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Sample records for fly ash concretes

  1. Sorptivity of fly ash concretes

    SciTech Connect

    Gopalan, M.K.

    1996-08-01

    A factorial experiment was designed to measure the sorptivity of cement and fly ash concretes in order to compare the durability of fly ash concrete against the cement concrete. Sorptivity measurements based on the capillary movement of water was made on three grades of cement concrete and six grades of fly ash mixes. The effect of curing was also studied by treating the samples in two curving conditions. A functional relationship of sorptivity against the strength, curing condition and fly ash content has been presented. The results were useful to analyze the factors influencing the durability of cement and fly ash concretes and to explain why some of the previously reported findings were contradictory. Curing conditions have been found to be the most important factor that affected the durability properties of fly ash concrete. When proper curing was provided, a mix with 40% fly ash was found to reduce the sorptivity by 37%. Under inadequate curing the sorptivity was found to increase by 60%. The influence of curing on cement concrete was found to be of much less importance.

  2. Treatment of fly ash for use in concrete

    DOEpatents

    Boxley, Chett

    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.

  3. 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.

  4. Treatment of fly ash for use in concrete

    DOEpatents

    Boxley, Chett; Akash, Akash; Zhao, Qiang

    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.

  5. Optimizing the use of fly ash in concrete

    SciTech Connect

    Thomas, M.

    2007-07-01

    The optimum amount of fly ash varies not only with the application, but also with composition and proportions of all the materials in the concrete mixture (especially the fly ash), the conditions during placing (especially temperature), construction practices (for example, finishing and curing) and the exposure conditions. This document discusses issues related to using low to very high levels of fly ash in concrete and provides guidance for the use of fly ash without compromising the construction process or the quality of the finished product. The nature of fly ashes including their physical, mineralogical and chemical properties is covered in detail, as well as fly ash variability due to coal composition and plant operating conditions. A discussion on the effects of fly ash characteristics on fresh and hardened concrete properties includes; workability, bleeding, air entrainment, setting time, heat of hydration, compressive strength development, creep, drying shrinkage, abrasion resistance, permeability, resistance to chlorides, alkali-silica reaction (ASR), sulfate resistance, carbonation, and resistance to freezing and thawing and deicer salt scaling. Case studies were selected as examples of some of the more demanding applications of fly ash concrete for ASR mitigation, chloride resistance, and green building.

  6. Fly ash and concrete: a study determines whether biomass, or coal co-firing fly ash, can be used in concrete

    SciTech Connect

    Wang, Shuangzhen; Baxter, Larry

    2006-08-01

    Current US national standards for using fly ash in concrete (ASTM C618) state that fly ash must come from coal combustion, thus precluding biomass-coal co-firing fly ash. The co-fired ash comes from a large and increasing fraction of US power plants due to rapid increases in co-firing opportunity fuels with coal. The fly ashes include coal fly ash, wood fly ash from pure wood combustion, biomass and coal co-fired fly ash SW1 and SW2. Also wood fly ash is blended with Class C or Class F to produce Wood C and Wood E. Concrete samples were prepared with fly ash replacing cement by 25%. All fly ash mixes except wood have a lower water demand than the pure cement mix. Fly ashes, either from coal or non coal combustion, increase the required air entraining agent (AEA) to meet the design specification of the mixes. If AEA is added arbitrarily without considering the amount or existence of fly ash results could lead to air content in concrete that is either too low or too high. Biomass fly ash does not impact concrete setting behaviour disproportionately. Switch grass-coal co-fired fly ash and blended wood fly ash generally lie within the range of pure coal fly ash strength. The 56 day flexure strength of all the fly ash mixes is comparable to that of the pure cement mix. The flexure strength from the coal-biomass co-fired fly ash does not differ much from pure coal fly ash. All fly ash concrete mixes exhibit lower chloride permeability than the pure cement mixes. In conclusion biomass coal co-fired fly ash perform similarly to coal fly ash in fresh and hardened concrete. As a result, there is no reason to exclude biomass-coal co-fired fly ash in concrete.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. High-performance, high-volume fly ash concrete

    SciTech Connect

    2008-01-15

    This booklet offers the construction professional an in-depth description of the use of high-volume fly ash in concrete. Emphasis is placed on the need for increased utilization of coal-fired power plant byproducts in lieu of Portland cement materials to eliminate increased CO{sub 2} emissions during the production of cement. Also addressed is the dramatic increase in concrete performance with the use of 50+ percent fly ash volume. The booklet contains numerous color and black and white photos, charts of test results, mixtures and comparisons, and several HVFA case studies.

  13. 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.

  14. Strength prediction of fly ash concretes by accelerated testing

    SciTech Connect

    Tokyay, M.

    1999-11-01

    Relationships between standard compressive strength at 7, 28, and 90 days and early strength attained by (1) autogeneous curing, (2) warm water curing, and (3) boiling water curing were obtained and a regression expression to predict the strength of concretes containing high-lime and low-lime fly ashes as partial cement replacement are proposed. The control concretes were designed for 28-day characteristic compressive strengths, f{sub ck28} = 40, 60, 65, and 70 MPa. All concretes were proportioned to keep the slump at 80--100 mm. The curing methods used were in accordance with the relevant ASTM and Turkish standards.

  15. 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.

  16. The influence of fly ash on obtaining quality plastic and hardened properties of portland cement concrete

    SciTech Connect

    Mohamad, A.B.

    1989-01-01

    An experimental test burn was done substituting coal with Refuse-Derived-Fuel(RDF) consisting mainly of waste paper and plastic with heating value of 6000 to 8000 BTU/lb. Twelve test burn days were run with 4 days of 5% RDF and 8 days of 10% RDF. The effect of RDF on the chemical and physical properties of fly ash and the effect of coal-RDF fly ash on the properties of plastic and hardened concrete were investigated. Coal fly ash from Merrimack Power Station was classified as an ASTM class F complying to the chemical and physical properties of ASTM C-618 specifications. Coal-RDF fly ash produced during the test burn showed chemical and physical properties comparable to coal fly ash. The average chemical and physical properties of coal-RDF fly ash complied to ASTM C-618 specifications. Concrete made with coal fly ash and coal-RDF fly ash showed increased slump in high paste mixes and decreased slump in low paste mixes. Air content decreased with increased fly ash at a constant dosage of air entrainment. Compressive strength the fly ash concrete at and beyond 28 days were comparable to ordinary portland cement concrete. Heavy metals were not leached from coal fly ash and coal-RDF fly ash concrete during a column test using a synthetic acid rain of pH 4.5 even though small quantities of cadmium and lead were found to leach from coal fly ash and coal-RDF fly ash during the beginning of the test. The volume of the acid rain was approximately equivalent to 7 years of precipitation, assuming 36 inches of rain per year. A microscopic investigation comparing the structure of pastes made with coal fly ash, coal-RDF fly ash, incinerator fly ash and incinerator bottom ash was conducted.

  17. A study on high strength concrete prepared with large volumes of low calcium fly ash

    SciTech Connect

    Poon, C.S.; Lam, L.; Wong, Y.L.

    2000-03-01

    This paper presents the results of a laboratory study on high strength concrete prepared with large volumes of low calcium fly ash. The parameters studied included compressive strength, heat of hydration, chloride diffusivity, degree of hydration, and pore structures of fly ash/cement concrete and corresponding pastes. The experimental results showed that concrete with a 28-day compressive strength of 80 MPA could be obtained with a water-to-binder (w/b) ratio of 0.24, with a fly ash content of 45%. Such concrete has lower heat of hydration and chloride diffusivity than the equivalent plain cement concrete or concrete prepared with lower fly ash contents. The test results showed that at lower w/b ratios, the contribution to strength by the fly ash was higher than in the mixes prepared with higher w/b ratios. The study also quantified the reaction rates of cement and fly ash in the cementitious materials. The results demonstrated the dual effects of fly ash in concrete: (1) act as a micro-aggregate and (2) being a pozzolana. It was also noted that the strength contribution of fly ash in concrete was better than in the equivalent cement/fly ash pastes suggesting the fly ash had improved the interfacial bond between the past and the aggregates in the concrete. Such an improvement was also reflected in the results of the mercury intrusion porosimetry (MIP) test.

  18. 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. PMID:25013870

  19. 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

  20. Investigation of high-volume fly ash concrete systems. Final report

    SciTech Connect

    Berry, E.E.; Hemmings, R.T.; Zhang, M.H.; Malhotra, V.M.; Bilodeau, A.; Carette, G.G.

    1993-10-01

    This report presents the findings of an extensive scientific and engineering investigation of the properties of high-volume fly ash (HVFA) concretes prepared from a broad range of portland cement and fly ash materials from sources throughout the United States. The purpose of the project was to support commercialization of HVFA concretes, and hence enhance the beneficial use of fly ash in value-added products. A total of sixteen HVFA concrete mixtures incorporating 8 widely different fly ashes and 2 cements of high and low alkali content were investigated. The proportion of fly ash in all the concrete mixtures was 58% by weight of the cementitious materials, with a water-to-binder (cement + fly ash) ratio of 0.33 for all the mixtures, and a high degree of workability maintained by use of a superplasticizer. All test concretes were air entrained. A broad range of engineering properties was evaluated including compressive strength, Young`s modulus of elasticity, flexural strength, splitting-tensile strength, abrasion resistance, drying shrinkage, creep, air-void parameters of the hardened concrete, resistance to freezing and thawing cycling, de-icing salt scaling resistance, resistance to chloride-ion penetration, water permeability, and sulphate resistance.

  1. 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

  2. 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. PMID:22837687

  3. CO2 capture using fly ash from coal fired power plant and applications of CO2-captured fly ash as a mineral admixture for concrete.

    PubMed

    Siriruang, Chaichan; Toochinda, Pisanu; Julnipitawong, Parnthep; Tangtermsirikul, Somnuk

    2016-04-01

    The utilization of fly ash as a solid sorbent material for CO2 capture via surface adsorption and carbonation reaction was evaluated as an economically feasible CO2 reduction technique. The results show that fly ash from a coal fired power plant can capture CO2 up to 304.7 μmol/g fly ash, consisting of 2.9 and 301.8 μmol/g fly ash via adsorption and carbonation, respectively. The CO2 adsorption conditions (temperature, pressure, and moisture) can affect CO2 capture performance of fly ash. The carbonation of CO2 with free CaO in fly ashes was evaluated and the results indicated that the reaction consumed most of free CaO in fly ash. The fly ashes after CO2 capture were further used for application as a mineral admixture for concrete. Properties such as water requirement, compressive strength, autoclave expansion, and carbonation depth of mortar and paste specimens using fly ash before and after CO2 capture were tested and compared with material standards. The results show that the expansion of mortar specimens using fly ash after CO2 capture was greatly reduced due to the reduction of free CaO content in the fly ash compared to the expansion of specimens using fresh fly ash. There were no significant differences in the water requirement and compressive strength of specimens using fly ash, before and after CO2 capture process. The results from this study can lead to an alternative CO2 capture technique with doubtless utilization of fly ash after CO2 capture as a mineral admixture for concrete. PMID:26803257

  4. Investigation of air-entraining admixture dosage in fly ash concrete

    SciTech Connect

    Ley, M.T.; Harris, N.J.; Folliard, K.J.; Hover, K.C.

    2008-09-15

    The amount of air-entraining admixture (AEA) needed to achieve a target air content in fresh concrete can vary significantly with differences in the fly ash used in the concrete. The work presented in this paper evaluates the ability to predict the AEA dosage on the basis of tests on the fly ash alone. All results were compared with the dosage of AEA required to produce an air content of 6% in fresh concrete. Fly ash was sampled from six separate sources. For four of these sources, samples were obtained both before and after the introduction of 'low-NOx burners'. Lack of definitive data about the coal itself or the specifics of the burning processes prevents the ability to draw specific conclusions about the impact of low-NOx burners on AEA demand. Nevertheless, the data suggest that modification of the burning process to meet environmental quality standards may affect the fly ash-AEA interaction.

  5. Drying shrinkage of fibre-reinforced lightweight aggregate concrete containing fly ash

    SciTech Connect

    Kayali, O.; Haque, M.N.; Zhu, B.

    1999-11-01

    Lightweight aggregate concretes containing fly ash with a compressive strength between 61 to 67 NPa were produced. The lightweight aggregate used was sintered fly ash. The concretes were reinforced with either polypropylene or steel fibres. The fibres did not affect the compressive strength, but did increase the tensile strength of these concretes. The modulus of elasticity of all the lightweight concretes tested was about 21 GPa, compared to 35 GPa for the normal-weight concrete. Fibre reinforcement did not affect the value of the elastic modulus. This type of lightweight concrete, containing fly ash as 23% of the total cementitious content, resulted in long-term shrinkage that is nearly twice as large as normal-weight concrete of somewhat similar strength. Polypropylene fibre reinforcement did not reduce drying shrinkage, while steel fibres did. Early shrinkage behavior of this type of lightweight concrete was similar to normal-weight concrete. However, the rate of shrinkage of the lightweight concrete remained constant until nearly 100 days of drying. This is different from normal-weight concrete that showed appreciably after 56 days. Shrinkage of normal-weight concrete stabilized after 400 days, which shrinkage of lightweight concrete did not appear to stabilize after a similar period of continuous drying.

  6. Fourth international conference on fly ash, silica fume, slag, and natural pozzolans in concrete: Supplemental proceedings

    SciTech Connect

    Berry, E.E.; Hemmings, R.T.; Zhang, M.H. ); Malhotra, V.M. )

    1992-03-01

    This report consists of four papers presented at a special session on high volume fly ash (HVFA) concrete. These four papers summarize an EPRI research project currently in progress that is investigating HVFA concretes. This objective of this research is to commercialize the HVFA concrete technology through: (1) an extensive measurement of basic engineering and durability properties; (2) an examination of the binder microstructure and cementation hydration reactions; and (3) technology transfer to industry and the construction community. Overall the data from the project that are summarized in these papers, show that commercial quality structural grade concrete (up to 50 MPa compressive strength at 90 days) can be made from a wide range of fly ashes and cements available throughout the USA. It has been shown in this project that fly ash is a reactive participant with the Portland cement in the cementing process, and also serves as a microaggregate in a multiphase composite binder formed during curing. The properties of the binder were found to significantly influence strength development, elastic modulus, and the stress-strain behavior of HVFA concrete. Overall, the data presented show that regardless of the type of fly ash (from the nine US ashes evaluated) and the two cements used, that air-entrained HVFA concrete exhibits excellent durability in all respects except under application of deicing salts where some surface scaling has been observed in the laboratory.

  7. Fly ash carbon passivation

    DOEpatents

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

    2013-05-14

    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 of 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.

  8. Fly-ash utilization

    SciTech Connect

    Lockerby, R.W.

    1984-01-01

    The over 200 references in this bibliography cover some of the uses found for fly-ash, which range from the manufacture of bricks and as a new type of concrete to the recovery of aluminum and other valuable ores from the ash. The entries are grouped under seven headings: General, Agriculture, Brickmaking, Cement/Concrete, Land Reclamation, Resource Recovery, and Other.

  9. Binary Effect of Fly Ash and Palm Oil Fuel Ash on Heat of Hydration Aerated Concrete

    PubMed Central

    Mehmannavaz, Taha; Ismail, Mohammad; Radin Sumadi, Salihuddin; Rafique Bhutta, Muhammad Aamer; Samadi, Mostafa

    2014-01-01

    The binary effect of pulverized fuel ash (PFA) and palm oil fuel ash (POFA) on heat of hydration of aerated concrete was studied. Three aerated concrete mixes were prepared, namely, concrete containing 100% ordinary Portland cement (control sample or Type I), binary concrete made from 50% POFA (Type II), and ternary concrete containing 30% POFA and 20% PFA (Type III). It is found that the temperature increases due to heat of hydration through all the concrete specimens especially in the control sample. However, the total temperature rises caused by the heat of hydration through both of the new binary and ternary concrete were significantly lower than the control sample. The obtained results reveal that the replacement of Portland cement with binary and ternary materials is beneficial, particularly for mass concrete where thermal cracking due to extreme heat rise is of great concern. PMID:24696646

  10. Fly ash properties and mercury sorbent affect mercury release from curing concrete

    SciTech Connect

    Danold W. Golightly; Chin-Min Cheng; Linda K. Weavers; Harold W. Walker; William E. Wolfe

    2009-04-15

    The release of mercury from concrete containing fly ashes from various generator boilers and powdered activated carbon sorbent used to capture mercury was measured in laboratory experiments. Release of gaseous mercury from these concretes was less than 0.31% of the total quantity of mercury present. The observed gaseous emissions of mercury during the curing process demonstrated a dependency on the organic carbon content of the fly ash, with mercury release decreasing with increasing carbon content. Further, lower gaseous emissions of mercury were observed for concretes incorporating ash containing activated carbon sorbent than would be expected based on the observed association with organic carbon, suggesting that the powdered activated carbon more tightly binds the mercury as compared to unburned carbon in the ash. Following the initial 28-day curing interval, mercury release diminished with time. In separate leaching experiments, average mercury concentrations leached from fly ash concretes were less than 4.1 ng/L after 18 h and 7 days, demonstrating that less than 0.02% of the mercury was released during leaching. 25 refs., 4 figs., 5 tabs.

  11. Leaching behavior of heavy metals from municipal solid wastes incineration (MSWI) fly ash used in concrete.

    PubMed

    Shi, Hui-Sheng; Kan, Li-Li

    2009-05-30

    The characteristics of municipal solid waste incineration (MSWI) fly ash, surface leaching toxicity and successive leaching concentration of heavy metals from MSWI fly ash-cement hardened pastes were studied. And, the relationships between leaching concentrations of heavy metals and leaching time were also discussed. Experimental results showed that immobilization effect of cement on MSWI fly ash is good. Even if MSWI fly ash-cement hardened pastes were damaged, the leaching toxicity is still in a safety range. In early leaching stage, the surface leaching rate is relatively a little high, up to 10(-5)-10(-4)cmd(-1) order of magnitude, in the later time of leaching, its rate rapidly declined, down to 10(-7). Most of leached heavy metals are produced at early ages. The leaching concentration of heavy metals and leaching time has strong positive relationships. In factual utilizing circumstances, heavy metals' leaching from MSWI fly ash-cement hardened pastes is a very slow and gradually diluting process. The leaching toxicity of heavy metals is far lower than that of the National Standard of China, and minimum harmful matters can be contained and released in the environment. Reusing of MSWI fly ash as partial replacement for cement in concrete mixes is potentially feasible. PMID:18838222

  12. Modelling chloride diffusion in concrete: Effect of fly ash and slag

    SciTech Connect

    Thomas, M.D.A.; Bamforth, P.B.

    1999-04-01

    The ability of concrete to resist the penetration of chloride ions is a critical parameter in determining the service life of steel-reinforced concrete structures exposed to deicing salts or marine environments. Data from long-term field and laboratory studies of concrete exposed to chloride environments were analyzed using a chloride transport model developed at the University of Toronto. The results show that the incorporation of fly ash and slag may have little impact on transport properties determined at early ages (e.g., 28 days), but can lead to order of magnitude improvements in the long term. This means that the rate of chloride penetration during the first 6 months or so of exposure is similar for concretes with and without these materials. However, after a few years of exposure, chloride ingress slows to a much-decreased rate in fly ash and slag concretes, leading to dramatic increases in the predicted service life. Predictive models and laboratory test methods for determining chloride ingress should take account of the time-dependent nature of the transport processes in concrete, especially when supplementary cementing materials, such as fly ash or slag, are used.

  13. Gaseous mercury from curing concretes that contain fly ash: laboratory measurements.

    PubMed

    Golightly, Danold W; Sun, Ping; Cheng, Chin-Min; Taerakul, Panuwat; Walker, Harold W; Weavers, Linda K; Golden, Dean M

    2005-08-01

    Total gaseous mercury in headspace air was measured for enclosed concretes dry curing at 40 degrees C for intervals of 2, 28, and 56 days. Release of mercury was confirmed for ordinary Portland cement concrete (OPC) and three concretes in which class F fly ash substituted for a fraction of the cement: (a) 33% fly ash (FA33), (b) 55% fly ash (FA55), and (c) 33% fly ash plus 0.5% mercury-loaded powdered activated carbon (HgPAC). Mean rates of mercury release (0.10-0.43 ng/day per kg of concrete) over the standard first 28 days of curing followed the order OPC < FA33 approximately FA55 < HgPAC. The mercury flux from exposed surfaces of these concretes ranged from 1.9 +/- 0.5 to 8.1 +/-2.0 ng/m(2)/h, values similar to the average flux for multiple natural substrates in Nevada, 4.2 +/- 1.4 ng/m(2)/h, recently published by others. Air sampling extending for 28 days beyond the initial 28-day maturation for OPC, FA55, and HgPAC suggested that the average Hg release rate by OPC is constant over 56 days and that mercury release rates for FA55 and HgPAC may ultimately diminish to levels exhibited by OPC concrete. The release of mercury from all samples was less than 0.1% of total mercury content over the initial curing period, implying that nearly all of the mercury was retained in the concrete. PMID:16124303

  14. Gaseous mercury from curing concretes that contain fly ash: laboratory measurements

    SciTech Connect

    Danold W. Golightly; Ping Sun; Chin-Min Cheng; Panuwat Taerakul; Harold W. Walker; Linda K. Weavers; Dean M. Golden

    2005-08-01

    Total gaseous mercury in headspace air was measured for enclosed concretes dry curing at 40 C for intervals of 2, 28, and 56 days. Release of mercury was confirmed for ordinary Portland cement concrete (OPC) and three concretes in which class F fly ash from coal-combustion substituted for a fraction of the cement: (a) 33% fly ash (FA33), (b) 55% fly ash (FA55), and (c) 33% fly ash plus 0.5% mercury-loaded powdered activated carbon (HgPAC). Mean rates of mercury release (0.10-0.43 ng/day per kg of concrete) over the standard first 28 days of curing followed the order OPC {lt} FA33 {approximately} FA55 {lt} HgPAC. The mercury flux from exposed surfaces of these concretes ranged from 1.9 {+-} 0.5 to 8.1 {+-} 2.0 ng/m{sup 2}/h, values similar to the average flux for multiple natural substrates in Nevada, 4.2 {+-} 1.4 ng/m{sup 2}/h, recently published by others. Air sampling extending for 28 days beyond the initial 28-day maturation for OPC, FA55, and HgPAC suggested that the average Hg release rate by OPC is constant over 56 days and that mercury release rates for FA55 and HgPAC may ultimately diminish to levels exhibited by OPC concrete. The release of mercury from all samples was less than 0.1% of total mercury content over the initial curing period, implying that nearly all of the mercury was retained in the concrete. 20 refs., 3 figs., 3 tabs.

  15. Effects of lightweight fly ash aggregate properties on the behavior of lightweight concretes.

    PubMed

    Kockal, Niyazi Ugur; Ozturan, Turan

    2010-07-15

    Influence of different lightweight fly ash aggregates on the behavior of concrete mixtures was discussed. The performance characteristics of lightweight concretes (LWCs) and normalweight concrete (NWC) were investigated through compressive strength, modulus of elasticity and splitting tensile strength representing the mechanical behavior; through rapid chloride permeability representing the transport properties and through rapid freezing and thawing cycling representing the durability of concrete. In order to investigate the aggregate-cement paste interfacial transition zone (ITZ), SEM observations were performed. Regression and graphical analysis of the experimental data obtained were also performed. An increase in compressive strength was observed with the increase in oven-dry density. The ratios of splitting tensile strength to compressive strength of lightweight aggregate concretes were found to be similar to that of normalweight concrete. All the 28- and 56-day concrete specimens had a durability factor greater than 85 and 90, respectively, which met the requirement for freezing and thawing durability. PMID:20399557

  16. Improve the strength of concrete-filled steel tubular columns by the use of fly ash

    SciTech Connect

    Li Gengying; Zhao Xiaohua; Chen Liqiang

    2003-05-01

    Concrete-filled steel tubular columns (CFTs) are becoming widely used in engineering. In the present paper, the addition of fly ash and an expansive agent to the concrete of CFTs or a thin layer of fly ash to the interface between steel tube and concrete (CFTFCs) to improve the compressive strength and the bond strength of CFTs was experimentally investigated. The results show that the expansive concrete-filled steel tubular columns (CFETs) have the highest bond strength and compressive strength at the age of 7 days, and CFTFCs have higher bond strength and compressive strength than fly ash concrete-filled steel tubular columns (CFFTs), which in turn are higher than CFTs. However, both bond strength and compressive strength of CFTFCs become the highest at the age of 28 days. The morphology (size and shape) of mineralogy and microstructure of the interface at the age of 28 days were also investigated by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It is shown that the strength improvement of CFTFCs mainly depends on the content of SiO{sub 2} and CaO in the interface, and higher content of SiO{sub 2} and/or lower content of CaO are preferred.

  17. 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. PMID:22954605

  18. Effect of coal combustion fly ash use in concrete on the mass transport release of constituents of potential concern.

    PubMed

    Garrabrants, Andrew C; Kosson, David S; DeLapp, Rossane; van der Sloot, Hans A

    2014-05-01

    Concerns about the environmental safety of coal combustion fly ash use as a supplemental cementitious material have necessitated comprehensive evaluation of the potential for leaching concrete materials containing fly ash used as a cement replacement. Using concrete formulations representative of US residential and commercial applications, test monoliths were made without fly ash replacement (i.e., controls) and with 20% or 45% of the portland cement fraction replaced by fly ash from four coal combustion sources. In addition, microconcrete materials were created with 45% fly ash replacement based on the commercial concrete formulation but with no coarse aggregate and an increased fine aggregate fraction to maintain aggregate-paste interfacial area. All materials were cured for 3 months prior to mass transport-based leach testing of constituents of potential concern (i.e., Sb, As, B, Ba, Cd, Cr, Mo, Pb, Se, Tl and V) according to EPA Method 1315. The cumulative release results were consistent with previously tested samples of concretes and mortars from international sources. Of the 11 constituents tested, only Sb, Ba, B, Cr and V were measured in quantifiable amounts. Microconcretes without coarse aggregate were determined to be conservative surrogates for concrete in leaching assessment since cumulative release from microconcretes were only slightly greater than the associated concrete materials. Relative to control materials without fly ash, concretes and microconcretes with fly ash replacement of cement had increased 28-d and 63-d cumulative release for a limited number 10 comparison cases: 2 cases for Sb, 7 cases for Ba and 1 case for Cr. The overall results suggest minimal leaching impact from fly ash use as a replacement for up to 45% of the cement fraction in typical US concrete formulations; however, scenario-specific assessment based on this leaching evaluation should be used to determine if potential environmental impacts exist. PMID:24359922

  19. 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

  20. Coal fly ash: the most powerful tool for sustainability of the concrete industry

    SciTech Connect

    Mehta, P.K.

    2008-07-01

    In the last 15 years the global cement industry has almost doubled its annual rate of direct emissions of carbon dioxide. These can be cut back by reducing global concrete consumption, reducing the volume of cement paste in mixtures and reducing the proportion of portland clinker in cement. It has recently been proved that use of high volumes of coal fly ash can produce low cost, durable, sustainable cement and concrete mixtures that would reduce the carbon footprint of both the cement and the power generation industries. 2 photos.

  1. 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]. PMID:26693505

  2. Reuse of municipal solid wastes incineration fly ashes in concrete mixtures.

    PubMed

    Collivignarelli, Carlo; Sorlini, Sabrina

    2002-01-01

    This study is aimed at assessing the feasibility of concrete production using stabilized m.s.w. (municipal solid waste) incineration fly ashes in addition to natural aggregates. The tested fly ashes were washed and milled, then stabilized by a cement-lime process and finally were reused as a "recycled aggregate" for cement mixture production, in substitution of a natural aggregate (with dosage of 200-400 kg m(-3)). These mixtures, after curing, were characterized with conventional physical-mechanical tests (compression, traction, flexure, modulus of elasticity, shrinkage). In samples containing 200 kg(waste) m(-3)(concrete), a good compressive strength was achieved after 28 days of curing. Furthermore, concrete leaching behavior was evaluated by means of different leaching tests, both on milled and on monolithic samples. Experimental results showed a remarkable reduction of metal leaching in comparison with raw waste. In some cases, similar behavior was observed in "natural" concrete (produced with natural aggregates) and in "waste containing" concrete. PMID:12423053

  3. The durability of concrete containing a high-level of fly ash or a ternary blend of supplementary cementing materials

    NASA Astrophysics Data System (ADS)

    Gilbert, Christine M.

    The research for this study was conducted in two distinct phases as follows: Phase 1: The objective was to determine the effect of fly ash on the carbonation of concrete. The specimens made for this phase of the study were larger in size than those normally used in carbonation studies and were are meant to more accurately reflect real field conditions. The results from early age carbonation testing indicate that the larger size specimens do not have a measured depth of carbonation as great as that of the smaller specimens typically used in carbonation studies at the same age and under the same conditions. Phase 2: The objective was to evaluate the performance of ternary concrete mixes containing a ternary cement blend consisting of Portland cement, slag and Type C fly ash. It was found that concrete mixtures containing the fly ash with the lower calcium (CaO) content (in binary or ternary blends) provided superior durability performance and resistance to ASR compared to that of the fly ash with the higher CaO content. Ternary blends (regardless of the CaO content of the fly ash) provided better overall durability performance than binary blends of cementing materials or the control.

  4. Development of High Strength Fly Ash Glass-ceramics by Concrete Sludge Addition

    NASA Astrophysics Data System (ADS)

    Ikeda, Kiyohiko; Yoshikawa, Akira; Hiratsuka, Akira; Tsujino, Ryoji; Kinoshita, Hiroyuki; Kawamura, Ryusuke; Nakayama, Yoshihisa; Iguchi, Manabu

    A large amount of fly ash is exhausted from the thermal powder plant and it is a poisonous substance including the heavy metals and dioxin. The glass solidification is an effective method as one of the waste solidification technologies. Further, producing new materials by mixing together more than two kinds of raw materials is a more useful method. However, a number of trials are required in this method. We selected glass-ceramics with the crystal structure of an Anorthite (CaO·Al2O3·2SiO2), fly ash as inorganic wastes and concrete sludge for construction materials. It is necessary to clarify the optimum production method. Batches were prepared by mixing these raw materials with various weight ratios. Glass samples were produced by melting the batches at 1450°C and quenching. They were reheated in the region of 950-1100°C to make into glass-ceramic. The properties of obtained glass-ceramics were examined by XRD analysis, SEM observation, and some material tests for the strength, hardness, toughness, and so on. The XRD analysis and SEM observation showed that the crystallized phase of the produced glass-ceramics were identified as an Anorthite. The material tests showed that the Vickers hardness was very high, while the chemical resistance was relatively low.

  5. Gaseous mercury release during steam curing of aerated concretes that contain fly ash and activated carbon sorbent

    SciTech Connect

    Danold W. Golightly; Chin-Min Cheng; Ping Sun; Linda K. Weavers; Harold W. Walker; Panuwat Taerakul; William E. Wolfe

    2008-09-15

    Gaseous mercury released from aerated concrete during both presteam curing at 25{sup o}C and steam curing at 80{sup o}C was measured in controlled laboratory experiments. Mercury release originated from two major components in the concrete mixture: (1) class F coal fly ash and (2) a mixture of the fly ash and powdered activated carbon onto which elemental mercury was adsorbed. Mercury emitted during each curing cycle was collected on iodated carbon traps in a purge-and-trap arrangement and subsequently measured by cold-vapor atomic fluorescence spectrometry. Through 3 h of presteam curing, the release of mercury from the freshly prepared mixture was less than 0.03 ng/kg of concrete. Releases of total mercury over the 21 h steam curing process ranged from 0.4 to 5.8 ng of mercury/kg of concrete and depended upon mercury concentrations in the concrete. The steam-cured concrete had a higher mercury release rate (ng kg{sup -1} h{sup -1}) compared to air-cured concrete containing fly ash, but the shorter curing interval resulted in less total release of mercury from the steam-cured concrete. The mercury flux from exposed concrete surfaces to mercury-free air ranged from 0.77 to 11.1 ng m{sup -2} h{sup -1}, which was similar to mercury fluxes for natural soils to ambient air of 4.2 ng m{sup -2} h{sup -1} reported by others. Less than 0.022% of the total quantity of mercury present from all mercury sources in the concrete was released during the curing process, and therefore, nearly all of the mercury was retained in the concrete. 31 refs., 4 figs., 2 tabs.

  6. Mix design and pollution control potential of pervious concrete with non-compliant waste fly ash.

    PubMed

    Soto-Pérez, Linoshka; Hwang, Sangchul

    2016-07-01

    Pervious concrete mix was optimized for the maximum compressive strength and the desired permeability at 7 mm/s with varying percentages of water-to-binder (W/B), fly ash-to-binder (FA/B), nano-iron oxide-to-binder (NI/B) and water reducer-to-binder (WR/B). The mass ratio of coarse aggregates in sizes of 4.75-9.5 mm to the binder was fixed at 4:1. Waste FA used in the study was not compliant with a standard specification for use as a mineral admixture in concrete. One optimum pervious concrete (Opt A) targeting high volume FA utilization had a 28-day compressive strength of 22.8 MPa and a permeability of 5.6 mm/s with a mix design at 36% W/B, 35% FA/B, 6% NI/B and 1.2% WR/B. The other (Opt B) targeting a less use of admixtures had a 28-day compressive strength and a permeability of 21.4 MPa and 7.6 mm/s, respectively, at 32% W/B, 10% FA/B, 0.5% NI/B and 0.8% WR/B. During 10 loads at a 2-h contact time each, the Opt A and Opt B achieved the average fecal coliform removals of 72.4% and 77.9% and phosphorus removals of 49.8% and 40.5%, respectively. Therefore, non-compliant waste FA could be utilized for a cleaner production of pervious concrete possessing a greater structural strength and compatible hydrological property and pollution control potential, compared to the ordinary pervious concrete. PMID:27042974

  7. The influence of fly ash and shell-fish on physical property of concrete cement

    NASA Astrophysics Data System (ADS)

    Rauf, Nurlaela; Hasruddin, M.

    2012-06-01

    The waste fly ash and shell fish are added to base material of cement (clinker, gypsum, trash and lime stone), for environmental reason. The ratio fly ash and shell fish was varied respectively 375:125; 250:250; 125:375, in grams weight for 2500 grams of total material. The chemical composition of raw material was determined by using x-rays fluorescence (XRF). Physical properties of sample match with Standar Nasional Indonesia (SNI). The physical properties of the best sample is made from composition of fly ash and shell fish as a substitution material on cement was 10% in weight, with ratio 250:250 in grams weight.

  8. 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.

  9. 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...

  10. Fly ash quality and utilization

    SciTech Connect

    Barta, L.E.; Lachner, L.; Wenzel, G.B.; Beer, M.J.

    1995-12-01

    The quality of fly ash is of considerable importance to fly ash utilizers. The fly ash puzzolanic activity is one of the most important properties that determines the role of fly ash as a binding agent in the cementing process. The puzzolanic activity, however is a function of fly ash particle size and chemical composition. These parameters are closely related to the process of fly ash formation in pulverized coal fired furnaces. In turn, it is essential to understand the transformation of mineral matter during coal combustion. Due to the particle-to-particle variation of coal properties and the random coalescence of mineral particles, the properties of fly ash particles e.g. size, SiO{sub 2} content, viscosity can change considerably from particle to particle. These variations can be described by the use of the probability theory. Since the mean values of these randomly changing parameters are not sufficient to describe the behavior of individual fly ash particles during the formation of concrete, therefore it is necessary to investigate the distribution of these variables. Examples of these variations were examined by the Computer Controlled Scanning Electron Microscopy (CCSEM) for particle size and chemical composition for Texas lignite and Eagel Butte mineral matter and fly ash. The effect of combustion on the variations of these properties for both the fly ash and mineral matter were studied by using a laminar flow reactor. It is shown in our paper, that there are significant variations (about 40-50% around the mean values) of the above-listed properties for both coal samples. By comparing the particle size and chemical composition distributions of the mineral matter and fly ash, it was possible to conclude that for the Texas lignite mineral matter, the combustion did not effect significantly the distribution of these properties, however, for the Eagel Butte coal the combustion had a major impact on these mineral matter parameters.

  11. Stabilization/solidification of fly ashes and concrete production from bottom and circulating ashes produced in a power plant working under mono and co-combustion conditions.

    PubMed

    Barbosa, Rui; Lapa, Nuno; Lopes, Helena; Gulyurtlu, Ibrahim; Mendes, Benilde

    2011-01-01

    Two combustion tests were performed in a fluidized bed combustor of a thermo-electric power plant: (1) combustion of coal; (2) co-combustion of coal (68.7% w/w), sewage sludge (9.2% w/w) and meat and bone meal (MBM) (22.1% w/w). Three samples of ashes (bottom, circulating and fly ashes) were collected in each combustion test. The ashes were submitted to the following assays: (a) evaluation of the leaching behaviour; (b) stabilization/solidification of fly ashes and evaluation of the leaching behaviour of the stabilized/solidified (s/s) materials; (c) production of concrete from bottom and circulating ashes. The eluates of all materials were submitted to chemical and ecotoxicological characterizations. The crude ashes have shown similar chemical and ecotoxicological properties. The s/s materials have presented compressive strengths between 25 and 40 MPa, low emission levels of metals through leaching and were classified as non-hazardous materials. The formulations of concrete have presented compressive strengths between 12 and 24 MPa. According to the Dutch Building Materials Decree, some concrete formulations can be used in both scenarios of limited moistening and without insulation, and with permanent moistening and with insulation. PMID:21605964

  12. 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%.

  13. Cellular lightweight concrete containing high-calcium fly ash and natural zeolite

    NASA Astrophysics Data System (ADS)

    Jitchaiyaphum, Khamphee; Sinsiri, Theerawat; Jaturapitakkul, Chai; Chindaprasirt, Prinya

    2013-05-01

    Cellular lightweight concrete (CLC) with the controlled density of approximately 800 kg/m3 was made from a preformed foam, Type-I Portland cement (OPC), fly ash (FA), or natural zeolite (NZ), and its compressive strength, setting time, water absorption, and microstructure of were tested. High-calcium FA and NZ with the median particle sizes of 14.52 and 7.72 μm, respectively, were used to partially replace OPC at 0, 10wt%, 20wt%, and 30wt% of the binder (OPC and pozzolan admixture). A water-to-binder mass ratio (W/B) of 0.5 was used for all mixes. The testing results indicated that CLC containing 10wt% NZ had the highest compressive strength. The replacement of OPC with NZ decreased the total porosity and air void size but increased the capillary porosity of the CLC. The incorporation of a suitable amount of NZ decreased the setting time, total porosity, and pore size of the paste compared with the findings with the same amount of FA. The total porosity and cumulative pore volume decreased, whereas the gel and capillary pores increased as a result of adding both pozzolans at all replacement levels. The water absorption increased as the capillary porosity increased; this effect depended on the volume of air entrained and the type or amount of pozzolan.

  14. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE

    SciTech Connect

    Robert F. Rathbone; Thomas L. Robl

    2002-10-30

    The Clean Air Act Amendments of 1990 require large reductions in emissions of NO{sub x} from coal-fired electric utility boilers. This will necessitate the use of ammonia injection, such as in selective catalytic reduction (SCR), in many power plants, resulting in the deposition of ammonia on the fly ash. The presence of ammonia could create a major barrier to fly ash utilization in concrete because of odor concerns. Although there have been limited studies of ammonia emission from concrete, little is known about the quantity of ammonia emitted during mixing and curing, and the kinetics of ammonia release. This is manifested as widely varying opinions within the concrete and ash marketing industry regarding the maximum acceptable levels of ammonia in fly ash. Therefore, practical guidelines for using ammoniated fly ash are needed in advance of the installation of many more SCR systems. The goal of this project was to develop practical guidelines for the handling and utilization of ammoniated fly ash in concrete, in order to prevent a decrease in the use of fly ash for this application. The objective was to determine the amount of ammonia that is released, over the short- and long-term, from concrete that contains ammoniated fly ash. The technical approach in this project was to measure the release of ammonia from mortar and concrete during mixing, placement, and curing. Work initially focused on laboratory mortar experiments to develop fundamental data on ammonia diffusion characteristics. Larger-scale laboratory experiments were then conducted to study the emission of ammonia from concrete containing ammoniated fly ash. The final phase comprised monitoring ammonia emissions from large concrete slabs. The data indicated that, on average, 15% of the initial ammonia was lost from concrete during 40 minutes of mixing, depending on the mix proportions and batch size. Long-term experiments indicated that ammonia diffusion from concrete was relatively slow, with greater

  15. 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.

  16. 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.

  17. Investigation of the use of fly-ash based autoclaved cellular concrete blocks in coal mines for air duct work. Final report, January 25, 1993--December 31, 1994

    SciTech Connect

    Horvath, M.L.

    1995-06-19

    Coal mines are required to provide ventilation to occupied portions of underground mines. Concrete block is used in this process to construct air duct walls. However, normal concrete block is heavy and not easy to work with and eventually fails dramatically after being loaded due to mine ceiling convergence and/or floor heave. Autoclaved cellular concrete block made from (70{plus_minus}%) coal fly ash is lightweight and less rigid when loaded. It is lighter and easier to use than regular concrete block for underground mine applications. It has also been used in surface construction around the world for over 40 years. Ohio Edison along with eight other electric utility companies, the Electric Power Research Institute (EPRI), and North American Cellular Concrete constructed a mobile demonstration plant to produce autoclaved cellular concrete block from utility fly ash. To apply this research in Ohio, Ohio Edison also worked with the Ohio Coal Development Office and CONSOL Inc. to produce autoclaved cellular concrete block not only from coal ash but also from LIMB ash, SNRB ash, and PFBC ash from various clean coal technology projects sponsored by the Ohio Coal Development Office. The purpose of this project was to demonstrate the potential for beneficial use of fly ash and clean coal technology by-products in the production of lightweight block.

  18. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE

    SciTech Connect

    Robert F. Rathbone; Thomas L. Robl

    2002-04-11

    Work completed in this reporting period focused primarily on continuing measurements of the rate of ammonia loss from concrete, and the measurement of ammonia gas in the air above concrete and flowable fill immediately after placement. Concrete slabs were prepared to monitor the loss of ammonia during mixing, the concentration in the airspace above the slabs soon after placement, and the total quantity of ammonia evolved over a longer time period. Variables tested include temperature, ventilation rate, water:cementitious (W:C) ratio, and fly ash source. Short-term data indicate that for concrete placed in areas with poor air ventilation the fly ash NH{sub 3} concentration should not exceed about 90 to 145 mg/kg ash, depending on the water:cement ratio and the fly ash replacement rate, if a concentration of 10 ppm NH{sub 3} in the air is assumed to be the maximum acceptable level. Longer-term experiments showed that the ammonia loss rate is dependent on ammonia source (that is ammoniated ash vs. non-ammoniated ash with ammonia added to the water), and is also dependent on W:C ratio and temperature. Experiments were also conducted to study the loss of ammonia from fresh concrete during mixing. It was found that a high water:cementitious mix lost a greater percentage of ammonia than a low W:C mix, with a medium W:C mix losing an amount intermediate between these two. However, a larger batch size resulted in a smaller percentage of ammonia lost. The data suggest that a significant quantity of ammonia could be lost from Ready Mix concrete during transit, depending on the transit time, batch size, and mix proportions.

  19. Rapid repair of wet asphaltic concrete using fly ash. Research report

    SciTech Connect

    Cherem-Sacal, D.; Price, D.A.; Fowler, D.W.; Meyer, A.H.

    1985-11-01

    During periods of wet weather, particularly when it is also cold, asphalt pavements develop potholes that cannot be immediately repaired with conventional asphalt materials. Materials are needed that can be successfully used to repair asphalt pavements in wet, or cold and wet, weather. The materials should be of reasonable cost and have at least a moderate life of one to three years. The work described in this volume is a summary of the research done on fly ash as part of the study.

  20. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE

    SciTech Connect

    Robert F. Rathbone; Thomas L. Robl

    2001-10-11

    Work completed in this reporting period focused on the measurement of the rate of ammonia loss from mortar and concrete, and the measurement of ammonia gas in the air above the materials immediately after placement. The majority of mortar experiments have been completed, and testing has begun on concrete. The mortar experiments indicate that the rate of ammonia loss is greater in mortars prepared using a higher water content and water:cement (W:C) ratio, although the higher rate is primarily observed within the first 2 days, after which the loss rates are nearly the same. The source of low-calcium (Class F) fly ash exerted a negligible influence on the loss rate. However, mortar prepared using a higher-calcium fly ash evolved ammonia at a slightly slower rate than the Class F ash mortars. The data also indicate that an increase in ventilation increases the ammonia loss rate from mortar, and suggest that a well-ventilated space could substantially increase the loss of ammonia from mortar and, by inference, a concrete slab. Analysis of ammonia concentrations in the air above freshly-placed mortars in an enclosed space indicate that the fly ash ammonia concentration should not exceed 100 mg N/kg ash in confined space applications. For most other applications with some ventilation the maximum acceptable concentration would be approximately 200 mg/kg. Early results from experiments on concrete suggest that, under similar conditions, ammonia diffusion from concrete occurs at a higher rate than in mortar. In addition, increasing the slump of concrete through the use of chemical admixtures has only a minor effect on the ammonia loss rate.

  1. Hierarchical Order of Influence of Mix Variables Affecting Compressive Strength of Sustainable Concrete Containing Fly Ash, Copper Slag, Silica Fume, and Fibres

    PubMed Central

    Natarajan, Sakthieswaran; Karuppiah, Ganesan

    2014-01-01

    Experiments have been conducted to study the effect of addition of fly ash, copper slag, and steel and polypropylene fibres on compressive strength of concrete and to determine the hierarchical order of influence of the mix variables in affecting the strength using cluster analysis experimentally. While fly ash and copper slag are used for partial replacement of cement and fine aggregate, respectively, defined quantities of steel and polypropylene fibres were added to the mixes. It is found from the experimental study that, in general, irrespective of the presence or absence of fibres, (i) for a given copper slag-fine aggregate ratio, increase in fly ash-cement ratio the concrete strength decreases and with the increase in copper slag-sand ratio also the rate of strength decrease and (ii) for a given fly ash-cement ratio, increase in copper slag-fine aggregate ratio increases the strength of the concrete. From the cluster analysis, it is found that the quantities of coarse and fine aggregate present have high influence in affecting the strength. It is also observed that the quantities of fly ash and copper slag used as substitutes have equal “influence” in affecting the strength. Marginal effect of addition of fibres in the compression strength of concrete is also revealed by the cluster analysis. PMID:24707213

  2. Hierarchical order of influence of mix variables affecting compressive strength of sustainable concrete containing fly ash, copper slag, silica fume, and fibres.

    PubMed

    Natarajan, Sakthieswaran; Karuppiah, Ganesan

    2014-01-01

    Experiments have been conducted to study the effect of addition of fly ash, copper slag, and steel and polypropylene fibres on compressive strength of concrete and to determine the hierarchical order of influence of the mix variables in affecting the strength using cluster analysis experimentally. While fly ash and copper slag are used for partial replacement of cement and fine aggregate, respectively, defined quantities of steel and polypropylene fibres were added to the mixes. It is found from the experimental study that, in general, irrespective of the presence or absence of fibres, (i) for a given copper slag-fine aggregate ratio, increase in fly ash-cement ratio the concrete strength decreases and with the increase in copper slag-sand ratio also the rate of strength decrease and (ii) for a given fly ash-cement ratio, increase in copper slag-fine aggregate ratio increases the strength of the concrete. From the cluster analysis, it is found that the quantities of coarse and fine aggregate present have high influence in affecting the strength. It is also observed that the quantities of fly ash and copper slag used as substitutes have equal "influence" in affecting the strength. Marginal effect of addition of fibres in the compression strength of concrete is also revealed by the cluster analysis. PMID:24707213

  3. Flexural Toughness of Steel Fiber Reinforced High Performance Concrete Containing Nano-SiO2 and Fly Ash

    PubMed Central

    Zhao, Ya-Nan; Li, Qing-Fu; Wang, Peng; Zhang, Tian-Hang

    2014-01-01

    This paper aims to clarify the effect of steel fiber on the flexural toughness of the high performance concrete containing fly ash and nano-SiO2. The flexural toughness was evaluated by two methods, which are based on ASTM C1018 and DBV-1998, respectively. By means of three-point bending method, the flexural toughness indices, variation coefficients of bearing capacity, deformation energy, and equivalent flexural strength of the specimen were measured, respectively, and the relational curves between the vertical load and the midspan deflection (PV-δ) were obtained. The results indicate that steel fiber has great effect on the flexural toughness parameters and relational curves (PV-δ) of the three-point bending beam specimen. When the content of steel fiber increases from 0.5% to 2%, the flexural toughness parameters increase gradually and the curves are becoming plumper and plumper with the increase of steel fiber content, respectively. However these flexural toughness parameters begin to decrease and the curves become thinner and thinner after the steel fiber content exceeds 2%. It seems that the contribution of steel fiber to the improvement of flexural toughness of the high performance concrete containing fly ash and nano-SiO2 is well performed only when the steel fiber content is less than 2%. PMID:24883395

  4. Flexural toughness of steel fiber reinforced high performance concrete containing nano-SiO2 and fly ash.

    PubMed

    Zhang, Peng; Zhao, Ya-Nan; Li, Qing-Fu; Wang, Peng; Zhang, Tian-Hang

    2014-01-01

    This paper aims to clarify the effect of steel fiber on the flexural toughness of the high performance concrete containing fly ash and nano-SiO2. The flexural toughness was evaluated by two methods, which are based on ASTM C1018 and DBV-1998, respectively. By means of three-point bending method, the flexural toughness indices, variation coefficients of bearing capacity, deformation energy, and equivalent flexural strength of the specimen were measured, respectively, and the relational curves between the vertical load and the midspan deflection (P(V)-δ) were obtained. The results indicate that steel fiber has great effect on the flexural toughness parameters and relational curves (P(V)-δ) of the three-point bending beam specimen. When the content of steel fiber increases from 0.5% to 2%, the flexural toughness parameters increase gradually and the curves are becoming plumper and plumper with the increase of steel fiber content, respectively. However these flexural toughness parameters begin to decrease and the curves become thinner and thinner after the steel fiber content exceeds 2%. It seems that the contribution of steel fiber to the improvement of flexural toughness of the high performance concrete containing fly ash and nano-SiO2 is well performed only when the steel fiber content is less than 2%. PMID:24883395

  5. ACAA fly ash basics: quick reference card

    SciTech Connect

    2006-07-01

    Fly ash is a fine powdery material created when coal is burned to generate electricity. Before escaping into the environment via the utility stacks, the ash is collected and may be stored for beneficial uses or disposed of, if necessary. The use of fly ash provides environmental benefits, such as the conservation of natural resources, the reduction of greenhouse gas emissions and eliminating the needed for ash disposal in landfills. It is also a valuable mineral resource that is used in construction and manufacturing. Fly ash is used in the production of Portland cement, concrete, mortars and stuccos, manufactured aggregates along with various agricultural applications. As mineral filler, fly ash can be used for paints, shingles, carpet backing, plastics, metal castings and other purposes. This quick reference card is intended to provide the reader basic source, identification and composition, information specifically related to fly ash.

  6. 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.

  7. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE

    SciTech Connect

    Robert F. Rathbone; Thomas L. Robl

    2001-04-11

    Work completed in this reporting period focused on finalization of the Work and Management Plan, sample acquisition and analysis, evaluation of ammonia measurement methods, and measurement of ammonia loss from mortar. All fly ash samples have been acquired and analyzed for chemical composition and particle fineness. Three non-ammoniated fly ash samples were obtained from power plants that do not inject ammonia for NOx or particulate control, while three ammoniated fly ashes originate from plants that inject ammonia into the flue gas. The fly ash sources were selected based on their marketability as concrete admixtures and ammonia content. Coarse and fine aggregates for mortar and concrete testing have also been secured and have been thoroughly characterized using ASTM methods. Methodologies for the measurement of ammonia in the gaseous and aqueous phase have been carefully considered in the context of their suitability for use in this project. These include ammonia detection tubes, carbon impregnated with sulfuric acid (CISA) tubes, titration, and electrochemical methods. It was concluded that each of these methods is potentially useful for different aspects of the project, depending on the phase and concentration of ammonia to be measured. Preparation of fly ash-containing mortars both with and without ammonia indicated that the ammonia has no significant influence on compressive strength. Finally, measurement of ammonia loss from mortar has begun and the results of several of these experiments are included herein. It has been found that, under the laboratory curing conditions devised, ammonia release from mortar occurs at a relatively rapid rate in the first 24 hours, proceeded by a much slower, essentially linear rate. Furthermore, at the end of the three-week experiments, it was calculated that greater than 80% of the initial ammonia concentration remained within the mortar.

  8. Kohonen's feature maps for fly ash categorization.

    PubMed

    Nataraja, M C; Jayaram, M A; Ravikumar, C N

    2006-12-01

    Fly ash is a common admixture used in concrete and may constitute up to 50% by weight of the total binder material. Incorporation of fly ash in Portland-cement concrete is highly desirable due to technological, economic, and environmental benefits. This article demonstrates the use of artificial intelligence neural networks for the classification of fly ashes in to different groups. Kohonen's Self Organizing Feature Maps is used for the purpose. As chemical composition of fly ash is crucial in the performance of concrete, eight chemical attributes of fly ashes have been considered. The application of simple Kohonen's one-dimensional feature maps permitted to differentiate three main groups of fly ashes. Three one-dimensional feature maps of topology 8-16, 8-24 and 8-32 were explored. The overall classification result of 8-16 topology was found to be significant and encouraging. The data pertaining to 80 fly ash samples were collected from standard published works. The categorization was found to be excellent and compares well with Canadian Standard Association's [CSA A 3000] classification scheme. PMID:17285691

  9. Compressive strength and resistance to chloride ion penetration and carbonation of recycled aggregate concrete with varying amount of fly ash and fine recycled aggregate.

    PubMed

    Sim, Jongsung; Park, Cheolwoo

    2011-11-01

    Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members. PMID:21784626

  10. Alkali ash material: a novel fly ash-based cement.

    PubMed

    Rostami, Hossein; Brendley, William

    2003-08-01

    The United States generates 110 million t of coal ash annually. Approximately 70 million t of this coal ash is fly ash, of which 27% is recycled and the remaining 73% is landfilled. Disposal of such a huge quantity of ash poses a significant environmental problem. A new cementitious material has been developed, called alkali ash material (AAM), which is used to produce concrete for construction. AAM can be used to create a variety of concrete strengths and could revolutionize the concrete product manufacturing industry due to its economic advantage. AAM contains 40-95% Class F fly ash and is used as cement to bind sand, stone, and fibers creating concrete. AAM concrete has been tested for strength, durability, mechanical properties, and, most importantly, economic viability. AAM concrete is economically and technically viable for many construction applications. Some properties include rapid strength gain (90% of ultimate in 1 d), high ultimate strengths (110 MPa or 16,000 psi in 1 d), excellent acid resistance, and freeze-thaw durability. AAM's resistance to chemical attack, such as sulfuric (H2SO4), nitric (HNO3), hydrochloric (HCl), and organic acids, is far better than portland cement concrete. AAM is resistant to freeze-thaw attack based on ASTM C-666 specifications. Potential immediate applications of AAM are blocks, pipe, median barriers, sound barriers, and overlaying materials. Eventual markets are high strength construction products, bridge beams, prestressed members, concrete tanks, highway appurtenances, and other concrete products. PMID:12966995

  11. 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.

  12. Potential products from North Dakota lignite fly ash. Final report

    SciTech Connect

    Anderson, G R

    1980-06-01

    Four major areas where fly ash can be used are explored. Concrete building blocks with fly ash replacing 50% of the portland cement have proven to be successful using current ASTM standards. Results in the ceramics area show that a ceramic-like product using fly ash and crushed glass with a small amount of clay as a green binder. Some preliminary results using sulfur ash in building materials are reported and with results of making wallboard from ash. (MHR)

  13. Kinetics of beneficiated fly ash by carbon burnout

    SciTech Connect

    Okoh, J.M.; Dodoo, J.N.D.; Diaz, A.; Ferguson, W.; Udinskey, J.R. Jr.; Christiana, G.A.

    1997-12-31

    The presence of carbon in fly ash requires an increase in the dosage of the air-entraining admixture for concrete mix, and may cause the admixture to lose efficiency. Specifying authorities for the concrete producers have set maximum allowable levels of residual carbon. These levels are the so called Loss On Ignition (LOI). The concrete producers` day-to-day purchasing decisions sets the LOI at 4%. The objective of the project is to investigate the kinetics of oxidation of residual carbon present in coal fly ash as a possible first step toward producing low-carbon fly ash from high-carbon, low quality fly ash.

  14. Brominated Sorbents for Small Cold-Side ESPs, Hot-Side ESPs and Fly Ash Use in Concrete

    SciTech Connect

    Landreth, Ronald

    2001-09-21

    This report summarizes the work conducted from September 16, 2005 through December 31, 2008 on the project entitled Brominated Sorbents for Small Cold-Side ESPs, Hot-Side ESPs and Fly Ash Use in Concrete . The project covers testing at three host sites: Progress Energy H.F. Lee Station and the Midwest Generation Crawford and Will County Stations. At Progress Energy Lee 1, parametric tests were performed both with and without SO{sub 3} injection in order to determine the impact on the mercury sorbent performance. In addition, tests were performed on the hot-side of the air preheater, before the SO{sub 3} is injected, with H-PAC sorbents designed for use at elevated temperatures. The BPAC injection provided the expected mercury removal when the SO{sub 3} injection was off. A mercury removal rate due to sorbent of more than 80% was achieved at an injection rate of 8 lb/MMacf. The operation with SO{sub 3} injection greatly reduced the mercury sorbent performance. An important learning came from the injection of H- on the hot-side of the air preheater before the SO{sub 3} injection location. The H-PAC injected in this manner appeared to be independent of the SO{sub 3} injection and provided better mercury removal than with injecting on the cold-side with SO{sub 3} injection. Consequently, one solution for plants like Lee, with SO{sub 3} injection, or plants with SO{sub 3} generated by the SCR catalyst, is to inject H-PAC on the hot-side before the SO{sub 3} is in the flue gas. Even better performance is possible by injecting on the cold-side without the SO{sub 3}, however. During the parametric testing, it was discovered that the injection of B-PAC (or H-PAC) was having a positive impact upon ESP performance. It was decided to perform a 3-day continuous injection run with B-PAC in order to determine whether Lee 1 could operate without SO{sub 3} injection. If the test proved positive, the continuous injection would continue as part of the long-term test. The injection of

  15. Ameliorative effect of fly ashes

    SciTech Connect

    Bhumbla, D.K.

    1991-01-01

    Agronomic effectiveness and environmental impact of fly ashes used to reclaim pyritic acid mine spoils were investigated in the laboratory and field. Mine spoils at two abandoned sites were amended with three rates of fly ash, three rates of rock phosphate, and seeded with alfalfa and wheat. Application of fly ash decreased bulk density and increased moisture retention capacity of spoils. Fly ash application reduced cation exchange capacity, acidity, toxic levels of Al, Fe, and Mn in soils by buffering soil pH at 6.5, and retarded pyrite oxidation. The reduction in cation exchange capacity was compensated by release of plant nutrients through diffusion and dissolution of plerospheres in fly ash. Improvement of spoil physical, chemical and microbial properties resulted in higher yield, more nitrogen fixation, and utilization of P from rock phosphate by alfalfa. Laboratory investigations demonstrated that neutralization potential and the amounts of amorphous oxides of iron were more important for classifying fly ashes than the total elemental analysis presently used in a taxonomic classification system. Contamination of the food chain through plant removal of Mo and As in fly ash treated mine spoils was observed only for Mo and only for the first year of cropping. Plant available As and Mo decreased with time. Laboratory leaching and adsorption studies and a field experiment showed that trace metals do not leach from fly ashes at near neutral pH and more oxyanions will leach from fly ashes with low neutralization potential and low amounts of amorphous oxides of iron.

  16. The effect of low-NO{sub x} combustion on residual carbon in fly ash and its adsorption capacity for air entrainment admixtures in concrete

    SciTech Connect

    Pedersen, K.H.; Jensen, A.D.; Dam-Johansen, K.

    2010-02-15

    Fly ash from pulverized coal combustion contains residual carbon that can adsorb the air-entraining admixtures (AEAs) added to control the air entrainment in concrete. This is a problem that has increased by the implementation of low-NO{sub x} combustion technologies. In this work, pulverized fuel has been combusted in an entrained flow reactor to test the impact of changes in operating conditions and fuel type on the AEA adsorption of ash and NO{sub x} formation. Increased oxidizing conditions, obtained by improved fuel-air mixing or higher excess air, decreased the AEA requirements of the produced ash by up to a factor of 25. This was due to a lower carbon content in the ash and a lower specific AEA adsorptivity of the carbon. The latter was suggested to be caused by changes in the adsorption properties of the unburned char and a decreased formation of soot, which was found to have a large AEA adsorption capacity based on measurements on a carbon black. The NO{sub x} formation increased by up to three times with more oxidizing conditions and thus, there was a trade-off between the AEA requirements of the ash and NO{sub x} formation. The type of fuel had high impact on the AEA adsorption behavior of the ash. Ashes produced from a Columbian and a Polish coal showed similar AEA requirements, but the specific AEA adsorptivity of the carbon in the Columbian coal ash was up to six times higher. The AEA requirements of a South African coal ash was unaffected by the applied operating conditions and showed up to 12 times higher AEA adsorption compared to the two other coal ashes. This may be caused by larger particles formed by agglomeration of the primary coal particles in the feeding phase or during the combustion process, which gave rise to increased formation of soot. (author)

  17. General nature and using potentiality of fly ash in China

    SciTech Connect

    Shao, J.; Wang, Z.; Shao, X.; Zhi, X.; Wang, G.

    1998-12-31

    China is the largest fly ash producer of the world. Currently, it produces at least 100 million tons of fly ash each year. Since the different coal types, different coal forming conditions, and different burners are used around the country, the nature of fly ash produced in different plants varies. The characteristics of fly ash influence their utilization. In this paper, numerous data about the characteristics of fly ash in China are collected and analyzed, such as the main chemical components of fly ash (SiO{sub 2}, Al{sub 2}O{sub 3}, K{sub 2}O, Na{sub 2}O, CaO, MgO, Fe{sub 2}O{sub 3}), LOI (C content), and some trace elements and radioactive elements, grain size distribution, phase compositions including types, shapes and contents of glassy bodies, types of inorganic minerals, specific gravity, specific surface, ratio of water requirement, ratio of water content, 28-day compressive strength, etc. Based upon these parameters, methods of fly ash utilization are analyzed systematically. The methods of utilization incorporated with the nature of fly ash can improve the level of fly ash utilization. Fly ash in China is primarily used in road construction, production of building materials (cement, concrete, bricks, tiles, ceramsites and mortar), backfilling, construction engineering, agriculture, and materials recovery of useful components.

  18. Increasing Class C fly ash reduces alkali silica reactivity

    SciTech Connect

    Hicks, J.K.

    2007-07-01

    Contrary to earlier studies, it has been found that incremental additions of Class C fly ash do reduce alkali silica reactivity (ASR), in highly reactive, high alkali concrete mixes. AST can be further reduced by substituting 5% metakaolin or silica fume for the aggregate in concrete mixes with high (more than 30%) Class C fly ash substitution. The paper reports results of studies using Class C fly ash from the Labadie Station plant in Missouri which typically has between 1.3 and 1.45% available alkalis by ASTM C311. 7 figs.

  19. Evaluation of fly ash from co-combustion of coal and petroleum coke for use in concrete

    SciTech Connect

    Scott, A.N.; Thomas, M.D.A.

    2007-01-15

    An investigation of fly ash (FA) produced from various blends of coal and petroleum coke (pet coke) fired at Belledune Generating Station, New Brunswick, Canada, was conducted to establish its performance relative to FA derived from coal-only combustion and its compliance with CSA A3000. The FA samples were beneficiated by an electrostatic separation process to produce samples for testing with a range of loss-on-ignition (LOI) values. The results of these studies indicate that the combustion of pet coke results in very little inorganic residue (for example, typically less than 0.5% ash) and the main impact on FA resulting from the co-combustion of coal and up to 25% pet coke is an increase in the unburned carbon content and LOI values. The testing of FA after beneficiation indicates that FA produced from fuels with up to 25% pet coke performs as good as FA produced from the same coal without pet coke.

  20. Stabilizing soft fine-grained soils with fly ash

    SciTech Connect

    Edil, T.B.; Acosta, H.A.; Benson, C.H.

    2006-03-15

    The objective of this study was to evaluate the effectiveness of self-cementing fly ashes derived from combustion of subbituminous coal at electric power plants for stabilization of soft fine-grained soils. California bearing ratio (CBR) and resilient modulus (M{sub r}) tests were conducted on mixtures prepared with seven soft fine-grained soils (six inorganic soils and one organic soil) and four fly ashes. The soils were selected to represent a relatively broad range of plasticity, with plasticity indices ranging between 15 and 38. Two of the fly ashes are high quality Class C ashes (per ASTM C 618) that are normally used in Portland cement concrete. The other ashes are off-specification ashes, meaning they do not meet the Class C or Class F criteria in ASTM C 618. Tests were conducted on soils and soil-fly ash mixtures prepared at optimum water content (a standardized condition), 7% wet of optimum water content (representative of the typical in situ condition in Wisconsin), and 9-18% wet of optimum water content (representative of a very wet in situ condition). Addition of fly ash resulted in appreciable increases in the CBR and M{sub r} of the inorganic soils. For water contents 7% wet of optimum, CBRs of the soils alone ranged between 1 and 5. Addition of 10% fly ash resulted in CBRs ranging between 8 and 17, and 18% fly ash resulted in CBRs between 15 and 31. Similarly, M{sub r} of the soil alone ranged between 3 and 15 MPa at 7% wet of optimum, whereas addition of 10% fly ash resulted in M{sub r} between 12 and 60 MPa and 18% fly ash resulted in M{sub r} between 51 and 106 MPa. In contrast, except for one fly ash, addition of fly ash generally had little effect on CBR or M{sub r} of the organic soil.

  1. Fundamental Study of Low NOx Combustion Fly Ash Utilization

    SciTech Connect

    E. M. Suubert; I. Kuloats; K. Smith; N. Sabanegh; R.H. Hurt; W. D. Lilly; Y. M. Gao

    1997-05-01

    This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over forty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives.

  2. FUNDAMENTAL STUDY OF LOW-NOx COMBUSTION FLY ASH UTILIZATION

    SciTech Connect

    ERIC M. SUUBERG; ROBERT H. HURT

    1998-10-19

    This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over fifty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives.

  3. Fundamental Study of Low-Nox Combustion Fly Ash Utilization

    SciTech Connect

    E. M. Suuberg; I. Kuloats; K. Smith; N. Sabanegh; R. H. Hurt; W. D. Lilly; Y. M. Gao

    1997-11-01

    This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over forty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives.

  4. Chemically activated fly ash (CAFA): A new type of fly ash based cement

    SciTech Connect

    Rostami, H.; Silverstrim, T.

    1996-12-31

    A new cementitious material has been developed, called Chemically Activated Fly Ash (CAFA), which is used to produce concrete for construction. CAFA can be used to create a variety of concrete strengths and could revolutionize the concrete product manufacturing industry due to its economy. CAFA contains 80--95% Class F fly ash and is used as cement to bind sand, stone, and fibers creating concrete. CAFA concrete has been tested for strength, durability, mechanical properties and, most importantly, economic viability. CAFA concrete is economically and technically viable for many construction applications. Some properties include rapid strength gain (90% of Ultimate in 1 day), high ultimate strengths (16,000 psi in 1 day), excellent acid resistance, and freeze thaw durability. CAFA`s resistance to chemical attack, such as, sulfuric (H{sub 2}SO{sub 4}), nitric (HNO{sub 3}), hydrochloric (HCl), and organic acids, is far better than portland cement concrete. CAFA is resistant to freeze thaw attack based on ASTM C-666 specification. Near term applications of CAFA material are, blocks, pipe, burial vaults, median barriers, sound barriers, and overlaying materials. Eventual markets are high strength construction products, bridge beams, prestressed members, concrete tanks, highway appurtenances, and other concrete products.

  5. Scale-Up and Demonstration of Fly Ash Ozonation Technology

    SciTech Connect

    Rui Afonso; R. Hurt; I. Kulaots

    2006-03-01

    The disposal of fly ash from the combustion of coal has become increasingly important. When the fly ash does not meet the required specification for the product or market intended, it is necessary to beneficiate it to achieve the desired quality. This project, conducted at PPL's Montour SES, is the first near full-scale ({approx}10 ton/day), demonstration of ash ozonation technology. Bituminous and sub bituminous ashes, including two ash samples that contained activated carbon, were treated during the project. Results from the tests were very promising. The ashes were successfully treated with ozone, yielding concrete-suitable ash quality. Preliminary process cost estimates indicate that capital and operating costs to treat unburned carbon are competitive with other commercial ash beneficiation technologies at a fraction of the cost of lost sales and/or ash disposal costs. This is the final technical report under DOE Cooperative Agreement No.: DE-FC26-03NT41730.

  6. 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.

  7. 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.

  8. Fly ash chemical classification based on lime

    SciTech Connect

    Fox, J.

    2007-07-01

    Typically, total lime content (CaO) of fly ash is shown in fly ash reports, but its significance is not addressed in US specifications. For certain applications a low lime ash is preferred. When a class C fly ash must be cementitious, lime content above 20% is required. A ternary S-A-C phase diagram pilot is given showing the location of fly ash compositions by coal rank and source in North America. Fly ashes from subbituminous coal from the Powder River Basin usually contain sufficient lime to be cementitious but blending with other coals may result in calcium being present in phases other than tricalcium aluminate. 9 refs., 1 fig.

  9. Utilization of fly ash in metallic composites

    SciTech Connect

    Rohatgi, P.K.; Guo, R.Q.; Golden, D.M.

    1996-10-01

    Fly ash particles have been successfully dispersed into aluminum alloy to make aluminum alloy-fly ash composites (Ashalloy) at University of Wisconsin-Milwaukee. Additions of solid and hollow particles of fly ash reduce the cost and density of aluminum castings while increasing their performance. Ashalloy represents a candidate material for high value added use of fly ash, while reducing the disposal volumes of fly ash for the electric utility industry and making the US foundries more competitive. The fly ash particle distribution in the matrix aluminum alloy and the microstructure of aluminum-fly ash composite was determined. Selected properties of cast aluminum-fly ash composites are also presented in this paper. Mechanical properties of aluminum-fly ash composites show that the composite possesses higher hardness and higher elastic modulus compared to the matrix alloy. The flow behavior of molten aluminum-fly ash slurries along with the components cast in aluminum-fly ash composites will be presented. Fly ash containing metal components have potential applications in covers, shrouds, casings, manifolds, valve covers, garden furniture, engine blocks in automotive, small engine and electromechanical industry sector.

  10. 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. PMID:21167631

  11. Petrographic characterization of economizer fly ash

    SciTech Connect

    Valentim, B.; Hower, J.C.; Soares, S.; Guedes, A.; Garcia, C.; Flores, D.; Oliveira, A.

    2009-11-15

    Policies for reducing NOx emissions have led power plants to restrict O{sub 2}, resulting in high-carbon fly ash production. Therefore, some potentially useful fly ash, such as the economizer fly ash, is discarded without a thorough knowledge of its composition. In order to characterize this type of fly ash, samples were collected from the economizer Portuguese power plant burning two low-sulfur bituminous coals. Characterization was also performed on economizer fly ash subsamples after wet sieving, density and magnetic separation. Analysis included atomic absorption spectroscopy, loss-on-ignition, scanning electron microscopy/energy-dispersive X-ray spectroscopy, optical microscopy, and micro-Raman spectroscopy.

  12. Identifying glass compositions in fly ash

    NASA Astrophysics Data System (ADS)

    Aughenbaugh, Katherine; Stutzman, Paul; Juenger, Maria

    2016-01-01

    In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS), calcium aluminosilicate glasses (CAS), a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

  13. 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. PMID:10936538

  14. Heavy metals leaching in Indian fly ash.

    PubMed

    Prasad, Bably; Mondal, Kajal Kumar

    2008-04-01

    Fly ash is an industrial waste generated from thermal power plants. Fly ash constitutes 80-85% of the total ash produced. A small part of fly ash is utilised in some sectors such as construction materials, building engineering, road, back fill, agriculture, selective engineering and processing useful materials. A large part of fly ash produced is disposed of with very high environmental risk. In the present paper, laboratory leaching test has been used to determine the potential mobility of Pb, Cd, Cr, Cu, Zn, Fe, Mn and Ni in fly ash samples, collected from Chandrapura Thermal Power Plant, Jharkhand and Ramagundam Super Thermal Power Plant, Andhra Pradesh, in order to assess their leachability when these wastes are disposed of. A cascade-leaching test was used at liquid-to-solid ratio (L/S) ranging between 20 and 100. Both fly ash samples exhibited neutral reactions, as indicated by pH values <11.75 and >7.0 at L/S=10 and contact time of 10 minutes. The percentage of leached amounts found to follow the trend Zn>Fe>Mn>Cr>Pb>Cu>Ni>Cd for fly ash from Chandrapura and Fe>Zn>Cu>Mn>Cr>Ni>Pb>Cd for fly ash from Ramagundam. Effect of pH on metals released from ash surface in aqueous solution followed a predictable pattern of decreasing release with increasing pH. PMID:19295096

  15. Utilization of CFB fly ash for construction applications

    SciTech Connect

    Conn, R.E.; Sellakumar, K.; Bland, A.E.

    1999-07-01

    Disposal in landfills has been the most common means of handling ash in circulating fluidized bed (CFB) boiler power plants. Recently, larger CFB boilers with generating capacities up to 300 MWe are currently being planned, resulting in increased volumes and disposal cost of ash by-product. Studies have shown that CFB ashes do not pose environmental concerns that should significantly limit their potential utilization. Many uses of CFB ash are being investigated by Foster Wheeler, which can provide more cost-effective ash management. Construction applications have been identified as one of the major uses for CFB ashes. Typically, CFB ash cannot be used as a cement replacement in concrete due to its unacceptably high sulfur content. However, CFB ashes can be used for other construction applications that require less stringent specifications including soil stabilization, road base, structural fill, and synthetic aggregate. In this study, potential construction applications were identified for fly ashes from several CFB boilers firing diverse fuels such as petroleum coke, refuse derived fuel (RDF) and coal. The compressive strength of hydrated fly ashes was measured in order to screen their potential for use in various construction applications. Based on the results of this work, the effects of both ash chemistry and carbon content on utilization potential were ascertained. Actual beneficial uses of ashes evaluated in this study are also discussed.

  16. FATE OF INHALED FLY ASH IN HAMSTERS

    EPA Science Inventory

    To determine pulmonary deposition, translocation, and clearance of inhaled fly ash, hamsters received a single 95-min nose-only exposure to neutron-activated fly ash. Over a period of 99 days postexposure, the hamsters were sacrificed in groups of six animals. Lungs, liver, kidne...

  17. Effects of fly ash particle size on strength of Portland cement fly ash mortars

    SciTech Connect

    Erdogdu, K.; Tuerker, P.

    1998-09-01

    Fly ashes do not have the same properties for different size fractions. It can be accepted that the effect of a fly ash on mortar strength is a combined effect of its size fractions. Therefore, it was concluded that by separating the size fractions and replacing cement with them, the combined bulk effect of a fly ash on strength can be better analyzed. In this study, different size fractions of fly ash were used to replace cement partially in standard compressive strength mortars. The authors attempted to interpret the strength of Portland cement-fly ash mortars in terms of the chemical, mineralogical, morphological, and physical properties of different fly ash size fractions used. Strengths of the mortars were compared at 2, 7, 28, and 90 days. Also strength of mortars with all-in ash (original ash containing all the fractions) were estimated by using strength of mortars with size fractions and the suitability of this estimation was discussed.

  18. Adsorption of phenolic compounds on fly ash

    SciTech Connect

    Akgerman, A.; Zardkoohi, M.

    1996-03-01

    Adsorption isotherms for adsorption of phenol, 3-chlorophenol, and 2,4-dichlorophenol from water onto fly ash were determined. These isotherms were modeled by the Freundlich isotherm. The fly ash adsorbed 67, 20, and 22 mg/g for phenol, chlorophenol, and 2,4-dichlorophenol, respectively, for the highest water phase concentrations used. The affinity of phenolic compounds for fly ash is above the expected amount corresponding to a monolayer coverage considering that the surface area of fly ash is only 1.87 m{sup 2}/g. The isotherms for contaminants studied were unfavorable, indicating that adsorption becomes progressively easier as more solutes are taken up. Phenol displayed a much higher affinity for fly ash than 3-chlorophenol and 2,4-dichlorophenol.

  19. Elastic properties of fly ash-stabilized mixes.

    PubMed

    Dimter, Sanja; Rukavina, Tatjana; Minažek, Krunoslav

    2015-12-01

    Stabilized mixes are used in the construction of bearing layers in asphalt and concrete pavement structures. Two nondestructive methods: resonant frequency method and ultrasonic pulse velocity method, were used for estimation of elastic properties of fly ash-stabilized mixes. Stabilized mixes were designed containing sand from the river Drava and binder composed of different share of cement and fly ash. The aim of the research was to analyze the relationship between the dynamic modulus of elasticity determined by different nondestructive methods. Data showed that average value of elasticity modulus obtained by the ultrasound velocity method is lower than the values of elasticity modulus obtained by resonant frequency method. For further analysis and enhanced discussion of elastic properties of fly ash stabilized mixes, see Dimter et al. [1]. PMID:26702415

  20. Erodibility of fly ash-treated minesoils

    SciTech Connect

    Gorman, J.M.; Sencindiver, J.C.; Singh, R.N.

    1997-12-31

    Fly ash, a by-product of coal-fired power plants, has been used successfully in reclaiming adverse mine sites such as abandoned mine lands by improving minesoil chemical and physical properties. But, the fine sand-silt particle size of fly ash may make it more susceptible to detachment and transport by erosive processes. Furthermore, the high content of silt-size particles in fly ash may make it more susceptable to surface crust formation resulting in reduced infiltration and increased surface runoff and erosion. In the summer of 1989, fly ash/wood waste mixtures were surface applied on two separate mine sites, one with 10% slope and the other 20% slope, in central Preston County, West Virginia. Erosion rates were measured directly using the Linear Erosion/Elevation Measuring Instrument (LEMI). Erosion measurements were taken during the first two growing seasons on both sites. Erosion values were up to five times greater on the fly ash-treated minesoil than on the minesoil without fly ash cover. Mulching with wood chips reduced fly ash erosion to about one-half the loss of the unmulched plots. Erosion was related to both the amount and type of ground cover. Increased vegetative ground cover resulted in reduced erosion. Mosses and fungi appeared to provide better erosion protection than grass-legume cover.

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

    SciTech Connect

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

    1996-09-01

    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 fly 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.

  2. Leaching characteristics of lead from melting furnace fly ash generated by melting of incineration fly ash.

    PubMed

    Okada, Takashi; Tomikawa, Hiroki

    2012-11-15

    This study investigated the effect of the chemical composition of incineration fly ash on the leaching characteristics of Pb from melting furnace fly ash generated by melting incineration fly ash. Melting furnace fly ash from both a real-scale melting process and lab-scale melting experiments was analyzed. In addition, the theoretical behavior of Cl that affects the leaching characteristics of Pb was simulated by a thermodynamic equilibrium calculation. Proportions of water-soluble Pb in the melting furnace fly ash were correlated with equivalent ratios of total Pb in the ash and Cl transferred to gas. The amount of Cl in the gas increased with an increase in the molar ratio of Cl to Na and K in the incineration fly ash. The thermodynamic calculation predicted that HCl generation is promoted by the increase in the molar ratio, and X-ray photoelectron spectroscopy indicated a possible presence of PbCl(2) in the melting furnace fly ash. These results implied that the formation of water-soluble PbCl(2) with HCl was affected by the relationships among the amounts of Na, K, and Cl in the incineration fly ash. This is highly significant in determining the leaching characteristics of Pb from the melting furnace fly ash. PMID:22789656

  3. Strength and microstructural characteristics of chemically activated fly ash-cement systems

    SciTech Connect

    Lee, C.Y.; Lee, H.K.; Lee, K.M

    2003-03-01

    The use of fly ash as a cement replacement material increases the long-term strength and durability of concrete. Despite these great benefits, the use of fly ash is limited due to the low early strength of fly ash concrete. To eliminate this problem, many studies have been conducted on accelerating the pozzolanic properties of fly ash. The study reported below investigated the strength and microstructural characteristics of fly ash-cement systems containing three kinds of activators--Na{sub 2}SO{sub 4}, K{sub 2}SO{sub 4}, and triethanolamine--to accelerate the early strength of fly ash mortars. Through the use of thermal gravity analysis, it was demonstrated that the activators not only decreased or maintained the amount of Ca(OH){sub 2} products, but also increased the production of ettringite at early ages. X-ray diffraction, scanning electron microcopy, and mercury intrusion porosimetry also confirmed that in the early curing stages of fly ash-cement pastes containing activators, large amounts of ettringite were formed, resulting in a reduction in the pore size ranging from 0.01 to 5 {mu}m. The research results support the supposition that the addition of small amounts of activators is a viable solution for increasing the early-age compressive strength of fly ash concrete.

  4. 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. PMID:24638274

  5. 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

  6. Release of Ammonium and Mercury from NOx Controlled Fly Ash

    SciTech Connect

    Schroeder, K.T.; Cardone, C.R.; Kim, A.G

    2007-07-01

    One of the goals of the Department of Energy is to increase the reuse of coal utilization byproducts (CUB) to 50% by 2010. This will require both developing new markets and maintaining traditional ones such as the use of fly ash in concrete. However, the addition of pollution control devices can introduce side-effects that affect the marketability of the CUB. Such can be the case when NOx control is achieved using selective catalytic or non-catalytic reduction (SCR or SNCR). Depending on site-specific details, the ammonia slip can cause elevated levels of NH3 in the fly ash. Disposal of ammoniated fly ash can present environmental concerns related to the amount of ammonia that might be released, the amount of water that might become contaminated, and the extent to which metals might be mobilized by the presence of the ammonia. Ammonia retained in fly ash appears to be present as either an ammonium salt or as a chemisorbed species. Mercury in the leachates correlated to neither the amount of leachable ammonium nor to the total amount of Hg in the ash. The strongest correlation was between the decreases in the amount of Hg leached with increased LOI.

  7. Kinetics of fly ash beneficiation by carbon burnout. Quarterly report, January--March 1996

    SciTech Connect

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

    1996-09-01

    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 benefication 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 fly 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 benefication 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 O{sub 2}} 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. 16 refs., 7 figs., 3 tabs.

  8. Experimental Study of Functionally Graded Beam with Fly Ash

    NASA Astrophysics Data System (ADS)

    Bajaj, K.; Shrivastava, Y.; Dhoke, P.

    2013-11-01

    Generally, concrete used in the field suffers from lack of durability and homogeneity. As cement is the only binding material in concrete and due to hike in its price, researchers have been looking for apt substitutes. For the sake of economy, strength and anti-corrosion functionally graded beam (FGB) has developed having one layer of normal concrete and another of high volume fly-ash concrete (HVFAC). The flexural behavior FGB has analyzed experimentally in this work with variation in interface as 0, 25, 50, 75 and 100 from bottom. In this study, HVFAC has prepared with replacement of cement by 20, 35 and 55 % with fly ash for M20 and M30 grade of concrete. It has seemed that there is 12.86 and 3.56 % increase in compressive and flexural strength of FGB. The bond strength FGM cube is optimum at 50 mm depth. As FGM is economical, having more durability and strength, so its adoption enables more sustainability in concrete industry.

  9. Kinetics of fly ash beneficiation by carbon burnout. Quarterly report, October 1996--December 1996

    SciTech Connect

    Dodoo, J.N.; Okoh, J.M.; Diaz, A.

    1997-06-01

    The presence of carbon in fly ash requires an increase in the dosage of the air-entraining admixture for concrete mix, and may cause the admixture to lose efficiency. Specifying authorities for the concrete producers have set maximum allowable levels of residual carbon. These levels are the so called {open_quotes}Loss On Ignition{close_quotes} (LOI). The concrete producer`s day-to-day purchasing decisions sets the LOI at 4%. The objective of the project is to investigate the kinetics of oxidation of residual carbon present in coal fly ash as a possible first step toward producing low-carbon fly ash from high-carbon, low quality fly ash.

  10. Elastic properties of fly ash-stabilized mixes

    PubMed Central

    Dimter, Sanja; Rukavina, Tatjana; Minažek, Krunoslav

    2015-01-01

    Stabilized mixes are used in the construction of bearing layers in asphalt and concrete pavement structures. Two nondestructive methods: resonant frequency method and ultrasonic pulse velocity method, were used for estimation of elastic properties of fly ash–stabilized mixes. Stabilized mixes were designed containing sand from the river Drava and binder composed of different share of cement and fly ash. The aim of the research was to analyze the relationship between the dynamic modulus of elasticity determined by different nondestructive methods. Data showed that average value of elasticity modulus obtained by the ultrasound velocity method is lower than the values of elasticity modulus obtained by resonant frequency method. For further analysis and enhanced discussion of elastic properties of fly ash stabilized mixes, see Dimter et al. [1]. PMID:26702415

  11. Fly Ash Amendments Catalyze Soil Carbon Sequestration

    SciTech Connect

    Amonette, James E.; Kim, Jungbae; Russell, Colleen K.; Palumbo, A. V.; Daniels, William L.

    2003-09-15

    We tested the effects of four alkaline fly ashes {Class C (sub-bituminous), Class F (bituminous), Class F [bituminous with flue-gas desulfurization (FGD) products], and Class F (lignitic)} on a reaction that simulates the enzyme-mediated formation of humic materials in soils. The presence of FGD products completely halted the reaction, and the bituminous ash showed no benefit over an ash-free control. The sub-bituminous and lignitic fly ashes, however, increased the amount of polymer formed by several-fold. The strong synergetic effect of these ashes when enzyme is present apparently arises from the combined effects of metal oxide co-oxidation (Fe and Mn oxides), alkaline pH, and physical stabilization of the enzyme (porous silica cenospheres).

  12. Increasing carbon content of fly ash: Consequences and recovery of lost value

    SciTech Connect

    Willauer, C.S.; Gasiorowski, S.A.

    1999-07-01

    In response to Phase 2 of the Clean Air Act of 1990, US electric utilities operating coal fired power plants are currently installing low NO {sub x} equipment to meet new air emissions requirements. As these plants begin to operate under the lower NO{sub x} requirements, more carbon remains in the plant's fly ash (a by-product of coal combustion) often exceeding the maximum allowable carbon content of 6% for use in concrete. The carbon content of the fly ash can be further elevated by alternate fuel strategies. As utilities continue to seek improvements in fuel economies by purchase of foreign coals and alternate fuels such as petroleum coke, the resulting carbon level of the fly ash can increase dramatically due to the combustion characteristics of these materials. While considerable reduction in fuel costs are possible, the variable, high-carbon fly ash must be disposed in landfills or used in low value, non-concrete applications. For utilities that have become accustomed to marketing the majority of their coal combustion products (CCPs) land filling is a highly unsatisfactory alternative. Recently, the American Coal Ash Association conducted a survey of electric-utilities to determine the impact of NOx reduction strategies on the marketability of rendered unusable for concrete markets. Shortage of fly ash, particularly fly ashes derived from eastern bituminous coals (Class F-ash) have occurred in the eastern US. This fact combined with the increased demand for cement in the same region has pushed prices higher for concrete grade, high-quality fly ash. Renewed interest has thus developed in processes to restore the value of the high-LOI fly ash.

  13. 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.

  14. 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.

  15. Size dependent cytotoxicity of fly ash particles

    SciTech Connect

    Liu, W.K.; Tam, J.S.K.; Wong, M.H.

    1988-01-01

    Fly ash samples were collected from the electrostatic precipitator of a coal-fired power plant in Hong Kong. The particles of the respirable range (smaller than 10 {mu}m) were divided into 4 groups according to their particle size (mass median aerodynamic diameters). The surface morphology and the metal contents (Fe, Mn, Al and Zn) of fly ash particles were examined by a scanning electron microscopy and an inductively coupled plasma spectrophotometer, respectively. The particles were very heterogeneous in size and shape as well as the concentration of metals. The cytotoxicity of these four groups of fly ash particles were evaluated using an in vitro rat alveolar macrophages culture assay. The viability of alveolar macrophages was lower when incubated with smaller size particles. This relationship was also reflected by the damage of the surface morphology of the cells and the release of cytoplasmic (lactate dehydrogenase) and lysosomal (acid phosphatase and {beta}-glucuronidase) marker enzymes into the culture media.

  16. Fly ash system technology improves opacity

    SciTech Connect

    2007-06-15

    Unit 3 of the Dave Johnston Power Plant east of Glenrock, WY, USA had problems staying at or below the opacity limits set by the state. The unit makes use of a Lodge Cottrell precipitator. When the plant changed to burning Power River Basin coal, ash buildup became a significant issue as the fly ash control system was unable to properly evacuate hoppers on the unit. To overcome the problem, the PLC on the unit was replaced with a software optimization package called SmartAsh for the precipitator fly ash control system, at a cost of $500,000. After the upgrade, there have been no plugged hoppers and the opacity has been reduced from around 20% to 3-5%. 2 figs.

  17. Utilization of lignite ash in concrete mixture

    SciTech Connect

    Demirbas, A.; Karslioglu, S.; Ayas, A.

    1995-12-01

    In this article 11 ashes from various Turkish lignite sources were studied to show the effects upon lignite ash quality for use as a mineral admixture in concrete. The lignite ashes were classified into two general types (Class A and Class B) based on total of silica, alumina, and iron oxide. Total content of the three major oxides must be more than 50% for Class A lignite ash and more than 70% for Class B lignite ash. When 25% of the cement was replaced by LA-1 (Class A) lignite ash, based on 300 kg/m{sup 3} cementitious material, the 28-day compressive strength increased 24.3% compared to the control mix. The optimal lignite ash replacement was 25% at 300 kg/m{sup 3} cementitious material.

  18. Using fly ash to mitigate explosions

    SciTech Connect

    Taulbee, D.

    2008-07-01

    In 2005 the University of Kentucky's Center for Applied Energy Research was given funding to evaluate the use of coal combustion by-products (CCBs) to reduce the explosive potential of ammonium nitrate (AN) fertilizers. Fly ash C (FAC), fly ash F (FAF) and flue gas desulfurization by-product (FGD) were evaluated. It was found that applying a CCB coating to the AN particles at concentrations of 5 wt% or greater prevented the AN explosion from propagating. The article reports on results so far and outlines further work to be done. 6 figs.

  19. Fly Ash Characteristics and Carbon Sequestration Potential

    SciTech Connect

    Palumbo, Anthony V.; Amonette, James E.; Tarver, Jana R.; Fagan, Lisa A.; McNeilly, Meghan S.; Daniels, William L.

    2007-07-20

    Concerns for the effects of global warming have lead to an interest in the potential for inexpensive methods to sequester carbon dioxide (CO2). One of the proposed methods is the sequestration of carbon in soil though the growth of crops or forests.4,6 If there is an economic value placed on sequestration of carbon dioxide in soil there may be an an opportunity and funding to utilize fly ash in the reclamation of mine soils and other degraded lands. However, concerns associated with the use of fly ash must be addressed before this practice can be widely adopted. There is a vast extent of degraded lands across the world that has some degree of potential for use in carbon sequestration. Degraded lands comprise nearly 2 X 109 ha of land throughout the world.7 Although the potential is obviously smaller in the United States, there are still approximately 4 X 106 ha of degraded lands that previously resulted from mining operations14 and an additional 1.4 X 108 ha of poorly managed lands. Thus, according to Lal and others the potential is to sequester approximately 11 Pg of carbon over the next 50 years.1,10 The realization of this potential will likely be dependent on economic incentives and the use of soil amendments such as fly ash. There are many potential benefits documented for the use of fly ash as a soil amendment. For example, fly ash has been shown to increase porosity, water-holding capacity, pH, conductivity, and dissolved SO42-, CO32-, HCO3-, Cl- and basic cations, although some effects are notably decreased in high-clay soils.8,13,9 The potential is that these effects will promote increased growth of plants (either trees or grasses) and result in greater carbon accumulation in the soil than in untreated degraded soils. This paper addresses the potential for carbon sequestration in soils amended with fly ash and examines some of the issues that should be considered in planning this option. We describe retrospective studies of soil carbon accumulation on

  20. Changeing of fly ash leachability after grinding

    NASA Astrophysics Data System (ADS)

    Lakatos, J.; Szabo, R.; Racz, A.; Banhidi, O.; Mucsi, G.

    2016-04-01

    Effect of grinding on the reactivity of fly ash used for geopolymer production was tested. Extraction technique using different alkaline and acidic solutions were used for detect the change of the solubility of elements due to the physical and mechano-chemical transformation of minerals in function of grinding time. Both the extraction with alkaline and acidic solution have detected improvement in solubility in function of grinding time. The enhancement in alkaline solution was approx. 100% in case of Si and Al. The acidic medium able to dissolve the fly ash higher manner than the alkaline, therefore the effect of grinding was found less pronounced.

  1. Pulmonary response to cadmium and nickel coated fly ash

    SciTech Connect

    Bajpai, R.; Waseem, M.; Kaw, J.L.

    1994-12-31

    Pulmonary reaction to fly ash coated with cadmium (Cd) or nickel (Ni) and to native fly ash was studied in rats after intratracheal inoculation of dust suspensions. The histopathological alterations and changes in biochemical and cellular constituents of the bronchoalveolar lavage were correlated with the metal content in lungs and kidneys. More Ni was adsorbed than Cd on fly ash particulates. Metal-coated fly ash was more toxic than uncoated fly ash. Cd-coated fly ash produced significantly more histopathological and biochemical changes than Ni-coated fly ash. A high concentration of Cd was detected in the kidneys of rats exposed to Cd-coated fly ash. 32 refs., 7 figs., 2 tabs.

  2. Eco-friendly fly ash utilization: potential for land application

    SciTech Connect

    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 like 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.

  3. Sustainable construction: composite use of tyres and ash in concrete.

    PubMed

    Snelson, D G; Kinuthia, J M; Davies, P A; Chang, S-R

    2009-01-01

    An investigation was carried out to establish the physical, mechanical and chemical characteristics of a non-standard (unprocessed) pulverised fuel ash (PFA) and waste tyres from a former landfill site at the Power Station Hill near Church Village, South Wales, United Kingdom. Investigations are on-going to establish the suitability of the fly ash and/or tyres in road construction (embankment and pavement) and also in concrete to be used in the construction of the proposed highway. This paper reports on concrete-based construction where concrete blends (using various levels of PFA as partial replacement for Portland cement (PC), and shredded waste tyres (chips 15-20mm) as aggregate replacement) were subjected to unconfined compressive strength tests to establish performance, hence, optimising mix designs. Strength development up to 180 days for the concrete made with PC-PFA blends as binders (PC-PFA concrete), with and without aggregate replacement with tyre chips, is reported. The binary PC-PFA concrete does not have good early strength but tends to improve at longer curing periods. The low early strength observed means that PC-PFA concrete cannot be used for structures, hence, only as low to medium strength applications such as blinding, low-strength foundations, crash barriers, noise reduction barriers, cycle paths, footpaths and material for pipe bedding. PMID:18799299

  4. Sustainable construction: Composite use of tyres and ash in concrete

    SciTech Connect

    Snelson, D.G.; Kinuthia, J.M.; Davies, P.A.; Chang, S.R.

    2009-01-15

    An investigation was carried out to establish the physical, mechanical and chemical characteristics of a non-standard (unprocessed) pulverised fuel ash (PFA) and waste tyres from a former landfill site at the Power Station Hill near Church Village, South Wales, United Kingdom. Investigations are on-going to establish the suitability of the fly ash and/or tyres in road construction (embankment and pavement) and also in concrete to be used in the construction of the proposed highway. This paper reports on concrete-based construction where concrete blends (using various levels of PFA as partial replacement for Portland cement (PC), and shredded waste tyres (chips 15-20 mm) as aggregate replacement) were subjected to unconfined compressive strength tests to establish performance, hence, optimising mix designs. Strength development up to 180 days for the concrete made with PC-PFA blends as binders (PC-PFA concrete), with and without aggregate replacement with tyre chips, is reported. The binary PC-PFA concrete does not have good early strength but tends to improve at longer curing periods. The low early strength observed means that PC-PFA concrete cannot be used for structures, hence, only as low to medium strength applications such as blinding, low-strength foundations, crash barriers, noise reduction barriers, cycle paths, footpaths and material for pipe bedding.

  5. The effect of fly ash and coconut fibre ash as cement replacement materials on cement paste strength

    NASA Astrophysics Data System (ADS)

    Bayuaji, R.; Kurniawan, R. W.; Yasin, A. K.; Fatoni, H. AT; Lutfi, F. M. A.

    2016-04-01

    Concrete is the backbone material in the construction field. The main concept of the concrete material is composed of a binder and filler. Cement, concrete main binder highlighted by environmentalists as one of the industry are not environmentally friendly because of the burning of cement raw materials in the kiln requires energy up to a temperature of 1450° C and the output air waste CO2. On the other hand, the compound content of cement that can be utilized in innovation is Calcium Hydroxide (CaOH), this compound will react with pozzolan material and produces additional strength and durability of concrete, Calcium Silicate Hydrates (CSH). The objective of this research is to explore coconut fibers ash and fly ash. This material was used as cement replacement materials on cement paste. Experimental method was used in this study. SNI-03-1974-1990 is standard used to clarify the compressive strength of cement paste at the age of 7 days. The result of this study that the optimum composition of coconut fiber ash and fly ash to substitute 30% of cement with 25% and 5% for coconut fibers ash and fly ash with similar strength if to be compared normal cement paste.

  6. Geopolymer concretes: a green construction technology rising from the ash

    SciTech Connect

    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 can be correlated to the stress level to which the structure is subjected. 1 fig., 6 photos.

  7. Insulation formed of precipitated silica and fly ash

    SciTech Connect

    Barito, R.W.; Downs, K.L.

    1987-07-21

    This patent describes a slab of board-like material for use as a thermal insulation comprising: a. a precipitated silica and a fly ash material, between 30% and 70% based upon the total weight of the precipitated silica and fly ash material; and b. a gas and water light envelope containing the mixture of precipitated silica and fly ash material.

  8. AUTOMATION OF THE RESISTIVITY MEASUREMENT FOR FLY ASH

    EPA Science Inventory

    The article describes the automation of the resistivity measurement for fly ash. Fly ash resistivity is an important consideration in the operation of particulate control devices based on electrostatic principles (the higher the resistivity of the fly ash, the more difficult it i...

  9. Aggregate material formulated with MSWI bottom ash and APC fly ash for use as secondary building material

    SciTech Connect

    Valle-Zermeño, R. del; Formosa, J.; Chimenos, J.M.; Martínez, M.; Fernández, A.I.

    2013-03-15

    Highlights: ► A concrete formulation was optimized using Bottom Ash and APC ash. ► 10% of APC ash achieves good compromise between economic and performance aspects. ► The crushed concrete was evaluated as secondary building granular material. ► The environmental behavior allows its use as secondary material. ► The abrasion resistance is not good enough for its use as a road sub-base material. - Abstract: The main goal of this paper is to obtain a granular material formulated with Municipal Solid Waste Incineration (MSWI) bottom ash (BA) and air pollution control (APC) fly ash to be used as secondary building material. Previously, an optimum concrete mixture using both MSWI residues as aggregates was formulated. A compromise between the environmental behavior whilst maximizing the reuse of APC fly ash was considered and assessed. Unconfined compressive strength and abrasion resistance values were measured in order to evaluate the mechanical properties. From these results, the granular mixture was not suited for certain applications owing to the high BA/APC fly ash content and low cement percentages used to reduce the costs of the final product. Nevertheless, the leaching test performed showed that the concentrations of all heavy metals were below the limits established by the current Catalan legislation for their reutilization. Therefore, the material studied might be mainly used in embankments, where high mechanical properties are not needed and environmental safety is assured.

  10. Mutagenicity of fly ash particles in Paramecium

    SciTech Connect

    Smith-Sonneborn, J.; Palizzi, R.A.; Herr, C.; Fisher, G.L.

    1981-01-09

    Paramecium, a protozoan that ingests nonnutritive particulate matter, was used to determine the mutagenicity of fly ash. Heat treatment inactivated mutagens that require metabolic conversion to their active form but did not destroy all mutagenicity. Extraction of particles with hydrochloric acid, but not dimethyl sulfoxide, removed detectable mutagenic activity.

  11. FLY ASH RECYCLE IN DRY SCRUBBING

    EPA Science Inventory

    The paper describes the effects of fly ash recycle in dry scrubbing. (Previous workers have shown that the recycle of product solids improves the utilization of slaked lime--Ca(OH)2--for sulfur dioxide (SO2) removal by spray dryers with bag filters.) In laboratory-scale experimen...

  12. Hydrothermal reaction of fly ash. Final report

    SciTech Connect

    Brown, P.W.

    1994-12-31

    The reactions which occur when fly ash is treated under hydrothermal conditions were investigated. This was done for the following primary reasons. The first of these is to determine the nature of the phases that form to assess the stabilities of these phases in the ambient environment and, finally, to assess whether these phases are capable of sequestering hazardous species. The second reason for undertaking this study was whether, depending on the composition of the ash and the presence of selected additives, it would be possible under hydrothermal conditions to form compounds which have cementitious properties. Formation of four classes of compounds, which bracket likely fly ash compositional ranges, were selected for study. The classes are calcium silicate hydrates, calcium selenates, and calcium aluminosulfates, and silicate-based glasses. Specific compounds synthesized were determined and their stability regions assessed. As part of stability assessment, the extent to which selected hazardous species are sequestered was determined. Finally, the cementing properties of these compounds were established. The results obtained in this program have demonstrated that mild hydrothermal conditions can be employed to improve the reactivity of fly ash. Such improvements in reactivity can result in the formation of monolithic forms which may exhibit suitable mechanical properties for selected applications as building materials. If the ashes involved are considered hazardous, the mechanical properties exhibited indicated the forms could be handled in a manner which facilitates their disposal.

  13. Flue gas desulfurization gypsum and fly ash

    SciTech Connect

    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 for 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.

  14. Increasing bioavailability of phosphorus from fly ash through vermicomposting.

    PubMed

    Bhattacharya, S S; Chattopadhyay, G N

    2002-01-01

    Due to the environmental problems created by large-scale fly ash generation throughout the world, efforts are being made to recycle these materials. An important component of the recycling effort is using fly ash to improve low-fertility soils. Because availability of many nutrients is very low in fly ash, available ranges of such nutrients must be improved to increase the effectiveness of fly ash as a soil amendment. In the present study, we assessed the possibility of increasing P bioavailability in fly ash through vermicomposting in a yard experiment. Fly ash was mixed with organic matter in the form of cow (Bos taurus) dung at 1:3, 1:1, and 3:1 ratios and incubated with and without epigeic earthworm (Eisenia fetida) for 50 d. The concentration of phosphate-solubilizing bacteria (PSB) was found to increase many fold in the earthworm-treated series of fly ash and organic matter combinations compared with the series without earthworm. This helped to transform considerable amounts of insoluble P from fly ash into more soluble forms and thus resulted in increased bioavailability of the nutrients in the vermicomposted series. Among different combinations of fly ash and organic matter, P availability in fly ash due to vermicomposting was significantly higher in the 1:1 fly ash to cow dung treatment compared with the other treatments. PMID:12469864

  15. 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. PMID:26060198

  16. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2011-10-01 2011-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  17. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2014-10-01 2014-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  18. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2012-10-01 2012-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  19. 46 CFR 148.225 - Calcined pyrites (pyritic ash, fly ash).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... be disposed of as prescribed in 33 CFR parts 151.55 through 151.77. ... 46 Shipping 5 2013-10-01 2013-10-01 false Calcined pyrites (pyritic ash, fly ash). 148.225 Section... § 148.225 Calcined pyrites (pyritic ash, fly ash). (a) This part does not apply to the shipment...

  20. Fly ash of mineral coal as ceramic tiles raw material.

    PubMed

    Zimmer, A; Bergmann, C P

    2007-01-01

    The aim of this work was to evaluate the use of mineral coal fly ash as a raw material in the production of ceramic tiles. The samples of fly ash came from Capivari de Baixo, a city situated in the Brazilian Federal State of Santa Catarina. The fly ash and the raw materials were characterized regarding their physical chemical properties, and, based on these results; batches containing fly ash and typical raw materials for ceramic tiles were prepared. The fly ash content in the batches varied between 20 and 80 wt%. Specimens were molded using a uniaxial hydraulic press and were fired. All batches containing ash up to 60 wt% present adequate properties to be classified as several kinds of products in the ISO 13006 standard () regarding its different absorption groups (pressed). The results obtained indicate that fly ash, when mixed with traditional raw materials, has the necessary requirements to be used as a raw material for production of ceramic tiles. PMID:16540298

  1. Manufacture of ceramic tiles from fly ash

    DOEpatents

    Hnat, J.G.; Mathur, A.; Simpson, J.C.

    1999-08-10

    The present invention relates to a process for forming glass-ceramic tiles. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants. 6 figs.

  2. Manufacture of ceramic tiles from fly ash

    DOEpatents

    Hnat, James G.; Mathur, Akshay; Simpson, James C.

    1999-01-01

    The present invention relates to a process for forming glass-ceramic tiles. Fly ash containing organic material, metal contaminants, and glass forming materials is oxidized under conditions effective to combust the organic material and partially oxidize the metallic contaminants and the glass forming materials. The oxidized glass forming materials are vitrified to form a glass melt. This glass melt is then formed into tiles containing metallic contaminants.

  3. Prevention of lead leaching from fly ashes by mechanochemical treatment.

    PubMed

    Nomura, Y; Fujiwara, K; Terada, A; Nakai, S; Hosomi, M

    2010-07-01

    Fly ashes from a municipal solid waste incinerator were subjected to mechanochemical (MC) treatment in a planetary ball mill, and the treated fly ashes were cemented with a binder. The leachability of lead (Pb) from the treated fly ashes and from the cement product were investigated, and the speciation of lead in the treated and untreated ashes was determined by X-ray absorption fine structure (XAFS) analysis. MC treatment of the fly ashes and subsequent cementation prevented Pb leaching by 99.9%, whereas MC treatment alone prevented Pb leaching by 92.8%. Analysis of the X-ray absorption near-edge spectrum of the untreated fly ashes revealed that the predominant Pb species in the ashes was PbCl(2). In contrast, the counterpart in the treated fly ashes was Pb(3)O(4) insoluble in water. The formation of a species of Pb with a lower solubility in water than that of PbCl(2) was confirmed by MC treatment of PbCl(2)-spiked fly ashes for 48h, indicating the reduction of PbCl(2) in the spiked fly ashes to Pb via Pb(3)O(4) during MC treatment. Our results indicate that such reduction to an insoluble species prevented Pb from leaching and that MC treatment followed by cementation is a feasible method for the recycling of fly ashes. PMID:20022740

  4. 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...

  5. Fly ash as a liming material for cotton.

    PubMed

    Stevens, Gene; Dunn, David

    2004-01-01

    A field experiment was conducted to determine the effect of fly ash from a coal combustion electric power facility on soil acidity in a cotton (Gossypium hirsutum L.) field. Fresh fly ash was applied to a Bosket fine sandy loam (fine-loamy, mixed, thermic Mollic Hapludalf) soil with an initial soil pH(salt) of 4.8. The fly ash was equivalent to 42 g kg(-1) calcium carbonate with 97% passing through a 60 mesh (U.S. standard) sieve. Fly ash was applied one day before cotton planting in 1999 at 0, 3.4, 6.7, and 10.1 Mg ha(-1). No fly ash was applied in 2000. Within 60 d of fly ash application in 1999, all rates of fly ash significantly increased soil pH above 6.0. Manganese levels in cotton petioles were reduced significantly by 6.7 and 10.1 Mg ha(-1) of fly ash. Soil boron (B) and sodium (Na) concentrations were significantly increased with fly ash. In 1999, B in cotton leaves ranged from 72 to 84 mg kg(-1) in plots with fly ash applications. However, no visual symptoms of B toxicity in plants were observed. In 1999, cotton lint yield decreased on average 12 kg ha(-1) for each Mg of fly ash applied. In 2000, cotton yields were significantly greater for the residual 3.4 and 6.7 Mg fly ash ha(-1) plots than the untreated check. Due to the adverse yield effects measured in the first year following application, fly ash would not be a suitable soil amendment for cotton on this soil at this time. PMID:14964389

  6. Use of incinerator bottom ash in concrete

    SciTech Connect

    Pera, J.; Coutaz, L.; Ambroise, J.; Chababbet, M.

    1997-01-01

    The aim of the present work was to show if municipal solid waste incinerator (MSWI) bottom ash could be an alternative aggregate for the production of building concrete presenting a characteristic 28-day compressive strength of 25 MPa. The aggregates passing the 20-mm sieve and retained on the 4-mm sieve were considered for investigation. They showed lower density, higher water absorption, and lower strength than natural gravel. They could be considered as average quality aggregates for use in concrete. When directly introduced in concrete, they led to swelling and cracking of specimens, due to the reaction between cement and metallic aluminium. Therefore, a treatment by sodium hydroxide was proposed to avoid such degradation, which made possible the partial replacement (up to 50%) of gravel in concrete without affecting the durability.

  7. The use of fly ash the thermal power plants in the construction

    NASA Astrophysics Data System (ADS)

    Fediuk, R. S.; Yushin, A. M.

    2015-10-01

    The problems of ecological and radiation safety of the construction of man-made waste like fly ash thermal power plants were researched. The chemical composition of TPPs ashes of Primorsky Territory was studied, defined their specific effective activity of natural radionuclides. The most modern research methods were used - differential thermal analysis, thermogravimetry, X-ray analysis. It was revealed that the ash of the Primorskaya TPP and Partizanskaya TPP has exceed the permissible parameters of radioactivity, so not suitable for use in construction. Ashes of Vladivostok TPP-2 and Artem TPP of Primorsky Region on parameters radioactivity and chemical composition have suitable for use as a filler in the concrete.

  8. Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash

    SciTech Connect

    Ivan Diaz-Loya, E.; Allouche, Erez N.; Eklund, Sven; Joshi, Anupam R.; Kupwade-Patil, Kunal

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Incinerator fly ash (IFA) is added to an alkali activated coal fly ash (CFA) matrix. Black-Right-Pointing-Pointer Means of stabilizing the incinerator ash for use in construction applications. Black-Right-Pointing-Pointer Concrete made from IFA, CFA and IFA-CFA mixes was chemically characterized. Black-Right-Pointing-Pointer Environmentally friendly solution to IFA disposal by reducing its toxicity levels. - Abstract: Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA's Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson's ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases

  9. Market opportunities for fly ash fillers in North America

    SciTech Connect

    Eckert, C.; Harris, T.; Gledhill, J. )

    1990-11-01

    Direct Acid Leaching (DAL) processed fly ash is derived from treating raw and beneficiated coal fly ash with hydrochloric acid. The DAL process allows for the production of fly ash with greater chemical purity and consistency than raw fly ash alone. In addition, DAL fly ash is similar to various minerals used in a wide range of applications that require filler minerals. This project investigates the feasibility of using three grades of DAL fly ash ranging from 10 microns to 30 microns in diameter as an alternative filler material to mineral fillers. Six major applications in North America, requiring large volumes of filler minerals were investigated by region including: (1) asphalt roofing shingles (2) carpet backing (3) joint compound and wallboard (4) industrial coatings (5) plastics (6) vinyl flooring. It is determined that calcium carbonate was the primary mineral filler DAL fly ash would be competing with in the applications investigated. Calcium carbonate is used in all applications investigated. The application which demonstrated the greatest potential for using DAL fly ash is asphalt shingles. Asphalt shingles were the largest calcium carbonate consuming application identified, consuming 4.8 million tons in 1988, and is the least sensitive to the dark color of the DAL fly ash. Although the DAL fly ash typically has a smaller particle size, in comparison to calcium carbonate, the asphalt shingle manufacturers felt it would be a good substitute. Other promising applications for DAL fly ash were industrial coatings and plastics where the calcium carbonate particle size requirements of 3 to 6 microns very closely matches the particle size of the DAL fly ash considered in this project. 17 figs., 36 tabs.

  10. 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.

  11. 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.

  12. Sorbate characteristics of fly ash. Volume I. Final report

    SciTech Connect

    Liskowitz, J.W.; Grow, J.; Sheih, M.; Trattner, R.; Kohut, J.; Zwillenberg, M.

    1983-08-01

    The objective of this investigation is to correlate the sorbate and leaching characteristics of fly ash with coal properties and monitored combustion conditions in order to design a system for the inexpensive treatment of industrial wastes and leachate from industrial landfills using mixtures of fly ash as inexpensive sorbents. Such a low-cost treatment system could also treat ash pond effluent for water reuse by powerplants as cooling tower makeup. Twelve unblended coals from 10 different mines were burned under monitored conditions in three different types of coal fired boilers in order to determine the influence of coal composition, ash fusion temperatures, boiler additives, combustion conditions and co-firing of natural gas or oil with the coal, on the leaching and sorbate characteristics of the fly ash produced. This included the determination of: (1) SiO/sub 2/, Al/sup 2/O/sub 3/, Fe/sub 2/O/sub 3/, CaO, K/sub 2/O, Na/sub 2/O, MgO, sulfur, ash fusion temperatures Ti, Cd, Sn, Ni, Pb, Mo, Cu, Cr, n, Mn, Ba and V in the coals and their respective fly ashes and bottom ashes; (2) Moessbauer spectra of a number of coals and their fly ashes; and (3) surface analysis of the fly ashes using ESCA. The leaching exhibited by the fly ashes with regard to pH, Cd, B, Sn, Ni, Pb, Mo, Cu, Cr, Mn and Fe was examined. In addition, the removal of Cd, B, Sn, Ni, Pb, Mo, Cu, Cr, Fe, As and organics by fly ash was evaluated, using from actual ash pond samples to model realistic inlet concentrations. The results show that fly ash can be used for the treatment of Cadmium, Boron, Tin, Molybdenum, Nickel, Lead, Copper, Chromium, Zinc, Manganese, Iron, Arsenic and organics in actual ash pond effluents. 18 references, 64 figures, 60 tables.

  13. Retention of elemental mercury in fly ashes in different atmospheres

    SciTech Connect

    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. In 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.

  14. Chemical constraints on fly ash glass compositions

    SciTech Connect

    John H. Brindle; Michael J. McCarthy

    2006-12-15

    The major oxide content and mineralogy of 75 European fly ashes were examined, and the major element composition of the glass phase was obtained for each. Correlation of compositional trends with the glass content of the ash was explored. Alkali content was deduced to have a major influence on glass formation, and this in turn could be related to the probable chemistry of clay minerals in the source coals. Maximal glass content corresponded to high aluminum content in the glass, and this is in accordance with the theoretical mechanism of formation of aluminosilicate glasses, in which network-modifying oxides are required to promote tetrahedral coordination of aluminum in glass chain structures. Iron oxide was found to substitute for alkali oxides where the latter were deficient, and some indications of preferred eutectic compositions were found. The work suggests that the proportion of the glass phase in the ash can be predicted from the coal mineralogy and that the utility of a given ash for processing into geopolymers or zeolites is determined by its source. 23 refs., 7 figs., 1 tab.

  15. The gamma-ray and neutron shielding factors of fly-ash brick materials.

    PubMed

    Singh, Vishwanath P; Badiger, N M

    2014-03-01

    A comprehensive study of gamma-ray exposure build-up factors (EBFs) of fly-ash brick materials has been carried out for photon energies of 0.015-15 MeV up to a penetration depth of 40 mfp (mean free path) by a geometrical progression (GP) fitting method. The EBF values of the fly-ash brick materials were found to be dependent upon the photon energy, penetration depth and chemical composition, and were found to be higher than the values for mud bricks and common bricks. Above a photon energy of 3 MeV for large penetration depths (>10 mfp), the EBF becomes directly proportional to Zeq. EBFs of fly-ashes were found to be less than or equal to those of concrete for low penetration depths (<10 mfp) for intermediate photon energies up to 1.5 MeV. The EBF values of fly-ash materials were found to be almost independent of Si concentration. The fast neutron removal cross sections of the fly-ash brick materials, mud bricks and common bricks were also calculated to understand their shielding effectiveness. The shielding effectiveness of the fly-ash materials against gamma-ray radiation was lower than that of common and mud bricks. PMID:24270465

  16. Effect of cement types, mineral admixtures, and bottom ash on the curing sensitivity of concrete

    NASA Astrophysics Data System (ADS)

    Hussain, Kinaanath; Choktaweekarn, Pongsak; Saengsoy, Warangkana; Srichan, Theerati; Tangtermsirikul, Somnuk

    2013-01-01

    The curing sensitivity of concrete with cement Types 1, 3, and 5 as well as multiple powders consisting of cement, fly ash, and limestone powder was studied. Bottom ash was also used in the study as an internal curing agent and a partial substitution of fine aggregate. The curing sensitivity index was calculated by considering the performances of compressive strength and carbonation depth. Specimens were subjected to two curing conditions: continuously water-cured and continuously air-cured. The results show that cement Type 3 has a lower curing sensitivity, while cement Type 5 increases the curing sensitivity. For the mixes without bottom ash, the use of fly ash increases the curing sensitivity, while limestone powder reduces the curing sensitivity of concrete. The use of bottom ash in concrete reduces the curing sensitivity, especially at a lower mass ratio of water to binder. Concrete with limestone powder, together with bottom ash, is least sensitive to curing. The curing sensitivity calculated from carbonation depth also has a similar tendency as that derived by considering compressive strength. From the test results of compressive strength and curing sensitivity, bottom ash has been proven to be an effective internal curing agent.

  17. Fundamental study of low-NOx combustion fly ash utilization. Semiannual report, May 1, 1998--October 31, 1998

    SciTech Connect

    Hurt, R.H.; Suuberg, E.M.

    1999-10-20

    The objective of the current work was to investigate the oxidation reactivity of fly ash carbons, using thermogravimetric analysis techniques. Good measures of the oxidation reactivity of fly ash carbon were the critical temperature (T{sub cr}) and the late burnout temperature (T{sub late}). The lower the critical temperature of the fly ash carbon, the more reactive the sample. By contrast, the higher T{sub late}, the less reactive the fly ash carbon. The difference between T{sub cr} and T{sub late} provided information about the reactivity distribution and was mainly dependent on fly ash carbon content (Loss-On-Ignition (LOI)). Fly ash carbons having different origins, some from lower rank coals and some from higher rank coals had slightly different reactivities. Class C fly ash carbons from low rank coals were more reactive than the typical class F fly ash carbons from higher rank coals. The reactivity parameters did not, however, provide any additional ability to predict the suitability of a given ash for use in concrete.

  18. A comparison between sludge ash and fly ash on the improvement in soft soil

    SciTech Connect

    Deng-Fong Lin; Kae-Long Lin; Huan-Lin Luo

    2007-01-15

    In this study, the strength of soft cohesive subgrade soil was improved by applying sewage sludge ash as a soil stabilizer. Test results obtained were compared with earlier tests conducted on soil samples treated with fly ash. Five different proportions of sludge ash and fly ash were mixed with soft cohesive soil, and tests such as pH value, compaction, California bearing ratio, unconfined compressive strength (UCS), and triaxial compression were performed to understand soil strength improvement because of the addition of both ashes. Results indicate that pH values increase with extending curing age for soil with sludge ash added. The UCS of sludge ash/soil were 1.4 2 times better than untreated soil. However, compressive strength of sludge ash/soil was 20 30 kPa less than fly ash/soil. The bearing capacities for both fly ash/soil and sludge ash/soil were five to six times and four times, respectively, higher than the original capacity. Moreover, the cohesive parameter of shear strength rose with increased amounts of either ash added. Friction angle, however, decreased with increased amounts of either ash. Consequently, results show that sewage sludge ash can potentially replace fly ash in the improvement of the soft cohesive soil. 9 refs., 5 figs., 2 tabs.

  19. Standard specification for coal fly ash and raw or calcined natural pozzolan for use as a mineral admixture in concrete. ASTM standard

    SciTech Connect

    1998-07-01

    This specification is under the jurisdiction of ASTM Committee C-9 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.24 on Ground Slag and Pozzolanic Admixtures. The current edition was approved Feb. 6, 1998 and published July 1998. It was originally published as C 618-68T to replace C 350 and C 402. The last previous edition was C 618-97.

  20. Properties of solid waste incinerator fly ash

    SciTech Connect

    Poran, C.J. ); Ahtchi-Ali, F. )

    1989-08-01

    Since the late 1950s solid waste incinerators have become widely used in the United States. The incineration of solid waste produces large quantities of bottom and fly ash, which has been disposed of primarily by landfilling. However, as landfills become undesirable other disposal methods are being sought. An experimental research program is conducted to determine engineering properties of solid waste incinerator fly ash (SWIF) in order to evaluate the feasibility of using the material for compacted fill and road and subbase construction. Moisture-density relationship, permeability, shear strength, and California bearing ratio (CBR) are investigated. The effects of densification on these engineering properties are also examined. In addition, the effectiveness of cement and lime stabilization is investigated using two common mix ratios. Test results of stabilized mixes are compared to the unstabilized material. Cement stabilization is found to be very effective in reducing permeability, and increasing shear strength and CBR values of the material. The results indicate that SWIF with cement stabilization may be used effectively for compacted fill and road subbase construction. Finally, some environmental aspects related to these applications are examined.

  1. Biologic effects of oil fly ash.

    PubMed Central

    Ghio, Andrew J; Silbajoris, Robert; Carson, Johnny L; Samet, James M

    2002-01-01

    Epidemiologic studies have demonstrated increased human morbidity and mortality with elevations in the concentration of ambient air particulate matter (PM). Fugitive fly ash from the combustion of oil and residual fuel oil significantly contributes to the ambient air particle burden. Residual oil fly ash (ROFA) is remarkable in the capacity to provoke injury in experimental systems. The unique composition of this emission source particle makes it particularly useful as a surrogate for ambient air PM in studies of biologic effects testing the hypothesis that metals mediate the biologic effects of air pollution particles. A majority of the in vitro and animal model investigations support the postulate that transition metals present in ROFA (especially vanadium) participate in Fenton-like chemical reactions to produce reactive oxygen species. This is associated with tyrosine phosphorylation, nuclear factor kappa B and other transcription factor activation, induction of inflammatory mediator expression, and inflammatory lung injury. It is also evident that vanadium accounts for a significant portion of the biologic activity of ROFA. The extrapolation of this body of investigation on ROFA to the field of ambient air PM is difficult, as particles in numerous environments have such small amounts of vanadium. PMID:11834466

  2. 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. PMID:22717068

  3. Fly ash and coal mineral matter surface transformations during heating

    SciTech Connect

    Baer, D R; Smith, R D

    1982-05-01

    A study is reported of surface segregation phenomena for fly ash and aluminosilicates representative of coal mineral matter during heating. The materials studied included a 20-..mu..m average diameter fly ash powder, a glass prepared from the fly ash, and Ca- and K-rich aluminosilicate minerals. The samples were heated both in air and under vacuum for extended periods at temperatures up to 1100/sup 0/C. XPS, Auger and SIMS methods were used to obtain relative surface elemental concentrations for major and minor components and depth profiles for some of the samples. Major differences were noted between samples heated in air (oxidizing) and those heated in vacuum (reducing) environments. For the fly ash glass heated in air Fe, Ti and Mg become enriched on the surfaces while heating in vacuum leads to Si surface segregation. Different trends upon heating were also observed for the Ca- and K-rich aluminosilicates. The results indicate two levels of surface enrichment upon the fly ash glass; a thin (< 500 A) layer and a thicker (1- to 2-..mu..m) layer most evident for heating in air where an Fe-rich layer is formed. The present results indicate that the rates of surface segregation may not be sufficiently fast on the time scale of fly ash formation to result in equilibrium surface segregation. It is concluded that condensation processes during fly ash formation probably play a major role in the observed fly ash surface enrichments.

  4. The recycling of the coal fly ash in glass production

    SciTech Connect

    Erol, M.M.; Kucukbayrak, S.; Ersoy-Mericboyu, A.

    2006-09-15

    The recycling of fly ash obtained from the combustion of coal in thermal power plant has been studied. Coal fly ash was vitrified by melting at 1773 K for 5 hours without any additives. The properties of glasses produced from coal fly ash were investigated by means of Differential Thermal Analysis (DTA), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. DTA study indicated that there was only one endothermic peak at 1003 K corresponding to the glass transition temperature. XRD analysis showed the amorphous state of the glass sample produced from coal fly ash. SEM investigations revealed that the coal fly ash based glass sample had smooth surface. The mechanical, physical and chemical properties of the glass sample were also determined. Recycling of coal fly ash by using vitrification technique resulted to a glass material that had good mechanical, physical and chemical properties. Toxicity characteristic leaching procedure (TCLP) results showed that the heavy metals of Pb, Cr, Zn and Mn were successfully immobilized into the glass. It can be said that glass sample obtained by the recycling of coal fly ash can be taken as a non-hazardous material. Overall, results indicated that the vitrification technique is an effective way for the stabilization and recycling of coal fly ash.

  5. Multinuclear NMR approach to coal fly ash characterization

    SciTech Connect

    Netzel, D.A.

    1991-09-01

    This report describes the application of various nuclear magnetic resonance (NMR) techniques to study the hydration kinetics and mechanisms, the structural properties, and the adsorption characteristics of coal fly ash. Coal fly ash samples were obtained from the Dave Johnston and Laramie River electric power generating plants in Wyoming. Hydrogen NMR relaxation times were measured as a function of time to observe the kinetics of hydration for the two coal fly ashes at different temperatures and water-to-cement ration. The kinetic data for the hydrated coal fly ashes were compared to the hydration of portland cement. The mechanism used to describe the kinetic data for the hydration of portland cement was applied, with reservation, to describe the hydration of the coal fly ashes. The results showed that the coal fly ashes differ kinetically from that of portland cement and from each other. Consequently, both coal fly ashes were judged to be poorer cementitious materials than portland cement. Carbon-13 NMR CP/MAS spectra were obtained for the anhydrous coal fly ashes in an effort to determine the type of organic species that may be present, either adsorbed on the surface or entrained.

  6. 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.

  7. Managing metolachlor and atrazine leaching losses using lignite fly ash.

    PubMed

    Ghosh, Rakesh Kumar; Singh, Neera

    2012-10-01

    Application of low cost amendment for pesticide retention in soil is an important area of research in environmental sciences. The present study reports the potential of coal fly ash (Inderprastha and Badarpur), a waste from thermal power stations, for retaining soil applied metolachlor and atrazine within the application zone. Both the fly ashes were highly effective in reducing the leaching losses of metolachlor and atrazine and at 2% and 5% fly ash amendment levels the herbicides were retained in the top 15 cm profile of the column. However, fly ashes varied in their capacity in reducing the downward mobility of herbicides, as the Inderprastha fly ash was more effective than the Badarpur fly ash. Although fly ash contained heavy metals like Cr, Cu or Pb, but they were not detected in the leachate. Also, concentration of other metals like Zn, Mn and Fe in leachate decreased after fly ash amendment. Results of this study have implications in reducing the leaching losses of these herbicides in agricultural soils. PMID:22854744

  8. Optical properties of fly ash. Volume 1, Final report

    SciTech Connect

    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 executive 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.

  9. 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. PMID:23706374

  10. Extraction of vanadium from athabasca tar sands fly ash

    NASA Astrophysics Data System (ADS)

    Gomez-Bueno, C. O.; Spink, D. R.; Rempel, G. L.

    1981-06-01

    The production of refinery grade oil from the Alberta tar sands deposits as currently practiced by Suncor (formally Great Canadian Oil Sands Ltd.—GCOS) generates a substantial amount of petroleum coke fly ash which contains appreciable amounts of valuable metals such as vanadium, nickel and titanium. Although the recovery of vanadium from petroleum ash is a well established commercial practice, it is shown in the present work that such processes are not suitable for recovery of vanadium from the GCOS fly ash. The fact that the GCOS fly ash behaves so differently when compared to other petroleum fly ash is attributed to its high silicon and aluminum contents which tie up the metal values in a silica-alumina matrix. Results of experiments carried out in this investigation indicate that such matrices can be broken down by application of a sodium chloride/water roast of the carbon-free fly ash. Based on results from a series of preliminary studies, a detailed investigation was undertaken in order to define optimum conditions for a vanadium extraction process. The process developed involves a high temperature (875 to 950 °C) roasting of the fly ash in the presence of sodium chloride and water vapor carried out in a rotary screw kiln, followed by dilute sodium hydroxide atmosphereic leaching (98 °C) to solublize about 85 pet of the vanadium originally present in the fly ash. It was found that the salt roasting operation, besides enhancing vanadium recovery, also inhibits silicon dissolution during the subsequent leaching step. The salt roasting treatment is found to improve vanadium recovery significantly when the fly ash is fully oxidized. This is easily achieved by burning off the carbon present in the “as received” fly ash under excess air. The basic leaching used in the new process selectively dissolves vanadium from the roasted ash, leaving nickel and titanium untouched.

  11. Electrodialytic removal of Cd from biomass combustion fly ash suspensions.

    PubMed

    Kirkelund, Gunvor M; Damoe, Anne J; Ottosen, Lisbeth M

    2013-04-15

    Due to relatively high concentrations of Cd, biomass combustion fly ashes often fail to meet Danish legislative requirements for recycling as fertilizer. In this study, the potential of using electrodialytic remediation for removal of Cd from four different biomass combustion fly ashes was investigated with the aim of enabling reuse of the ashes. The ashes originated from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. A series of laboratory scale electrodialytic remediation experiments were conducted with each ash. The initial Cd concentration in the ashes varied between 8.8 mg Cd/kg (co-firing ash) and 64 mg Cd/kg (pre-washed straw ash), and pH varied from 3.7 (co-firing ash) to 13.3 (wood ash). In spite of such large variations between the ashes, the electrodialytic method showed to be sufficiently robust to treat the ashes so the final Cd concentration was below 2.0mg Cd/kg DM in at least one experiment done with each ash. This was obtained within 2 weeks of remediation and at liquid to solid (L/S) ratios of L/S 16 for the pre-washed straw ash and L/S 8 for the straw, co-firing and wood ash. PMID:23454460

  12. Feasibility study on solidification of municipal solid waste incinerator fly ash with circulating fluidized bed combustion coal fly ash.

    PubMed

    Liu, Wenshi; Hou, Haobo; Zhang, Chuhao; Zhang, Dajie

    2009-05-01

    The objective of this study was to assess the feasibility of solidification of municipal solid waste incinerator (MSWI) fly ash with circulation fluidized bed combustion (CFBC) fly ash, which is unsuitable as a cement replacement due to its high amounts of carbon, lime and anhydrite. The solidification process was conducted on samples prepared from MSWI fly ash, binders (cement clinkers and CFBC fly ash were mixed at two replacement ratios) and water (water/solid weight ratio = 0.4), among which the MSWI fly ash replaced each binder at the ratio of 0, 20, 40, 60 and 80% by dry weight. The samples were subjected to compressive strength tests and Toxicity Characteristic Leaching Procedure and the results showed that all solidified MSWI fly ash can meet the landfill standard imposed by US EPA after 28 days of curing. Micro-analysis (X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrophotometry) revealed that the main hydrate products were C-S-H gel and ettringite, which have a positive effect on heavy metals retention. Therefore, this method provides a possibility to achieve a cheap and effective solution for MSWI fly ash management and use for CFBC fly ash. PMID:19423575

  13. Possible applications for municipal solid waste fly ash.

    PubMed

    Ferreira, C; Ribeiro, A; Ottosen, L

    2003-01-31

    The present study focuses on existing practices related to the reuse of Municipal Solid Waste (MSW) fly ash and identifies new potential uses. Nine possible applications were identified and grouped into four main categories: construction materials (cement, concrete, ceramics, glass and glass-ceramics); geotechnical applications (road pavement, embankments); "agriculture" (soil amendment); and, miscellaneous (sorbent, sludge conditioning). Each application is analysed in detail, including final-product technical characteristics, with a special emphasis on environmental impacts. A comparative analysis of the different options is performed, stressing the advantages but also the weaknesses of each option. This information is systemized in order to provide a framework for the selection of best technology and final products. The results presented here show new possibilities for this waste reuse in a short-term, in a wide range of fields, resulting in great advantages in waste minimization as well as resources conservation. PMID:12493209

  14. Sorbate characteristics of fly ash. Semi annual progress report

    SciTech Connect

    Liskowitz, J.W.

    1980-01-01

    This one year investigation is concerned with relating the sorbent characteristics of fly ash produced from test coal obtained from 19 mines located in Virginia, West Virginia and Pennsylvania. Six of the test coals and their respective fly ashes have been sampled and boiler conditions monitored in P.S.E. and G. coal fired boilers operated under minimum, intermediate and full power. Major, minor and trace elemental analysis as well as Mossbauer spectra of three of the coals and their respective ashes have been completed. The atom composition of the surface of these fly ashes has also been determined by ESCA. The pH and concentration of the major, minor and trace elements that leach out of the fly ash initially have been determined on the fly ashes produced from the Militant, Deep Hollow and Wellmore Cactus coals. All leachate samples to date exhibited an acidic pH. This leaching essentially ceases as the pH approached neutral conditions. This was found to occur after 4 liters of water was passed through each fly ash sample in a lysimeter. The lysimeter studies to define the sorbent characteristics of the fly ashes have not been completed yet.

  15. 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. PMID:26701627

  16. Vitrification of municipal solid waste incineration fly ash using biomass ash as additives.

    PubMed

    Alhadj-Mallah, Moussa-Mallaye; Huang, Qunxing; Cai, Xu; Chi, Yong; Yan, JianHua

    2015-01-01

    Thermal melting is an energy-costing solution for stabilizing toxic fly ash discharged from the air pollution control system in the municipal solid waste incineration (MSWI) plant. In this paper, two different types of biomass ashes are used as additives to co-melt with the MSWI fly ash for reducing the melting temperature and energy cost. The effects of biomass ashes on the MSWI fly ash melting characteristics are investigated. A new mathematical model has been proposed to estimate the melting heat reduction based on the mass ratios of major ash components and measured melting temperature. Experimental and calculation results show that the melting temperatures for samples mixed with biomass ash are lower than those of the original MSWI fly ash and when the mass ratio of wood ash reaches 50%, the deformation temperature (DT), the softening, hemisphere temperature (HT) and fluid temperature (FT) are, respectively, reduced by 189°C, 207°C, 229°C, and 247°C. The melting heat of mixed ash samples ranges between 1650 and 2650 kJ/kg. When 50% wood ash is mixed, the melting heat is reduced by more than 700 kJ/kg for the samples studied in this paper. Therefore, for the vitrification treatment of the fly ash from MSW or other waste incineration plants, wood ash is a potential fluxing assistant. PMID:25220259

  17. Vegetation establishment on soil-amended weathered fly ash

    SciTech Connect

    Semalulu, O.; Barnhisel, R.I.; Witt, S.

    1998-12-31

    A field study was conducted with the following objectives in mind: (1) to study the effect of soil addition to weathered fly ash on the establishment and survival of different grasses and legumes, (2) to identify suitable grasses and/or legume species for vegetation of fly ash, (3) to study the fertilizer N and P requirements for successful vegetation establishment on fly ash and ash-soil mixtures, (4) to examine the nutrient composition of the plant species tested, and (5) to study the plant availability of P from fly ash and ash-soil mixtures. Three rooting media were used: weathered fly ash, and 33% or 50% soil blended with the ash. Four experiments were established on each of these media to evaluate warm season grasses in pure stands, warm season grasses inter-seeded with legumes, cool season grasses, and cool season grasses inter-seeded with legumes. Soil used in this study was more acidic than the fly ash. Only the results from characterization of the rooting media, ground cover, and yield will be presented here.

  18. Development of Classified Fly Ash as a Pozzolanic Material

    NASA Astrophysics Data System (ADS)

    Rukzon, Sumrerng; Chindaprasirt, Prinya

    This research studies the potential for using classified fly ash from Mae Moh power plant in Thailand as a pozzolanic material. Three different fly ash finenesses viz., coarse Original Fly Ash (OFA), Medium Fly Ash (MFA) and Fine Fly Ash (FFA) were used for the study. Ordinary Portland Cement (OPC) was partially replaced with fly ash at 20 and 40% by weight of binder. The water to binder ratio was kept constant at 0.5 and the flow of mortar was maintained at 110±5% with the aid of superplasticizer (SP). Compressive strength, carbonation depth and porosity test of mortars were determined. FFA has a high potential to be used as a good pozzolanic material. The use of FFA produces mortars with good strength and low porosity. The resistance to carbonation of mortar improves with partial replacement of FFA in comparison with the normal coarse fly ash. The use of FFA results in a strong and dense mortar which is due to better dispersion and filling effect as well as an increase in the pozzolanic reaction.

  19. Water holding capacities of fly ashes: Effect of size fractionation

    SciTech Connect

    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 the 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.

  20. Impacts of fly-ash on soil and plant responses.

    PubMed

    Gupta, Dharmendra K; Rai, Upendra N; Tripathi, Rudra D; Inouhe, Masahiro

    2002-12-01

    Coal combustion produces carbon dioxides, SO x, NO x and a variety of byproducts, including fly-ash, flue gas and scrubber sludge. Fly-ash consists of minute glass-like particles and its deposition on leaves inhibits the normal transpiration and photosynthesis of plants. Fly-ash also affects the physicochemical characteristics of soil because it is generally very basic, rich in various essential and non-essential elements, but poor in both nitrogen and available phosphorus. The massive fly-ash materials have been a potential resource for the agricultural activities as well as the other industrial purposes. Practical value of fly-ash in agriculture as an 'effective and safe' fertiliser or soil amendment can be established after repeated field experiments. Here remains to be disclosed the biological processes and interactions due to 'lack and excess' of the fly-ash exposures along with abiotic and biotic factors. These may involve the symbiotic fixation of nitrogen and the biological extraction of metals following immobilisation of toxic heavy metal ions, as well as other neutralisation and equilibration processes during weathering. Nitrogen-fixing plants with an apparent heavy metal-tolerance can be helpful as the early colonisers of fly-ash dumps and nearby areas. PMID:12579443

  1. Transformation of nitrogen during vermicomposting of fly ash.

    PubMed

    Bhattacharya, Satya S; Chattopadhyay, Gunindra N

    2004-12-01

    In view of environmental problems generated by large-scale production of fly ash, increasing attention is now being paid to the recycling fly ash as a source of plant nutrients in agriculture. However, the low amount of nitrogen in such materials forms a major constraint for such application. In the present study, the possibility of improving the N status in mixtures of fly ash and organic matter was investigated by adopting vermicomposting technology. Different combinations of fly ash and cow (Bos taurus) dung; namely fly ash alone, cow dung alone and fly ash + cow dung at 1:1, 1:3 and 3:1 ratios were incubated with and without epigeic earthworms (Eisenia fetida) for 50 days. The occurrence of N in different bio-available forms; namely easily mineralizable, NH4+ and NO3- tended to increase considerably in the series treated with earthworms. This behaviour was attributed primarily to increased microbiological activity in the vermicomposted samples and also to a considerable rise in the concentration of nitrogen-fixing bacteria in this series. Among the three combinations of vermicomposted fly ash and cow dung, the 1:1 mixture appeared to exhibit the highest availability of nitrogen. PMID:15666451

  2. The use of coal fly ash for soil stabilization

    SciTech Connect

    Brown, T.H.; Brown, M.A.; Sorini, S.S.; Huntington, G.

    1991-12-01

    The objective of this work was to examine the potential use of Wyoming subbituminous coal fly ash materials for cementation of soil materials. Specimens made from Laramie River (LR) fly ash had higher unconfined compression strength and more brittleness than the Specimens made with Dave Johnston (DJ) fly ash. However, soil/DJ fly ash mixtures that were cured for 28 days had relatively good strengths without the brittleness that the LR specimens developed. These characteristics of the DJ fly ash may be important attributes for road stabilization applications. The detailed mineralogical evaluation provides some insight into which minerals may enhance development of strength in these materials. In general, selective dissolution of the soil/fly ash mixtures shows that many of the potentially toxic elements (e.g., B, Cr, Fe, Mn, Ni, Pb) are associated with the sulfide phase (HNO{sub 3} extractable) and with the residual material. In this study, the dynamics of elemental release from the element pools did not result in toxic conditions. The formation of colloidal material capable of mobilizing potentially toxic elements was not found in the soil/fly ash mixtures. Apparently, the high pH of the materials enhanced immobilization of the high molecular weight material.

  3. Effect of chemical admixtures on properties of high-calcium fly ash geopolymer

    NASA Astrophysics Data System (ADS)

    Rattanasak, Ubolluk; Pankhet, Kanokwan; Chindaprasirt, Prinya

    2011-06-01

    Owing to the high viscosity of sodium silicate solution, fly ash geopolymer has the problems of low workability and rapid setting time. Therefore, the effect of chemical admixtures on the properties of fly ash geopolymer was studied to overcome the rapid set of the geopolymer in this paper. High-calcium fly ash and alkaline solution were used as starting materials to synthesize the geopolymer. Calcium chloride, calcium sulfate, sodium sulfate, and sucrose at dosages of 1wt% and 2wt% of fly ash were selected as admixtures based on concrete knowledge to improve the properties of the geopolymer. The setting time, compressive strength, and degree of reaction were recorded, and the microstructure was examined. The results show that calcium chloride significantly shortens both the initial and final setting times of the geopolymer paste. In addition, sucrose also delays the final setting time significantly. The degrees of reaction of fly ash in the geopolymer paste with the admixtures are all higher than those of the control paste. This contributes to the obvious increases in compressive strength.

  4. Heavy metal migration during electroremediation of fly ash from different wastes--modelling.

    PubMed

    Lima, A T; Rodrigues, P C; Mexia, J T

    2010-03-15

    Fly ash is an airborne material which is considered hazardous waste due to its enrichment on heavy metals. Depending on the waste from which they are originated, fly ash may be further valorised, e.g. as soil amendment or concrete and ceramics adjuvant, or landfilled, when defined as hazardous material. In any case, heavy metal content has to be decreased either for fly ash valorisation or for complying with landfill criteria. The electrodialytic (EDR) process is a remediation technique based on the principle of electrokinetics and dialysis, having the aim to remove heavy metals from contaminated solid media. EDR was here applied to fly ashes from the combustion of straw (ST), from the incineration of municipal solid waste (DK and PT) and from the co-combustion of wood (CW). A statistical study, using F tests, Bonferroni multiple comparison method and a categorical regression, was carried out to determine which variables ("Ash type", "Duration", "Initial pH", "Final pH", "Acidification" and "Dissolution") were the most significant for EDR efficiency. After establishing these, the selected variables were then used to characterize some kinetic parameters, from metals migration during EDR, using a biregressional design. Cd, Cr, Cu, Ca and Zn migration velocity and acceleration to the electrodes (anode and cathode) were then considered. Cd and Cu migration to the cathode were found to be significantly influenced by "Ash type", "Duration", "Final pH" and "Dissolution". PMID:19883974

  5. The leaching characteristics of selenium from coal fly ashes

    SciTech Connect

    Wang, T.; Wang, J.; Burken, J.G.; Ban, H.; Ladwig, K.

    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 for 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.

  6. Usage of fly ash as a coal desulphurization reagent

    SciTech Connect

    Yaman, S.; Kuecuekbayrak, S.

    1996-12-31

    This paper covers the direct usage of fly ash to remove sulphur from coal. Experiments were carried out on a high sulphur Turkish lignite. 5 g of fly ash was extracted in 200 ml of water under pressure and the dilute solution containing water extractable parts of fly ash was used as desulphurization reagent. Oxygen pressure was created over desulphurization medium during the extraction period by which dissolved oxygen was concentrated in the solution. Effects of temperature, partial pressure of oxygen, and time were investigated in the ranges of 403--498 K, 0.0--1.5 MPa and 15--90 min, respectively.

  7. 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.

  8. Construction Placement and Hardened Properties of Shotcrete with Highly Functional Fly Ash

    NASA Astrophysics Data System (ADS)

    Yuno, Kunihiro; Ishii, Mitsuhiro; Hashimoto, Chikanori; Mizuguchi, Hiroyuki

    Shikoku Electric Power Co., Inc. has developed the technology to manufacture a brand name "Finash" about 12 years ago, by sorting and classifying coal ash generated in coal fired power plants. "Finash" is highly functional fly ash (HFA) is produced by removing irregular coarse particles. It is important for the production of HFA to minimize the variation in quality of coal ash with sophisticated classification technique and extracting good-quality spherical fine particles. It is now widely utilized as concrete admixture for general civil engineering structures and buildings in Japan. When highly functional fly ash (HFA) is used as shotcrete admixture to substitute for fine aggregate of 100kg/m3, the shotcrete has the advantages of decreasing the amount of dust and rebound during spraying operation, improving the hardened properties of concrete, etc. Therefore, it has been applied in many tunnel construction projects. This paper discusses about the various characteristics such as construction placement, strength, neutralization and dry shrinkage of shotcrete using highly functional fly ash (HFA), using the results that is obtained from spray test in an actual road tunnel.

  9. Biotoxicity evaluation of fly ash and bottom ash from different municipal solid waste incinerators.

    PubMed

    Chou, Jing-Dong; Wey, Ming-Yen; Liang, Hsiu-Hao; Chang, Shih-Hsien

    2009-08-30

    Different types of municipal solid waste incinerator (MSWI) fly and bottom ash were extracted by TCLP and PBET procedures. The biotoxicity of the leachate of fly ash and bottom ash was evaluated by Vibrio fischeri light inhibition test. The results indicate the following: (1) The optimal solid/liquid ratio was 1:100 for PBET extraction because it had the highest Pb and Cu extractable mass from MSWI fly ash. (2) The extractable metal mass from both fly ash and bottom ash by PBET procedure was significantly higher than that by TCLP procedure. (3) The metal concentrations of fly ash leachate from a fluidized bed incinerator was lower than that from mass-burning and mass-burning combined with rotary kiln incinerator. (4) The TCLP and PBET leachate from all MSWI fly ash samples showed biotoxicity. Even though bottom ash is regarded as a non-hazardous material, its TCLP and PBET leachate also showed biotoxicity. The pH significantly influenced the biotoxicity of leachate. PMID:19264394

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

    SciTech Connect

    Bernal, Susan A.; Provis, John L.; Walkley, Brant; San Nicolas, Rackel; Gehman, John D.; Brice, David G.; Kilcullen, Adam R.; Duxson, Peter; Deventer, Jannie S.J. van

    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 nuclear 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.

  11. Optical properties of fly ash. Volume 2, Final report

    SciTech Connect

    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 executive summary of the whole program followed by the dissertation of Ghosal and Ebert. Volume 2 contains the dissertation of Ebert which covers the measurements of the optical constants of slags, and calculations of the radiant properties of fly ash dispersions. A list of publications and conference presentations resulting from the work is also included.

  12. COMPOUND FORMS OF FOSSIL FUEL FLY ASH EMISSIONS

    EPA Science Inventory

    A methodology for identifying inorganic compounds in particulate emissions from fossil fuel combustion processes is described. Samples collected from power plants burning coal and oil fuels of different compositions provided a typical range of fly ashes for the investigations. El...

  13. Fly ash based zeolitic pigments for application in anticorrosive paints

    NASA Astrophysics Data System (ADS)

    Shaw, Ruchi; Tiwari, Sangeeta

    2016-04-01

    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+ with Mg2+ and Ca2+ 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 epoxy 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).

  14. Column oil agglomeration of fly ash with ultrasonics

    SciTech Connect

    Gray, M.L.; Champagne, K.J.; Soong, Y.; Finseth, D.H.

    1999-07-01

    A promising oil agglomeration process has been developed for the beneficiation of fly ash using a six-foot agglomeration column. Carbon concentrates have been separated from fly ash with yields greater than 60 % and purities of 55 to 74 %. The parameters examined in the study include ultrasonic exposure, pulse rate, frequency, agitation speed, and blade configuration. The effects of the experimental variables on the quality of separation are discussed.

  15. KINETICS OF FLY ASH BENEFICIATION BY CARBON BURNOUT

    SciTech Connect

    Dr. Joseph N.D. Dodoo; Dr. Joseph M. Okoh

    2000-11-01

    Surface area analyses performed on fly ash samples reveal that the surface area is controlled by carbon content. The higher surface areas found in large particles are due to the presence of highly porous carbonaceous particles. Adsorption-desorption isotherms and t-plots of fly ash samples indicate that fly ash is porous. BJH Adsorption/Desorption pore size analysis reveal that pore diameters are independent of sieve size. They appear to be dependent only on the nature of the material which confers porosity. Based on the results of Brown and Dykstra (41) it is reasonable to assume that calculations of reaction rates at temperatures above 550 C were confounded by weight losses from processes other than carbon oxidation and, therefore, are not useful in determination of the temperature dependence of carbon oxidation in fly ash. The results of the present study indicate that temperatures below 550 C should be used for future studies in order to satisfactorily assess the temperature dependence of carbon oxidation in fly ash. Furthermore, it is also advisable that percent carbon determinations be performed on fly ash samples after the oxidation reactions to determine whether all carbon present in fly ash is oxidized. This will ensure that reaction rates are representative of the complete oxidation of carbon. An inverse relationship was determined between reaction rates and oxygen concentration for this study. As discussed, this may be due to volatilization of volatiles from fly ash and ease of transport of products away from the reaction sites by the action of the vacuum applied to the samples. A more accurate determination of oxygen dependence of carbon oxidation can be accomplished by the use of specialty gases containing different concentrations of oxygen which could eliminate the need to apply vacuum to the samples.

  16. Post-treatment of fly ash by ozone in a fixed bed reactor

    SciTech Connect

    Kim Hougaard Pedersen; Merc Casanovas Meli; Anker Degn Jensen; Kim Dam-Johansen

    2009-01-15

    The residual carbon in fly ash produced from pulverized coal combustion can adsorb the air-entraining admixtures (AEAs) added to enhance air entrainment in concrete. This behavior of the ash can be suppressed by exposing the fly ash to oxidizing species, which oxidizes the carbon surface and thus prevents the AEA to be adsorbed. In the present work, two fly ashes have been ozonated in a fixed bed reactor and the results showed that ozonation is a potential post-treatment method that can lower the AEA requirements of a fly ash up to 6 times. The kinetics of the carbon oxidation by ozone was found to be fast. A kinetic model has been formulated, describing the passivation of carbon, and it includes the stoichiometry of the ozone consumption (0.8 mol of O{sub 3}/kg of C) and an ineffective ozone loss caused by catalytic decomposition. The simulated results correlated well with the experimental data. 28 refs., 7 figs., 3 tabs.

  17. Effect of fly ash on the optimum sulfate of Portland Cement

    NASA Astrophysics Data System (ADS)

    Niemuth, Mark D.

    Calcium sulfate is typically added to ordinary portland cement (OPC) clinker during grinding to prevent flash set and to improve early-age strength development without causing volume instabilities. Recent changes to ASTM C150, Standard Specification for Portland Cement, have enabled greater flexibility in determining optimum sulfate levels in portland cement by not requiring ASTM C563, Approximation of Optimum SO3 in Hydraulic Cement Using Compressive Strength, to be used in setting sulfate target levels. ASTM C563 requires strength testing using only the hydraulic cement, which is not always indicative of the optimum sulfate for field use, since supplementary materials (e.g., fly ash) may be used by the concrete producer. Adding additional sulfate to account for the sulfate demand of fly ashes can enable an improvement in the early age strength for cement-fly ash systems and decrease in problems that may be attributed to OPC-admixture-fly ash incompatibility such as abnormal setting and slow strength gain. This thesis provides experimental data on the strength development and heat release during early hydration for cement-fly ash systems with different sulfate levels. The thesis focused on high calcium fly ashes, but low calcium fly ash was also tested. It is demonstrated that some fly ashes have their own sulfate demand and when these ashes are used in cement-fly ash blends there is effectively an increase in the optimal sulfate level that could be used for the OPC. It is also shown that optimum sulfate determined by heat of hydration measured with isothermal calorimetry is similar to the optimum sulfate determined by compressive strength at 1 day. Using isothermal calorimetry can result in substantial time and cost savings at plants for determining the optimal sulfate content. Theories for the mechanisms that drive the differences in sulfate demand in OPC are reviewed. These theories are adapted for OPC-fly ash blends and are outlined, tested and discussed. The

  18. Plasma torch burns bright for fly-ash vitrification

    SciTech Connect

    Tardy, P.; Labrot, M.; Pineau, D.

    1994-12-01

    Municipal solid waste incineration generates two main kinds of residues--bottom ash and fly ash. Bottom ash usually is nontoxic and can be disposed in nontoxic waste landfills or, as in France, used as road aggregates after passing toxicity characteristic leaching procedures tests. Fly ash consists of fine particles separated from exhaust gases in incinerator-gas cleaning systems. Fly ash generally contains heavy metals (such as lead, cadmium and mercury) and semivolatile organic compounds. These toxics are readily leachable and will pollute groundwater if carelessly disposed in landfills. Fly-ash storage regulations in Europe have become increasingly restrictive. For example, since December 1992, fly ash in France must be landfilled in special ''final waste storage centers.'' These new regulations and difficulties associated with opening new storage centers have resulted in a sharp rise in dumping costs. In this context, new treatment processes are being developed that eventually will enhance the value of the end-product. Vitrification yields the best results of all processing methods, because the end-product is chemically inert.

  19. Mutagenicity and genotoxicity of coal fly ash water leachate

    SciTech Connect

    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 metals - 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.

  20. [Study on mercury re-emissions during fly ash utilization].

    PubMed

    Meng, Yang; Wang, Shu-Xiao

    2012-09-01

    The amount of fly ash produced during coal combustion is around 400 million tons per year in China. About 65%-68% of fly ash is used in building material production, road construction, architecture and agriculture. Some of these utilization processes include high temperature procedures, which may lead to mercury re-emissions. In this study, experiments were designed to simulate the key process in cement production and steam-cured brick production. A temperature programmed desorption (TPD) method was used to study the mercury transformation in the major utilization processes. Mercury re-emission during the fly ash utilization in China was estimated based on the experimental results. It was found that mercury existed as HgCl2 (Hg2 Cl2), HgS and HgO in the fly ash. During the cement production process, more than 98% of the mercury in fly ash was re-emitted. In the steam-curing brick manufacturing process, the average mercury re-emission percentage was about 28%, which was dominated by the percentage of HgCl2 (Hg2 Cl2). It is estimated that the mercury re-emission during the fly ash utilization have increased from 4.07 t in 2002 to 9.18 t in 2008, of which cement industry contributes about 96.6%. PMID:23243850

  1. Ceramic glass from flying-ash

    SciTech Connect

    Chiang, J.F.; Xu, You-Wu; Chen, Pinzhen

    1996-10-01

    A ceramic glass composition compromises of mainly SiO{sub 2}, Al{sub 2}O{sub 3}, MgO and with small percent of CaO, TiO{sub 2}, B{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}/FeO, K{sub 2}O, Na{sub 2}O, and P{sub 2}O{sub 5} has been produced. A convenient source of raw materials is a mixture of flying-ash from power plant, borax manufacturing plant waste, and titanium pigment waste. The ceramic glass is formed from an intermediate ceramic mixture which is subjected to heat treatment. The solid is annealed at another temperature for several hours, and then is reduced to a lower temperature at a rate of 20-30{degrees}C/hour. The final product, the ceramic glass possesses many useful mechanical and chemical properties, such as high compressive strength, high bending strength, high hardness, high impact resistance, acid and alkaline resistance, etc. The ceramic glass can be used as laboratory counter-top, reaction still, manufacture of fluid transfer tubing, sandpaper/grit, and many other industrial applications.

  2. Aggregate material formulated with MSWI bottom ash and APC fly ash for use as secondary building material.

    PubMed

    del Valle-Zermeño, R; Formosa, J; Chimenos, J M; Martínez, M; Fernández, A I

    2013-03-01

    The main goal of this paper is to obtain a granular material formulated with Municipal Solid Waste Incineration (MSWI) bottom ash (BA) and air pollution control (APC) fly ash to be used as secondary building material. Previously, an optimum concrete mixture using both MSWI residues as aggregates was formulated. A compromise between the environmental behavior whilst maximizing the reuse of APC fly ash was considered and assessed. Unconfined compressive strength and abrasion resistance values were measured in order to evaluate the mechanical properties. From these results, the granular mixture was not suited for certain applications owing to the high BA/APC fly ash content and low cement percentages used to reduce the costs of the final product. Nevertheless, the leaching test performed showed that the concentrations of all heavy metals were below the limits established by the current Catalan legislation for their reutilization. Therefore, the material studied might be mainly used in embankments, where high mechanical properties are not needed and environmental safety is assured. PMID:23102641

  3. Fly Ash Disposal in Ash Ponds: A Threat to Ground Water Contamination

    NASA Astrophysics Data System (ADS)

    Singh, R. K.; Gupta, N. C.; Guha, B. K.

    2016-07-01

    Ground water contamination due to deposition of fly ash in ash ponds was assessed by simulating the disposal site conditions using batch leaching test with fly ash samples from three thermal power plants. The periodic analysis of leachates was performed for selected elements, Fe, Cu, Ni, Cr, Pb and Cd in three different extraction solutions to determine the maximum amount that can be leached from fly ash. It was observed that at low pH value, maximum metals are released from the surface of the ash into leachate. The average concentration of these elements found in ground water samples from the nearby area of ash ponds shows that almost all the metals except `Cr' are crossing the prescribed limits of drinking water. The concentration of these elements at this level can endanger public health and environment.

  4. Multitechnique multielemental analysis of coal and fly ash

    SciTech Connect

    Nadkarni, R.A.

    1980-05-01

    The coal sample is first ashed with high temperature ashing or with RF plasma low temperature ashing. The coal ash or fly ash can be analyzed for major ash elements by fusing with lithium tetraborate in an automatic fusion device, the Claisse Fluxer. The ash samples are also dissolved in a Parr bomb in a mixture of aqua regia and HF. Subsequently, the solutions are analyzed for eight major (Al, Ca, Fe, K, Mg, Na, Si, and Ti) and 20 trace elements (As, B, Ba, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Sr, U, V, and Zn) by inductively coupled plasma emission spectroscopy. Mercury in coal and fly ash is determined on a separate aliquot by the cold vapor atomic absorption technique. Fluorine and chlorine in the samples are determined by fusing with Na/sub 2/CO/sub 3/ and Eschka mixture, respectively, and then measuring the two ions in solution with specific ion electrodes. Oxygen in the samples can be determined rapidly and nondestructively by 14-MeV neutron activation analysis. These methods have been tested by analyzing several NBS coal and fly ash standards with good accuracy and reproducibility. 10 tables.

  5. Toxicological evaluation of the effects of waste-to-energy ash-concrete on two marine species

    SciTech Connect

    Hamilton, K.L.; Nelson, W.G.; Curley, J.L. )

    1993-10-01

    The toxicological effects of waste-to-energy ash-concrete on survivorship, growth, and fecundity (end-point parameters) of Mysidopsis bahia and on survivorship and growth of Menidia beryllina were evaluated with the 7-d static-renewal toxicity test. Leachate and elutriate solutions were prepared from experimental ash-concrete test cylinders constructed from concrete with additions of either bottom ash (mix BA), mixed bottom ash and scrubber residue, or mixed bottom ash and fly ash (60:40%, mix BA:FA). Control experiments with concrete (without ash) and pH (7-9.5) were conducted to assess any toxic effects of the stabilization process. pH did not affect end-point parameters of Mysidopsis bahia or Menidia beryllina. However, the 100% elutriate solution made from concrete reduced survivorship of Mysidopsis bahia. For experiments with ash-concrete test cylinders with the BA mixture, 10-d leachate solution reduced survivorship of Mysidopsis bahia and the 100% elutriate solutions reduced survivorship of Mysidopsis bahia and Manidia beryllina. With the BA:SR mixture, the 100 and 50% elutriate solutions reduced survivorship of Menidia beryllina. The BA:FA 10- and 5-d leachate solutions and the 100, 50, and 25% elutriate solutions reduced survivorship of Menidia beryllina. The BA:FA 10- and 5-d leachate solutions and the 100, 50, 25% elutriate solutions reduced survivorship of Mysidopsis bahia.

  6. Reduction of metal leaching in brown coal fly ash using geopolymers.

    PubMed

    Bankowski, P; Zou, L; Hodges, R

    2004-10-18

    Current regulations classify fly ash as a prescribed waste and prohibit its disposal in regular landfill. Treatment of the fly ash can reduce the leach rate of metals, and allow it to be disposed in less prescribed landfill. A geopolymer matrix was investigated as a potential stabilisation method for brown coal fly ash. Precipitator fly ash was obtained from electrostatic precipitators and leached fly ash was collected from ash disposal ponds, and leaching tests were conducted on both types of geopolymer stabilised fly ashes. The ratio of fly ash to geopolymer was varied to determine the effects of different compositions on leaching rates. Fourteen metals and heavy metals were targeted during the leaching tests and the results indicate that a geopolymer is effective at reducing the leach rates of many metals from the fly ash, such as calcium, arsenic, selenium, strontium and barium. The major element leachate concentrations obtained from leached fly ash were in general lower than that of precipitator fly ash. Conversely, heavy metal leachate concentrations were lower in precipitator fly ash than leached pond fly ash. The maximum addition of fly ash to this geopolymer was found to be 60wt% for fly ash obtained from the electrostatic precipitators and 70wt% for fly ash obtained from ash disposal ponds. The formation of geopolymer in the presence of fly ash was studied using 29Si MAS-NMR and showed that a geopolymer matrix was formed. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) imaging showed the interaction of the fly ash with the geopolymer, which was related to the leachate data and also the maximum percentage fly ash addition. PMID:15511575

  7. Problems encountered during the use of ammonium-contaminated fly ash

    SciTech Connect

    Brugghen, F.W. van der; Gast, C.H.; Berg, J.W. van den

    1996-01-01

    The most extensively used technology for flue gas treatment to reduce NO{sub x}-emission is selective reduction with ammonia, either at 1000{degrees}C in the gas phase (SNCR) or at 350{degrees}C in the presence of a catalyst (SCR). Operational problems that are encountered during application of these processes are mainly caused by the slip of unreacted ammonia through the reaction zone or the catalyst. This ammonia slip can lead to the formation and deposition of ammonium salts in colder parts of the installation. In coal fired boilers contamination of the fly ash with ammonium salts is possible, which can restrict re-use, especially because of the ammonia smell during application. Results will be described of laboratory tests with the preparation of mortars containing fly ash with 100, 200 and 300 mg/kg ammonium. Ammonia concentrations were continuously measured in ambient air during concrete mortar preparation and the pouring of concrete floors. Furthermore, the compressive strength and the ammonium content of the hardened concrete were followed. Other tests were carried out at a production facility for sintered artificial gravel. Fly ash with 300 mg/kg ammonium was used during these tests. Effects on working conditions, product quality, ammonia emission and operational problems of the installation were established and will be described.

  8. Characterization of mutagenic coal fly ash and extracts.

    PubMed

    Griest, W H; Caton, J E; Rao, T K; Harmon, S H; Yeatts, L B; Henderson, G M

    1982-11-01

    Post-electrostatic precipitator (ESP) fly ash samples were collected from a coal-fired electric power generation plant under three modes of plant operation: normal operation, a low NOx-emission mode of combustion, and operation with the ESP shorted-out. Results of chemical and physical characterization of the ashes were compared with bacterial mutagenicity bioassay to determine parameters or compounds correlating with bioactivity. The general physical properties, ultimate composition, and trace elemental and radiochemical species determined did not correlate with the mutagenicity. Only the presence of aromatic hydrocarbons and chemically derivatizable polar organic compounds appeared to be associated with mutagenicity of the fly ash. PMID:6757160

  9. Beneficiating value-added products from combustion fly ash

    SciTech Connect

    Soong, Y.; McMahan, L.; Gray, D.; Fauth, T.A.; Link, K.; Champagne, J.; Schoffstall, M.R.

    1999-07-01

    Two separation techniques, a dry triboelectrostatic and a wet agglomeration column technique, were developed for beneficiating value-added products from combustion fly ashes. The dry triboelectrostatic separation of fly ash derived from both coal combustion and the combustion of coal mixed with 10 wt.% biomass were conducted. Two different types of triboelectrostatic separators - parallel plate and louvered plate separators - were used for this study. It was found that the quality of separation was dependent upon the nature of fly ash and the configuration of the separator utilized. The development of an oil agglomeration process for the recovery of unburned carbon from fly ash required the optimization of the process. The beneficiation was performed using the six-foot agglomeration column under batch mode conditions. A systematic study on the effects of agglomerant, agitation speeds, air flows, feed rates and agglomerant/ash ratios on the quality of beneficiation was conducted. Preliminary results indicate that the unburned carbon products with the purity of 66 to 71% and the yields of 55 to 57% could be obtained under the optimum conditions studied. Selected applications (i.e., activated carbon, molecular sieves and catalytic application) from the fly ash derived products were explored.

  10. 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. PMID:18838261

  11. Illinois basin coal fly ashes. 1. Chemical characterization and solubility

    USGS Publications Warehouse

    Roy, W.R.; Griffin, R.A.; Dickerson, D.R.; Schuller, R.M.; Martin, S.M.C.

    1984-01-01

    Twelve precipitator-collected fly ash samples (nine derived from high-sulfur Illinois Basin coals and three from Western U.S. coals) were found to contain a variety of paraffins, aryl esters, phenols, and polynuclear aromatic hydrocarbons including phenanthrene, pyrene, and chrysene but all at very low concentrations. Less than 1% of the organic carbon in the samples was extractable into benzene. Solubility studies with a short-term (24-h) extraction procedure and a long-term (20-week) procedure indicate that the inorganic chemical composition of some types of fly ash effluent is time dependent and may be most toxic to aquatic ecosystems when initially mixed with water and pumped to disposal ponds. Some acidic, high-Cd fly ashes would be classified as hazardous wastes if coal ash was included in this waste category by future RCRA revisions. ?? 1984 American Chemical Society.

  12. Frost susceptibility properties of Soma-B fly ash

    SciTech Connect

    Cokca, E.

    1997-04-01

    This paper assesses the effect of freeze-thaw properties of compacted fly ash specimens likely to affect its use as fill material, on the basis of laboratory investigations conducted on Soma-B Thermal Power Plant ashes in western Turkey. Test specimens were subjected to compaction. Changes in strength with curing time and freeze-thaw cycles are measured using unconfined compression tests, and increases in strength with curing time and the number of freeze-thaw cycles were observed. The findings suggest that compacted Soma-B fly ash could serve as fill material, particularly over weak subgrades with no negative environmental effects, provided that the degree of saturation of the compacted fly ash embankment is at a specific value.

  13. Belgian MSWI fly ashes and APC residues: a characterisation study.

    PubMed

    De Boom, Aurore; Degrez, Marc

    2012-06-01

    Municipal Solid Waste Incineration (MSWI) produces different sorts of residues, bottom ash, fly ashes and Air Pollution Control (APC) residues. Generally, fly ashes and APC residues are mixed at the MSWI plant and manage as a sole residue. In this study, fly ashes and APC residues have been sampled separately at different Belgian MSWI plant and analysed by X-ray fluorescence in order to highlight the composition differences that may appear between the solids. Ca and Cl are found to be the major elements in most of the samples. Lithophilic elements, such as Al and Si, are richer in furnace and boiler ashes, as can be expected. Leaching tests also show differences between the residues; leachates from furnace and boiler ashes are alkaline while those from bag filter residues present a pH value of 6, which impacts the leaching of heavy metals (Pb and Zn). The results suggest that it could be advantageous to manage fly ashes and APC residues separately by adjusting the treatment to their specificities. PMID:22244614

  14. A novel method for immobilization of heavy metals from MSW incinerator fly ash via use of Sorel cement

    SciTech Connect

    Macakova, S.; Hepworth, M.H.

    1996-12-31

    Since fly ash contains a higher concentration of toxic elements than bottom ash, it is not usually possible to deposit it in ordinary landfills. The special landfill sites (ash monofills) for ash, which do not endanger ground water supplies are both temporary and an expensive solution and are not acceptable by people who live adjacent to them. According to the United States Supreme Court decision ruling on May 2, 1994, incinerator ash from municipal combustion facilities are subject to the Resource Conservation and Recovery Act as potentially hazardous waste. In the autumn of 1993, a research program was initiated by one of the authors to employ a novel method for stabilization of the fly ash from electrostatic precipitators. The novelty of this method is that it used by-products from magnesium processing plants to prepare magnesia cement, so called Sorel cement, to stabilize fly ash from MSWI. Sorel cement is a combination of magnesium oxide and magnesium chloride, currently by-products of a combination of magnesium oxide and magnesium chloride, currently by-products of magnesium processing operations. The main goal of this research program was to treat fly ash prior to its disposal and to investigate the possibility of utilizing a new ash-concrete product.

  15. Leaching of Mixtures of Biochar and Fly Ash

    SciTech Connect

    Palumbo, Anthony Vito; Porat, Iris; Phillips, Jana Randolph; Amonette, J. E.; Drake, Meghan M; Brown, Steven D; Schadt, Christopher Warren

    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 nitrogen 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.

  16. Fly ash: Perspective resource for geo-polymer materials production

    NASA Astrophysics Data System (ADS)

    Kargin, Aleksey; Baev, Vladimir; Mashkin, Nikolay; Uglyanica, Andrey

    2016-01-01

    The present paper presents the information about the chemical and mineralogical composition of the ash and slag and their amounts at the dumps of the thermoelectric plants located in the city of Kemerovo. It is known that about 85% of ash and slag from the thermoelectric plants in Russia are removed by means of the hydraulic sluicing systems and only about 15% - by the systems of pneumatic ash handling. Currently, however, the transition from the "wet" ash removal systems to the "dry" ones is outlined. This process is quite logical since the fly ash has the higher reactivity compared with the hydraulic sluicing ash and therefore it is of the great interest for recycling and use. On the other hand, the recent trend is the increased use of fly ash in the production of geo-polymers due to their availability, workability and the increased life of the final product. The analysis is carried out to check the possibility of using the fly ash from various Kemerovo thermoelectric plants as a raw material for the production of the alkali-activated binder.

  17. Potential of Hazardous Waste Encapsulation in Concrete Compound Combination with Coal Ash and Quarry Fine Additives.

    PubMed

    Lieberman, Roy Nir; Anker, Yaakov; Font, Oriol; Querol, Xavier; Mastai, Yitzhak; Knop, Yaniv; Cohen, Haim

    2015-12-15

    Coal power plants are producing huge amounts of coal ash that may be applied to a variety of secondary uses. Class F fly ash may act as an excellent scrubber and fixation reagent for highly acidic wastes, which might also contain several toxic trace elements. This paper evaluates the potential of using Class F fly ashes (<20% CaO), in combination with excessive fines from the limestone quarry industry as a fixation reagent. The analysis included leaching experiments (EN12457-2) and several analytical techniques (ICP, SEM, XRD, etc.), which were used in order to investigate the fixation procedure. The fine sludge is used as a partial substitute in concrete that can be used in civil engineering projects, as it an environmentally safe product. PMID:26510011

  18. Effect of ash circulation in gasification melting system on concentration and leachability of lead in melting furnace fly ash.

    PubMed

    Okada, Takashi; Suzuki, Masaru

    2013-11-30

    In some gasification-melting plants, generated melting furnace fly ash is returned back to the melting furnace for converting the ash to slag. This study investigated the effect of such ash circulation in the gasification-melting system on the concentration and leachability of lead in the melting furnace fly ash. The ash circulation in the melting process was simulated by a thermodynamic calculation, and an elemental analysis and leaching tests were performed on a melting furnace fly ash sample collected from the gasification-melting plant with the ash circulation. It was found that by the ash circulation in the gasification-melting, lead was highly concentrated in the melting furnace fly ash to the level equal to the fly ash from the ash-melting process. The thermodynamic calculation predicted that the lead volatilization by the chlorination is promoted by the ash circulation resulting in the high lead concentration. In addition, the lead extraction from the melting furnace fly ash into a NaOH solution was also enhanced by the ash circulation, and over 90% of lead in the fly ash was extracted in 5 min when using 0.5 mol l(-1) NaOH solution with L/S ratio of 10 at 100 °C. Based on the results, a combination of the gasification-melting with the ash circulation and the NaOH leaching method is proposed for the high efficient lead recovery. PMID:24121545

  19. Fly ash as a liming material for corn production

    SciTech Connect

    Tarkalson, D.D.; Hergert, G.W.; Stevens, W.B.; McCallister, D.L.; Kackman, S.D.

    2005-05-01

    Fly ash produced as a by-product of subbituminous coal combustion can potentially serve as an alternative liming material without negatively affecting corn (Zea mays L.) production in areas where use of conventional liming materials can be uneconomical due to transportation costs. A study was conducted to determine if fly ash produced from the Nebraska Public Power District Gerald Gentleman Power Station located in Sutherland, NE could be used as an alternative liming material. Combinations of dry fly ash (DFA), wet fly ash (WFA), beet lime (by-product of sugar beet (Beta vulgaris L.) processing) (BL), and agricultural lime (AGL) were applied at rates ranging from 0.43 to 1.62 times the recommended lime rate to plots on four acidic soils (Anselmo fine sandy loam, Hord fine sandy loam, Holdrege sandy loam, and Valentine fine sand). Soil samples were collected to a depth of 0.2 m from plots and analyzed for pH before lime applications and twice periodically after lime application. The Hord and Valentine soils were analyzed for exchangeable Ca, Mg, K, Na,and Al for determination of percent Al saturation on selected treatments and sampling dates. Corn grain yields were determined annually. It is concluded that the fly ash utilized in this study and applied at rates in this study, increases soil pH comparable to agricultural lime and is an appropriate alternative liming material.

  20. Chloride chemical form in various types of fly ash.

    PubMed

    Zhu, Fenfen; Takaoka, Masaki; Shiota, Kenji; Oshita, Kazuyuki; Kitajima, Yoshinori

    2008-06-01

    Chloride content is a critical problem for the reuse of fly ash as a raw material in cement, and the method used by recyclers to reduce the fly ash chloride content depends on the chemical form of the chlorides. However, limited information is available on the quantitative distribution of chlorides and the identity of some chlorides such as Friedel's salt. We examined chloride forms and percentages using X-ray absorption near edge structure and X-ray diffraction analyses, as well as corresponding washing experiments. Approximately 15% of the chlorine in raw fly ash was estimated to be in the form of NaCI, 10% in KCl, 50% in CaCl2, and the remainder in the form of Friedel's salt. Fly ash collected in a bag filter with the injection of calcium hydroxide for acid gas removal (CaFA) contained 35% chlorine as NaCl, 11% as KCI, 37% as CaCl2, 13% as Friedel's salt, and the remaining 4% as CaClOH. In fly ash collected in a bag filter with the injection of sodium bicarbonate for acid gas removal (NaFA), approximately 79% of chlorine was in NaCl, 12% was in KCl, and 9% was in Friedel's salt. PMID:18589947

  1. Chloride chemical form in various types of fly ash

    SciTech Connect

    Fenfen Zhu; Masaki Takaoka; Kenji Shiota; Kazuyuki Oshita; Yoshinori Kitajima

    2008-06-01

    Chloride content is a critical problem for the reuse of fly ash as a raw material in cement, and the method used by recyclers to reduce the fly ash chloride content depends on the chemical form of the chlorides. However, limited information is available on the quantitative distribution of chlorides and the identity of some chlorides such as Friedel's salt. We examined chloride forms and percentages using X-ray absorption near edge structure and X-ray diffraction analyses, as well as corresponding washing experiments. Approximately 15% of the chlorine in raw fly ash was estimated to be in the form of NaCl, 10% in KCl, 50% in CaCl{sub 2}, and the remainder in the form of Friedel's salt. Fly ash collected in a bag filter with the injection of calcium hydroxide for acid gas removal (CaFA) contained 35% chlorine as NaCl, 11% as KCl, 37% as CaCl{sub 2}, 13% as Friedel's salt, and the remaining 4% as CaClOH. In fly ash collected in a bag filter with the injection of sodium bicarbonate for acid gas removal (NaFA), approximately 79% of chlorine was in NaCl, 12% was in KCl, and 9% was in Friedel's salt. 25 refs., 4 figs., 4 tabs.

  2. Comparative study on the characteristics of fly ash and bottom ash geopolymers.

    PubMed

    Chindaprasirt, Prinya; Jaturapitakkul, Chai; Chalee, Wichian; Rattanasak, Ubolluk

    2009-02-01

    This research was conducted to compare geopolymers made from fly ash and ground bottom ash. Sodium hydroxide (NaOH) and sodium silicate (Na(2)SiO(3)) solutions were used as activators. A mass ratio of 1.5 Na(2)SiO(3)/NaOH and three concentrations of NaOH (5, 10, and 15M) were used; the geopolymers were cured at 65 degrees C for 48 h. A Fourier transform infrared spectrometer (FT-IR), differential scanning calorimeter (DSC), and scanning electron microscope (SEM) were used on the geopolymer pastes. Geopolymer mortars were also prepared in order to investigate compressive strength. The results show that both fly ash and bottom ash can be utilized as source materials for the production of geopolymers. The properties of the geopolymers are dependent on source materials and the NaOH concentration. Fly ash is more reactive and produces a higher degree of geopolymerization in comparison with bottom ash. The moderate NaOH concentration of 10 M is found to be suitable and gives fly ash and bottom ash geopolymer mortars with compressive strengths of 35 and 18 MPa. PMID:18715775

  3. Comparative study on the characteristics of fly ash and bottom ash geopolymers

    SciTech Connect

    Chindaprasirt, Prinya; Jaturapitakkul, Chai; Chalee, Wichian; Rattanasak, Ubolluk

    2009-02-15

    This research was conducted to compare geopolymers made from fly ash and ground bottom ash. Sodium hydroxide (NaOH) and sodium silicate (Na{sub 2}SiO{sub 3}) solutions were used as activators. A mass ratio of 1.5 Na{sub 2}SiO{sub 3}/NaOH and three concentrations of NaOH (5, 10, and 15 M) were used; the geopolymers were cured at 65 deg. C for 48 h. A Fourier transform infrared spectrometer (FT-IR), differential scanning calorimeter (DSC), and scanning electron microscope (SEM) were used on the geopolymer pastes. Geopolymer mortars were also prepared in order to investigate compressive strength. The results show that both fly ash and bottom ash can be utilized as source materials for the production of geopolymers. The properties of the geopolymers are dependent on source materials and the NaOH concentration. Fly ash is more reactive and produces a higher degree of geopolymerization in comparison with bottom ash. The moderate NaOH concentration of 10 M is found to be suitable and gives fly ash and bottom ash geopolymer mortars with compressive strengths of 35 and 18 MPa.

  4. Edaphological characteristics of unweathered and weathered fly ashes from Gondwana and lignite coal.

    PubMed

    Khandkar, U R; Gangwar, M S; Srivastava, P C; Singh, M

    1993-01-01

    Naturally weathered and unweathered samples of fly ashes produced from Gondwana and lignite coals were characterized for their edaphological properties. The particle size distribution in these fly ashes varied widely, and the percentage of [Formula: see text] size particles governed their water holding capacity. All fly ashes were noncoherent in the dry state and had lower particle density than quartz and mulite. The fly ashes were low in available N, but were sufficient in available P, K, Ca, Mg, S, Cu, Fe, Mn, Zn and B. Among the fly ashes, unweathered lignite fly ash was the richest source of K, Ca, Mg, S and Fe, while weathered lignite fly ash had the highest amounts of Mn, Zn and B. The pH of the fly ashes was closely related to the ratio of exchangeable Ca to exchangeable Al. The fly ashes were high in soluble salt, but were poor in cation exchange capacity. As an amendment to correct soil pH, the fly ashes had a poor buffering capacity. Weathering decreased the total Fe, available S and exchangeable Na percentages, but increased the organic C content of the fly ashes. Invariably, an excess of soluble salts and exchangeable Na could limit plant growth on fly ash dumps. Toxic levels of B and Al existed in only some fly ashes. PMID:15091893

  5. Dielectric properties of epoxy resin fly ash composite

    NASA Astrophysics Data System (ADS)

    Pattanaik, A.; Bhuyan, S. K.; Samal, S. K.; Behera, A.; Mishra, S. C.

    2016-02-01

    Epoxy resin is widely used as an insulating material in high voltage applications. Ceramic fillers are always added to the polymer matrix to enhance its mechanical properties. But at the same time, filler materials decreases the electrical properties. So while making the fly ash epoxy composite, it is obvious to detect the effect of fly ash reinforcement on the dielectric nature of the material. In the present research work, fly ash is added to four different weight percentages compositions and post-curing has been done in the atmospheric condition, normal oven and micro oven. Tests were carried out on the developed polymer composite to measure its dielectric permittivity and tan delta value in a frequency range of 1 Hz - 1 MHz. The space charge behaviours were also observed by using the pulse electroacoustic (PEA) technique. The dielectric strength and losses are compared for different conditions.

  6. Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment.

    PubMed

    Lorenzo, Ma P; Goñi, S; Guerrero, A

    2003-01-01

    The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na(2)SO(4)+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al(2)O(3) content of the fly ash. The diffusion of SO(4)(2-), Na+ and Cl- ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition. PMID:14522197

  7. Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment

    SciTech Connect

    Lorenzo, MaP.; Goni, S.; Guerrero, A

    2003-07-01

    The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na{sub 2}SO{sub 4}+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al{sub 2}O{sub 3} content of the fly ash. The diffusion of SO{sub 4}{sup 2-}, Na{sup +} and Cl{sup -} ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition.

  8. 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.

  9. Factors affecting the shrinkage of fly ash geopolymers

    NASA Astrophysics Data System (ADS)

    Ridtirud, Charoenchai; Chindaprasirt, Prinya; Pimraksa, Kedsarin

    2011-02-01

    The shrinkage of fly ash geopolymers was studied in the present study. Fly ash was used as the source material for making the geopolymers. The effects of the concentration of NaOH, sodium silicate-to-NaOH ratio, liquid-to-ash ratio, curing temperature, and curing time on shrinkage were investigated. The geopolymers were cured at 25, 40, and 60°C, respectively. The results indicate that the shrinkage of geopolymers is strongly dependent on curing temperature and liquid-to-ash ratio. The increase in shrinkage is associated with the low strength development of geopolymers. It is also found that NaOH concentration and sodium silicate-to-NaOH ratio also affect the shrinkage of geopolymers but to a lesser extent.

  10. Temporal and spatial variations in fly ash quality

    USGS Publications Warehouse

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

    2001-01-01

    Fly ash quality, both as the amount of petrographically distinguishable carbons and in chemistry, varies in both time and space. Temporal variations are a function of a number of variables. Variables can include variations in the coal blend organic petrography, mineralogy, and chemistry; variations in the pulverization of the coal, both as a function of the coal's Hardgrove grindability index and as a function of the maintenance and settings of the pulverizers; and variations in the operating conditions of the boiler, including changes in the pollution control system. Spatial variation, as an instantaneous measure of fly ash characteristics, should not involve changes in the first two sets of variables listed above. Spatial variations are a function of the gas flow within the boiler and ducts, certain flow conditions leading to a tendency for segregation of the less-dense carbons in one portion of the gas stream. Caution must be applied in sampling fly ash. Samples from a single bin, or series of bins, m ay not be representative of the whole fly ash, providing a biased view of the nature of the material. Further, it is generally not possible to be certain about variation until the analysis of the ash is complete. ?? 2001 Elsevier Science B.V. All rights reserved.

  11. Continuous air Agglomeration Method for high Carbon fly ash Beneficiation

    SciTech Connect

    Gray, McMahan L.; Champagne, Kenneth J.; Finseth, Dennis H.

    1998-09-29

    The carbon and mineral components of fly ash are effectively separated by a continuous air agglomeration method, resulting in a substantially carbon-free mineral stream and a highly concentrated carbon product. The method involves mixing the fly ash comprised of carbon and inorganic mineral matter with a liquid hydrocarbon to form a slurry, contacting the slurry with an aqueous solution, dispersing the hydrocarbon slurry into small droplets within the aqueous solution by mechanical mixing and/or aeration, concentrating the inorganic mineral matter in the aqueous solution, agglomerating the carbon and hydrocarbon in the form of droplets, collecting the droplets, separating the hydrocarbon from the concentrated carbon product, and recycling the hydrocarbon.

  12. Vitrification of fly ash by swirling-flow furnace

    SciTech Connect

    Ito, Tadashi

    1996-12-31

    According to the amendment of the Waste Disposal and Public Cleansing Law of 1992, fly ash is regulated as Specially controlled waste and wide attention is now being paid to the melting and vitrification treatment of fly ash, which can reduce overall volume, detoxify and recover sources. Kobe Steel has demonstrated its operation using a swirling-flow furnace and has perfected a vitrification technique. The demonstration test has confirmed stable melting, high decomposition ratio of dioxins and the soundness of the slag. Kobe Steel has successfully developed a new technique for heightening the quality of slag and a new process for the heavy metals recovery from collected dust.

  13. Continuous air agglomeration method for high carbon fly ash beneficiation

    DOEpatents

    Gray, McMahon L.; Champagne, Kenneth J.; Finseth, Dennis H.

    2000-01-01

    The carbon and mineral components of fly ash are effectively separated by a continuous air agglomeration method, resulting in a substantially carboree mineral stream and a highly concentrated carbon product. The method involves mixing the fly ash comprised of carbon and inorganic mineral matter with a liquid hydrocarbon to form a slurry, contacting the slurry with an aqueous solution, dispersing the hydrocarbon slurry into small droplets within the aqueous solution by mechanical mixing and/or aeration, concentrating the inorganic mineral matter in the aqueous solution, agglomerating the carbon and hydrocarbon in the form of droplets, collecting the droplets, separating the hydrocarbon from the concentrated carbon product, and recycling the hydrocarbon.

  14. Bronchiolitis obliterans from exposure to incinerator fly ash.

    PubMed

    Boswell, R T; McCunney, R J

    1995-07-01

    Inhalation of toxic substances in the workplace can result in a variety of respiratory disorders. One relatively rare sequela of the inhalation of toxic fumes is bronchiolitis obliterans, a condition characterized by fibrosis and narrowing of the small airways. Several substances have been reported to cause bronchiolitis obliterans, including ammonia, chlorine, hydrogen fluoride, hydrogen sulfide, nitrogen dioxide, ozone, phosgene, and other irritant fumes. Little has been reported on the pulmonary effects of fly ash produced by the incineration of coal and oil. We report a case of bronchiolitis obliterans with a component of partially reversible airway obstruction in a 39-year-old male occupationally exposed to incinerator fly ash. PMID:7552470

  15. Production of inorganic pellet binders from fly-ash. Technical report, March 1--May 31, 1995

    SciTech Connect

    Kawatra, S.K.; Eisele, T.C.

    1995-12-31

    Fly-ash is produced by all coal-fired utilities, and it must be removed from the plant exhaust gases, collected, and disposed of. While much work has been done in the past to utilize fly-ash rather than disposing of it, we nevertheless do not find widespread examples of successful industrial utilization. This is because past work has tended to find uses only for high-quality, easily-utilized fly-ashes, which account for less than 25% of the fly-ash that is produced. The main factor which makes fly-ashes unusable is a high unburned carbon content. In this project, physical separation technologies are being used to remove this carbon, and to convert these unusable fly-ashes into usable products. The main application being studied for the processed fly-ash is as a binder for inorganic materials, such as iron-ore pellets. In the second quarter, additional fly-ash samples were collected from the E. D. Edwards station (Bartonville, IL). Experimentation was begun to study the removal of carbon from these fly-ashes by froth flotation, and make and test pellets that use fly-ash as binder. During the current quarter, flotation experiments were continued on the fly- ashes. Three types of ashes were studied: 1. Ash from the disposal pond (``wet`` ash); 2. Dry fly-ash collected directly from the standard burners (``low-carbon`` ash); 3. Dry fly-ash collected from the low-NOx burners (``high-carbon`` ash). Each of these was chemically analyzed, and conventional flotation experiments were carried out to determine the optimum reagent dosages for carbon removal. Decarbonized ashes were then made from each ash type, in sufficient quantity to be used in pelletization experiments.

  16. Speciation and mobility of cadmium in straw and wood combustion fly ash.

    PubMed

    Hansen, H K; Pedersen, A J; Ottosen, L M; Villumsen, A

    2001-10-01

    Two fly ashes from biomass combustion have been analysed regarding cadmium speciation and mobility. A fly ash from straw combustion contained 10 mg Cd/kg dry matter, and around 50% of the cadmium was leachable in water. The possible main speciation of cadmium in this fly ash was CdCl2. When adding this fly ash to agricultural soil a threat for groundwater contamination and plant uptake is existing. A fly ash from wood chip combustion had 28.6 mg Cd/kg dry matter. In this fly ash, the cadmium was bound more heavily, with only small amounts of cadmium leached in mild extractants. A possible speciation of cadmium in this fly ash was as oxide or as CdSiO3. Long-term effects and accumulation of cadmium could be a problem when adding this fly ash to agricultural or forest soils. PMID:11572586

  17. 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.

  18. Enhancing performance and durability of slag made from incinerator bottom ash and fly ash.

    PubMed

    Chiou, Ing-Jia; Wang, Kuen-Sheng; Tsai, Chen-Chiu

    2009-02-01

    This work presents a method capable of melting the incinerator bottom ash and fly ash in a plasma furnace. The performance of slag and the strategies for recycling of bottom ash and fly ash are improved by adjusting chemical components of bottom ash and fly ash. Ashes are separated by a magnetic process to improve the performance of slag. Analytical results indicate that the air-cooled slag (ACS) and magnetic-separated slag (MSS) have hardness levels below 590 MPa, indicating fragility. Additionally, the hardness of crystallized slag (RTS) is between 655 and 686 MPa, indicating toughness. The leached concentrations of heavy metals for these three slags are all below the regulatory limits. ACS appears to have better chemical stability than MSS, and is not significantly different from RTS. In the potential alkali-silica reactivity of slag, MSS falls on the border between the harmless zone and the potentially harmful zone. ACS and RTS fall in the harmless zone. Hence, the magnetic separation procedure of ashes does not significantly improve the quality of slag. However, RTS appears to improve its quality. PMID:18544471

  19. Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash.

    PubMed

    Diaz-Loya, E Ivan; Allouche, Erez N; Eklund, Sven; Joshi, Anupam R; Kupwade-Patil, Kunal

    2012-08-01

    Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA's Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson's ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045 mg/L, Arsenic from 0.256 down to 0.132 mg/L, Selenium from 1.05 down to 0.29 mg/L, Silver from 0.011 down to .001 mg/L, Barium from 2.06 down to 0.314 mg/L and Mercury from 0.007 down to 0.001 mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805 mg/L and Pd from 0.002 up to 0.029 mg/L, these were well below the maximum limits of 1.00 and 5

  20. Hydrothermal reactions of fly ash. Final report

    SciTech Connect

    Brown, P.W.

    1995-12-31

    The emphasis of the work done has been to determine the reactivities of two ashes believed to be representative of those generated. A bituminous ash and a lignitic ash have been investigated. The reactions of these ashes undergo when subjected to mild hydrothermal conditions were explored. The nature of the reactions which the ashes undergo when alkaline activators, calcium hydroxide and calcium sulfate are present was also investigated. It was determined that calcium silicate hydrate, calcium aluminate hydrate, and the calcium sulfoaluminate hydrate ettringite form under these conditions. It appears 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}3CaSO{sub 4}{center_dot}32H{sub 2}O (ettringite) formation needs to be considered in ashes which contain significant amounts of sulfate. Therefore the stability region for ettringite was established. It was also determined that calcium silicate hydrate, exhibiting a high internal surface area, will readily form with hydrothermal treatment between 50{degrees} and 100{degrees}C. This phase is likely to have a significant capacity to take up heavy metals and oxyanions and this ability is being explored.

  1. Phenolic acids as bioindicators of fly ash deposit revegetation

    SciTech Connect

    L. Djurdjevic; M. Mitrovic; P. Pavlovic; G. Gajic; O. Kostic

    2006-05-15

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the 'Nikola Tesla-A' thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges. Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

  2. Effect of fly ash on sorption behavior of metribuzin in agricultural soils.

    PubMed

    Singh, Neera; Raunaq; Singh, Shashi B

    2012-01-01

    This investigation was undertaken to determine the effect of two different fly ashes [Kota and Inderprastha (IP)] amendment on the sorption behavior of metribuzin in three Indian soil types. The IP fly ash was very effective in increasing the metribuzin sorption in the soils. The sorption with IP amendment was increased by 15-92%, whereas with the Kota fly ash an increase in sorption by 13-38% was noted. The adsorption isotherms fitted very well to the Freundlich adsorption equation and, in general, slope (1/n) values less then unity were observed. Although both the fly ashes significantly decreased metribuzin desorption, the IP fly ash was comparatively more effective in retaining metribuzin in the soils. Metribuzin sorption in the IP fly ash-amended soils showed strong correlation with the fly ash content and compared to K(f)/K(d) values, K(FA) values (sorption normalized to fly ash content) showed less variation. Metribuzin sorption-desorption did not correlate to the organic carbon content of the soil-fly ash mixture. The study demonstrates that all coal fly ashes may not be effective in enhancing the sorption of metribuzin in soils to the same extent. However, among the fly ashes used in this study, the IP fly ash was observed to be significantly effective in enhancing the sorption of metribuzin in soils. This may play an important role in reducing the run off and leaching losses of the herbicide by retaining it in the soil. PMID:22251208

  3. BIOAVAILABILITY OF 1-NITROPYRENE FROM MODEL COAL FLY ASH AND ITS UPTAKE BY ALVEOLAR MACROPHAGES

    EPA Science Inventory

    Alveolar macrophage cultures exposed to coal fly ash vapor-coated with 1-nitropyrene were used as a model system to study the bioavailability and the uptake of a nitroaromatic hydrocarbon from coal combustion emissions. Initially, 1-nitropyrene-coated fly ash and uncoated fly ash...

  4. Ultrasonic studies of fly ash/polyurea composites

    NASA Astrophysics Data System (ADS)

    Qiao, Jing; Amirkhizi, Alireza V.; Nemat-Nasser, Sia; Wu, Gaohui

    2013-04-01

    Due to its excellent thermo-mechanical properties, polyurea is attracting more and more attention in blast-mitigating applications. In order to enhance its capability of blast-induced stress-wave management, we seek to develop polyurea-based composites in this work. Fly ash which consists of hollow particles with porous shell and low apparent density was chosen as filler and a series of fly ash/polyurea composites with various fly ash volume fractions were fabricated. The dynamic mechanical behavior of the composites was determined by a personal computer (PC) based ultrasonic system in the 0.5-2MHz frequency range between -60°C to 30°C temperatures. Velocity and attenuation of both longitudinal and shear ultrasonic waves were measured. The complex longitudinal and shear moduli were then computed from these measurements. Combining these results provided an estimate of the complex bulk and Young's moduli of the fly ash/polyurea composites at high frequencies. These results will be presented and compared with those of pure polyurea elastomer.

  5. PREFERENTIAL PARTITIONING OF PAHS AND PCBS TO COAL FLY ASH

    EPA Science Inventory

    It has long been known that fly ash has a significant capacity for the adsorption of several classes of anthropogenic pollutants, including toxic metals, nutrients and organic compounds. This adsorption capacity has been utilized by wastewater treatment plants for the removal of ...

  6. Phytoremediation of metals from fly ash through bacterial augmentation.

    PubMed

    Kumari, Babita; Singh, S N

    2011-01-01

    Different combinations of four bacterial strains isolated from fly ash were used by us to study their impact on phytoextraction of metals from fly ash by Brassica juncea grown in fly ash amended with farm yard manure (50:50 w/w). Out of 11 bacterial consortia, a combination of two strains i.e. Paenibacillus macerans NBRFT5 + Bacillus pumilus NBRFT9 (C7) inoculated in the rhizosphere was found to enhance Pb accumulation maximally by 278%, Mn by 75%, Zn by 163%, Cr by 226% and Ni by 414% compared to control. It is possible that these bacteria, known for N(2) fixation, solubilization of phosphorus and uptake of micronutrient, could promote the plant growth resulting in higher accumulation of metals. However, a combination of four bacteria, namely Micrococcus roseus NBRFT2 + Bacillus endophyticus NBRFT4 + Paenibacillus macerans NBRFT5 + Bacillus pumilus NBRFT9 (C4) was able to increase Cd uptake maximally by 237%. Further, the translocation of metal was invariably more from root to stem than from stem to leaf which was regulated by plant transport mechanism and metal mobility. Bacteria are known to excrete protons, organic acids, enzymes and siderophores to enhance the mobilization of metals which boosted the phytoextraction of metals from fly ash. PMID:21080221

  7. MERCURY CAPTURE ON COAL COMBUSTION FLY ASH. (R827649)

    EPA Science Inventory

    A study was performed at the Energy and Environmental Research Center (EERC) to test the hypotheses that (1) different carbon types contained in coal combustion fly ash have variable sorption capabilities relative to mercury and (2) the inorganic fraction of coal combustion fl...

  8. Fly Ash as a Liming Material for Corn Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fly ash produced as a by-product of sub-bituminous coal combustion can potentially serve as an alternative liming material without negatively affecting corn (Zea mays L.) production in areas where use of conventional liming materials can be uneconomical due to transportation costs. A study was cond...

  9. Synthesis of multiwalled carbon nanotubes on fly ash derived catalysts.

    PubMed

    Dunens, Oscar M; MacKenzie, Kieran J; Harris, Andrew T

    2009-10-15

    Carbon nanotubes (CNTs) are an allotrope of carbon with unique properties that make them potentially useful in a vast range of applications. However, CNTs are predominantly produced using expensive and/or nonrecyclable catalyst supports, e.g., mesoporous silica and alumina. In this work, coal combustion fly ash, a bulk waste product with limited uses, was impregnated with iron nitrate and successfully used as a substrate to produce industrial grade multiwalled carbon nanotubes (MWNTs) by fluidized bed chemical vapor deposition. CNTs were analyzed using thermogravimetric analysis, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The most successful catalyst trialed at 650 degrees C using ethylene as a carbon source was a 5 wt % Fe fly ash catalyst, which produced a CNT yield in respect to metal loading of approximately 82.5%. The MWNTs had outer diameters of between 12 and 20 nm with a reasonable degree of wall graphitization (I(G)/I(D) of 1.17). Advantages of utilizing fly ash as a catalyst support are its availability at low cost at the megaton scale, its high thermal stability, and suitability for use in industrial fluidized bed reactors. Potential applications for the fly ash produced CNTs include use in composite materials. PMID:19921910

  10. Electrical conductivity and dielectric property of fly ash geopolymer pastes

    NASA Astrophysics Data System (ADS)

    Hanjitsuwan, Sakonwan; Chindaprasirt, Prinya; Pimraksa, Kedsarin

    2011-02-01

    The electrical conductivity and dielectric property of fly ash geopolymer pastes in a frequency range of 100 Hz-10 MHz were studied. The effects of the liquid alkali solution to ash ratios (L/A) were analyzed. The mineralogical compositions and microstructures of fly ash geopolymer materials were also investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The 10 mol sodium hydroxide solution and sodium silicate solution at a sodium silicate-to-sodium hydroxide ratio of 1.0 were used in making geopolymer pastes. The pastes were cured at 40°C. It is found that the electrical conductivity and dielectric constant are dependent on the frequency range and L/A ratios. The conductivity increases but the dielectric constant decreases with increasing frequency.