved sources were examined in each : mix. When Class C...

Glass-ceramic from mixtures of bottom ash and fly ash.

PubMed

Vu, Dinh Hieu; Wang, Kuen-Sheng; Chen, Jung-Hsing; Nam, Bui Xuan; Bac, Bui Hoang

2012-12-01

Along with the gradually increasing yield of the residues, appropriate management and treatment of the residues have become an urgent environmental protection problem. This work investigated the preparation of a glass-ceramic from a mixture of bottom ash and fly ash by petrurgic method. The nucleation and crystallization kinetics of the new glass-ceramic can be obtained by melting the mixture of 80% bottom ash and 20% fly ash at 950 °C, which was then cooled in the furnace for 1h. Major minerals forming in the glass-ceramics mainly are gehlenite (Ca(2)Al(2)SiO(7)) & akermanite (Ca(2)MgSiO(7)) and wollastonite (CaSiO(3)). In addition, regarding chemical/mechanical properties, the chemical resistance showing durability, and the leaching concentration of heavy metals confirmed the possibility of engineering and construction applications of the most superior glass-ceramic product. Finally, petrurgic method of a mixture of bottom ash and fly ash at 950 °C represents a simple, inexpensive, and energy saving method compared with the conventional heat treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Rehabilitating asphalt highways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butalia, T.S.

2007-07-01

Coal fly ash has been used on two Ohio full-depth reclamation projects in Delaware and Warren. The object of the project carried out with the Department of Civil and Environmental Engineering and Geodetic Science at Ohio State University is to demonstrate the effective use of Class fly ash in combination with lime or lime kiln dust in the full depth reclamation of asphalt pavements. The article describes the mixes used for the highway reconstruction of part of Section Line Road Delaware County and of a road in Warren County. During construction the pavement sections were instrumented with several structural andmore » environmental monitoring devices and data is being collected on a quarterly basis. Falling Weight Deflectometer (FWD) tests to measure load defection behaviour, resilient of pavement layers and soil and base structural layer coefficient are being carried out twice a year. It was shown that use of fly ash increased the elastic modulus of base layers. This article first appeared in the Feb/May 2007 issue of Asphalt Contractor. 4 photos.« less

Mutagenicity and genotoxicity of coal fly ash water leachate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, R.; Mukherjee, A.

2009-03-15

Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to storage or ash ponds located near power stations. This has lain to waste thousands of hectares of land all over the world. Since leaching is often the cause of off-site contamination and pathway of introduction into the human environment, a study on the genotoxic effects of fly ash leachate is essential. Leachate prepared from the fly ash sample was analyzed for metal content, and tested for mutagenicity and genotoxicity. Analyses of metals show predominance of the metalsmore » - sodium, silicon, potassium, calcium, magnesium, iron, manganese, zinc, and sulphate. The Ames Salmonella mutagenicity assay, a short-term bacterial reverse mutation assay, was conducted on two-tester strains of Salmonella typhimurium strains TA97a and TA102. For genotoxicity, the alkaline version of comet assay on fly ash leachate was carried in vitro on human blood cells and in vivo on Nicotiana plants. The leachate was directly mutagenic and induced significantconcentration-dependent increases in DNA damage in whole blood cells, lymphocytes, and in Nicotiana plants. The comet parameters show increases in tail DNA percentage (%), tail length (mu m), and olive tail moment (arbitrary units). Our results indicate that leachate from fly ash dumpsites has the genotoxic potential and may lead to adverse effects on vegetation and on the health of exposed human populations.« less

Chemical and physical properties of cyclone fly ash from the grate-fired boiler incinerating forest residues at a small municipal district heating plant (6MW).

PubMed

Pöykiö, R; Rönkkömäki, H; Nurmesniemi, H; Perämäki, P; Popov, K; Välimäki, I; Tuomi, T

2009-03-15

In Finland, the new limit values for maximal allowable heavy metal concentrations for materials used as an earth construction agent came into force in July 2006. These limit values are applied if ash is utilized, e.g. in roads, cycling paths, pavements, car parks, sport fields, etc. In this study we have determined the most important chemical and physical properties of the cyclone fly ash originating from the grate-fired boiler incinerating forest residues (i.e. wood chips, sawdust and bark) at a small municipal district heating plant (6 MW), Northern Finland. This study clearly shows that elements are enriched in cyclone fly ash, since the total element concentrations in the cyclone fly ash were within 0.2-10 times higher than those in the bottom ash. The total concentrations of Cd (25 mg kg(-1); d.w.), Zn (3630 mg kg(-1); d.w.), Ba (4260 mg kg(-1); d.w.) and Hg (1.7 mg kg(-1); d.w.) exceeded the limit values, and therefore the cyclone fly ash cannot be used as an earth construction agent. According to the leached amounts of Cr (38 mg kg(-1); d.w.), Zn (51 mg kg(-1); d.w.) and sulphate (50,000 mg kg(-1); d.w.), the cyclone fly ash is classified as a hazardous waste, and it has to be deposited in a hazardous waste landfill.

Arsenic and selenium capture by fly ashes at low temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. Antonia Lopez-Anton; Mercedes Diaz-Somoano; D. Alan Spears

2006-06-15

Arsenic and selenium compounds may be emitted to the environment during coal conversion processes, although some compounds are retained in the fly ashes, in different proportions depending on the characteristics of the ashes and process conditions. The possibility of optimizing the conditions to achieve better trace element retention appears to be an attractive, economical option for reducing toxic emissions. This approach requires a good knowledge of fly ash characteristics and a thorough understanding of the capture mechanism involved in the retention. In this work the ability of two fly ashes, one produced in pulverized coal combustion and the other inmore » fluidized bed combustion, to retain arsenic and selenium compounds from the gas phase in coal combustion and coal gasification atmospheres was investigated. To explore the possible simultaneous retention of mercury, the influence of the unburned coal particle content was also evaluated. Retention capacities between 2 and 22 mg g{sup -1} were obtained under different conditions. The unburned coal particle content in the fly ash samples does not significantly modify retention capacities. 21 refs., 6 figs., 5 tabs.« less

Leaching characteristics of solid wastes from thermal power plants of western Turkey and comparison of toxicity methodologies.

PubMed

Baba, Alper; Kaya, Abidin

2004-11-01

Use of lignite in power generation has led to increasing environmental problems associated not only with gaseous emissions, but also with the disposal of ash residues. In particular, use of low quality coals with high ash content results in huge quantities of both fly and bottom ashes to be disposed of. A main problem related to coal ash disposal is the heavy metal content of the residue. In this regard, experimental results of numerous studies indicate that toxic trace metals may leach when fly and bottom ashes are in contact with water. In this study, fly and bottom ash samples obtained from thermal power plants, namely Yenikoy, Kemerkoy and Yatagan, located at the southwestern coast of Turkey, were subjected to toxicity tests such as the extraction (EP) and toxicity characteristic leaching (TCLP) procedures of the US Environmental Protection Agency (USEPA) and the so-called 'Method A' extraction procedure of the American Society of Testing and Material (ASTM). The geochemical composition of ash samples showed variations depending on the coal burned in the plants. Furthermore, the EP, TCLP and ASTM toxicity tests showed variations such that the ash samples were classified as 'toxic waste' based on EP and TCLP results whereas they were classified as 'non-toxic' based on ASTM results, indicating test results are pH dependent. When the extraction results were compared with the chemical composition of water samples obtained in the vicinity of the thermal power plants, it was found that the results obtained using the ASTM procedure cannot be used to predict subsurface contamination whereas the EP and TCLP procedures can be used.

Chemical composition and properties of ashes from combustion plants using Miscanthus as fuel.

PubMed

Lanzerstorfer, Christof

2017-04-01

Miscanthus giganteus is one of the energy crops considered to show potential for a substantial contribution to sustainable energy production. In the literature there is little data available about the chemical composition of ashes from the combustion of Miscanthus and practically no data about their physical properties. However, for handling, treatment and utilization of the ashes this information is important. In this study ashes from two biomass combustion plants using Miscanthus as fuel were investigated. The density of the ashes was 2230±35kg/m 3 , which was similar to the density of ashes from straw combustion. Also the bulk densities were close to those reported for straw ashes. The flowability of the ashes was a little worse than the flowability of ashes from wood combustion. The measured heavy metal concentrations were below the usual limits for utilization of the ashes as soil conditioner. The concentrations in the bottom ash were similar to those reported for ash from forest residue combustion plants. In comparison with cyclone fly ashes from forest residue combustion the measured heavy metal concentrations in the cyclone fly ash were considerably lower. Cl - , S and Zn were enriched in the cyclone fly ash which is also known for ashes from wood combustion. In comparison with literature data obtained from Miscanthus plant material the concentrations of K, Cl - and S were lower. This can be attributed to the fact that the finest fly ash is not collected by the cyclone de-dusting system of the Miscanthus combustion plants. Copyright © 2016. Published by Elsevier B.V.

EVALUATING THE EFFECTS OF FLY ASH EXPOSURE ON FISH EARLY LIFE STAGES: FATHEAD MINNOW EMBRYO-LARVAL TESTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greeley Jr, Mark Stephen; Elmore, Logan R; McCracken, Kitty

2012-05-01

On December 22, 2008, a dike containing fly ash and bottom ash in an 84-acre complex of the Tennessee Valley Authority's (TVA) Kingston Steam Plant in East Tennessee failed and released a large quantity of ash into the adjacent Emory River. Ash deposits extended as far as 4 miles upstream (Emory River mile 6) of the Plant, and some ash was carried as far downstream as Tennessee River mile 564 ({approx}4 miles downstream of the Tennessee River confluence with the Clinch River). A byproduct of coal burning power plants, fly ash contains a variety of metals and other elements which,more » at sufficient concentrations and in specific forms, can be toxic to biological systems. The effects of fly ash contamination on exposed fish populations depend on the magnitude and duration of exposure, with the most significant risk considered to be the effects of specific ash constituents, especially selenium, on fish early life stages. Uptake by adult female fish of fly ash constituents through the food chain and subsequent maternal transfer of contaminants to the developing eggs is thought to be the primary route of selenium exposure to larval fish (Woock and others 1987, Coyle and others 1993, Lemly 1999, Moscatello and others 2006), but direct contact of the fertilized eggs and developing embryos to ash constituents in river water and sediments is also a potential risk factor (Woock and others 1987, Coyle and others 1993, Jezierska and others 2009). To address the risk of fly ash from the Kingston spill to the reproductive health of downstream fish populations, ORNL has undertaken a series of studies in collaboration with TVA including: (1) a field study of the bioaccumulation of fly ash constituents in fish ovaries and the reproductive condition of sentinel fish species in reaches of the Emory and Clinch Rivers affected by the fly ash spill; (2) laboratory tests of the potential toxicity of fly ash from the spill area on fish embryonic and larval development (reported in the current technical manuscript); (3) additional laboratory experimentation focused on the potential effects of long-term exposures to fly ash on fish survival and reproductive competence; and (4) a combined field and laboratory study examining the in vitro developmental success of embryos and larvae obtained from fish exposed in vivo for over two years to fly ash in the Emory and Clinch Rivers. These fish reproduction and early life-stage studies are being conducted in conjunction with a broader biological monitoring program administered by TVA that includes a field study of the condition of larval fish in the Emory and Clinch Rivers along with assessments of water quality, sediment composition, ecotoxicological studies, terrestrial wildlife studies, and human and ecological risk assessment. Information and data generated from these studies will provide direct input into risk assessment efforts and will also complement and help support other phases of the overall biomonitoring program. Fish eggs, in general, are known to be capable of concentrating heavy metals and other environmental contaminants from water-borne exposures during embryonic development (Jezierska and others 2009), and fathead minnow embryos in particular have been shown to concentrate methylmercury (Devlin 2006) as well as other chemical toxicants. This technical report focuses on the responses of fathead minnow embryos to simple contact exposures to fly ash in laboratory toxicity tests adapted from a standard fathead minnow (Pimephales promelas) 7-d embryo-larval survival and teratogenicity test (method 1001.0 in EPA 2002) with mortality, hatching success, and the incidences of developmental abnormalities as measured endpoints.« less

Characterization and modes of occurrence of elements in feed coal and coal combustion products from a power plant utilizing low-sulfur coal from the Powder River Basin, Wyoming

USGS Publications Warehouse

Brownfield, Michael E.; Cathcart, James D.; Affolter, Ronald H.; Brownfield, Isabelle K.; Rice, Cynthia A.; O'Connor, Joseph T.; Zielinski, Robert A.; Bullock, John H.; Hower, James C.; Meeker, Gregory P.

2005-01-01

The U.S. Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana utility company to determine the physical and chemical properties of feed coal and coal combustion products from a coal-fired power plant. The Indiana power plant utilizes a low-sulfur (0.23 to 0.47 weight percent S) and lowash (4.9 to 6.3 weight percent ash) subbituminous coal from the Wyodak-Anderson coal zone in the Tongue River Member of the Paleocene Fort Union Formation, Powder River Basin, Wyoming. Based on scanning electron microscope and X-ray diffraction analyses of feed coal samples, two mineral suites were identified: (1) a primary or detrital suite consisting of quartz (including beta-form grains), biotite, feldspar, and minor zircon; and (2) a secondary authigenic mineral suite containing alumino-phosphates (crandallite and gorceixite), kaolinite, carbonates (calcite and dolomite), quartz, anatase, barite, and pyrite. The primary mineral suite is interpreted, in part, to be of volcanic origin, whereas the authigenic mineral suite is interpreted, in part, to be the result of the alteration of the volcanic minerals. The mineral suites have contributed to the higher amounts of barium, calcium, magnesium, phosphorus, sodium, strontium, and titanium in the Powder River Basin feed coals in comparison to eastern coals. X-ray diffraction analysis indicates that (1) fly ash is mostly aluminate glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals; and (2) bottom ash is predominantly quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite, and spinel group minerals. Microprobe and scanning electron microscope analyses of fly ash samples revealed quartz, zircon, and monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, wollastonite, and periclase. The abundant calcium and magnesium mineral phases in the fly ash are attributed to the presence of carbonate, clay, and phosphate minerals in the feed coal and their alteration to new phases during combustion. The amorphous diffraction-scattering maxima or glass 'hump' appears to reflect differences in chemical composition of fly ash and bottom ash glasses. In Wyodak-Anderson fly and bottom ashes, the center point of scattering maxima is due to calcium and magnesium content, whereas the glass 'hump' of eastern fly ash reflects variation in aluminum content. The calcium- and magnesium-rich and alumino-phosphate mineral phases in the coal combustion products can be attributed to volcanic minerals deposited in peat-forming mires. Dissolution and alteration of these detrital volcanic minerals occurred either in the peat-forming stage or during coalification and diagenesis, resulting in the authigenic mineral suite. The presence of free lime (CaO) in fly ash produced from Wyodak-Anderson coal acts as a self-contained 'scrubber' for SO3, where CaO + SO3 form anhydrite either during combustion or in the upper parts of the boiler. Considering the high lime content in the fly ash and the resulting hydration reactions after its contact with water, there is little evidence that major amounts of leachable metals are mobilized in the disposal or utilization of this fly ash.

Investigating Electrostatic Precipitator Design Parameters for Efficient Control of Particulate Matter in Thermal Power Plant: A Case Study

NASA Astrophysics Data System (ADS)

Rai, P.; Gautam, N.; Chandra, H.

2018-06-01

This work deals with the analysis and modification of operational parameters for meeting the emission standards, set by Central Pollution Control Board (CPCB)/State Pollution Control Board (SPCB) from time to time of electrostatic precipitator (ESP). The analysis is carried out by using standard chemical analysis supplemented by the relevant data collected from Korba East Phase (Ph)-III thermal power plant, under Chhattisgarh State Electricity Board (CSEB) operating at Korba, Chhattisgarh. Chemical analysis is used to predict the emission level for different parameters of ESP. The results reveal that for a constant outlet PM concentration and fly ash percentage, the total collection area decreases with the increase in migration velocity. For constant migration velocity and outlet PM concentration, the total collection area increases with the increase in the fly ash percent. For constant migration velocity and outlet e PM concentration, the total collection area increases with the ash content in the coal. i.e. from minimum ash to maximum ash. As far as the efficiency is concerned, it increases with the fly ash percent, ash content and the inlet dust concentration but decreases with the outlet PM concentration at constant migration velocity, fly ash and ash content.

Investigating Electrostatic Precipitator Design Parameters for Efficient Control of Particulate Matter in Thermal Power Plant: A Case Study

NASA Astrophysics Data System (ADS)

Rai, P.; Gautam, N.; Chandra, H.

2018-02-01

This work deals with the analysis and modification of operational parameters for meeting the emission standards, set by Central Pollution Control Board (CPCB)/State Pollution Control Board (SPCB) from time to time of electrostatic precipitator (ESP). The analysis is carried out by using standard chemical analysis supplemented by the relevant data collected from Korba East Phase (Ph)-III thermal power plant, under Chhattisgarh State Electricity Board (CSEB) operating at Korba, Chhattisgarh. Chemical analysis is used to predict the emission level for different parameters of ESP. The results reveal that for a constant outlet PM concentration and fly ash percentage, the total collection area decreases with the increase in migration velocity. For constant migration velocity and outlet PM concentration, the total collection area increases with the increase in the fly ash percent. For constant migration velocity and outlet e PM concentration, the total collection area increases with the ash content in the coal. i.e. from minimum ash to maximum ash. As far as the efficiency is concerned, it increases with the fly ash percent, ash content and the inlet dust concentration but decreases with the outlet PM concentration at constant migration velocity, fly ash and ash content.

Characterization and environmental risk assessment of heavy metals found in fly ashes from waste filter bags obtained from a Chinese steel plant.

PubMed

Zhou, Yun; Ning, Xun-an; Liao, Xikai; Lin, Meiqing; Liu, Jingyong; Wang, Jianghui

2013-09-01

The environmental risk of exposure to six heavy metals (Cu, Pb, Zn, Cr, Ni, and Cd) found in fly ashes from waste filter bags obtained from a steel plant was estimated based on the mineralogical compositions, total concentrations and speciation of the metals in the fly ashes. The results indicated that the fly ashes mainly consisted of hematite, magnetite, cyanite, spinel, coesite and amorphous materials. The concentrations of Zn and Pb were much higher than that of other materials. After Zn and Pb, Ni was present in the highest concentration, followed by Cu, Cr and Cd. Each heavy metal was distributed differently in fly ashes. The levels of Zn, Cd and Pb in the active fraction were very high, and ranged from 64.83 to 81.96%, 34.48 to 82.4% and 6.92 to 79.65% respectively, while Cu, Cr and Ni were mainly present in the residual fraction. The risk assessment code (RAC) values of fly ashes showed that the Zn and Cd present in the H3 sample presented a very high risk, with RAC values greater than 50%. The Cu present in the H3 sample, Cd in the H2 sample and Zn in the H4 and H5 samples presented a high risk. The Pb present in the H2 sample, Cd in the H4 sample, Ni in the H1 and H5 samples, and Zn in the H1 sample presented a medium risk. A low risk was presented by the Cu present in the H1, H2, H4 and H5 samples, the Pb in the H1, H3 and H5 samples, the Cd in the H1 and H5 samples, and the Ni in the H2 sample. No risk was presented by Cr in any sample. Copyright © 2013 Elsevier Inc. All rights reserved.

Glass-ceramics from municipal incinerator fly ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boccaccini, A.R.; Petitmermet, M.; Wintermantel, E.

1997-11-01

In countries where the population density is high and the availability of space for landfilling is limited, such as the west-European countries and Japan, the significance of municipal solid waste incineration, as part of the waste management strategy, is continuously increasing. In Germany and Switzerland, for example, more than {approximately}40% of unrecycled waste is being or will be incinerated. Also, in other countries, including the US, the importance of waste incineration will increase in the next few years. Although incineration reduces the volume of the waste by {approximately} 90%, it leaves considerable amounts of solid residues, such as bottom andmore » boiler ashes, and filter fly ashes. Consequently, new technological options for the decontamination and/or inertization of incinerator filter fly ash are being developed with the objective of rendering a product that can be reused or, at least, be deposited in standard landfill sites with no risk. The proposed alternatives include immobilization by cement-based techniques, wet chemical treatments and thermal treatments of vitrification. Of these, vitrification is the most promising solution, because, if residues are melted at temperatures > 1,300 C, a relatively inert glass is produced. In the present investigation, glass-ceramics were obtained by a controlled crystallization heat treatment of vitrified incinerator filter fly ashes. The mechanical and other technical properties of the products were measured with special emphasis on assessing their in vitro toxic potential.« less

Novel, inorganic composites using porous, alkali-activated, aluminosilicate binders

NASA Astrophysics Data System (ADS)

Musil, Sean

Geopolymers are an inorganic polymeric material composed of alumina, silica, and alkali metal oxides. Geopolymers are chemical and fire resistant, can be used as refractory adhesives, and are processed at or near ambient temperature. These properties make geopolymer an attractive choice as a matrix material for elevated temperature composites. This body of research investigated numerous different reinforcement possibilities and variants of geopolymer matrix material and characterized their mechanical performance in tension, flexure and flexural creep. Reinforcements can then be chosen based on the resulting properties to tailor the geopolymer matrix composites to a specific application condition. Geopolymer matrix composites combine the ease of processing of polymer matrix composites with the high temperature capability of ceramic matrix composites. This study incorporated particulate, unidirectional fiber and woven fiber reinforcements. Sodium, potassium, and cesium based geopolymer matrices were evaluated with cesium based geopolymer showing great promise as a high temperature matrix material. It showed the best strength retention at elevated temperature, as well as a very low coefficient of thermal expansion when crystallized into pollucite. These qualities made cesium geopolymer the best choice for creep resistant applications. Cesium geopolymer binders were combined with unidirectional continuous polycrystalline mullite fibers (Nextel(TM) 720) and single crystal mullite fibers, then the matrix was crystallized to form cubic pollucite. Single crystal mullite fibers were obtained by the internal crystallization method and show excellent creep resistance up to 1400°C. High temperature flexural strength and flexural creep resistance of pollucite and polycrystalline/single-crystal fibers was evaluated at 1000-1400°C.

Determination of 30 elements in coal and fly ash by thermal and epithermal neutron-activation analysis

USGS Publications Warehouse

Rowe, J.J.; Steinnes, E.

1977-01-01

Thirty elements are determined in coal and fly ash by instrumental neutron-activation analysis using both thermal and epithermal irradiation. Gamma-ray spectra were recorded 7 and 20 days after the irradiations. The procedure is applicable to the routine analysis of coals and fly ash. Epithermal irradiation was found preferable for the determination of Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, Cs, Ba, Sm, Tb, Hf, Ta, W, Th and U, whereas thermal irradiation was best for Sc, Cr, Fe, Co, La, Ce, Nd, Eu, Yb and Lu. Results for SRM 1632 (coal) and SRM 1633 (fly ash) agree with those of other investigators. ?? 1977.

Correlation between hardness and water absorption properties of Saudi kaolin and white clay geopolymer coating

NASA Astrophysics Data System (ADS)

Ramasamy, Shamala; Abdullah, Mohd Mustafa Al Bakri; Huang, Yue; Hussin, Kamarudin; Wang, Jin; Shahedan, Noor Fifinatasha

2017-09-01

Geopolymer is an uprising technology that is being studied worldwide. Geopolymer raw materials are basically aluminosilicate source materials. However, this technology is yet to infiltrate into pipelines and coating industries which initiated our research idea. The idea of creating universal geopolymer based coating material is mainly to help oil and gas industry reduce its maintenance cost. Kaolin based geopolymer paste was coated on glass reinforced epoxy (GRE) substrates which are majorly used as pipeline material in the oil and gas industry at Saudi Arabia. Kaolin and white clay was chosen as raw material to study the possibilities of utilizing underused aluminosilicate raw materials for geopolymer coating. To obtain suitable formulation, Na2SiO3/NaOH ratio was varied from 0.40 untill 0.60 while other parameters such as solid/liquid ratio and NaOH molarity were kept constant at values as per previous works. Geopolymer coated GRE substrates were then subjected to water absorption, flexural strength and hardness test to validate our findings. Water absorption is a crucial test as for coating materials which justifies the pratical usability of the coating product. Upon testing, kaolin and white clay based geopolymer coating each shows promising properties at Na2SiO3/NaOH ratio of 0.45 and 0.50 each.

Sorption of metolachlor and atrazine in fly ash amended soils: comparison of optimized isotherm models.

PubMed

Ghosh, Rakesh K; Singh, Neera

2012-01-01

Adsorption of metolachlor and atrazine was studied in the fly ash (Inderprastha and Badarpur)- amended Inceptisol and Alfisol soils using batch method. Results indicated that sorption of both the herbicides in soil+fly ash mixtures was highly nonlinear and sorption decreased with a higher herbicide concentration in the solution. Also, nonlinearity increased with an increase in the level of fly ash amendment from 0-5%. Three two-parameter monolayer isotherms viz. Langmuir, Temkin, Jovanovic and one imperical Freundlich models were used to fit the experimental data. Data analysis and comparison revealed that the Temkin and the Freundlich isotherms were best-suited to explain the sorption results and the observed and the calculated adsorption coefficient values showed less variability. The study suggested that sorption mechanism of metolachlor and atrazine involved the physical association at the sorbate surface and the nonlinearity in the sorption at higher pesticide or fly ash concentration was due to a decrease in the heat of adsorption and higher binding energy.