Utilising Fine and Coarse Recycled Aggregates from the Gulf Region in Concrete

NASA Astrophysics Data System (ADS)

Jones, M. Rod; Halliday, Judith E.; Csetenyi, Laszlo; Zheng, Li; Strompinis, N.

This paper explores the feasibility in utilising materials generated from C&DW to produce a `green' concrete. The two materials that are considered here are, (i) up-sizing silt-size material generated from recycled aggregates to produce a synthetic silt-sand and (ii) processed recycled coarse aggregates (RA) sourced from a Gulf Region landfill site. The work has demonstrated that there is potential for utilising silt wastes into foamed concrete, which can then be crushed to a sand-sized material suitable for use in concrete, however the porous nature of the material has highlighted that the water demand of this RA is high. RAs were characterised to BS EN 12620 and found suitable for use in concrete. The effect of RA on concrete properties is minimal when used up to 35% replacement levels, provided that they are pre-soaked.

Probabilistic Analysis of Structural Member from Recycled Aggregate Concrete

NASA Astrophysics Data System (ADS)

Broukalová, I.; Šeps, K.

2017-09-01

The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. Considering demands of maximising recycled aggregate use and minimising of cement consumption, composite from recycled concrete aggregate was proposed. The objective of the presented investigations was to verify feasibility of the recycled aggregate cement based fibre reinforced composite in a structural member. Reliability of wall from recycled aggregate fibre reinforced composite was assessed in a probabilistic analysis of a load-bearing capacity of the wall. The applicability of recycled aggregate fibre reinforced concrete in structural applications was demonstrated. The outcomes refer to issue of high scatter of material parameters of recycled aggregate concretes.

Replacement of Fine Aggregate by using Recyclable Materials in Paving Blocks

NASA Astrophysics Data System (ADS)

Koganti, Shyam Prakash; Hemanthraja, Kommineni; Sajja, Satish

2017-08-01

Cement concrete paving blocks are precast hard products complete out of cement concrete. The product is made in various sizes and shapes like square, round and rectangular blocks of different dimensions with designs for interlocking of adjacent tiles blocks. Several Research Works have been carried out in the past to study the possibility of utilizing waste materials and industrial byproducts in the manufacturing of paver blocks. Various industrial waste materials like quarry dust, glass powder, ceramic dust and coal dust are used as partial replacement of fine aggregate and assessed the strength parameters and compared the profit percentages after replacement with waste materials. Quarry dust can be replaced by 20% and beyond that the difference in strength is not much higher but considering cost we can replace upto 40% so that we can get a profit of almost 10%. Similarly we can replace glass powder and ceramic dust by 20% only beyond that there is decrement in strength and even with 20% replacement we can get 1.34 % and 2.42% of profit. Coal dust is not suitable for alternative material as fine aggregate as it reduces the strength.

Strength of masonry blocks made with recycled concrete aggregates

NASA Astrophysics Data System (ADS)

Matar, Pierre; Dalati, Rouba El

The idea of recycling concrete of demolished buildings aims at preserving the environment. Indeed, the reuse of concrete as aggregate in new concrete mixes helped to reduce the expenses related to construction and demolition (C&D) waste management and, especially, to protect the environment by reducing the development rate of new quarries. This paper presents the results of an experimental study conducted on masonry blocks containing aggregates resulting from concrete recycling. The purpose of this study is to investigate the effect of recycled aggregates on compressive strength of concrete blocks. Tests were performed on series of concrete blocks: five series each made of different proportions of recycled aggregates, and one series of reference blocks exclusively composed of natural aggregates. Tests showed that using recycled aggregates with addition of cement allows the production of concrete blocks with compressive strengths comparable to those obtained on concrete blocks made exclusively of natural aggregates.

A study on the performance of concrete containing recycled aggregates and ceramic as materials replacement

NASA Astrophysics Data System (ADS)

Azmi, N. B.; Khalid, F. S.; Irwan, J. M.; Anting, N.; Mazenan, P. N.

2017-11-01

Natural fine aggregate materials are commonly used in development and commercial construction in Malaysia. In fact, concrete production was increased as linear with the growing Malaysia economy. However, an issue was production of concrete was to locate adequate sources of natural fine aggregates. There lot of studies have been conducted in order to replace the fine aggregate in which natural fine aggregate replace with the waste material in concrete preparation. Therefore, this study aims to utilize the Recycled Concrete Aggregate (RCA) and ceramic waste which has great potential to replace the natural aggregate in concrete mix with different type of method, admixture, and parameters. This research were focused on compressive strength and water absorption test to determine the optimum mix ratio of concrete mix. The concrete aggregate was chosen due to improvement capillary bonding mechanisms and ceramic presented similar strength compared to the conventional concrete using natural aggregate. Percent of replacement have been used in this study was at 25%, 35% and 45% of the RCA and 5%, 10% and 15% for ceramic, respectively. Furthermore, this research was conduct to find the optimum percentage of aggregate replacement, using water-cement ratio of 0.55 with concrete grade 25/30. The best percentage of replacement was the RCA35% C15% with the compressive strength of 34.72 MPa and the water absorption was satisfied.

Experimental research on durability of recycled aggregate concrete under freeze- thaw cycles

NASA Astrophysics Data System (ADS)

Cheng, Yanqiu; Shang, Xiaoyu; Zhang, Youjia

2017-07-01

The freeze-thaw durability of recycled aggregate concrete has significance for the concrete buildings in the cold region. In this paper, the rapid freezing and thawing cycles experience on recycle aggregate concrete was conducted to study on the effects of recycle aggregate amount, water-binder ratio and fly ash on freeze-thaw durability of recycle aggregate concrete. The results indicates that recycle aggregate amount makes the significant influence on the freeze-thaw durability. With the increase of recycled aggregates amount, the freeze-thaw resistance for recycled aggregate concrete decreases. Recycled aggregate concrete with lower water cement ratio demonstrates better performance of freeze-thaw durability. It is advised that the amount of fly ash is less than 30% for admixture of recycled aggregates in the cold region.

Behaviour of Recycled Coarse Aggregate Concrete: Age and Successive Recycling

NASA Astrophysics Data System (ADS)

Sahoo, Kirtikanta; Pathappilly, Robin Davis; Sarkar, Pradip

2016-06-01

Recycled Coarse Aggregate (RCA) concrete construction technique can be called as `green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio ( w/ c). The present work is an attempt to study the behaviour of RCA concrete from two samples of parent concrete having different age group with regard to the relationship of compressive strength with water cement ratios. Number of recycling may influence the mechanical properties of RCA concrete. The influence of age and successive recycling on the properties such as capillary water absorption, drying shrinkage strain, air content, flexural strength and tensile splitting strength of the RCA concrete are examined. The relationship between compressive strength at different w/ c ratios obtained experimentally is investigated for the two parameters such as age of parent concrete and successive recycling. The recycled concrete using older recycled aggregate shows poor quality. While the compressive strength reduces with successive recycling gradually, the capillary water absorption increases abruptly, which leads to the conclusion that further recycling may not be advisable.

Experimental Study of the Possibility to Make a Mortar with Ternary Sand (Natural and Artificial Fine Aggregates)

NASA Astrophysics Data System (ADS)

Baali, L.; Naceri, A.; Rahmouni, Z.; Mehidi, M. W. Noui

This experimental study investigates the possibility to make a mortar with a ternary sand (natural and artificial fine aggregates). This method is utilized to correct the particle size distribution of various sands used in mortar. For this investigation, three sands have been used: a dune sand (DS), a slag sand (SS), and brick sand (BS) at different proportions in mortar. After crushing, the artificial fine aggregate (blast furnace slag and waste brick fine aggregate) was sifted in order to use it as fine aggregate. The effect of the quality and grain size distribution of natural fine aggregate (i.e., DS) and artificial fine aggregates (i.e., SS and BS) on the physical properties of ternary sand confected (density, porosity, fineness modulus, equivalent sand, particle size distribution, water absorption) and properties of fresh and hardened mortar were analysed. In the same way for this study, the physical properties and chemical compositions of DS, SS, BS and cement were investigated. The results obtained show that the mechanical strength on mortar depends of the nature and particle size distribution of sand studied. The reuse of this recycled material (slag blast furnace and waste brick) in the industry would contribute to the protection of the environment. This study shows the potential of this method to make mortar with ternary sand (natural and artificial fine aggreagates) in order to improve the physical properties of sand. Utilising natural and artificial fine aggregates to produce quality mortar should yield significant environmental benefits.

Optimal policies for aggregate recycling from decommissioned forest roads.

PubMed

Thompson, Matthew; Sessions, John

2008-08-01

To mitigate the adverse environmental impact of forest roads, especially degradation of endangered salmonid habitat, many public and private land managers in the western United States are actively decommissioning roads where practical and affordable. Road decommissioning is associated with reduced long-term environmental impact. When decommissioning a road, it may be possible to recover some aggregate (crushed rock) from the road surface. Aggregate is used on many low volume forest roads to reduce wheel stresses transferred to the subgrade, reduce erosion, reduce maintenance costs, and improve driver comfort. Previous studies have demonstrated the potential for aggregate to be recovered and used elsewhere on the road network, at a reduced cost compared to purchasing aggregate from a quarry. This article investigates the potential for aggregate recycling to provide an economic incentive to decommission additional roads by reducing transport distance and aggregate procurement costs for other actively used roads. Decommissioning additional roads may, in turn, result in improved aquatic habitat. We present real-world examples of aggregate recycling and discuss the advantages of doing so. Further, we present mixed integer formulations to determine optimal levels of aggregate recycling under economic and environmental objectives. Tested on an example road network, incorporation of aggregate recycling demonstrates substantial cost-savings relative to a baseline scenario without recycling, increasing the likelihood of road decommissioning and reduced habitat degradation. We find that aggregate recycling can result in up to 24% in cost savings (economic objective) and up to 890% in additional length of roads decommissioned (environmental objective).

Recycled Coarse Aggregate Produced by Pulsed Discharge in Water

NASA Astrophysics Data System (ADS)

Namihira, Takao; Shigeishi, Mitsuhiro; Nakashima, Kazuyuki; Murakami, Akira; Kuroki, Kaori; Kiyan, Tsuyoshi; Tomoda, Yuichi; Sakugawa, Takashi; Katsuki, Sunao; Akiyama, Hidenori; Ohtsu, Masayasu

In Japan, the recycling ratio of concrete scraps has been kept over 98 % after the Law for the Recycling of Construction Materials was enforced in 2000. In the present, most of concrete scraps were recycled as the Lower Subbase Course Material. On the other hand, it is predicted to be difficult to keep this higher recycling ratio in the near future because concrete scraps increase rapidly and would reach to over 3 times of present situation in 2010. In addition, the demand of concrete scraps as the Lower Subbase Course Material has been decreased. Therefore, new way to reuse concrete scraps must be developed. Concrete scraps normally consist of 70 % of coarse aggregate, 19 % of water and 11 % of cement. To obtain the higher recycling ratio, the higher recycling ratio of coarse aggregate is desired. In this paper, a new method for recycling coarse aggregate from concrete scraps has been developed and demonstrated. The system includes a Marx generator and a point to hemisphere mesh electrode immersed in water. In the demonstration, the test piece of concrete scrap was located between the electrodes and was treated by the pulsed discharge. After discharge treatment of test piece, the recycling coarse aggregates were evaluated under JIS and TS and had enough quality for utilization as the coarse aggregate.

Mechanical properties of recycled concrete with demolished waste concrete aggregate and clay brick aggregate

NASA Astrophysics Data System (ADS)

Zheng, Chaocan; Lou, Cong; Du, Geng; Li, Xiaozhen; Liu, Zhiwu; Li, Liqin

2018-06-01

This paper presents an experimental investigation on the effect of the replacement of natural coarse aggregate (NCA) with either recycled concrete aggregate (RCA) or recycled clay brick aggregate (RBA) on the compressive strengths of the hardened concrete. Two grades (C25 and C50) of concrete were investigated, which were achieved by using different water-to-cement ratios. In each grade concrete five different replacement rates, 0%, 25%, 50%, 75% and 100% were considered. In order to improve the performance of the recycled aggregates in the concrete mixes, the RCA and RBA were carefully sieved by using the optimal degradation. In this way the largest reduction in the 28-day compressive strength was found to be only 7.2% and 9.6% for C25 and C50 recycled concrete when the NCA was replaced 100% by RCA, and 11% and 13% for C25 and C50 recycled concrete when the NCA was replaced 100% by RBA. In general, the concrete with RCA has better performance than the concrete with RBA. The comparison of the present experimental results with those reported in literature for hardened concrete with either RCA or RBA demonstrates the effectiveness in improving the compressive strength by using the optimal gradation of recycled aggregates.

Risk assessment by percolation leaching tests of extensive green roofs with fine fraction of mixed recycled aggregates from construction and demolition waste.

PubMed

López-Uceda, Antonio; Galvín, Adela P; Ayuso, Jesús; Jiménez, José Ramón; Vanwalleghem, Tom; Peña, Adolfo

2018-03-19

Extensive green roofs are urban construction systems that provide thermal regulation and sound proofing for the buildings involved, in addition to providing an urban heat island mitigation or water retention. On the other hand, policies towards reduction of energy consumption, a circular economy and sustainability are core in the European Union. Motivated by this, an experimental study was carried out to evaluate the environmental risk assessment according to release levels of polluting elements on leachates of different green roof substrate mixtures based on recycled aggregates from construction and demolition waste through (i) the performance in laboratory of two procedures: compliance and percolation tests and (ii) an upscaled experimental leaching test for long-term on-site prediction. Four plots were built on a building roof and covered with autochthonous Mediterranean plants in Córdoba, South of Spain. As growing substrate, four mixtures were used of a commercial growing substrate with different proportions of a fine mixed recycled aggregate ranging from 0 to 75% by volume. The results show that these mixtures were classified as non-hazardous materials according to legal limits of the Landfill Directive 2003/33/CE. The release levels registered in extensive green roofs were lower compared to the laboratory test data. This shows how laboratory conditions can overestimate the potential pollutant effect of these materials compared to actual conditions.

Recycling of quarry waste as part of sustainable aggregate production: Norwegian and Italian point of view

NASA Astrophysics Data System (ADS)

Antonella Dino, Giovanna; Willy Danielsen, Svein; Chiappino, Claudia; Primavori, Piero; Engelsen, Christian John

2016-04-01

Resource preservation is one of the main challenges in Europe, together with waste management and recycling; recently several researchers are interested in the recovering of critical raw materials and secondary raw materials from landfill. Aggregate supply, even if it is not "critical" sensus stricto (s.s.), is one of the European priorities (low value but high volume needs). On the other side, the management of quarry waste , mainly from dimension stones, but also as fines from aggregate crushing, is still a matter of concern. Such materials are managed in different ways both locally and nationwide, and often they are landfilled, because of an unclear legislation and a general lack of data. Most of time the local authorities adopt the maximum precaution principle or the enterprises find it little profitable to recover them, so that the sustainable recycling of such material is not valued. Several studies have shown, depending on the material specific characteristics, the viability of recycling quarry waste into new raw materials used in glass and ceramic industries, precast concrete production, infrastructures etc. (Loudes et al. 2012, Dino&Marian 2015, Bozzola et al 2012, Dino et al. 2012, etc.). Thus, aggregate production may be one of the profitable ways to use quarry waste and is falling under the priority of EU (aggregate supply). Positive economic and environmental effects are likely to be achieved by systematic recycling of quarry waste planned by industries (industrial planning) and public authorities (national and local planning of aggregate exploitation). Today, the recycling level varies to a great extent and systematic recovery is not common among European Countries. In Italy and Norway no significant incentives on recycling or systematic approaches for local aggregate exploitation exist. The environmental consequences can be overexploitation of the natural resources, land take for the landfills, environmental contamination and landscape alteration by

Compressive strength and hydration processes of concrete with recycled aggregates

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

Koenders, Eduardus A.B., E-mail: e.a.b.koenders@coc.ufrj.br; Microlab, Delft University of Technology; Pepe, Marco, E-mail: mapepe@unisa.it

2014-02-15

This paper deals with the correlation between the time evolution of the degree of hydration and the compressive strength of Recycled Aggregate Concrete (RAC) for different water to cement ratios and initial moisture conditions of the Recycled Concrete Aggregates (RCAs). Particularly, the influence of such moisture conditions is investigated by monitoring the hydration process and determining the compressive strength development of fully dry or fully saturated recycled aggregates in four RAC mixtures. Hydration processes are monitored via temperature measurements in hardening concrete samples and the time evolution of the degree of hydration is determined through a 1D hydration and heatmore » flow model. The effect of the initial moisture condition of RCAs employed in the considered concrete mixtures clearly emerges from this study. In fact, a novel conceptual method is proposed to predict the compressive strength of RAC-systems, from the initial mixture parameters and the hardening conditions. -- Highlights: •The concrete industry is more and more concerned with sustainability issues. •The use of recycled aggregates is a promising solution to enhance sustainability. •Recycled aggregates affect both hydration processes and compressive strength. •A fundamental approach is proposed to unveil the influence of recycled aggregates. •Some experimental comparisons are presented to validate the proposed approach.« less

Multi-factor Effects on the Durability of Recycle Aggregate Concrete

NASA Astrophysics Data System (ADS)

Ma, Huan; Cui, Yu-Li; Zhu, Wen-Yu; Xie, Xian-Jie

2016-05-01

Recycled Aggregate Concrete (RAC) was prepared with different recycled aggregate replacement ratio, 0, 30%, 70% and 100% respectively. The performances of RAC were examined by the freeze-thaw cycle, carbonization and sulfate attack to assess the durability. Results show that test sequence has different effects on the durability of RAC; the durability is poorer when carbonation experiment was carried out firstly, and then other experiment was carried out again; the durability is better when recycled aggregate replacement ratio is 70%.

Evaluation of recycled concrete as aggregate in new concrete pavements.

DOT National Transportation Integrated Search

2014-04-01

This study evaluated the use of recycled concrete as coarse aggregate in new concrete pavements. : Recycled concrete aggregate (RCA) produced from demolished pavements in three geographically dispersed locations in Washington state were used to perfo...

Recycled concrete aggregate in portland cement concrete.

DOT National Transportation Integrated Search

2013-01-01

Aggregates can be produced by crushing hydraulic cement concrete and are known as recycled concrete : aggregates (RCA). This report provides results from a New Jersey Department of Transportation study to identify : barriers to the use of RCA in new ...

Mechanical properties of concrete containing recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate replacement

NASA Astrophysics Data System (ADS)

Khalid, Faisal Sheikh; Azmi, Nurul Bazilah; Sumandi, Khairul Azwa Syafiq Mohd; Mazenan, Puteri Natasya

2017-10-01

Many construction and development activities today consume large amounts of concrete. The amount of construction waste is also increasing because of the demolition process. Much of this waste can be recycled to produce new products and increase the sustainability of construction projects. As recyclable construction wastes, concrete and ceramic can replace the natural aggregate in concrete because of their hard and strong physical properties. This research used 25%, 35%, and 45% recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate in producing concrete. Several tests, such as concrete cube compression and splitting tensile tests, were also performed to determine and compare the mechanical properties of the recycled concrete with those of the normal concrete that contains 100% natural aggregate. The concrete containing 35% RCA and 35% ceramic waste showed the best properties compared with the normal concrete.

Acoustic emission monitoring of recycled aggregate concrete under bending

NASA Astrophysics Data System (ADS)

Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

2015-03-01

The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.

Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture †

PubMed Central

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-del Pozo, Julia Mª; Guerra-Romero, M. Ignacio

2014-01-01

The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique. PMID:28788188

Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard.

PubMed

Rodríguez-Robles, Desirée; García-González, Julia; Juan-Valdés, Andrés; Morán-Del Pozo, Julia Mª; Guerra-Romero, Manuel I

2014-08-13

Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW.

Environmental suitability of recycled concrete aggregate in highways.

DOT National Transportation Integrated Search

2015-01-01

The use of recycled concrete aggregate materials in highway constructions as compared to the use of virgin : materials reduces virgin natural resource demands on the environment. In order to evaluate their potential use of : recycle materials in high...

Investigations on Fresh and Hardened Properties of Recycled Aggregate Self Compacting Concrete

NASA Astrophysics Data System (ADS)

Revathi, P.; Selvi, R. S.; Velin, S. S.

2013-09-01

In the recent years, construction and demolition waste management issues have attracted the attention from researchers around the world. In the present study, the potential usage of recycled aggregate obtained from crushed demolition waste for making self compacting concrete (SCC) was researched. The barriers in promoting the use of recycled material in new construction are also discussed. In addition, the results of an experimental study involving the use of recycled concrete aggregate as coarse aggregates for producing self-compacting concrete to study their flow and strength characteristics are also presented. Five series of mixture were prepared with 0, 25, 50, 75, and 100 % coarse recycled aggregate adopting Nan Su's mix proportioning method. The fresh concrete properties were evaluated through the slump flow, J-ring and V-funnel tests. Compressive and tensile strengths were also determined. The results obtained showed that SCC could be successfully developed by incorporating recycled aggregates.

Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard †

PubMed Central

Rodríguez-Robles, Desirée; García-González, Julia; Juan-Valdés, Andrés; Pozo, Julia Mª Morán-del; Guerra-Romero, Manuel I

2014-01-01

Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW. PMID:28788164

Recycling of construction debris as aggregate in the Mid-Atlantic Region, USA

USGS Publications Warehouse

Robinson, G.R.; Menzie, W.D.; Hyun, H.

2004-01-01

Reclaimed asphalt pavement (RAP) and portland cement concrete (RPCC) are abundant and available substitutes for natural aggregate in many areas. This paper presents an overview of factors that affect recycled aggregate cost, availability, and engineering performance, and the results of a survey of business practices in the Mid-Atlantic region. For RAP, processing costs are less than those for virgin natural aggregate. Use of efficient asphalt pavement stripping technology, on-site reclamation, and linked two-way transport of asphalt debris and processed asphalt paving mix between asphalt mix plants and paving sites has led to extensive recycling of asphalt pavement in the Mid-Atlantic region of the US. Most of the sites that recycle asphalt pavement (RAP) are located in or near urban areas close to important transportation corridors. RPCC is a viable aggregate source in urban settings where unit costs for processed aggregate from RPCC and natural aggregate are comparable. Disposal fees charged at RPCC recycling sites help defray processing costs and the significantly lower tipping fees at recycling sites versus landfill disposal sites encourage recycling of construction debris as aggregate. Construction contractors and construction debris recycling centers, many of which have the ability to crush and process concrete debris at the job site, produce most RPCC. Production of RPCC aggregate from construction debris that is processed on site using portable equipment moved to the construction site eliminates transportation costs for aggregate and provides an economic incentive for RPCC use. Processing costs, quality and performance issues, and lack of large quantities where needed limit RPCC use. Most RPCC suppliers in the Mid-Atlantic area are located in counties with population densities greater than 400 people/km2 (1036 people/mile2) and that have high unit-value costs and limited local availability of natural aggregate. ?? 2004 Published by Elsevier B.V.

Characteristics of Recycled Concrete Aggregates from Precast Slab Block Buildings

NASA Astrophysics Data System (ADS)

Venkrbec, Václav; Nováková, Iveta; Henková, Svatava

2017-10-01

Precast slab block buildings (PSBB) typically and frequently occur in Central and Eastern Europe, as well as elsewhere in the world. Some of these buildings are currently used beyond their service life capacity. The utilization of recycled materials from these buildings with regard to applying the principles of sustainable construction and using recycled materials will probably be significant in the following years. Documentation from the manufacturing processes of prefabricated blocks for precast slab block buildings is not available, and also it is difficult to declare technological discipline during the construction of these buildings. Therefore, properties of recycled concrete aggregates (RCA) produced from construction and demolition waste (C&DW) of precast slab block buildings build between 1950s to 1990s are not sufficiently known. The demolition of these buildings is very rare today, but it can be assumed an increase in demolitions of these buildings in the future. The use of RCA in new concrete requires verification/testing of the geometrical and physical properties of RCA according to the EN 12 620+A1 standard. The aim of the contribution is to present a case study of the demolition of slab block building with emphasis on RCA usage. The paper presents the results of the tests according to European standards for determining selected geometrical and physical properties of the RCA. The paper describes and evaluates tests such as determination of particle size distribution - Sieve Analysis, content of fine particles, determination of density and water absorption. The results of the properties testing of RCA are compared with the properties of natural aggregate. The general boundary conditions of RCA particular tests are presented.

Design of Road Pavement Using Recycled Aggregate

NASA Astrophysics Data System (ADS)

Remišová, Eva; Decký, Martin; Mikolaš, Milan; Hájek, Matej; Kovalčík, Luboš; Mečár, Martin

2016-10-01

The presented article gives special attention to codified clauses of the road construction law, the relevant clauses of the standards and technical regulations to design and control the quality of recycled aggregate constructions. The article also presents the authors’ suggestions to design of earth constructions and pavements of roads according to the Slovak technical standards, technical regulations and objectively determined results of research and development of road infrastructure. The article presents a comparison of the mechanical characteristics measurements of the structural layers of road pavements built from the recycled and natural aggregate. It also presents correlation functions of results obtained from in situ and in laboratory CBR (Californian Bearing Ratio) measuring, representing the world's most widely used control method of bearing capacity of mentioned construction layers.

Research on Durability of Big Recycled Aggregate Self-Compacting Concrete Beam

NASA Astrophysics Data System (ADS)

Gao, Shuai; Liu, Xuliang; Li, Jing; Li, Juan; Wang, Chang; Zheng, Jinkai

2018-03-01

Deflection and crack width are the most important durability indexes, which play a pivotal role in the popularization and application of the Big Recycled Aggregate Self-Compacting Concrete technology. In this research, comparative study on the Big Recycled Aggregate Self-Compacting Concrete Beam and ordinary concrete beam were conducted by measuring the deflection and crack width index. The results show that both kind of concrete beams have almost equal mid-span deflection value and are slightly different in the maximum crack width. It indicates that the Big Recycled Aggregate Self-Compacting Concrete Beam will be a good substitute for ordinary concrete beam in some less critical structure projects.

Development of construction materials using nano-silica and aggregates recycled from construction and demolition waste.

PubMed

Mukharjee, Bibhuti Bhusan; Barai, Sudhirkumar V

2015-06-01

The present work addresses the development of novel construction materials utilising commercial grade nano-silica and recycled aggregates retrieved from construction and demolition waste. For this, experimental work has been carried out to examine the influence of nano-silica and recycled aggregates on compressive strength, modulus of elasticity, water absorption, density and volume of voids of concrete. Fully natural and recycled aggregate concrete mixes are designed by replacing cement with three levels (0.75%, 1.5% and 3%) of nano-silica. The results of the present investigation depict that improvement in early days compressive strength is achieved with the incorporation of nano-silica in addition to the restoration of reduction in compressive strength of recycled aggregate concrete mixes caused owing to the replacement of natural aggregates by recycled aggregates. Moreover, the increase in water absorption and volume of voids with a reduction of bulk density was detected with the incorporation of recycled aggregates in place of natural aggregates. However, enhancement in density and reduction in water absorption and volume of voids of recycled aggregate concrete resulted from the addition of nano-silica. In addition, the results of the study reveal that nano-silica has no significant effect on elastic modulus of concrete. © The Author(s) 2015.

Parameters for assessing recycled aggregate and their correlation.

PubMed

Tam, Vivian W Y; Tam, C M

2009-02-01

Construction and demolition (C&D) waste has consumed a large portion of the landfill areas in Hong Kong. Among them, concrete occupies more than 70% of the total C&D waste by volume. Thus it is necessary to recycle concrete waste to preserve landfill areas. Various governmental departments of the Hong Kong Special Administrative Region (HKSAR) are encouraging the use of recycled aggregate (RA) in the Hong Kong construction industry by issuing various guidelines and specifications. Owing to uncertainty in their properties, however, practitioners are sceptical in using it as a substitute. In this study, an attempt has been made to look at relations among six main parameters that describe the behaviour of RA: (1) particle size distribution; (2) particle density; (3) porosity and absorption; (4) particle shape; (5) strength and toughness; and (6) chloride and sulphate contents. RA samples were obtained from nine demolition sites with service lives ranging from 10 to 40 years and another set of samples was collected from the Tuen Mun Area 38 recycling plant. The behaviour of these samples was compared with that of normal aggregate samples. This study revealed that there is a strong correlation among various parameters, and by measuring three of them: either 'particle density' or 'porosity and absorption' or 'particle shape', and 'strength and toughness', and 'chloride and sulphate contents', it is possible to assess the behaviour of RA. This can significantly help by reducing RA testing time and cost before using it as recycled aggregate concrete.

Study on Effects of Different Replacement Rate on Bending Behavior of Big Recycled Aggregate Self Compacting Concrete

NASA Astrophysics Data System (ADS)

Li, Jing; Guo, Tiantian; Gao, Shuai; Jiang, Lin; Zhao, Zhijun; Wang, Yalin

2018-03-01

Big recycled aggregate self compacting concrete is a new type of recycled concrete, which has the advantages of low hydration heat and green environmental protection, but its bending behavior can be affected by different replacement rate. Therefor, in this paper, the research status of big Recycled aggregate self compacting concrete was systematically introduced, and the effect of different replacement rate of big recycled aggregate on failure mode, crack distribution and bending strength of the beam were studied through the bending behavior test of 4 big recycled aggregate self compacting concrete beams. The results show that: The crack distribution of the beam can be affected by the replacement rate; The failure modes of big recycled aggregate beams are the same as those of ordinary concrete; The plane section assumption is applicable to the big recycled aggregate self compacting concrete beam; The higher the replacement rate, the lower the bending strength of big recycled aggregate self compacting concrete beams.

Effect of fly ash on the strength of porous concrete using recycled coarse aggregate to replace low-quality natural coarse aggregate

NASA Astrophysics Data System (ADS)

Arifi, Eva; Cahya, Evi Nur; Christin Remayanti, N.

2017-09-01

The performance of porous concrete made of recycled coarse aggregate was investigated. Fly ash was used as cement partial replacement. In this study, the strength of recycled aggregate was coMPared to low quality natural coarse aggregate which has high water absorption. Compression strength and tensile splitting strength test were conducted to evaluate the performance of porous concrete using fly ash as cement replacement. Results have shown that the utilization of recycled coarse aggregate up to 75% to replace low quality natural coarse aggregate with high water absorption increases compressive strength and splitting tensile strength of porous concrete. Using fly ash up to 25% as cement replacement improves compressive strength and splitting tensile strength of porous concrete.

Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations.

PubMed

Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Qiao, Qiyun; Ma, Heng

2016-03-02

The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC) protective layer (EPS modules as the external insulation layer), and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

PubMed Central

Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Qiao, Qiyun; Ma, Heng

2016-01-01

The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC) protective layer (EPS modules as the external insulation layer), and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls. PMID:28773274

Aggregates from natural and recycled sources; economic assessments for construction applications; a materials flow study

USGS Publications Warehouse

Wilburn, David R.; Goonan, Thomas G.

1998-01-01

Increased amounts of recycled materials are being used to supplement natural aggregates (derived from crushed stone, sand and gravel) in road construction. An understanding of the economics and factors affecting the level of aggregates recycling is useful in estimating the potential for recycling and in assessing the total supply picture of aggregates. This investigation includes a descriptive analysis of the supply sources, technology, costs, incentives, deterrents, and market relationships associated with the production of aggregates.

Separability studies of construction and demolition waste recycled sand.

PubMed

Ulsen, Carina; Kahn, Henrique; Hawlitschek, Gustav; Masini, Eldon A; Angulo, Sérgio C

2013-03-01

The quality of recycled aggregates from construction and demolition waste (CDW) is strictly related to the content of porous and low strength phases, and specifically to the patches of cement that remain attached to the surface of natural aggregates. This phase increases water absorption and compromises the consistency and strength of concrete made from recycled aggregates. Mineral processing has been applied to CDW recycling to remove the patches of adhered cement paste on coarse recycled aggregates. The recycled fine fraction is usually disregarded due to its high content of porous phases despite representing around 50% of the total waste. This paper focus on laboratory mineral separability studies for removing particles with a high content of cement paste from natural fine aggregate particles (quartz/feldspars). The procedure achieved processing of CDW by tertiary impact crushing to produce sand, followed by sieving and density and magnetic separability studies. The attained results confirmed that both methods were effective in reducing cement paste content and producing significant mass recovery (80% for density concentration and 60% for magnetic separation). The production of recycled sand contributes to the sustainability of the construction environment by reducing both the consumption of raw materials and disposal of CDW, particularly in large Brazilian centers with a low quantity of sand and increasing costs of this material due to long transportation distances. Copyright © 2012 Elsevier Ltd. All rights reserved.

Microstructure and Mechanical Properties of Recycled Aggregate Concrete in Seawater Environment

PubMed Central

Yue, Pengjun; Tan, Zhuoying; Guo, Zhiying

2013-01-01

This study aims to conduct research about the microstructure and basic properties of recycled aggregate concrete under seawater corrosion. Concrete specimens were fabricated and tested with different replacement percentages of 0%, 30%, and 60% after immersing in seawater for 4, 8, 12, and 16 months, respectively. The basic properties of recycled aggregate concrete (RAC) including the compressive strength, the elastic modulus, and chloride penetration depth were explicitly investigated. And the microstructure of recycled concrete aggregate (RCA) was revealed to find the seawater corrosion by using scanning electron microscope (SEM). The results showed that higher amount of the RCA means more porosity and less strength, which could lower both the compressive strength and resistance to chloride penetration. This research could be a guide in theoretical and numerical analysis for the design of RAC structures. PMID:24453830

Mechanical Properties of Lightweight Concrete Using Recycled Cement-Sand Brick as Coarse Aggregates Replacement

NASA Astrophysics Data System (ADS)

Joohari, Ilya; Farhani Ishak, Nor; Amin, Norliyati Mohd

2018-03-01

This paper presents the result of replacing natural course aggregate with recycled cement-sand brick (CSB) towards the mechanical properties of concrete. Natural aggregates were used in this study as a control sample to compare with recycled coarse aggregates. This study was also carried to determine the optimum proportion of coarse aggregates replacement to produce lightweight concrete. Besides, this study was conducted to observe the crack and its behaviour development during the mechanical testing. Through this study, four types of concrete mixed were prepared, which were the control sample, 25%, 50% and 75% replacement of CSB. The test conducted to determine the effectiveness of recycled CSB as coarse aggregates replacement in this study were slump test, density measurement, compression test, and flexural test and. The strength of concrete was tested at 7 days and 28 days of curing. From the results obtained, the optimum proportion which produced the highest strength is 25% replacement of recycled CSB. The compressive and flexural strength has decreased by 10%-12% and 4%-34% respectively compared to the control sample. The presence of recycled coarse aggregates in sample has decreased the density of concrete by 0.8%-3% compared to the control sample.

Physio-chemical reactions in recycle aggregate concrete.

PubMed

Tam, Vivian W Y; Gao, X F; Tam, C M; Ng, K M

2009-04-30

Concrete waste constitutes the major proportion of construction waste at about 50% of the total waste generated. An effective way to reduce concrete waste is to reuse it as recycled aggregate (RA) for the production of recycled aggregate concrete (RAC). This paper studies the physio-chemical reactions of cement paste around aggregate for normal aggregate concrete (NAC) and RAC mixed with normal mixing approach (NMA) and two-stage mixing approach (TSMA) by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Four kinds of physio-chemical reactions have been recorded from the concrete samples, including the dehydration of C(3)S(2)H(3), iron-substituted ettringite, dehydroxylation of CH and development of C(6)S(3)H at about 90 degrees C, 135 degrees C, 441 degrees C and 570 degrees C, respectively. From the DSC results, it is confirmed that the concrete samples with RA substitution have generated less amount of strength enhancement chemical products when compared to those without RA substitution. However, the results from the TSMA are found improving the RAC quality. The pre-mix procedure of the TSMA can effectively develop some strength enhancing chemical products including, C(3)S(2)H(3), ettringite, CH and C(6)S(3)H, which shows that RAC made from the TSMA can improve the hydration processes.

Tests for Plastic Fines in Aggregates Related to Stripping in Asphalt Paving Mixtures

DOT National Transportation Integrated Search

1988-03-01

This study was undertaken for determining the best aggregate test method that indicates the presence of detrimental plastic fines in the fine aggregate, which may induce stripping in hot mix asphalt (HMA) mixtures. Ten fine aggregates representing a ...

Field validation of recycled concrete fines usage.

DOT National Transportation Integrated Search

2015-03-01

The amount of recycled concrete fines permitted in concrete mixing water is limited by ASTM C 1602 to 5.0 percent of the mixing : water, by mass, in order to avoid detrimental effects on concrete properties. Depending upon the exact nature of the rec...

Sustainable management and supply of natural and recycled aggregates in a medium-size integrated plant.

PubMed

Faleschini, Flora; Zanini, Mariano Angelo; Pellegrino, Carlo; Pasinato, Stefano

2016-03-01

The consumption of natural aggregates in civil engineering applications can cause severe environmental impacts on a regional scale, depleting the stock of bulk resources within a territory. Several methods can improve the environmental sustainability of the whole aggregates' supply process, including natural and recycled aggregates' productive chains, for instance promoting the use of recycled aggregates (RA). However, when quarrying and recycling activities are considered as stand-alone processes, also the RA supply chain may not be as sustainable as expected, due to the high environmental loads associated to transportation, if high distances from the production to the use sites are involved. This work gives some insights on the environmental impact assessment of the aggregates' industry in the Italian context, through a comparative assessment of the environmental loads of natural and recycled aggregates' productive chains. An integrated plant for the extraction of virgin aggregates and recycling of construction and demolition waste (C&DW) was analyzed as significant case study, with the aim to identify the influence of sustainable solutions on the overall emissions of the facility. A Life Cycle Assessment (LCA) approach was used, using site-specific data and paying particular attention on transportation-related impacts, land use, avoided landfill and non-renewable resources preservation. From this work it was possible to evaluate the influence of transportation and PV energy use on the overall environmental emissions of natural and recycled aggregates' productive chains. Copyright © 2016 Elsevier Ltd. All rights reserved.

Indirect determination of particle shape of fine aggregate.

DOT National Transportation Integrated Search

1973-01-01

Three methods developed by various agencies for measuring indirectly the particle shapes of fine aggregates were used along with a visual classification procedure to study aggregates from eight commercial sources along with a reference sand. The meth...

Utilisation of Waste Marble Dust as Fine Aggregate in Concrete

NASA Astrophysics Data System (ADS)

Vigneshpandian, G. V.; Aparna Shruthi, E.; Venkatasubramanian, C.; Muthu, D.

2017-07-01

Concrete is the important construction material and it is used in the construction industry due to its high compressive strength and its durability. Now a day’s various studies have been conducted to make concrete with waste material with the intention of reducing cost and unavailability of conventional materials. This paper investigates the strength properties of concrete specimens cast using waste marble dust as replacement of fine aggregate. The marble pieces are finely crushed to powdered and the gradation is compared with conventional fine aggregate. Concrete specimen were cast using wmd in the laboratory with different proportion (25%, 50% and 100%) by weight of cement and from the studies it reveals that addition of waste marble dust as a replacement of fine aggregate marginally improves compressive, tensile and flexural strength in concrete.

A GIS analysis of suitability for construction aggregate recycling sites using regional transportation network and population density features

USGS Publications Warehouse

Robinson, G.R.; Kapo, K.E.

2004-01-01

Aggregate is used in road and building construction to provide bulk, strength, support, and wear resistance. Reclaimed asphalt pavement (RAP) and reclaimed Portland cement concrete (RPCC) are abundant and available sources of recycled aggregate. In this paper, current aggregate production operations in Virginia, Maryland, and the District of Columbia are used to develop spatial association models for the recycled aggregate industry with regional transportation network and population density features. The cost of construction aggregate to the end user is strongly influenced by the cost of transporting processed aggregate from the production site to the construction site. More than 60% of operations recycling aggregate in the mid-Atlantic study area are located within 4.8 km (3 miles) of an interstate highway. Transportation corridors provide both sites of likely road construction where aggregate is used and an efficient means to move both materials and on-site processing equipment back and forth from various work sites to the recycling operations. Urban and developing areas provide a high market demand for aggregate and a ready source of construction debris that may be processed into recycled aggregate. Most aggregate recycling operators in the study area are sited in counties with population densities exceeding 77 people/km2 (200 people/mile 2). No aggregate recycling operations are sited in counties with less than 19 people/km2 (50 people/mile2), reflecting the lack of sufficient long-term sources of construction debris to be used as an aggregate source, as well as the lack of a sufficient market demand for aggregate in most rural areas to locate a recycling operation there or justify the required investment in the equipment to process and produce recycled aggregate. Weights of evidence analyses (WofE), measuring correlation on an area-normalized basis, and weighted logistic regression (WLR), are used to model the distribution of RAP and RPCC operations relative

Experimental testing of hot mix asphalt mixture made of recycled aggregates.

PubMed

Rafi, Muhammad Masood; Qadir, Adnan; Siddiqui, Salman Hameed

2011-12-01

The migration of population towards big cities generates rapid construction activities. These activities not only put pressure on natural resources but also produce construction, renovation and demolition waste. There is an urgent need to find out ways to handle this waste owing to growing environmental concerns. This can reduce pressure on natural resources as well. This paper presents the results of experimental studies which were carried out on hot mix asphalt mixture samples. These samples were manufactured by adding recycled aggregates (RA) with natural crushed stone aggregates (CSA). Three levels of addition of RA were considered in the presented studies. RA were obtained from both the concrete waste of construction, renovation and demolition activities and reclaimed asphalt pavement. Separate samples were manufactured with the coarse and fine aggregate fractions of both types of RA. Samples made with CSA were used as control specimens. The samples were prepared and tested using the Marshall method. The performance of the samples was investigated in terms of density-void and stability/flow analysis and was compared with the performance criteria as given by National Highway Authority for wearing course material in Pakistan. Based on this data optimum asphalt contents were determined. All the samples made by adding up to 50% RA conform to the specification requirements of wearing course material as given by National Highway Authority in terms of optimum asphalt contents, voids in mineral aggregates and stability/flow. A statistical analysis of variation of these samples confirmed that addition is also possible statistically.

The influence of fine aggregates on the 3D printing performance

NASA Astrophysics Data System (ADS)

Lin, J. C.; Wu, X.; Yang, W.; Zhao, R. X.; Qiao, L. G.

2018-01-01

Influences of nature Particle, size, grain shape and fineness modulus of fine aggregates on the 3D printing performance of cement-based mortar were investigated. Results showed that the working performance of the mortar is not only dependent on the fineness of the aggregate, but also the gradation and grain size of the aggregate. And the mechanical properties of the mortar are increasing with the increase of Mx in the same test condition. The research shows that it is effective to choose different properties of materials for different design requirements, and the fluidity of mortar must be decreased under assuring construction quality and the pumpability of 3D printing materials.

Properties of Concrete Paving Blocks and Hollow Tiles with Recycled Aggregate from Construction and Demolition Wastes.

PubMed

Rodríguez, Carlos; Miñano, Isabel; Aguilar, Miguel Ángel; Ortega, José Marcos; Parra, Carlos; Sánchez, Isidro

2017-11-30

In recent years there has been an increasing tendency to recycle the wastes generated by building companies in the construction industry, demolition wastes being the most important in terms of volume. The aim of this work is to study the possibility of using recycled aggregates from construction and demolition wastes in the preparation of precast non-structural concretes. To that purpose, two different percentages (15% and 30%) of natural aggregates were substituted by recycled aggregates in the manufacture of paving blocks and hollow tiles. Dosages used by the company have not been changed by the introduction of recycled aggregate. Precast elements have been tested by means of compressive and flexural strength, water absorption, density, abrasion, and slipping resistance. The results obtained show the possibility of using these wastes at an industrial scale, satisfying the requirements of the Spanish standards for these elements.

An Experimental Study of Mortars with Recycled Ceramic Aggregates: Deduction and Prediction of the Stress-Strain.

PubMed

Cabrera-Covarrubias, Francisca Guadalupe; Gómez-Soberón, José Manuel; Almaral-Sánchez, Jorge Luis; Arredondo-Rea, Susana Paola; Gómez-Soberón, María Consolación; Corral-Higuera, Ramón

2016-12-21

The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications.

An Experimental Study of Mortars with Recycled Ceramic Aggregates: Deduction and Prediction of the Stress-Strain

PubMed Central

Cabrera-Covarrubias, Francisca Guadalupe; Gómez-Soberón, José Manuel; Almaral-Sánchez, Jorge Luis; Arredondo-Rea, Susana Paola; Gómez-Soberón, María Consolación; Corral-Higuera, Ramón

2016-01-01

The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (σ-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the σ-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications. PMID:28774151

Correlation analysis between sulphate content and leaching of sulphates in recycled aggregates from construction and demolition wastes.

PubMed

Barbudo, Auxi; Galvín, Adela P; Agrela, Francisco; Ayuso, Jesús; Jiménez, Jose Ramón

2012-06-01

In some recycled aggregates applications, such as component of new concrete or roads, the total content of soluble sulphates should be measured and controlled. Restrictions are usually motivated by the resistance or stability of the new structure, and in most cases, structural concerns can be remedied by the use of techniques such as sulphur-resistant cements. However, environmental risk assessment from recycling and reuse construction products is often forgotten. The purpose of this study is to analyse the content of soluble sulphate on eleven recycled aggregates and six samples prepared in laboratory by the addition of different gypsum percentages. As points of reference, two natural aggregates were tested. An analysis of the content of the leachable amount of heavy metals regulated by European regulation was included. As a result, the correlation between solubility and leachability data allow suggest a limiting gypsum amount of 4.4% on recycled aggregates. This limit satisfies EU Landfill Directive criteria, which is currently used as reference by public Spanish Government for recycled aggregates in construction works. Copyright © 2012 Elsevier Ltd. All rights reserved.

The aggregation efficiency of very fine volcanic ash

NASA Astrophysics Data System (ADS)

Del Bello, E.; Taddeucci, J.; Scarlato, P.

2013-12-01

Explosive volcanic eruptions can discharge large amounts of very small sized pyroclasts (under 0.090 mm) into the atmosphere that may cause problems to people, infrastructures and environment. The transport and deposition of fine ash are ruled by aggregation that causes premature settling of fine ash and, as consequence, significantly reduces the concentration of airborne material over long distances. Parameterizing the aggregation potential of fine ash is then needed to provide accurate modelling of ash transport and deposition from volcanic plumes. Here we present the first results of laboratory experiments investigating the aggregation efficiency of very fine volcanic particles. Previous laboratory experiments have shown that collision kinetic and relative humidity provide the strongest effect on aggregation behaviour but were only limited to particles with size > 0.125 mm. In our work, we focus on natural volcanic ash at ambient humidity with particles size < 0.090 mm, by taking into account the effect of grain size distribution on aggregation potential. Two types of ash were used in our experiments: fresh ash, collected during fall-out from a recent plume-forming eruption at Sakurajima (Japan -July 2013) and old ash, collected from fall-out tephra deposits at Campi Flegrei (Italy, ca. 10 ka), to account for the different chemical composition and morphoscopic effects of altered ash on aggregation efficiency. Total samples were hand sieved to obtain three classes with unimodal grain size distributions (<0.090 mm, <0.063 mm, <0.032 mm). Bimodal grain size distributions were also obtained by mixing the three classes in different proportions. During each experiments, particles were sieved from the top of a transparent tank where a fan, placed at the bottom, allows turbulent dispersion of particles. Collision and sticking of particles on a vertical glass slide were filmed with a high speed cameras at 6000 fps. Our lenses arrangement provide high image resolution

Properties of Concrete Paving Blocks and Hollow Tiles with Recycled Aggregate from Construction and Demolition Wastes

PubMed Central

Rodríguez, Carlos; Miñano, Isabel; Aguilar, Miguel Ángel; Parra, Carlos

2017-01-01

In recent years there has been an increasing tendency to recycle the wastes generated by building companies in the construction industry, demolition wastes being the most important in terms of volume. The aim of this work is to study the possibility of using recycled aggregates from construction and demolition wastes in the preparation of precast non-structural concretes. To that purpose, two different percentages (15% and 30%) of natural aggregates were substituted by recycled aggregates in the manufacture of paving blocks and hollow tiles. Dosages used by the company have not been changed by the introduction of recycled aggregate. Precast elements have been tested by means of compressive and flexural strength, water absorption, density, abrasion, and slipping resistance. The results obtained show the possibility of using these wastes at an industrial scale, satisfying the requirements of the Spanish standards for these elements. PMID:29189745

Durability of recycled aggregate concrete using pozzolanic materials.

PubMed

Ann, K Y; Moon, H Y; Kim, Y B; Ryou, J

2008-01-01

In this study, pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS) were used to compensate for the loss of strength and durability of concrete containing recycled aggregate. As a result, 30% PFA and 65% GGBS concretes increased the compressive strength to the level of control specimens cast with natural granite gravel, but the tensile strength was still lowered at 28 days. Replacement with PFA and GGBS was effective in raising the resistance to chloride ion penetrability into the concrete body, measured by a rapid chloride ion penetration test based on ASTM C 1202-91. It was found that the corrosion rate of 30% PFA and 65% GGBS concretes was kept at a lower level after corrosion initiation, compared to the control specimens, presumably due to the restriction of oxygen and water access. However, it was less effective in increasing the chloride threshold level for steel corrosion. Hence, it is expected that the corrosion time for 30% PFA and 65% GGBS concrete containing recycled aggregate mostly equates to the corrosion-free life of control specimens.

Effect of Fly-Ash on Corrosion Resistance Characteristics of Rebar Embedded in Recycled Aggregate Concrete

NASA Astrophysics Data System (ADS)

Revathi, Purushothaman; Nikesh, P.

2018-04-01

In the frame of an extended research programme dealing with the utilization of recycled aggregate in concrete, the corrosion resistance characteristics of rebars embedded in recycled aggregate concrete is studied. Totally five series of concrete mixtures were prepared with fly-ash as replacement for cement in the levels of 10-30% by weight of cement. Corrosion studies by 90 days ponding test, linear polarization test and impressed voltage tests were carried out, in order to investigate whether corrosion behaviour of the rebars has improved due to the replacement of cement with fly-ash. Results showed that the replacement of cement with fly-ash in the range of 20-30% improves the corrosion resistance characteristics of recycled aggregate concrete.

Leaching and mechanical behaviour of concrete manufactured with recycled aggregates.

PubMed

Sani, D; Moriconi, G; Fava, G; Corinaldesi, V

2005-01-01

The reuse of debris from building demolition is of increasing public interest because it decreases the volume of material to be disposed to landfill. This research is focused on the evaluation of the possibility of reusing recycled aggregate from construction or demolition waste (C&D) as a substitute for natural aggregate in concrete production. In most applications, cement based materials are used for building construction due to their cost effectiveness and performance; however their impact on the surrounding environment should be monitored. The interstitial pore fluid in contact with hydrated cementitious materials is characterized by persistent alkaline pH values buffered by the presence of hydrate calcium silicate, portlandite and alkaline ions. An experimental plan was carried out to investigate concrete structural properties in relation to alkali release in aqueous solution. Results indicate that the presence of recycled aggregate increases the leachability of unreactive ions (Na, K, Cl), while for calcium the substitution resulted in a lower net leaching. In spite of the lower mechanical resistance (40% less), such a waste concrete may be suggested as more environmentally sustainable.

Data on optimum recycle aggregate content in production of new structural concrete.

PubMed

Paul, Suvash Chandra

2017-12-01

This data presented herein are the research summary of "mechanical behavior and durability performance of concrete containing recycled concrete aggregate" (Paul, 2011) [1]. The results reported in this article relate to an important parameter of optimum content of recycle concrete aggregate (RCA) in production of new concrete for both structural and non-structural applications. For the purpose of the research various types of physical, mechanical and durability tests are performed for concrete made with different percentages of RCA. Therefore, this data set can be a great help of the readers to understand the mechanism of RCA in relates to the concrete properties.

Blasted copper slag as fine aggregate in Portland cement concrete.

PubMed

Dos Anjos, M A G; Sales, A T C; Andrade, N

2017-07-01

The present work focuses on assessing the viability of applying blasted copper slag, produced during abrasive blasting, as fine aggregate for Portland cement concrete manufacturing, resulting in an alternative and safe disposal method. Leaching assays showed no toxicity for this material. Concrete mixtures were produced, with high aggregate replacement ratios, varying from 0% to 100%. Axial compressive strength, diametrical compressive strength, elastic modulus, physical indexes and durability were evaluated. Assays showed a significant improvement in workability, with the increase in substitution of fine aggregate. With 80% of replacement, the concrete presented lower levels of water absorption capacity. Axial compressive strength and diametrical compressive strength decreased, with the increase of residue replacement content. The greatest reductions of compressive strength were found when the replacement was over 40%. For tensile strength by diametrical compression, the greatest reduction occurred for the concrete with 80% of replacement. After the accelerated aging, results of mechanic properties showed a small reduction of the concrete with blasted copper slag performance, when compared with the reference mixture. Results indicated that the blasted copper slag is a technically viable material for application as fine aggregate for concrete mixtures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selective Convolutional Descriptor Aggregation for Fine-Grained Image Retrieval.

PubMed

Wei, Xiu-Shen; Luo, Jian-Hao; Wu, Jianxin; Zhou, Zhi-Hua

2017-06-01

Deep convolutional neural network models pre-trained for the ImageNet classification task have been successfully adopted to tasks in other domains, such as texture description and object proposal generation, but these tasks require annotations for images in the new domain. In this paper, we focus on a novel and challenging task in the pure unsupervised setting: fine-grained image retrieval. Even with image labels, fine-grained images are difficult to classify, letting alone the unsupervised retrieval task. We propose the selective convolutional descriptor aggregation (SCDA) method. The SCDA first localizes the main object in fine-grained images, a step that discards the noisy background and keeps useful deep descriptors. The selected descriptors are then aggregated and the dimensionality is reduced into a short feature vector using the best practices we found. The SCDA is unsupervised, using no image label or bounding box annotation. Experiments on six fine-grained data sets confirm the effectiveness of the SCDA for fine-grained image retrieval. Besides, visualization of the SCDA features shows that they correspond to visual attributes (even subtle ones), which might explain SCDA's high-mean average precision in fine-grained retrieval. Moreover, on general image retrieval data sets, the SCDA achieves comparable retrieval results with the state-of-the-art general image retrieval approaches.

Integral recycling of municipal solid waste incineration (MSWI) bottom ash fines (0-2mm) and industrial powder wastes by cold-bonding pelletization.

PubMed

Tang, P; Brouwers, H J H

2017-04-01

The cold-bonding pelletizing technique is applied in this study as an integrated method to recycle municipal solid waste incineration (MSWI) bottom ash fines (BAF, 0-2mm) and several other industrial powder wastes. Artificial lightweight aggregates are produced successfully based on the combination of these solid wastes, and the properties of these artificial aggregates are investigated and then compared with others' results reported in literature. Additionally, methods for improving the aggregate properties are suggested, and the corresponding experimental results show that increasing the BAF amount, higher binder content and addition of polypropylene fibres can improve the pellet properties (bulk density, crushing resistance, etc.). The mechanisms regarding to the improvement of the pellet properties are discussed. Furthermore, the leaching behaviours of contaminants from the produced aggregates are investigated and compared with Dutch environmental legislation. The application of these produced artificial lightweight aggregates are proposed according to their properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Occurrence and fate of acrylamide in water-recycling systems and sludge in aggregate industries.

PubMed

Junqua, Guillaume; Spinelli, Sylvie; Gonzalez, Catherine

2015-05-01

Acrylamide is a hazardous substance having irritant and toxic properties as well as carcinogen, mutagen, and impaired fertility possible effects. Acrylamide might be found in the environment as a consequence of the use of polyacrylamides (PAMs) widely added as a flocculant for water treatment. Acrylamide is a monomer used to produce polyacrylamide (PAM) polymers. This reaction of polymerization can be incomplete, and acrylamide molecules can be present as traces in the commercial polymer. Thus, the use of PAMs may generate a release of acrylamide in the environment. In aggregate industries, PAM is widely involved in recycling process and water reuse (aggregate washing). Indeed, these industries consume large quantities of water. Thus, European and French regulations have favored loops of recycling of water in order to reduce water withdrawals. The main goal of this article is to study the occurrence and fate of acrylamide in water-recycling process as well as in the sludge produced by the flocculation treatment process in aggregate production plants. Moreover, to strengthen the relevance of this article, the objective is also to demonstrate if the recycling system leads to an accumulation effect in waters and sludge and if free acrylamide could be released by sludge during their storage. To reach this objective, water sampled at different steps of recycling water process has been analyzed as well as different sludge corresponding to various storage times. The obtained results reveal no accumulation effect in the water of the water-recycling system nor in the sludge.

Durability assessment of recycled concrete aggregates for use in new concrete.

DOT National Transportation Integrated Search

2012-06-01

The primary goal of this research project was to investigate the long-term durability of concrete incorporating : recycled concrete aggregate (RCA) through accelerated laboratory testing. Overall it was found that modifications to : standard aggregat...

Laboratory evaluation of recycled concrete as aggregate in new concrete pavements.

DOT National Transportation Integrated Search

2014-09-01

The Washington State Department of Transportation (WSDOT) has initiated a research project to investigate the use of recycled concrete as : aggregates (RCA) in Portland (hydraulic) cement concrete pavements (PCCP). The planned source for the RCA in t...

Upscaling the pollutant emission from mixed recycled aggregates under compaction for civil applications.

PubMed

Galvín, Adela P; Ayuso, Jesús; Barbudo, Auxi; Cabrera, Manuel; López-Uceda, Antonio; Rosales, Julia

2017-12-27

In general terms, plant managers of sites producing construction wastes assess materials according to concise, legally recommended leaching tests that do not consider the compaction stage of the materials when they are applied on-site. Thus, the tests do not account for the real on-site physical conditions of the recycled aggregates used in civil works (e.g., roads or embankments). This leads to errors in estimating the pollutant potential of these materials. For that reason, in the present research, an experimental procedure is designed as a leaching test for construction materials under compaction. The aim of this laboratory test (designed specifically for the granular materials used in civil engineering infrastructures) is to evaluate the release of pollutant elements when the recycled aggregate is tested at its commercial grain-size distribution and when the material is compacted under on-site conditions. Two recycled aggregates with different gypsum contents (0.95 and 2.57%) were used in this study. In addition to the designed leaching laboratory test, the conventional compliance leaching test and the Dutch percolation test were performed. The results of the new leaching method were compared with the conventional leaching test results. After analysis, the chromium and sulphate levels obtained from the newly designed test were lower than those obtained from the conventional leaching test, and these were considered more seriously pollutant elements. This result confirms that when the leaching behaviour is evaluated for construction aggregates without density alteration, crushing the aggregate and using only the finest fraction, as is done in the conventional test (which is an unrealistic situation for aggregates that are applied under on-site conditions), the leaching behaviour is not accurately assessed.

Magnitude assessment of free and hydrated limes present in RPCC aggregates : research implementation plan.

DOT National Transportation Integrated Search

2005-10-11

Aggregates obtained from recycled reinforced Portland cement concrete (RPCC) pavement used as base or : subbase may produce tufa in the underdrain outlet pipes. The most likely source of the tufa is related to the : fine aggregate and cement paste. I...

Leaching assessment of concrete made of recycled coarse aggregate: physical and environmental characterisation of aggregates and hardened concrete.

PubMed

Galvín, A P; Agrela, F; Ayuso, J; Beltrán, M G; Barbudo, A

2014-09-01

Each year, millions of tonnes of waste are generated worldwide, partially through the construction and demolition of buildings. Recycling the resulting waste could reduce the amount of materials that need to be manufactured. Accordingly, the present work has analysed the potential reuse of construction waste in concrete manufacturing by replacing the natural aggregate with recycled concrete coarse aggregate. However, incorporating alternative materials in concrete manufacturing may increase the pollutant potential of the product, presenting an environmental risk via ground water contamination. The present work has tested two types of concrete batches that were manufactured with different replacement percentages. The experimental procedure analyses not only the effect of the portion of recycled aggregate on the physical properties of concrete but also on the leaching behaviour as indicative of the contamination degree. Thus, parameters such as slump, density, porosity and absorption of hardened concrete, were studied. Leaching behaviour was evaluated based on the availability test performed to three aggregates (raw materials of the concrete batches) and on the diffusion test performed to all concrete. From an environmental point of view, the question of whether the cumulative amount of heavy metals that are released by diffusion reaches the availability threshold was answered. The analysis of concentration levels allowed the establishment of different groups of metals according to the observed behaviour, the analysis of the role of pH and the identification of the main release mechanisms. Finally, through a statistical analysis, physical parameters and diffusion data were interrelated. It allowed estimating the relevance of porosity, density and absorption of hardened concrete on diffusion release of the metals in study. Copyright © 2014 Elsevier Ltd. All rights reserved.

Compressive strength performance of OPS lightweight aggregate concrete containing coal bottom ash as partial fine aggregate replacement

NASA Astrophysics Data System (ADS)

Muthusamy, K.; Mohamad Hafizuddin, R.; Mat Yahaya, F.; Sulaiman, M. A.; Syed Mohsin, S. M.; Tukimat, N. N.; Omar, R.; Chin, S. C.

2018-04-01

Concerns regarding the negative impact towards environment due to the increasing use of natural sand in construction industry and dumping of industrial solid wastes namely coal bottom ash (CBA) and oil palm shell (OPS) has resulted in the development of environmental friendly lightweight concrete. The present study investigates the effect of coal bottom ash as partial fine aggregate replacement towards workability and compressive strength of oil palm shell lightweight aggregate concrete (OPS LWAC). The fresh and mechanical properties of this concrete containing various percentage of coal bottom ash as partial fine aggregate replacement were investigated. The result was compared to OPS LWAC with 100 % sand as a control specimen. The concrete workability investigated by conducting slump test. All specimens were cast in form of cubes and water cured until the testing age. The compressive strength test was carried out at 7 and 28 days. The finding shows that integration of coal bottom ash at suitable proportion enhances the strength of oil palm shell lightweight aggregate concrete.

Utilization of recycled glass derived from cathode ray tube glass as fine aggregate in cement mortar.

PubMed

Ling, Tung-Chai; Poon, Chi-Sun

2011-08-30

Rapid advances in the electronic industry led to an excessive amount of early disposal of older electronic devices such as computer monitors and old televisions (TV) before the end of their useful life. The management of cathode ray tubes (CRT), which have been a key component in computer monitors and TV sets, has become a major environmental problem worldwide. Therefore, there is a pressing need to develop sustainable alternative methods to manage hazardous CRT glass waste. This study assesses the feasibility of utilizing CRT glass as a substitute for natural aggregates in cement mortar. The CRT glass investigated was an acid-washed funnel glass of dismantled CRT from computer monitors and old TV sets. The mechanical properties of mortar mixes containing 0%, 25%, 50%, 75% and 100% of CRT glass were investigated. The potential of the alkali-silica reaction (ASR) and leachability of lead were also evaluated. The results confirmed that the properties of the mortar mixes prepared with CRT glass was similar to that of the control mortar using sand as fine aggregate, and displayed innocuous behaviour in the ASR expansion test. Incorporating CRT glass in cement mortar successfully prevented the leaching of lead. We conclude that it is feasible to utilize CRT glass in cement mortar production. Copyright © 2011 Elsevier B.V. All rights reserved.

HEAVY METALS IN RECOVERED FINES FOR CONSTRUCTION AND DEMOLITION DEBRIS RECYCLING FACILITIES IN FLORIDA

EPA Science Inventory

A major product recovered from the processing and recycling of construction and demolition (C&D) debris is screened soil, also referred to as fines. A proposed reuse option for C&D debris fines is fill material, typically in construction projects as a substitute for natural soil....

Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst.

PubMed

Gurdián, Hebé; García-Alcocel, Eva; Baeza-Brotons, Francisco; Garcés, Pedro; Zornoza, Emilio

2014-04-21

The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash) and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes.

Microstructure of Concrete with Aggregates from Construction and Demolition Waste Recycling Plants.

PubMed

Bravo, Miguel; Santos Silva, António; de Brito, Jorge; Evangelista, Luís

2016-02-01

This paper intends to analyze the microstructure of concrete with recycled aggregates (RA) from construction and demolition waste from various Portuguese recycling plants. To that effect, several scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed. Various concrete mixes were evaluated in order to analyze the influence of the RA's collection point and consequently of their composition on the mixes' characteristics. Afterward all the mixes were subjected to the capillary water absorption test in order to quantitatively evaluate their porosity. Results from the SEM/EDS analysis were compared with those from capillary water absorption test. The SEM/EDS analysis showed that the bond capacity of aggregates to the new cement paste is greatly influenced by the RA's nature. On the other hand, there was an increase in porosity with the incorporation of RA.

Study on the durability of concrete using granulated blast furnace slag as fine aggregate

NASA Astrophysics Data System (ADS)

Shi, Dongsheng; Liu, Qiang; Xue, Xinxin; He, Peiyuan

2018-03-01

In order to assessing the durability of concrete using granulated blastfurnace slag (GBS) as fine aggregate and compare it with natural river sand concrete, three different size of specimen were produced by using the same mix proportion with 3 different water cement ratios and 3 replacement ratios, and using it to measure the three aspects on the durability of concrete including freeze-thaw performance, dry-shrinkage performance and anti-chloride-permeability performance. In this paper. The test results show that using GBS as fine aggregate can slightly improve anti-chloride-permeability performance and dry-shrinkage performance of concrete in the condition of low water cement ratio, on the other hand, using GBS or natural river sand as fine aggregate has almost similar durability of concrete.

Mechanical and Physical Properties of Polyester Polymer Concrete Using Recycled Aggregates from Concrete Sleepers

PubMed Central

Carrión, Francisco; Montalbán, Laura; Real, Julia I.

2014-01-01

Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate), and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption) was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%), and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior. PMID:25243213

Mechanical and physical properties of polyester polymer concrete using recycled aggregates from concrete sleepers.

PubMed

Carrión, Francisco; Montalbán, Laura; Real, Julia I; Real, Teresa

2014-01-01

Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate), and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption) was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%), and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior.

Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst

PubMed Central

Gurdián, Hebé; García-Alcocel, Eva; Baeza-Brotons, Francisco; Garcés, Pedro; Zornoza, Emilio

2014-01-01

The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash) and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes. PMID:28788613

Optimization and influence of parameter affecting the compressive strength of geopolymer concrete containing recycled concrete aggregate: using full factorial design approach

NASA Astrophysics Data System (ADS)

Krishnan, Thulasirajan; Purushothaman, Revathi

2017-07-01

There are several parameters that influence the properties of geopolymer concrete, which contains recycled concrete aggregate as the coarse aggregate. In the present study, the vital parameters affecting the compressive strength of geopolymer concrete containing recycled concrete aggregate are analyzedby varying four parameters with two levels using full factorial design in statistical software Minitab® 17. The objective of the present work is to gain an idea on the optimization, main parameter effects, their interactions and the predicted response of the model generated using factorial design. The parameters such as molarity of sodium hydroxide (8M and 12M), curing time (6hrs and 24 hrs), curing temperature (60°C and 90°C) and percentage of recycled concrete aggregate (0% and 100%) are considered. The results show that the curing time, molarity of sodium hydroxide and curing temperature were the orderly significant parameters and the percentage of Recycled concrete aggregate (RCA) was statistically insignificant in the production of geopolymer concrete. Thus, it may be noticeable that the RCA content had negligible effect on the compressive strength of geopolymer concrete. The expected responses from the generated model showed a satisfactory and rational agreement to the experimental data with the R2 value of 97.70%. Thus, geopolymer concrete comprising recycled concrete aggregate can solve the major social and environmental concerns such as the depletion of the naturally available aggregate sources and disposal of construction and demolition waste into the landfill.

Recycled sand in lime-based mortars.

PubMed

Stefanidou, M; Anastasiou, E; Georgiadis Filikas, K

2014-12-01

The increasing awareness of the society about safe guarding heritage buildings and at the same time protecting the environment promotes strategies of combining principles of restoration with environmentally friendly materials and techniques. Along these lines, an experimental program was carried out in order to investigate the possibility of producing repair, lime-based mortars used in historic buildings incorporating secondary materials. The alternative material tested was recycled fine aggregates originating from mixed construction and demolition waste. Extensive tests on the raw materials have been performed and mortar mixtures were produced using different binding systems with natural, standard and recycled sand in order to compare their mechanical, physical and microstructure properties. The study reveals the improved behavior of lime mortars, even at early ages, due to the reaction of lime with the Al and Si constituents of the fine recycled sand. The role of the recycled sand was more beneficial in lime mortars rather than the lime-pozzolan or lime-pozzolan-cement mortars as a decrease in their performance was recorded in the latter cases due to the mortars' structure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of new test procedures for measuring fine and coarse aggregates specific gravity.

DOT National Transportation Integrated Search

2009-09-01

The objective of the research is to develop and evaluate new test methods at determining the specific gravity and absorption of both fine and coarse aggregates. Current methods at determining the specific gravity and absorption of fine and coarse agg...

Recycled blocks with improved sound and fire insulation containing construction and demolition waste.

PubMed

Leiva, Carlos; Solís-Guzmán, Jaime; Marrero, Madelyn; García Arenas, Celia

2013-03-01

The environmental problem posed by construction and demolition waste (C&D waste) is derived not only from the high volume produced, but also from its treatment and disposal. Treatment plants receive C&D waste which is then transformed into a recycled mixed aggregate. The byproduct is mainly used for low-value-added applications such as land escape restoration, despite the high quality of the aggregate. In the present work, the chemical composition properties and grading curve properties of these aggregates are defined. Furthermore, the resulting recycled concrete with a high proportion of recycled composition, from 20% to 100% replacement of fine and coarse aggregate, is characterized physically and mechanically. An environmental study of the new construction material when all aggregates are substituted by C&D waste shows a low toxicity level, similar to that of other construction materials. The new material also has improved properties with respect to standard concrete such as high fire resistance, good heat insulation, and acoustic insulation. Copyright © 2012 Elsevier Ltd. All rights reserved.

On Time/Space Aggregation of Fine-Scale Error Estimates (Invited)

NASA Astrophysics Data System (ADS)

Huffman, G. J.

2013-12-01

Estimating errors inherent in fine time/space-scale satellite precipitation data sets is still an on-going problem and a key area of active research. Complicating features of these data sets include the intrinsic intermittency of the precipitation in space and time and the resulting highly skewed distribution of precipitation rates. Additional issues arise from the subsampling errors that satellites introduce, the errors due to retrieval algorithms, and the correlated error that retrieval and merger algorithms sometimes introduce. Several interesting approaches have been developed recently that appear to make progress on these long-standing issues. At the same time, the monthly averages over 2.5°x2.5° grid boxes in the Global Precipitation Climatology Project (GPCP) Satellite-Gauge (SG) precipitation data set follow a very simple sampling-based error model (Huffman 1997) with coefficients that are set using coincident surface and GPCP SG data. This presentation outlines the unsolved problem of how to aggregate the fine-scale errors (discussed above) to an arbitrary time/space averaging volume for practical use in applications, reducing in the limit to simple Gaussian expressions at the monthly 2.5°x2.5° scale. Scatter diagrams with different time/space averaging show that the relationship between the satellite and validation data improves due to the reduction in random error. One of the key, and highly non-linear, issues is that fine-scale estimates tend to have large numbers of cases with points near the axes on the scatter diagram (one of the values is exactly or nearly zero, while the other value is higher). Averaging 'pulls' the points away from the axes and towards the 1:1 line, which usually happens for higher precipitation rates before lower rates. Given this qualitative observation of how aggregation affects error, we observe that existing aggregation rules, such as the Steiner et al. (2003) power law, only depend on the aggregated precipitation rate

[Based on Curing Age of Calcined Coal Gangue Fine Aggregate Mortar of X-Ray Diffraction and Scanning Electron Microscopy Analysis].

PubMed

Dong, Zuo-chao; Xia, Jun-wu; Duan, Xiao-mu; Cao, Ji-chang

2016-03-01

By using X-ray diffraction (XRD) and environmental scanning electron microscope (SEM) analysis method, we stud- ied the activity of coal gangue fine aggregate under different calcination temperature. In view of the activity of the highest-700 degrees C high temperature calcined coal gangue fine aggregate mortar of hydration products, microstructure and strength were discussed in this paper, and the change laws of mortar strength with curing age (3, 7, 14, 28, 60 and 90 d) growth were analyzed. Test results showed that coal gangue fine aggregate with the increase of calcination temperature, the active gradually increases. When the calcination temperature reaches 700 degrees C, the activity of coal gangue fine aggregate is the highest. When calcining temperature continues to rise, activity falls. After 700 degrees C high temperature calcined coal gangue fine aggregate has obvious ash activity, the active components of SiO2 and Al2 O3 can be with cement hydration products in a certain degree of secondary hydration reaction. Through on the top of the activity of different curing age 700 degrees C high temperature calcined coal gangue fine aggregate mortar, XRD and SEM analysis showed that with the increase of curing age, secondary hydration reaction will be more fully, and the amount of hydration products also gradually increases. Compared with the early ages of the cement mortar, the products are more stable hydration products filling in mortar microscopic pore, which can further improve the microstructure of mortar, strengthen the interface performance of the mortar. The mortar internal structure is more uniform, calcined coal gangue fine aggregate and cement mortar are more of a strong continuous whole, which increase the later strength of hardened cement mortar, 700 degrees C high temperature calcined coal gangue fine aggregate pozzolanic effect is obvious.

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products

PubMed Central

Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

2015-01-01

Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete’s water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction. PMID:28787809

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products.

PubMed

Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

2015-12-25

Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete's water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction.

Mechanical Behavior of Recycled Aggregate Concrete-Filled Steel Tubular Columns before and after Fire.

PubMed

Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Wang, Ruwei; Ren, Lele

2017-03-09

Recycled aggregate concrete (RAC) is an environmentally friendly building material. This paper investigates the mechanical behavior of recycled aggregate concrete filled steel tube (RACFST) columns exposed to fire. Two groups of 12 columns were designed and tested, under axial compression, before and after fire, to evaluate the degradation of bearing capacity due to fire exposure. Six specimens were subjected to axial compression tests at room temperature and the other six specimens were subjected to axial compression tests after a fire exposure. The main parameters of the specimens include the wall thickness of the steel tube (steel content) and the type of concrete materials. Several parameters as obtained from the experimental results were compared and analyzed, including the load-bearing capacity, deformation capacity, and failure characteristics of the specimens. Meanwhile, rate of loss of bearing capacity of specimens exposed to fire were calculated based on the standards EC4 and CECS28:90. The results show that concrete material has a large influence on the rate of loss of bearing capacity in the case of a relatively lower steel ratio. While steel content has little effect on the rate of loss of bearing capacity of concrete-filled steel tube (CFST) columns after fire, it has a relatively large influence on the loss rate of bearing capacity of the RACFST columns. The loss of bearing capacity of the specimens from the experiment is more serious than that from the calculation. As the calculated values are less conservative, particular attention should be given to the application of recycled aggregate concrete in actual structures.

Mechanical Behavior of Recycled Aggregate Concrete-Filled Steel Tubular Columns before and after Fire

PubMed Central

Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Wang, Ruwei; Ren, Lele

2017-01-01

Recycled aggregate concrete (RAC) is an environmentally friendly building material. This paper investigates the mechanical behavior of recycled aggregate concrete filled steel tube (RACFST) columns exposed to fire. Two groups of 12 columns were designed and tested, under axial compression, before and after fire, to evaluate the degradation of bearing capacity due to fire exposure. Six specimens were subjected to axial compression tests at room temperature and the other six specimens were subjected to axial compression tests after a fire exposure. The main parameters of the specimens include the wall thickness of the steel tube (steel content) and the type of concrete materials. Several parameters as obtained from the experimental results were compared and analyzed, including the load-bearing capacity, deformation capacity, and failure characteristics of the specimens. Meanwhile, rate of loss of bearing capacity of specimens exposed to fire were calculated based on the standards EC4 and CECS28:90. The results show that concrete material has a large influence on the rate of loss of bearing capacity in the case of a relatively lower steel ratio. While steel content has little effect on the rate of loss of bearing capacity of concrete-filled steel tube (CFST) columns after fire, it has a relatively large influence on the loss rate of bearing capacity of the RACFST columns. The loss of bearing capacity of the specimens from the experiment is more serious than that from the calculation. As the calculated values are less conservative, particular attention should be given to the application of recycled aggregate concrete in actual structures. PMID:28772634

Feasibility of Using Unbound Mixed Recycled Aggregates from CDW over Expansive Clay Subgrade in Unpaved Rural Roads

PubMed Central

Del Rey, Isaac; Ayuso, Jesús; Galvín, Adela P.; Jiménez, José R.; Barbudo, Auxi

2016-01-01

Social awareness aims to increase practical skills, such as sustainable development, which seeks to increase the use of different types of waste in construction activities. Although insufficient attention is sometimes given to these actions, it is essential to spread information regarding new studies in the field of waste recycling, which encourages and promotes waste use. Reusing and recycling construction waste in the creation of buildings and infrastructure are fundamental strategies to achieving sustainability in the construction and engineering sectors. In this context, the concept of waste would no longer exist, as waste would become a material resource. Therefore, this study analyses the behaviours of two unbound mixed recycled aggregates (MRA) in the structural layers of an unpaved rural road with low traffic (category T43). The sections were built on inappropriate soil (A-7-6) with a high degree of free swelling. The experimental road consisted of three sections: the first was made with natural aggregates (NA) that were used as a control, the second was composed of MRA in the subbase and NA in the base, and the third section was completely composed of MRA. The materials were characterised in the laboratory. The behaviours of the structural layers in the experimental road were determined by controlling compaction (“in situ” density and moisture) and measuring the deflections and load capacity (deflectometer) during the 18 months after construction. The results show that the sections made with recycled aggregates meet the technical specifications required by General Technical Specifications for Road and Bridge Works (PG-3). Therefore, the water-soluble sulphate content and Los Angeles abrasion coefficient limits can be increased for recycled aggregates without compromising the quality of this type of road with low traffic. To the best of our knowledge, this is the first study regarding the use of unbound MRA made from construction and demolition waste

Effect of crumb rubber on the mechanical properties of crushed recycled pavement materials.

PubMed

Li, Jie; Saberian, Mohammad; Nguyen, Bao Thach

2018-07-15

The low-carbon footprint of using recycled construction and demolition (C&D) aggregates in civil engineering infrastructure applications has been considered to be a significant solution for the replacement of conventional pavement aggregates. Investigations regarding the use of crumb rubber in the base and subbase layers of pavement have been well documented. However, information on the effects of crumb rubber and its size within C&D aggregates as the base/subbase layers is still very limited. In this study, crumb rubber with particle sizes ranging from 400 to 600 μm (fine) to 10-15 mm (coarse), 20 mm recycled crushed concrete (RCC), and 20 mm crushed rock (CR) were used. The crumb rubber was added to the two groups of C&D aggregates at 0.5, 1 and 2% by weight percentages of the aggregates. The effect of crumb rubber on the mechanical properties (such as California bearing ratio, unconfined compressive strength, aggregate crushing value, dynamic lightweight cone penetrometer, Clegg impact value, Los Angeles abrasion values, and resilient modulus) of the C&D aggregates was then examined. Based on the experimental test results, it was found that crumb rubber can be recycled as a waste material for the base and subbase layers in the pavement. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study on Mechanical Properties of Concrete Using Plastic Waste as an Aggregate

NASA Astrophysics Data System (ADS)

Jaivignesh, B.; Sofi, A.

2017-07-01

Disposal of large quantity of plastic causes land, water and air pollution etc.., so a study is conducted to recycle the plastic in concrete. This work investigates about the replacement of natural aggregate with non-biodegradable plastic aggregate made up of mixed plastic waste in concrete. Several tests are conducted such as compressive strength of cube, split tensile strength of cylinder, flexural strength test of prism to identify the properties and behavior of concrete using plastic aggregate. Replacement of fine aggregate weight by 10%, 15%, 20% with Plastic fine (PF) aggregate and for each replacement of fine aggregate 15%, 20%, 25% of coarse aggregate replacement also conducted with Plastic Coarse(PC) aggregate. In literatures reported that the addition of plastic aggregate in concrete causes the reduction of strength in concrete due to poor bonding between concrete and plastic aggregate, so addition of 0.3% of steel fiber by weight of cement in concrete is done to improve the concrete strength. Totally 60 cubes, 60 cylinders and 40 prisms are casted to identify the compressive strength, split tensile strength and flexural strength respectively. Casted specimens are tested at 7 and 28 days. The identified results from concrete using plastic aggregate are compared with conventional concrete. Result shows that reduction in mechanical properties of plastic aggregate added concrete. This reduction in strength is mainly due to poor bond strength between cement and plastic aggregate.

The use of Papuan iron sand and river sand for fine aggregate in mortar for nuclear radiation shield application

NASA Astrophysics Data System (ADS)

Dahlan, K.; Haryati, E.; Aninam, Y. S.

2018-03-01

This study explores the effect of fine aggregate on mortar properties and its application as a nuclear shield. This study was based on a hypothesis that the types of aggregate applied as radiation shield determined the level of its effectiveness on preventing nuclear radiation. There are two types and sources of fine aggregate that was used as main ingredients for mortar production in this research, namely iron sand and river sand. Both types of sand were derived from the respective regions of Sarmi and Jayapura, Papua. The results showed that the mortar materials that were produced with the iron sand provided better results in dispelling radiation than that of river sand. The compressive strength of fine aggregate from the iron sand was 21.62 MPa, while the compressive strength of the river sand was 16.8 MPa. Measuring the attenuation coefficient of material, we found that the largest aggregated value of mortar with fine iron sand reached 0.0863 / cm. On the other hand, the smallest HVT (Half Value Thickness) was obtained from the iron sand mortar, at 8.03 cm.

Evaluation of cement and fly ash treated recycled asphalt pavement and aggregates for base construction.

DOT National Transportation Integrated Search

2011-12-01

Many entities currently use recycled asphalt pavement (RAP) and other aggregates as base material, temporary haul roads, : and, in the case of RAP, hot mix asphalt construction. Several states currently allow the use of RAP combined with cement : for...

The influence of clay fineness upon sludge recycling in a ceramic matrix

NASA Astrophysics Data System (ADS)

Szőke, A. M.; Muntean, M.; Sándor, M.; Brotea, L.

2016-04-01

The feasibility of sludge recycling in the ceramic manufacture was evaluated through laboratory testing. Such residues have similar chemical and mineralogical composition with the raw mixture of the green ceramic body used in construction. Several ceramic masses with clay and various proportion of sludge have been synthesized and then characterized by their physical-mechanical properties. The fineness of the clay, the main component of the green ceramic body, has been considered for every raw mixture. The proportion of the sludge waste addition depends on the clay fineness and the sintering capacity also, increases with the clay fineness. The ceramic properties, particularly, the open porosity, and mechanical properties, in presence of small sludge proportion (7, 20%) shows small modification. The introduction of such waste into building ceramic matrix (bricks, tiles, and plates) has a very good perspective.

Enhancement of properties of recycled coarse aggregate concrete using bacteria

NASA Astrophysics Data System (ADS)

Sahoo; Arakha; Sarkar; P; Jha

2016-01-01

Due to rapid construction, necessity for raw materials of concrete, especially coarse aggregate, tends to increase the danger of early exhaustion of the natural resources. An alternative source of raw materials would perhaps delay the advent of this early exhaustion. Recycled coarse aggregate (RCA) plays a great role as an alternative raw material that can replace the natural coarse aggregate (NCA) for concrete. Previous studies show that the properties of RCA concrete are inferior in quality compared to NCA concrete. This article attempts to study the improvement of properties of RCA concrete with the addition of bacteria named as Bacillus subtilis. The experimental investigation was carried out to evaluate the improvement of the compressive strength, capillary water absorption, and drying shrinkage of RCA concrete incorporating bacteria. The compressive strength of RCA concrete is found to be increased by about 20% when the cell concentration of B. subtilis is 106 cells/ml. The capillary water absorption as well as drying shrinkage of RCA are reduced when bacteria is incorporated. The improvement of RCA concrete is confirmed to be due to the calcium carbonate precipitation as observed from the microstructure studies carried out on it such as EDX, SEM, and XRD.

Application of Recycled Ceramic Aggregates for the Production of Mineral-Asphalt Mixtures.

PubMed

Andrzejuk, Wojciech; Barnat-Hunek, Danuta; Siddique, Rafat; Zegardło, Bartosz; Łagód, Grzegorz

2018-04-24

This paper describes a method of designing and producing innovative mineral⁻asphalt mixtures, which utilize waste aggregate from the recycling of sanitary ceramics. The work presents the basic properties of the ceramic material, the investigation concerning the microstructure of the aggregate obtained from the grinding of waste, and a comparison with the images obtained for the aggregates usually employed in mineral⁻asphalt mixtures. The mixtures were designed for the application in the wearing course. Four series of mixtures were prepared. In the first and second, the ceramic aggregate constituted a partial substitute for dolomite, whereas in the third, we substituted granodiorite, and the fourth series contained only dolomite. The mixtures were examined for the content of soluble binder, the bulk density of samples, the presence of voids, the space filled with binder, and the susceptibility to water and frost corrosion. The obtained results were compared with the standard requirements. The microstructure as well as the contact zone in the considered mineral⁻asphalt mixtures are presented based on research conducted by means of a scanning electron microscope (SEM).

Application of Recycled Ceramic Aggregates for the Production of Mineral-Asphalt Mixtures

PubMed Central

Andrzejuk, Wojciech; Barnat-Hunek, Danuta; Siddique, Rafat; Zegardło, Bartosz; Łagód, Grzegorz

2018-01-01

This paper describes a method of designing and producing innovative mineral–asphalt mixtures, which utilize waste aggregate from the recycling of sanitary ceramics. The work presents the basic properties of the ceramic material, the investigation concerning the microstructure of the aggregate obtained from the grinding of waste, and a comparison with the images obtained for the aggregates usually employed in mineral–asphalt mixtures. The mixtures were designed for the application in the wearing course. Four series of mixtures were prepared. In the first and second, the ceramic aggregate constituted a partial substitute for dolomite, whereas in the third, we substituted granodiorite, and the fourth series contained only dolomite. The mixtures were examined for the content of soluble binder, the bulk density of samples, the presence of voids, the space filled with binder, and the susceptibility to water and frost corrosion. The obtained results were compared with the standard requirements. The microstructure as well as the contact zone in the considered mineral–asphalt mixtures are presented based on research conducted by means of a scanning electron microscope (SEM). PMID:29695115

Designing fine aggregate mixtures to evaluate fatigue crack-growth in asphalt mixtures.

DOT National Transportation Integrated Search

2011-04-01

Fatigue cracking is a significant form of pavement distress in flexible pavements. The properties of the : sand-asphalt mortars or fine aggregate matrix (FAM) can be used to characterize the evolution of fatigue : crack growth and self-healing in asp...

A Factorial Design Approach to Analyse the Effect of Coarse Recycled Concrete Aggregates on the Properties of Hot Mix Asphalt

NASA Astrophysics Data System (ADS)

Tanty, Kiranbala; Mukharjee, Bibhuti Bhusan; Das, Sudhanshu Shekhar

2018-06-01

The present study investigates the effect of replacement of coarse fraction of natural aggregates by recycled concrete aggregates on the properties of hot mix asphalt (HMA) using general factorial design approach. For this two factors i.e. recycled coarse aggregates percentage [RCA (%)] and bitumen content percentage [BC (%)] are considered. Tests have been carried out on the HMA type bituminous concrete, prepared with varying RCA (%) and BC (%). Analysis of variance has been performed on the experimental data to determine the effect of the chosen factors on various parameters such as stability, flow, air void, void mineral aggregate, void filled with bitumen and bulk density. The study depicts that RCA (%) and BC (%) have significant effect on the selected responses as p value is less than the chosen significance level. In addition to above, the outcomes of the statistical analysis indicate that interaction between factors have significant effects on void mineral aggregate and bulk density of bituminous concrete.

A Factorial Design Approach to Analyse the Effect of Coarse Recycled Concrete Aggregates on the Properties of Hot Mix Asphalt

NASA Astrophysics Data System (ADS)

Tanty, Kiranbala; Mukharjee, Bibhuti Bhusan; Das, Sudhanshu Shekhar

2018-02-01

The present study investigates the effect of replacement of coarse fraction of natural aggregates by recycled concrete aggregates on the properties of hot mix asphalt (HMA) using general factorial design approach. For this two factors i.e. recycled coarse aggregates percentage [RCA (%)] and bitumen content percentage [BC (%)] are considered. Tests have been carried out on the HMA type bituminous concrete, prepared with varying RCA (%) and BC (%). Analysis of variance has been performed on the experimental data to determine the effect of the chosen factors on various parameters such as stability, flow, air void, void mineral aggregate, void filled with bitumen and bulk density. The study depicts that RCA (%) and BC (%) have significant effect on the selected responses as p value is less than the chosen significance level. In addition to above, the outcomes of the statistical analysis indicate that interaction between factors have significant effects on void mineral aggregate and bulk density of bituminous concrete.

Comminution and sizing processes of concrete block waste as recycled aggregates.

PubMed

Gomes, P C C; Ulsen, C; Pereira, F A; Quattrone, M; Angulo, S C

2015-11-01

Due to the environmental impact of construction and demolition waste (CDW), recycling is mandatory. It is also important that recycled concrete aggregates (RCA) are used in concrete to meet market demands. In the literature, the influence of RCAs on concrete has been investigated, but very limited studies have been conducted on how the origin of concrete waste and comminution processes influence RCA characteristics. This paper aims to investigate the influence of three different comminution and sizing processes (simple screening, crushing and grinding) on the composition, shape and porosity characteristics of RCA obtained from concrete block waste. Crushing and grinding implies a reduction of RCA porosity. However, due to the presence of coarse quartz rounded river pebbles in the original concrete block mixtures, the shape characteristics deteriorated. A large amount of powder (<0.15 mm) without detectable anhydrous cement was also generated. Copyright © 2015 Elsevier Ltd. All rights reserved.

The influence of fines on strength and drainage characteristics of aggregate bases.

DOT National Transportation Integrated Search

1996-01-01

One of the most commonly used dense-graded aggregate mixes in Virginia is designated as Type 2lB. In an effort to improve drainage characteristics of the 21B material it was proposed to decrease the maximum allowable percentage of fines from 7% to 5%...

The mechanical properties of brick containing recycled concrete aggregate and polyethylene terephthalate waste as sand replacement

NASA Astrophysics Data System (ADS)

Sheikh Khalid, Faisal; Bazilah Azmi, Nurul; Natasya Mazenan, Puteri; Shahidan, Shahiron; Ali, Noorwirdawati

2018-03-01

This research focuses on the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. This study aims to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate (RCA) and polyethylene terephthalate (PET) waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 0.5%, 1.0% and 1.5% by weight of natural sand. Based on the results of compressive strength, only RCA 25% with 0.5% PET achieve lower strength than normal bricks while others showed a high strength. However, all design mix reaches strength more than 7N/mm2 as expected. Besides that, the most favorable mix design that achieves high compressive strength is 75% of RCA with 0.5% PET.

Spark plasma sintering of highly dense fine-grained mineral aggregates

NASA Astrophysics Data System (ADS)

Koizumi, S.; Suzuki, T. S.; Sakka, Y.; Hiraga, T.

2017-12-01

To obtain highly dense and fine-grained mineral aggregates, which are suitable for laboratory measurements of their physical and chemical properties, we applied spark plasma sintering (SPS) to synthetic mineral powders and powders originated from naturally derived crystals. SPS is an emerging consolidation technique which has been applied to various metals and ceramics and rarely to geomaterials (e.g., Guignard et al., 2011). The technique uses spark plasma created by a pulse direct current during heat treatment of powders in a graphite die. It has been found that the technique provides better densification with little grain growth during sintering compared to a conventional sintering technique in many materials. To obtain ideal highly dense fine-grained materials, it is essential to prepare starting powders suitable for the sintering and also to find appropriate sintering conditions of applied uniaxial pressures, pulsed current patterns and heating rates. We prepared synthetic mineral powers through solid state reaction of source powders at high temperature well developed by our group (Koizumi et al. 2010). We also used jet milling at wet condition and subsequent elutriation to prepare olivine powders with sub-micron particle size and equiaxed particle shape. At heating rate of ≦10°C/min and an achievement of highest temperature of 1150°C, Fe-free olivine aggregate with average grain size of 200 nm with porosity of 0.003% was obtained. We also could obtain olivine aggregate, which was sintered from powders of Horoman peridotite, with average grain size of 500 nm and porosity of 0.2%. We will show results of other minerals including major rock forming minerals of the Earth's crust.

Evaluation of the Effects of Crushed and Expanded Waste Glass Aggregates on the Material Properties of Lightweight Concrete Using Image-Based Approaches

PubMed Central

Abd Elrahman, Mohamed; Sikora, Pawel; Rucinska, Teresa; Horszczaruk, Elzbieta

2017-01-01

Recently, the recycling of waste glass has become a worldwide issue in the reduction of waste and energy consumption. Waste glass can be utilized in construction materials, and understanding its effects on material properties is crucial in developing advanced materials. In this study, recycled crushed and expanded glasses are used as lightweight aggregates for concrete, and their relation to the material characteristics and properties is investigated using several approaches. Lightweight concrete specimens containing only crushed and expanded waste glass as fine aggregates are produced, and their pore and structural characteristics are examined using image-based methods, such as scanning electron microscopy (SEM), X-ray computed tomography (CT), and automated image analysis (RapidAir). The thermal properties of the materials are measured using both Hot Disk and ISOMET devices to enhance measurement accuracy. Mechanical properties are also evaluated, and the correlation between material characteristics and properties is evaluated. As a control group, a concrete specimen with natural fine sand is prepared, and its characteristics are compared with those of the specimens containing crushed and expanded waste glass aggregates. The obtained results support the usability of crushed and expanded waste glass aggregates as alternative lightweight aggregates. PMID:29186854

Evaluation of the Effects of Crushed and Expanded Waste Glass Aggregates on the Material Properties of Lightweight Concrete Using Image-Based Approaches.

PubMed

Chung, Sang-Yeop; Abd Elrahman, Mohamed; Sikora, Pawel; Rucinska, Teresa; Horszczaruk, Elzbieta; Stephan, Dietmar

2017-11-25

Recently, the recycling of waste glass has become a worldwide issue in the reduction of waste and energy consumption. Waste glass can be utilized in construction materials, and understanding its effects on material properties is crucial in developing advanced materials. In this study, recycled crushed and expanded glasses are used as lightweight aggregates for concrete, and their relation to the material characteristics and properties is investigated using several approaches. Lightweight concrete specimens containing only crushed and expanded waste glass as fine aggregates are produced, and their pore and structural characteristics are examined using image-based methods, such as scanning electron microscopy (SEM), X-ray computed tomography (CT), and automated image analysis (RapidAir). The thermal properties of the materials are measured using both Hot Disk and ISOMET devices to enhance measurement accuracy. Mechanical properties are also evaluated, and the correlation between material characteristics and properties is evaluated. As a control group, a concrete specimen with natural fine sand is prepared, and its characteristics are compared with those of the specimens containing crushed and expanded waste glass aggregates. The obtained results support the usability of crushed and expanded waste glass aggregates as alternative lightweight aggregates.

Experimental Study on Thermal Conductivity of Self-Compacting Concrete with Recycled Aggregate.

PubMed

Fenollera, María; Míguez, José Luis; Goicoechea, Itziar; Lorenzo, Jaime

2015-07-20

The research focuses on the use of recycled aggregate (RA), from waste pieces generated during production in precast plants for self-compacting concrete (SCC) manufactured with a double sustainable goal: recycle manufacturing waste (consumption) and improvement of the thermal properties of the manufactured product (energy efficiency). For this purpose, a mechanical study to ensure technical feasibility of the concrete obtained has been conducted, as well as a thermal analysis of recycled SCC specimens of 50 N/mm² resistance, with different RA doses (0%, 20%, 50% and 100%). The main parameters that characterize a SCC in both states, fresh (slump-flow) and hard (compressive strength), have been tested; also, a qualitative analysis of the thermal conductivity using infrared thermography (IRT) and quantitative analysis with heat flow meter at three temperatures 20 °C, 25 °C and 30 °C have been performed. The results suggest the existence of two different thermal behaviors: concretes with 0% and 20% of RA, and on the other hand concretes with 50% and 100% of RA. It has also demonstrated the validity of the IRT as sampling technique in estimating the thermal behavior of materials having reduced range of variation in parameters.

Evaluation of cement and fly ash treated recycled asphalt pavement and aggregates for base construction : tech summary.

DOT National Transportation Integrated Search

2011-12-01

INTRODUCTION: Many entities currently use recycled asphalt pavement (RAP) and other aggregates as base materials, temporary haul roads, and, in the case of RAP, hot mix asphalt construction. Several : states currently allow the use of RAP combined wi...

Properties of concrete containing ground palm oil fuel ash as fine aggregate replacement

NASA Astrophysics Data System (ADS)

Saffuan, W. A.; Muthusamy, K.; Salleh, N. A. Mohd; Nordin, N.

2017-11-01

Environmental degradation resulting from increasing sand mining activities and disposal of palm oil fuel ash (POFA), a solid waste generated from palm oil mill needs to be resolved. Thus, the present research investigates the effect of ground palm oil fuel ash as partial fine aggregate replacement on workability, compressive and flexural strength of concrete. Five mixtures of concrete containing POFA as partial sand replacement designed with 0%, 10%, 20%, 30% and 40% of POFA by the weight of sand were used in this experimental work. The cube and beam specimens were casted and water cured up to 28 days before subjected to compressive strength and flexural strength testing respectively. Finding shows that concrete workability reduces as the amount of POFA added become larger. It is worth to note that 10% of POFA is the best amount to be used as partial fine aggregate replacement to produce concrete with enhanced strength.

Performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate with different mix design ratio

NASA Astrophysics Data System (ADS)

Azmi, N. B.; Khalid, F. S.; Irwan, J. M.; Mazenan, P. N.; Zahir, Z.; Shahidan, S.

2018-04-01

This study is focuses to the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. The objective is to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate and polyethylene terephthalate waste and to determine the optimum mix ratio of bricks containing recycled concrete aggregate and polyethylene terephthalate waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 1.0%, 1.5%, 2.0% and 2.5% by weight of natural sand. Based on the results of compressive strength, it indicates that the replacement of RCA shows an increasing strength as the strength starts to increase from 25% to 50% for both mix design ratio. The strength for RCA 75% volume of replacement started to decrease as the volume of PET increase. However, the result of water absorption with 50% RCA and 1.0% PET show less permeable compared to control brick at both mix design ratio. Thus, one would expect the density of brick decrease and the water absorption to increase as the RCA and PET content is increased.

Experimental Study on Thermal Conductivity of Self-Compacting Concrete with Recycled Aggregate

PubMed Central

Fenollera, María; Míguez, José Luis; Goicoechea, Itziar; Lorenzo, Jaime

2015-01-01

The research focuses on the use of recycled aggregate (RA), from waste pieces generated during production in precast plants for self-compacting concrete (SCC) manufactured with a double sustainable goal: recycle manufacturing waste (consumption) and improvement of the thermal properties of the manufactured product (energy efficiency). For this purpose, a mechanical study to ensure technical feasibility of the concrete obtained has been conducted, as well as a thermal analysis of recycled SCC specimens of 50 N/mm2 resistance, with different RA doses (0%, 20%, 50% and 100%). The main parameters that characterize a SCC in both states, fresh (slump-flow) and hard (compressive strength), have been tested; also, a qualitative analysis of the thermal conductivity using infrared thermography (IRT) and quantitative analysis with heat flow meter at three temperatures 20 °C, 25 °C and 30 °C have been performed. The results suggest the existence of two different thermal behaviors: concretes with 0% and 20% of RA, and on the other hand concretes with 50% and 100% of RA. It has also demonstrated the validity of the IRT as sampling technique in estimating the thermal behavior of materials having reduced range of variation in parameters. PMID:28793449

Structural Design and Economic Evaluation of Roller Compacted Concrete Pavement with Recycled Aggregates

NASA Astrophysics Data System (ADS)

Abut, Yavuz; Taner Yildirim, Salih

2017-10-01

Using recycled aggregates in the concrete offers advantages in many areas such as waste management, energy save and natural resources, conservation of ecological balance, low CO2 emissions, and users are encouraged in this regard to use these materials. In this study, the profit / loss account arising in the structural design phase was investigated when Reclaimed Asphalt Pavement (RAP), which is limited to use in Roller Compacted Concrete (RCC) pavements, was used as coarse aggregate. RAP materials were used as coarse aggregates by the levels of 0%, 15% and 20% and mechanical properties such as compressive strength, flexural strength, splitting tensile strength and modulus of elasticity were investigated. In the last stage, the mechanical properties obtained from these experimental studies were entered into KENSLABS software as input, and the slab layer thicknesses were determined according to three different subgrade conditions and a certain fatigue criterion. According to the results, it has been determined that the use of RAP at a level of 20% is a serious reducing effect on mechanical properties and and the use of RAP at a level of 15% does not bring a great economic benefit but it is reasonable to use it as coarse aggregate in RCC mixes in consideration of environmental effects.

Sustainable aggregates production : green applications for aggregate by-products.

DOT National Transportation Integrated Search

2015-06-01

Increased emphasis in the construction industry on sustainability and recycling requires production of : aggregate gradations with lower dust (cleaner aggregates) and smaller maximum sizeshence, increased : amount of quarry by-products (QBs). QBs ...

The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

PubMed Central

Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

2014-01-01

In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete’s compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength. PMID:28788279

The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths.

PubMed

Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

2014-12-08

In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete's compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

Diffusional creep of fine-grained olivine aggregates: Chemical and melt effects

NASA Astrophysics Data System (ADS)

Yabe, K.; Hiraga, T.

2017-12-01

Since olivine is the major constituent mineral of the earth's upper mantle, flow properties of the upper mantle are often estimated based on flow laws of olivine aggregate which are determined by high-temperature creep experiments. Recently, Miyazaki et al. (2013) showed that crystallographic preferred orientation (CPO) which has been interpreted as the main cause for seismic wave anisotropy in mantle asthenosphere could be formed in diffusional creep regime. The detail of diffusional creep of olivine aggregates is not clear yet. The strength of olivine aggregates synthesized using sol-gel method (Faul and Jackson 2007) was more than one order of magnitude harder in viscosity than those synthesized from natural mantle rocks (Hirth and Kohlstedt 1995, Hansen et al. 2011) even at the same experimental conditions. This discrepancy can be interpreted by a presence of melt and/or impurity. The purpose of this study is to examine the effects of chemical composition and presence of the melt phase on the creep properties of olivine aggregates. At first, Fe-bearing olivine aggregates were prepared by vacuum sintering of nano-sized olivine powder synthesized from highly pure and fine-grained (<100 nm) source powders. Samples with and without dopants of Al2O3 and CaO were prepared. Then uniaxial compression tests at 1 atm were conducted. Deformation experiments showed that all the samples were deformed by diffusional creep mechanism. Both doped and non-doped samples exhibited sample strength at low temperature (=1150˚C), while the doped sample became significantly weaker with showing higher temperature sensitivity compared to non-doped samples at higher temperature. The temperature sensitivity of doped samples didn't change below and above solidus, which indicate the weakening due to chemical effect, not by the melting. Non-doped samples exhibits essentially the same strength as olivine aggregates synthesized from sol-gel method (Faul and Jackson 2007), while doped sample is

Deformation Behavior of Recycled Concrete Aggregate during Cyclic and Dynamic Loading Laboratory Tests

PubMed Central

Sas, Wojciech; Głuchowski, Andrzej; Gabryś, Katarzyna; Soból, Emil; Szymański, Alojzy

2016-01-01

Recycled concrete aggregate (RCA) is a relatively new construction material, whose applications can replace natural aggregates. To do so, extensive studies on its mechanical behavior and deformation characteristics are still necessary. RCA is currently used as a subbase material in the construction of roads, which are subject to high settlements due to traffic loading. The deformation characteristics of RCA must, therefore, be established to find the possible fatigue and damage behavior for this new material. In this article, a series of triaxial cyclic loading and resonant column tests is used to characterize fatigue in RCA as a function of applied deviator stress after long-term cyclic loading. A description of the shakedown phenomenon occurring in the RCA and calculations of its resilient modulus (Mr) as a function of fatigue are also presented. Test result analysis with the stress-life method on the Wohler S-N diagram shows the RCA behavior in accordance with the Basquin law. PMID:28773905

Properties of lightweight aggregate concrete prepared with PVC granules derived from scraped PVC pipes.

PubMed

Kou, S C; Lee, G; Poon, C S; Lai, W L

2009-02-01

This paper aims to investigate the fresh and hardened properties of lightweight aggregate concretes that are prepared with the use of recycled plastic waste sourced from scraped PVC pipes to replace river sand as fine aggregates. A number of laboratory prepared concrete mixes were tested, in which river sand was partially replaced by PVC plastic waste granules in percentages of 0%, 5%, 15%, 30% and 45% by volume. Two major findings are identified. The positive side shows that the concrete prepared with a partial replacement by PVC was lighter (lower density), was more ductile (greater Poisson's ratios and reduced modulus of elasticity), and had lower drying shrinkage and higher resistance to chloride ion penetration. The negative side reveals that the workability, compressive strength and tensile splitting strength of the concretes were reduced. The results gathered would form a part of useful information for recycling PVC plastic waste in lightweight concrete mixes.

Sequestering Lead in Paint by Utilizing Deconstructed Masonry Materials as Recycled Aggregate in Concrete. Revision 1

DTIC Science & Technology

2008-05-27

into a new insoluble lead-phosphate mineral for on-site or off-site paint stripping; and 4. Encapsulation, where a liquid coating is applied over the...convert the LBP-contaminated masonry materials from hazardous wastes into new , environmentally friendly construction materials at minimum cost. 4...used to produce high strength concrete (Andrzej and Alina, 2002). The major concerns for use of recycled aggregates in new construction are now more

Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content.

PubMed

López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

2016-01-26

In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m³ of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m³ of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works.

Activity of slip in amphibolite facies, fine-grained recrystallized quartz aggregates: high differential stress during high-T creep of quartz?

NASA Astrophysics Data System (ADS)

Viegas, G.; Menegon, L. M.; Archanjo, C. J.

2016-12-01

Quartz axis fabrics are a valuable tool to investigate strain partitioning/distribution in both naturally- and experimentally deformed quartz. Previous works have shown that slip dominates at high temperatures (> 600º C) and water-rich, commonly sub-magmatic conditions, typically associated with large grain sizes and grain boundary migration microstructures. In the Pernambuco shear zone, sheared quartz veins from a protomylonitic granitoid formed during the main amphibolite facies event constrained at mid-crustal conditions (550-600ºC, 5 kbar). The veins contain heterogeneously-deformed primary quartz grains, which typically form both flattened and elongated ribbons as well as more equant porphyroclasts surrounded by aggregates of fine-grained (ca. 20 µm) recrystallized aggregates. Recrystallized quartz with the same fine grain size may also occur in intracrystalline bands within the porphyroclasts. Chessboard extinction is widely observed in the porphyroclasts, and subgrain boundaries are either parallel or normal to the (0001) direction, suggesting slip on both basal and prismatic planes during recrystallization. Crystallographic preferred orientations (CPOs) of porphyroclasts (≥ 100 µm) show maxima of (0001) axes subparallel to Z and X, suggesting coeval glide along both basal and prism planes during shearing. In the recrystallized aggregates, fabric strength tends to become weaker, but still records glide along and directions. These preliminary results suggest that naturally deformed quartz veins record coeval activity of and slip during dynamic recrystallization under amphibolite facies conditions. The microstructure suggests that the CPO of the fine-grained aggregates is host-controlled and results from dominant subgrain rotation recrystallization. To our knowledge, activity of slip in fine-grained recrystallized aggregates has never been reported before. Thus, these preliminary results call into question the general view that slip is expected to be

Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

NASA Astrophysics Data System (ADS)

Salau, M. A.; Oseafiana, O. J.; Oyegoke, T. O.

2015-11-01

This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.

Quality assessment for recycling aggregates from construction and demolition waste: An image-based approach for particle size estimation.

PubMed

Di Maria, Francesco; Bianconi, Francesco; Micale, Caterina; Baglioni, Stefano; Marionni, Moreno

2016-02-01

The size distribution of aggregates has direct and important effects on fundamental properties of construction materials such as workability, strength and durability. The size distribution of aggregates from construction and demolition waste (C&D) is one of the parameters which determine the degree of recyclability and therefore the quality of such materials. Unfortunately, standard methods like sieving or laser diffraction can be either very time consuming (sieving) or possible only in laboratory conditions (laser diffraction). As an alternative we propose and evaluate the use of image analysis to estimate the size distribution of aggregates from C&D in a fast yet accurate manner. The effectiveness of the procedure was tested on aggregates generated by an existing C&D mechanical treatment plant. Experimental comparison with manual sieving showed agreement in the range 81-85%. The proposed technique demonstrated potential for being used on on-line systems within mechanical treatment plants of C&D. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chemical-mineralogical characterization of C&D waste recycled aggregates from São Paulo, Brazil.

PubMed

Angulo, S C; Ulsen, C; John, V M; Kahn, H; Cincotto, M A

2009-02-01

This study presents a methodology for the characterization of construction and demolition (C&D) waste recycled aggregates based on a combination of analytical techniques (X-ray fluorescence (XRF), soluble ions, semi-quantitative X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTG) and hydrochloric acid (HCl) selective dissolution). These combined analytical techniques allow for the estimation of the amount of cement paste, its most important hydrated and carbonated phases, as well as the amount of clay and micas. Details of the methodology are presented here and the results of three representative C&D samples taken from the São Paulo region in Brazil are discussed. Chemical compositions of mixed C&D aggregate samples have mostly been influenced by particle size rather than the visual classification of C&D into red or grey and geographical origin. The amount of measured soluble salts in C&D aggregates (0.15-25.4mm) is lower than the usual limits for mortar and concrete production. The content of porous cement paste in the C&D aggregates is around 19.3% (w/w). However, this content is significantly lower than the 43% detected for the C&D powders (<0.15 mm). The clay content of the powders was also high, potentially resulting from soil intermixed with the C&D waste, as well as poorly burnt red ceramic. Since only about 50% of the measured CaO is combined with CO(2), the powders have potential use as raw materials for the cement industry.

Evaluation and testing of a lightweight fine aggregate concrete bridge deck in Buchanan County, Iowa : tech transfer summaries.

DOT National Transportation Integrated Search

2016-05-01

Using saturated lightweight fine aggregate (LWFA) in concrete mixtures : can replenish water that is depleted during cement hydration without : influencing the water-to-cement (w/c) ratio. This process, known as : internal curing (IC), can contribute...

Stripping in hot mix asphalt produced by aggregates from construction and demolition waste.

PubMed

Pérez, I; Pasandín, A R; Gallego, J

2012-01-01

This paper analyses the effect of water on the durability of hot asphalt mixtures made with recycled aggregates from construction and demolition debris. Indirect tensile stress tests were carried out to evaluate stripping behaviour. The mixtures tested were fabricated with 0, 20, 40 and 60% recycled aggregates. Two types of natural aggregates were used: schist and calcite dolomite. An increase in the percentage of recycled aggregates was found to produce a decrease in the tensile stress ratio of the hot asphalt mixtures. To study this phenomenon, two and three factor analyses of variance (ANOVA) were performed with indirect tensile stress being used as the dependent variable. The factors studied were the percentage of recycled aggregates (0, 20, 40 and 60%), the moisture state (dry, wet) and the type of natural aggregate (schist, calcite). On the basis of the ANOVA results, it was found that the most important factor affecting resistance was the moisture state (dry, wet) of the specimens. The percentage of recycled aggregate also affected indirect tensile stress, especially in the dry state. The type of natural aggregate did not have a significant effect on indirect tensile stress. The hot asphalt mixture specimens made with different percentages of recycled aggregates from construction and demolition debris and of natural quarry aggregates showed poor stripping behaviour. This stripping behaviour can be related to both the poor adhesion of the recycled aggregates and the high absorption of the mortar of cement adhered to them.

Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content

PubMed Central

López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

2016-01-01

In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m3 of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m3 of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works. PMID:28787874

Recycling of rubble from building demolition for low-shrinkage concretes.

PubMed

Corinaldesi, Valeria; Moriconi, Giacomo

2010-04-01

In this project concrete mixtures were prepared that were characterized by low ductility due to desiccation by using debris from building demolition, which after a suitable treatment was used as aggregate for partial replacement of natural aggregates. The recycled aggregate used came from a recycling plant, in which rubble from building demolition was selected, crushed, cleaned, sieved, and graded. Such aggregates are known to be more porous as indicated by the Saturated Surface Dry (SSD) moisture content. The recycled concrete used as aggregates were added to the concrete mixture in order to study their influence on the fresh and hardened concrete properties. They were added either after water pre-soaking or in dry condition, in order to evaluate the influence of moisture in aggregates on the performance of concrete containing recycled aggregate. In particular, the effect of internal curing, due to the use of such aggregates, was studied. Concrete behavior due to desiccation under dehydration was studied by means of both drying shrinkage test and German angle test, through which shrinkage under the restrained condition of early age concrete can be evaluated. Copyright 2009 Elsevier Ltd. All rights reserved.

Effect of Graphene Oxide on Mechanical Properties of Recycled Mortar

NASA Astrophysics Data System (ADS)

Fang, Changle; Long, Wujian; Wei, Jingjie; Xiao, Bingxu; Yan, Chen

2017-12-01

The use of recycled aggregate as replacement of natural aggregate has increased in recent years in order to reduce the high consumption of natural resources in construction industry. This paper presents an experimental investigation on the effect of graphene oxide (GO) on the mechanical properties of recycled mortar. It is showed that the recycled mortar with GO has a better mechanical properties than the recycled mortar without GO. Microstructural analysis of the recycled mortar with GO showed to have much denser and better crystallization of hydration product.

Ceramic ware waste as coarse aggregate for structural concrete production.

PubMed

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

2015-01-01

The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

Chemical-mineralogical characterization of C and D waste recycled aggregates from Sao Paulo, Brazil

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

Angulo, S.C.; Ulsen, C.; John, V.M.

2009-02-15

This study presents a methodology for the characterization of construction and demolition (C and D) waste recycled aggregates based on a combination of analytical techniques (X-ray fluorescence (XRF), soluble ions, semi-quantitative X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTG) and hydrochloric acid (HCl) selective dissolution). These combined analytical techniques allow for the estimation of the amount of cement paste, its most important hydrated and carbonated phases, as well as the amount of clay and micas. Details of the methodology are presented here and the results of three representative C and D samples taken from the Sao Paulo region in Brazil are discussed.more » Chemical compositions of mixed C and D aggregate samples have mostly been influenced by particle size rather than the visual classification of C and D into red or grey and geographical origin. The amount of measured soluble salts in C and D aggregates (0.15-25.4 mm) is lower than the usual limits for mortar and concrete production. The content of porous cement paste in the C and D aggregates is around 19.3% (w/w). However, this content is significantly lower than the 43% detected for the C and D powders (<0.15 mm). The clay content of the powders was also high, potentially resulting from soil intermixed with the C and D waste, as well as poorly burnt red ceramic. Since only about 50% of the measured CaO is combined with CO{sub 2}, the powders have potential use as raw materials for the cement industry.« less

Recycled material availability in Maryland - a synthesis study.

DOT National Transportation Integrated Search

2016-10-01

There is growing interest in using recycled materials in highway construction nationwide. The research study focused : on four types of recycled materials: recycled concrete aggregate (RCA), reclaimed asphalt pavement (RAP), dredged : materials, and ...

Effect of Graphene Oxide on the Damping Capability of Recycled Mortar

NASA Astrophysics Data System (ADS)

Wei, Jing-Jie; Long, Wu-Jian; Fang, Chang-Le; Li, Hao-Dao; Guo, Yue-Gui

2018-03-01

The use of recycled aggregate as replacement of natural aggregate has increased in recent years in order to reduce the high consumption of natural resources in construction industry. This paper presents an experimental investigation on the effect of graphene oxide (GO) on the damping capability of recycled mortar. The effect of GO on damping capability was examined by using dynamic mechanical analyzer (DMA), It is showed that the recycled mortar with GO has a better damping capability than the recycled mortar without GO. Microstructural analysis of the recycled mortar with GO showed to have much denser and better crystallization of hydration products.

Laser characterization of fine aggregate.

DOT National Transportation Integrated Search

2012-12-01

This report describes the results of a research effort to establish the feasibility of using a laser monitoring system to provide real-time data to characterize aggregate properties in a laboratory or field environment. This was accomplished by using...

Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete

PubMed Central

López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

2016-01-01

This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors’ knowledge, there have not been any upscaled applications of concrete with MRA and low cement content. PMID:28787892

Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete.

PubMed

López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

2016-02-02

This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors' knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

Effects of recycled shingles and increased RAP percentages : [research brief].

DOT National Transportation Integrated Search

2012-01-01

As asphalt binder becomes more expensive, the use of recycled asphalt materials becomes : more attractive. Recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) offer a partial substitute for virgin aggregate and binder in asphalt pavem...

Field site leaching from recycled concrete aggregates applied as sub-base material in road construction.

PubMed

Engelsen, Christian J; Wibetoe, Grethe; van der Sloot, Hans A; Lund, Walter; Petkovic, Gordana

2012-06-15

The release of major and trace elements from recycled concrete aggregates used in an asphalt covered road sub-base has been monitored for more than 4 years. A similar test field without an asphalt cover, directly exposed to air and rain, and an asphalt covered reference field with natural aggregates in the sub-base were also included in the study. It was found that the pH of the infiltration water from the road sub-base with asphalt covered concrete aggregates decreased from 12.6 to below pH 10 after 2.5 years of exposure, whereas this pH was reached within only one year for the uncovered field. Vertical temperature profiles established for the sub-base, could explain the measured infiltration during parts of the winter season. When the release of major and trace elements as function of field pH was compared with pH dependent release data measured in the laboratory, some similar pH trends were found. The field concentrations of Cd, Ni, Pb and Zn were found to be low throughout the monitoring period. During two of the winter seasons, a concentration increase of Cr and Mo was observed, possibly due to the use of de-icing salt. The concentrations of the trace constituents did not exceed Norwegian acceptance criteria for ground water and surface water Class II. Copyright © 2012 Elsevier B.V. All rights reserved.

Use of recycled aggregates from construction and demolition waste in geotechnical applications: A literature review.

PubMed

Cardoso, Rafaela; Silva, Rui Vasco; Brito, Jorge de; Dhir, Ravindra

2016-03-01

The use of recycled aggregates (RA) in construction constitutes a significant step towards a more sustainable society and also creates a new market opportunity to be exploited. In recent years, several case-studies have emerged in which RA were used in Geotechnical applications, such as filling materials and in unbound pavement layers. This paper presents a review of the most important physical properties of different types of RA and their comparison with natural aggregates (NA), and how these properties affect their hydraulic and mechanical behaviour when compacted. Specifically, the effects of compaction on grading size distribution curves and density are analysed, as well as the consequences of particle crushing on the resilient modulus, CBR and permeability. The paper also contains an analysis of the influence of incorporating different RA types on the performance of unbound road pavement layers as compared with those built with NA by means of the International Roughness Index and deflection values. The results collected from the literature indicate that the performance of most RA is comparable to that of NA and can be used in unbound pavement layers or in other applications requiring compaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Separation and collection of coarse aggregate from waste concrete by electric pulsed power

NASA Astrophysics Data System (ADS)

Shigeishi, Mitsuhiro

2017-09-01

Waste concrete accounts for a substantial fraction of construction waste, and the recycling of waste concrete as concrete aggregate for construction is an important challenge associated with the rapid increase in the amount of waste concrete and the tight supply of natural aggregate. In this study, we propose a technique based on the use of high-voltage pulsed electric discharge into concrete underwater for separating and collecting aggregate from waste concrete with minimal deterioration of quality. By using this technique, the quality of the coarse aggregate separated and collected from concrete test specimens is comparable to that of coarse aggregate recycled by heating and grinding methods, thus satisfying the criteria in Japan Industrial Standard (JIS) A 5021 for the oven-dry density and the water absorption of coarse aggregate by advanced recycling.

Cold-in-place recycling in New York State.

DOT National Transportation Integrated Search

2010-07-01

Cold in-place recycling (CIPR) is a continuous multi-step process in which the existing asphalt pavement is : recycled using specialized equipment that cold mills the asphaltic pavement and blends asphalt emulsion and : aggregate (if necessary) with ...

Recycling ground granulated blast furnace slag as cold bonded artificial aggregate partially used in self-compacting concrete.

PubMed

Gesoğlu, Mehmet; Güneyisi, Erhan; Mahmood, Swara Fuad; Öz, Hatice Öznur; Mermerdaş, Kasım

2012-10-15

Ground granulated blast furnace slag (GGBFS), a by-product from iron industry, was recycled as artificial coarse aggregate through cold bonding pelletization process. The artificial slag aggregates (ASA) replaced partially the natural coarse aggregates in production of self-compacting concrete (SCC). Moreover, as being one of the most widely used mineral admixtures in concrete industry, fly ash (FA) was incorporated as a part of total binder content to impart desired fluidity to SCCs. A total of six concrete mixtures having various ASA replacement levels (0%, 20%, 40%, 60%, and 100%) were designed with a water-to-binder (w/b) ratio of 0.32. Fresh properties of self-compacting concretes (SCC) were observed through slump flow time, flow diameter, V-funnel flow time, and L-box filling height ratio. Compressive strength of hardened SCCs was also determined at 28 days of curing. It was observed that increasing the replacement level of ASA resulted in decrease in the amount of superplasticizer to achieve a constant slump flow diameter. Moreover, passing ability and viscosity of SCC's enhanced with increasing the amount of ASA in the concrete. The maximum compressive strength was achieved for the SCC having 60% ASA replacement. Copyright © 2012 Elsevier B.V. All rights reserved.

Recycling of air pollution control residues from municipal solid waste incineration into lightweight aggregates.

PubMed

Quina, Margarida J; Bordado, João M; Quinta-Ferreira, Rosa M

2014-02-01

This work focuses on the assessment of technological properties and on the leaching behavior of lightweight aggregates (LWA) produced by incorporating different quantities of air pollution control (APC) residues from municipal solid waste (MSW) incineration. Currently this hazardous waste has been mostly landfilled after stabilization/solidification. The LWA were produced by pelletizing natural clay, APC residues as-received from incineration plant, or after a washing treatment, a small amount of oil and water. The pellets were fired in a laboratory chamber furnace over calcium carbonate. The main technological properties of the LWA were evaluated, mainly concerning morphology, bulk and particle densities, compressive strength, bloating index, water adsorption and porosity. Given that APC residues do not own expansive (bloating) properties, the incorporation into LWA is only possible in moderate quantities, such as 3% as received or 5% after pre-washing treatment. The leaching behavior of heavy metals from sintered LWA using water or acid solutions was investigated, and despite the low acid neutralization capacity of the synthetic aggregates, the released quantities were low over a wide pH range. In conclusion, after a washing pre-treatment and if the percentage of incorporation is low, these residues may be incorporated into LWA. However, the recycling of APC residues from MSW incineration into LWA does not revealed any technical advantage. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of Fine Aggregate Morphology by Image Method and Its Effect on Skid-Resistance of Micro-Surfacing.

PubMed

Xiao, Yue; Wang, Feng; Cui, Peide; Lei, Lei; Lin, Juntao; Yi, Mingwei

2018-05-29

Micro-surfacing is a widely used pavement preventive maintenance technology used all over the world, due to its advantages of fast construction, low maintenance cost, good waterproofness, and skid-resistance performance. This study evaluated the fine aggregate morphology and surface texture of micro-surfacing by AIMS (aggregate image measurement system), and explored the effect of aggregate morphology on skid-resistance of single-grade micro-surfacing. Sand patch test and British pendulum test were also used to detect skid-resistance for comparison with the image-based method. Wet abrasion test was used to measure skid-resistance durability for feasibility verification of single-grade micro-surfacing. The results show that the effect of Form2D on the skid-resistance of micro-surfacing is much stronger than that of angularity. Combining the feasibility analysis of durability and skid-resistance, 1.18⁻2.36 grade micro-surfacing meets the requirements of durability and skid-resistance at the same time. This study also determined that, compared with British pendulum test, the texture result obtained by sand patch test fits better with results of image method.

Recycled concrete aggregate as road base: Leaching constituents and neutralization by soil Interactions and dilution.

PubMed

Gupta, Nautasha; Kluge, Matt; Chadik, Paul A; Townsend, Timothy G

2018-02-01

Recycled Concrete Aggregate (RCA) is often used as a replacement for natural aggregate in road construction activities because of its excellent mechanical properties, and this trend should increase as more transportation departments include RCA in specifications and design manuals. Concerns raised by some engineers and contractors include impacts from leachate generated by RCA, both from transport of metals to water sources and the impact of a high pH leachate on corrosion of underlying metal drainage pipes. In this study, RCA collected from various regions of Florida exhibited pH ranging from 10.5 to 12.3. Concentrations of Al, Ba, Cr, Fe, Mo, Na, Ni, Sb, and Sr measured using batch leaching tests exceeded applicable risk-based thresholds on at least some occasions, but the concentrations measured suggest that risk to water supplies should be controlled because of dilution and attenuation. Two mechanisms of pH neutralization were evaluated. Soil acidity plays a role, but laboratory testing and chemical modeling found that at higher liquid-to-solid ratios the acidity is exhausted. If high pH leachate did reach groundwater, chemical modeling indicated that groundwater dilution and carbonation would mitigate groundwater pH effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cold in-place recycling and full-depth recycling with asphalt products (CIR&FDRwAP).

DOT National Transportation Integrated Search

2009-03-01

In the 60s, 70s, and 80s, many Illinois local road agencies successfully used conventional asphalt : emulsions for In-Place Recycling to produce Emulsion-Aggregate-Mixtures (EAMs). In more recent years, these : emulsions have not been ...

An overview of aggregate resources in the United States

USGS Publications Warehouse

Langer, William H.; Scott, P.W.; Bristow, C.M.

2002-01-01

In 2000 the USA produced about 2.7 billion tonnes of aggregate worth about $13.7 billion. Both crushed stone and sand and gravel are produced in virtually every State, although limited quantities are available in the Gulf Coastal Plain, the Colorado Plateau , the Wyoming Basin and the Great Plains. Prices vary depending on the product and location. Most aggregates are transported by road, and minor amounts by railroad, barge on navigable inland channels, and through the Great Lake ports. Imports and exports of aggregates are very minor. A major amount f crushed stone aggregates is consumed by concrete aggregate. Recycled aggregates account for about 8% of total demand, although the amount recycled is thought to be increasing. Current issues facing the inductry unclude the differences in quality specifications between States, adjusting to the increasing concern for the impact of aggregate mining on the environmentm, health issues from particulate matter and crystalline silica, and the complexity of obtaining permits for extraction. Redcustion in the number od companies extracting aggregrates is likely to occur through acquisitions.

The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis

PubMed Central

Wang, Fusong; Wang, Zipeng; Li, Chao; Xiao, Yue; Wu, Shaopeng; Pan, Pan

2017-01-01

Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4–8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling. PMID:28772935

The Rejuvenating Effect in Hot Asphalt Recycling by Mortar Transfer Ratio and Image Analysis.

PubMed

Wang, Fusong; Wang, Zipeng; Li, Chao; Xiao, Yue; Wu, Shaopeng; Pan, Pan

2017-05-24

Using a rejuvenator to improve the performance of asphalt pavement is an effective and economic way of hot asphalt recycling. This research analyzes the rejuvenating effect on aged asphalt by means of a Mortar Transfer Ratio (MTR) test, which concerns the ratio of asphalt mortar that moves from recycled aggregates (RAP aggregates) to fresh added aggregates when aged asphalt is treated with a regenerating agent and comes into contact with fresh aggregates. The proposed MTR test analyzes the regeneration in terms of the softening degree on aged asphalt when the rejuvenator is applied. The covered area ratio is studied with an image analyzing tool to understand the possibility of mortar transferring from RAP aggregates to fresh aggregates. Additionally, a micro-crack closure test is conducted and observed through a microscope. The repairing ability and diffusion characteristics of micro-cracks can therefore be analyzed. The test results demonstrate that the proposed mortar transfer ratio is a feasible way to evaluate rejuvenator diffusion during hot recycling. The mortar transfer ratio and uncovered area ratio on fresh aggregates are compatible, and can be used to quantify the contribution of the rejuvenator. Within a certain temperature range, the diffusing effect of the rejuvenator is better when the diffusing temperature is higher. The diffusion time of the rejuvenator is optimum when diffusion occurs for 4-8 h. When the rejuvenator is properly applied, the rough and cracking surface can be repaired, resulting in better covered aggregates. The micro-closure analysis visually indicates that rejuvenators can be used to repair the RAP aggregates during hot recycling.

Experimental investigation of photocatalytic effects of concrete in air purification adopting entire concrete waste reuse model.

PubMed

Xu, Yidong; Chen, Wei; Jin, Ruoyu; Shen, Jiansheng; Smallbone, Kirsty; Yan, Chunyang; Hu, Lei

2018-07-05

This research investigated the capacities of recycled aggregate concrete adopting entire concrete waste reuse model in degrading NO 2. Two major issues within environmental sustainability were addressed: concrete waste reuse rate and mitigation of hazards substances in the polluted air. The study consisted of two stages: identification of proper replacement rates of recycled concrete wastes in new concrete mixture design, and the evaluation of photocatalytic performance of recycled aggregate concrete in degrading NO 2 . It was found that replacement rates up to 3%, 30%, and 50% for recycled power, recycled fine aggregate, and recycled coarse aggregate respectively could be applied in concrete mixture design without deteriorating concrete strength. Recycled aggregates contained both positive attributes ("internal curing") and negative effects (e.g., lower hardness) to concrete properties. It was found that 30%-50% of natural coarse aggregate replaced by recycled coarse aggregates coated with TiO 2 would significantly improve the photocatalytic performance of concrete measured by degradation rate of NO 2 . Micro-structures of recycled aggregates observed under microscope indicated that soaking recycled aggregates in TiO 2 solution resulted in whiskers that filled the porosity within recycled aggregates which enhanced concrete strength. Copyright © 2018 Elsevier B.V. All rights reserved.

Environmental suitability of recycled concrete aggregate in highways : [research summary].

DOT National Transportation Integrated Search

2015-01-01

Natural highway aggregate is a finite resource that with continued use in construction : activities but some good quality aggregates used in existing concrete structures may be : re-used to replace with the natural aggregate. Due to the repair or rep...

Utilizing Coal Fly Ash and Recycled Glass in Developing Green Concrete Materials

DOT National Transportation Integrated Search

2012-06-01

The environmental impact of Portland cement concrete production has motivated researchers and the construction industry to evaluate alternative technologies for incorporating recycled cementing materials and recycled aggregates in concrete. One such ...

Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates.

PubMed

Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B

2015-01-01

Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

Hot in-Place Recycling of Asphalt Pavements.

DTIC Science & Technology

1987-08-04

WEARING SPECIFIED THICKNESS SURFACE • b. With ’Tew Aggregate, Modifier, And Asphalt ," ..’ . ,,, /f",’"" 4.. Figure 8. Typical Cold In-Place...34. .. .; ’-. , .?-. . ; ,....",.’.". ’. .- +-;-?,..- . .-’. , .. ’.,,..-, . ..- ?.,,,..-N ....-, ..,-. -".,,’." - HOT IN-PLACE RECYCLING OF ASPHALT PAVEMENTS An Engineering Report by0 Michael Lawrence Dowdy Submitted...for asphalt pavements. This type of asphalt pavement recycling process is becoming

Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks.

PubMed

Xiao, Zhao; Ling, Tung-Chai; Kou, Shi-Cong; Wang, Qingyuan; Poon, Chi-Sun

2011-08-01

Utilization of construction and demolition (C&D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However, the presence of large quantities of crushed clay brick in some the C&D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50-75% for fine aggregates. Copyright © 2011 Elsevier Ltd. All rights reserved.

Investigation of Self Consolidating Concrete Containing High Volume of Supplementary Cementitious Materials and Recycled Asphalt Pavement Aggregates

NASA Astrophysics Data System (ADS)

Patibandla, Varun chowdary

The use of sustainable technologies such as supplementary cementitiuous materials (SCMs), and/or recycled materials is expected to positively affect the performance of concrete mixtures. However, it is important to study and qualify such mixtures and check if the required specifications of their intended application are met before they can be implemented in practice. This study presents the results of a laboratory investigation of Self Consolidating concrete (SCC) containing sustainable technologies. A total of twelve concrete mixtures were prepared with various combinations of fly ash, slag, and recycled asphalt pavement (RAP). The mixtures were divided into three groups with constant water to cementitiuous materials ratio of 0.37, and based on the RAP content; 0, 25, and 50% of coarse aggregate replaced by RAP. All mixtures were prepared to achieve a target slump flow equal to or higher than 500 mm (24in). A control mixture for each group was prepared with 100% Portland cement whereas all other mixtures were designed to have up to 70% of portland cement replaced by a combination of supplementary cementitiuous materials (SCMs) such as class C fly ash and granulated blast furnace slag. The properties of fresh concrete investigated in this study include flowability, deformability; filling capacity, and resistance to segregation. In addition, the compressive strength at 3, 14, and 28 days, the tensile strength, and the unrestrained shrinkage up to 80 days was also investigated. As expected the inclusion of the sustainable technologies affected both fresh and hardened concrete properties. Analysis of the experimental data indicated that inclusion of RAP not only reduces the ultimate strength, but it also affected the compressive strength development rate. Moreover, several mixes satisfied compressive strength requirements for pavements and bridges; those mixes included relatively high percentages of SCMs and RAP. Based on the results obtained in this study, it is not

Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

PubMed Central

Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B.

2015-01-01

Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA. PMID:26161440

Benefits of aggregates surface modification in concrete production

NASA Astrophysics Data System (ADS)

Junak, J.; Sicakova, A.

2017-10-01

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

The use of Crumb Rubber as Substitute of Fine Aggregate for Hot Asphalt Mixture using Polymer Modified Bitumen

NASA Astrophysics Data System (ADS)

Setyawan, A.; Nugroho, S. K.; Irsyad, A. M.; Mutaqo, H. F.; Ramadhan, P.; Sumarsono, A.; Pramesti, F. P.

2018-03-01

The development of road pavement to fulfilled the need of modern life is not only focused on heavy duty road, but also a light duty road for the convenience of road users according to its function. For example the use of pavement on the jogging track, rail crossing, playground and so on. Due to the need of an alternative and the innovation of a comfortable pavement layer, but sufficiently strong in holding the load on the layer. The alternative innovation that can be used for the respective requirement is the utilization of waste old tires as substitute material in pavement construction. In this case the use of crumb rubber made from old tire rubber as an 100% fine aggregate substitute on the asphalt mixtures is investigated. To improve the strength and durability of the mixtures, the addition of polymer modified bitumen was incorporated. The two types of asphalt mixture selected in this study by using a continuous gradation of asphalt concrete and a gap gradation of hot roll asphalt. Testing to be implemented in this research is volumetric characteristics, Marshall characteristics, resistance to abrasion and impact and permeability. Replacement of fine aggregate with crumb rubber on asphalt concrete mixture with 60/70 penetration grade bitumen and polymer modified asphalt SBS E-55 in this research are expected to be an alternative in improving the quality of pavement and overcoming the environmental problems by reuse the waste materials.

Evaluate the use of reclaimed concrete aggregate in french drain applications.

DOT National Transportation Integrated Search

2014-02-01

Recycled concrete aggregate (RCA) is often used as a replacement of virgin aggregate in road : foundations (base course), embankments, hot-mix asphalt, and Portland cement concrete; however, the : use of RCA in exfiltration drainage systems, such as ...

Properties of concrete with tire derived aggregate and crumb rubber as a lighthweight substitute for mineral aggregates in the concrete mix

NASA Astrophysics Data System (ADS)

Siringi, Gideon Momanyi

Scrap tires continue to be a nuisance to the environment and this research proposes one way of recycling them as a lightweight aggregate which can substitute for mineral aggregates in concrete. Aggregates derived from scrap tires are often referred to as Tire Derived Aggregate (TDA). First, the focus is how much mineral aggregate can be replaced by these waste tires and how the properties of concrete are affected with the introduction of rubber. This is being mindful of the fact that for a new material to be acceptable as an engineering material, its properties and behavior has to be well understood, the materials must perform properly and be acceptable to the regulating agencies. The role played by the quantity of TDA and Crumb Rubber replacing coarse aggregate and fine aggregate respectively as well as different treatment and additives in concrete on its properties are examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, Splitting Tensile Strength based on ASTM C496, Modulus of Rupture (flexural strength) based on ASTM C78 and Bond strength of concrete developed with reinforcing steel based on ASTM C234.Through stress-strain plots, the rubberized concrete is compared in terms of change in ductility, toughness and Elastic Modulus. Results indicate that while replacement of mineral aggregates with TDA results in reduction in compressive strength, this may be mitigated by addition of silica fume or using a smaller size of TDA to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product with lower density while utilizing recycled TDA. From the results, it is observed that 7-10% of weight of mineral aggregates can be replaced by an equal volume of TDA to produce concrete with compressive strength of up to 4000 psi (27.5 MPa). Rubberized concrete would have higher ductility and toughness with

Magnitude assessment of free and hydrated limes present in RPCC aggregates.

DOT National Transportation Integrated Search

2002-02-01

The tendency of tufa to block pavement drains in northeastern Ohio can be associated with the total calcium content of the : aggregate material. In the present project, recycled Portland Cement Concrete (RPCC) aggregates are examined when : leached w...

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

PubMed

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

2012-10-30

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

Performance of I-57 recycled concrete pavements.

DOT National Transportation Integrated Search

2009-01-01

In 1986-1987 the Illinois Department of Transportation (IDOT) constructed a demonstration project on I-57 near Effingham, Illinois to evaluate the viability : of recycling an existing jointed reinforced concrete pavement for use as its primary aggreg...

Use of wastes derived from earthquakes for the production of concrete masonry partition wall blocks

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

Xiao Zhao; Faculty of Architecture, Civil Engineering and Environment Engineering and Mechanics, Sichuan University; Ling, Tung-Chai

2011-08-15

Highlights: > Solved the scientific and technological challenges impeding use of waste rubble derived from earthquake, by providing an alternative solution of recycling the waste in moulded concrete block products. > Significant requirements for optimum integration on the utilization of the waste aggregates in the production of concrete blocks are investigated. > A thorough understanding of the mechanical properties of concrete blocks made with waste derived from earthquake is reported. - Abstract: Utilization of construction and demolition (C and D) wastes as recycled aggregates in the production of concrete and concrete products have attracted much attention in recent years. However,more » the presence of large quantities of crushed clay brick in some the C and D waste streams (e.g. waste derived collapsed masonry buildings after an earthquake) renders the recycled aggregates unsuitable for high grade use. One possibility is to make use of the low grade recycled aggregates for concrete block production. In this paper, we report the results of a comprehensive study to assess the feasibility of using crushed clay brick as coarse and fine aggregates in concrete masonry block production. The effects of the content of crushed coarse and fine clay brick aggregates (CBA) on the mechanical properties of non-structural concrete block were quantified. From the experimental test results, it was observed that incorporating the crushed clay brick aggregates had a significant influence on the properties of blocks. The hardened density and drying shrinkage of the block specimens decreased with an increase in CBA content. The use of CBA increased the water absorption of block specimens. The results suggested that the amount of crushed clay brick to be used in concrete masonry blocks should be controlled at less than 25% (coarse aggregate) and within 50-75% for fine aggregates.« less

Use of recycled plastics in concrete: A critical review.

PubMed

Gu, Lei; Ozbakkaloglu, Togay

2016-05-01

Plastics have become an essential part of our modern lifestyle, and the global plastic production has increased immensely during the past 50years. This has contributed greatly to the production of plastic-related waste. Reuse of waste and recycled plastic materials in concrete mix as an environmental friendly construction material has drawn attention of researchers in recent times, and a large number of studies reporting the behavior of concrete containing waste and recycled plastic materials have been published. This paper summarizes the current published literature until 2015, discussing the material properties and recycling methods of plastic and the influence of plastic materials on the properties of concrete. To provide a comprehensive review, a total of 84 studies were considered, and they were classified into sub categories based on whether they dealt with concrete containing plastic aggregates or plastic fibers. Furthermore, the morphology of concrete containing plastic materials is described in this paper to explain the influence of plastic aggregates and plastic fibers on the properties of concrete. The properties of concretes containing virgin plastic materials were also reviewed to establish their similarities and differences with concrete containing recycled plastics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluate the use of reclaimed concrete aggregate in french drain applications : [summary].

DOT National Transportation Integrated Search

2014-02-01

Recycled concrete aggregate (RCA) is often used : as a replacement of virgin aggregate in road : foundations (base course), embankments, hot-mix : asphalt, and Portland cement concrete. However, : the use of RCA in exfiltration drainage systems, : su...

Applying the three R's: Reduce, reuse, and recycle in the chemical industry.

PubMed

Mostafa, Mohamed K; Peters, Robert W

2017-03-01

Pollution prevention (P2) assessment was conducted by applying the three R's, reduce, reuse, and recycle, in a chemical industry for the purpose of reducing the amount of wastewater generated, reusing paint wastewater in the manufacture of cement bricks, recycling cooling water, and improving water usage efficiency. The results of this study showed that the annual wastewater flow generated from the paint manufacturing can be reduced from 1,100 m 3 to 488.4 m 3 (44.4% reduction) when a high-pressure hose is used. Two mixtures were prepared. The first mixture (A) contains cement, coarse aggregate, fine aggregate, Addicrete BVF, and clean water. The second mixture (B) contains the same components used in the first mixture, except that paint wastewater was used instead of the clean water. The prepared samples were tested for water absorption, toxicity, reactivity, compressive strength, ignitability, and corrosion. The tests results indicated that using paint wastewater in the manufacture of the cement bricks improved the mechanical properties of the bricks. The toxicity test results showed that the metals concentration in the bricks did not exceed the U.S. EPA limits. This company achieved the goal of zero liquid discharge (ZLD), especially after recycling 2,800 m 3 of cooling water. The total annual saving could reach $42,570 with a payback period of 41 days. This research focused on improving the water usage efficiency, reducing the quantity of wastewater generated, and potentially reusing wastewater in the manufacture of cement bricks. Reusing paint wastewater in the manufacture of the bricks prevents the hazardous pollutants in the wastewater (calcium carbonate, styrene acrylic resins, colored pigments, and titanium dioxide) from entering and polluting the surface water and the environment. We think that this paper will help to find the most efficient and cost-effective way to manage paint wastewater and conserve fresh water resources. We also believe that this

Preliminary evaluation of physical and chemical characterization of waste palm oil shell as cool material replaced in asphaltic concrete as fine aggregate

NASA Astrophysics Data System (ADS)

Anuar, M. A. M.; Anting, N.; Shahidan, S.; Lee, Y. Y.; Din, M. F. Md; Khalid, F. S.; Nazri, W. M. H. W.

2017-11-01

Malaysia is one of the biggest producer of palm oil product and currently as main source of economy for the country. During the production of crude palm oil, a large amount of waste material is generated, such as palm oil fibres, palm oil shells and empty fruit bunches. Palm oil shell aggregate (POSA) is identified as a material that shows good potential to be used as a fine aggregate replacement in asphaltic concrete. On other hand, the chemical compound that exist in the Palm Oil Shell (POS) have shown a good potential as reflective component in cool-material. The purpose of this study is to obtain the physical and chemical properties of palm oil shell. The result shows the apparent particle density of Palm Oil Shell is 1.6 mg/m3. The specific gravity of palm oil shell was obtained with the value 1.6 and the water absorption amount of palm oil shell recorded from this study was 25.1%. The X-Ray Fluorescence study shows that palm oil shell contains the highest amount of SiO2 (46.412 wt%) and the second highest amount of Fe2O3 (34.016 wt%), both is the main output of relectivity compound. As a conclusion, waste palm oil shell has a potential to be used as alternative material for fine aggregate replacement. Besides that, the amount of chemical element that consist in palm oil shell which high in SiO2 and Fe2O3, promising the benefit to mitigate urban heat island as a cooling material agent.

Permeability of Concrete with Recycled Concrete Aggregate and Pozzolanic Materials under Stress

PubMed Central

Wang, Hailong; Sun, Xiaoyan; Wang, Junjie; Monteiro, Paulo J.M.

2016-01-01

The research reported herein studied the permeability of concrete containing recycled-concrete aggregate (RA), superfine phosphorous slag (PHS), and ground granulated blast-furnace slag (GGBS) with and without stress. Test results showed that the chloride diffusion coefficient of RA concrete (RAC) without external loads decreased with time, and the permeability of RAC is much lower than that of the reference concrete due to the on-going hydration and the pozzolanic reaction provided by the PHS and GGBS additives in the RAC mixture. The permeability of chloride under flexural load is much more sensitive than that under compressive load due to the differences in porosity and cracking pattern. At low compressive stress levels, the permeability of chloride decreased by the closing of pores and microcracks within RAC specimens. However, in a relatively short time the chloride diffusion coefficient and the chloride content increased rapidly with the increase of compressive stress when it exceeded a threshold stress level of approximate 35% of the ultimate compressive strength. Under flexural stress, the chloride transport capability increased with the increase of stress level and time. At high compressive and flexural stress levels, creep had a significant effect on the permeability of chloride in the RAC specimens due to the damage from the nucleation and propagation of microcracks over time. It is apparent that mortar cracking has more of a significant effect on the chloride transport in concrete than cracking in the interfacial transition zone (ITZ). PMID:28773376

Permeability of Concrete with Recycled Concrete Aggregate and Pozzolanic Materials under Stress.

PubMed

Wang, Hailong; Sun, Xiaoyan; Wang, Junjie; Monteiro, Paulo J M

2016-03-30

The research reported herein studied the permeability of concrete containing recycled-concrete aggregate (RA), superfine phosphorous slag (PHS), and ground granulated blast-furnace slag (GGBS) with and without stress. Test results showed that the chloride diffusion coefficient of RA concrete (RAC) without external loads decreased with time, and the permeability of RAC is much lower than that of the reference concrete due to the on-going hydration and the pozzolanic reaction provided by the PHS and GGBS additives in the RAC mixture. The permeability of chloride under flexural load is much more sensitive than that under compressive load due to the differences in porosity and cracking pattern. At low compressive stress levels, the permeability of chloride decreased by the closing of pores and microcracks within RAC specimens. However, in a relatively short time the chloride diffusion coefficient and the chloride content increased rapidly with the increase of compressive stress when it exceeded a threshold stress level of approximate 35% of the ultimate compressive strength. Under flexural stress, the chloride transport capability increased with the increase of stress level and time. At high compressive and flexural stress levels, creep had a significant effect on the permeability of chloride in the RAC specimens due to the damage from the nucleation and propagation of microcracks over time. It is apparent that mortar cracking has more of a significant effect on the chloride transport in concrete than cracking in the interfacial transition zone (ITZ).

Efficient use of recycled concrete in transportation infrastructure

DOT National Transportation Integrated Search

2011-01-21

This study examined current national and international practices regarding the use of recycled concrete aggregates (RCA) as engineering materials by the transportation industry as well as a history of Michigan's experience with RCA. In the laboratory...

Feasibility of using recycled glass in asphalt.

DOT National Transportation Integrated Search

1990-01-01

This report was written in response to HJR 301, which "requests the VDOT to conduct a study of the feasibility of using recycled glass as supplemental aggregates in asphalt." The laboratory study did not indicate that there would be any adverse affec...

Evaluation of concrete recycling system efficiency for ready-mix concrete plants.

PubMed

Vieira, Luiz de Brito Prado; Figueiredo, Antonio Domingues de

2016-10-01

The volume of waste generated annually in concrete plants is quite large and has important environmental and economic consequences. The use of fresh concrete recyclers is an interesting way for the reuse of aggregates and water in new concrete production. This paper presents a study carried out for over one year by one of the largest ready-mix concrete producers in Brazil. This study focused on the evaluation of two recyclers with distinct material separation systems, herein referred to as drum-type and rotary sieve-type equipment. They were evaluated through characterization and monitoring test programs to verify the behaviour of recovered materials (aggregates, water, and slurry). The applicability of the recovered materials (water and aggregates) was also evaluated in the laboratory and at an industrial scale. The results obtained with the two types of recyclers used were equivalent and showed no significant differences. The only exception was in terms of workability. The drum-type recycler generated fewer cases that required increased pumping pressure. The analysis concluded that the use of untreated slurry is unfeasible because of its intense negative effects on the strength and workability of concrete. The reclaimed water, pre-treated to ensure that its density is less than 1.03g/cm(3), can be used on an industrial scale without causing any harm to the concrete. The use of recovered aggregates consequently induces an increase in water demand and cement consumption to ensure the workability conditions of concrete that is proportional to the concrete strength level. Therefore, the viability of their use is restricted to concretes with characteristic strengths lower than 25MPa. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of recycled asphaltic concrete : final report.

DOT National Transportation Integrated Search

1977-01-01

This report describes a project in which approximately 6,200 tons (5,630 Mg) of asphaltic concrete were recycled through a conventional asphalt batch plant. During the construction of the project, a buildup of asphalt-coated fines occurred in the dry...

Assessment of Pb-slag, MSWI bottom ash and boiler and fly ash for using as a fine aggregate in cement mortar.

PubMed

Saikia, Nabajyoti; Cornelis, Geert; Mertens, Gilles; Elsen, Jan; Van Balen, Koenraad; Van Gerven, Tom; Vandecasteele, Carlo

2008-06-15

Three types of wastes, metallurgical slag from Pb production (SLG), the sand-sized (0.1-2 mm) fraction of MSWI bottom ash from a grate furnace (SF), and boiler and fly ash from a fluidised bed incinerator (BFA), were characterized and used to replace the fine aggregate during preparation of cement mortar. The chemical and mineralogical behaviour of these wastes along with the reactivities of the wastes with lime and the hydration behaviour of ordinary Portland cement paste with and without these wastes added were evaluated by various chemical and instrumental techniques. The compressive strengths of the cement mortars containing waste as a partial substitution of fine aggregates were also assessed. Finally, leaching studies of the wastes and waste containing cement mortars were conducted. SLG addition does not show any adverse affect during the hydration of cement, or on the compressive strengths behaviours of mortars. Formation of expansive products like ettringite, aluminium hydroxide and H2 gas due to the reaction of some constituents of BFA and SF with alkali creates some cracks in the paste as well as in the cement mortars, which lower the compressive strength of the cement mortars. However, utilization of all materials in cement-based application significantly improves the leaching behaviour of the majority of the toxic elements compared to the waste as such.

Process to recycle shredder residue

DOEpatents

Jody, Bassam J.; Daniels, Edward J.; Bonsignore, Patrick V.

2001-01-01

A system and process for recycling shredder residue, in which separating any polyurethane foam materials are first separated. Then separate a fines fraction of less than about 1/4 inch leaving a plastics-rich fraction. Thereafter, the plastics rich fraction is sequentially contacted with a series of solvents beginning with one or more of hexane or an alcohol to remove automotive fluids; acetone to remove ABS; one or more of EDC, THF or a ketone having a boiling point of not greater than about 125.degree. C. to remove PVC; and one or more of xylene or toluene to remove polypropylene and polyethylene. The solvents are recovered and recycled.

Toxicity and environmental and economic performance of fly ash and recycled concrete aggregates use in concrete: A review.

PubMed

Kurda, Rawaz; Silvestre, José D; de Brito, Jorge

2018-04-01

This paper presents an overview of previous studies on the environmental impact (EI) and toxicity of producing recycled concrete aggregates (RCA), fly ash (FA), cement, superplasticizer, and water as raw materials, and also on the effect of replacing cement and natural aggregates (NA) with FA and RCA, respectively, on the mentioned aspects. EI and toxicity were analysed simultaneously because considering concrete with alternative materials as sustainable depends on whether their risk assessment is high. Therefore, this study mainly focuses on the cradle-to-gate EI of one cubic meter of concrete, namely abiotic depletion potential (ADP), global warming potential (GWP), ozone depletion potential (ODP), photochemical ozone creation (POCP), acidification potential (AP), eutrophication potential (EP), non-renewable energy (PE-NRe) and renewable energy (PE-Re). In terms of toxicity, leachability (chemical and ecotoxicological characterization) was considered. The results also include the economic performance of these materials, and show that the incorporation of FA in concrete significantly decreases the EI and cost of concrete. Thus, the simultaneous incorporation of FA and RCA decrease the EI, cost, use of landfill space and natural resources extraction. Nonetheless, the leaching metals of FA decrease when they are incorporated in concrete. Relative to FA, the incorporation of RCA does not significantly affect the EI and cost of concrete, but it significantly reduces the use of landfill space and the need of virgin materials.

Magnitude assessment of free and hydrated limes present in RPCC aggregates : executive summary.

DOT National Transportation Integrated Search

2002-02-01

The tendency of tufa to block pavement drains in northeastern Ohio can be associated with the total calcium content of the aggregate material. In the present project, recycled Portland Cement Concrete (RPCC) aggregates are examined when leached with ...

Coal Combustion Wastes Reuse in Low Energy Artificial Aggregates Manufacturing.

PubMed

Ferone, Claudio; Colangelo, Francesco; Messina, Francesco; Iucolano, Fabio; Liguori, Barbara; Cioffi, Raffaele

2013-10-31

Sustainable building material design relies mostly on energy saving processes, decrease of raw materials consumption, and increase of waste and by-products recycling. Natural and lightweight artificial aggregates production implies relevant environmental impact. This paper addresses both the issues of residues recycling and energy optimization. Particularly, three coal combustion wastes (Weathered Fly Ash, WFA; Wastewater Treatment Sludge, WTS; Desulfurization Device Sludge, DDS) supplied by the Italian electric utility company (ENEL) have been employed in the manufacture of cold bonded artificial aggregates. Previously, the residues have been characterized in terms of chemical and mineralogical compositions, water content, particle size distribution, and heavy metal release behavior. These wastes have been used in the mix design of binding systems with the only addition of lime. Finally, the artificial aggregates have been submitted to physical, mechanical, and leaching testing, revealing that they are potentially suitable for many civil engineering applications.

Coal Combustion Wastes Reuse in Low Energy Artificial Aggregates Manufacturing

PubMed Central

Ferone, Claudio; Colangelo, Francesco; Messina, Francesco; Iucolano, Fabio; Liguori, Barbara; Cioffi, Raffaele

2013-01-01

Sustainable building material design relies mostly on energy saving processes, decrease of raw materials consumption, and increase of waste and by-products recycling. Natural and lightweight artificial aggregates production implies relevant environmental impact. This paper addresses both the issues of residues recycling and energy optimization. Particularly, three coal combustion wastes (Weathered Fly Ash, WFA; Wastewater Treatment Sludge, WTS; Desulfurization Device Sludge, DDS) supplied by the Italian electric utility company (ENEL) have been employed in the manufacture of cold bonded artificial aggregates. Previously, the residues have been characterized in terms of chemical and mineralogical compositions, water content, particle size distribution, and heavy metal release behavior. These wastes have been used in the mix design of binding systems with the only addition of lime. Finally, the artificial aggregates have been submitted to physical, mechanical, and leaching testing, revealing that they are potentially suitable for many civil engineering applications. PMID:28788372

Use of rubble from building demolition in mortars.

PubMed

Corinaldesi, V; Giuggiolini, M; Moriconi, G

2002-01-01

Because of increasing waste production and public concerns about the environment, it is desirable to recycle materials from building demolition. If suitably selected, ground, cleaned and sieved in appropriate industrial crushing plants, these materials can be profitably used in concrete. Nevertheless, the presence of masonry instead of concrete rubble is particularly detrimental to the mechanical performance and durability of recycled-aggregate concrete and the same negative effect is detectable when natural sand is replaced by fine recycled aggregate fraction. An alternative use of both masonry rubble and fine recycled material fraction could be in mortars. These could contain either recycled instead of natural sand or powder obtained by bricks crushing as partial cement substitution. In particular, attention is focused on the modification that takes place when either polypropylene or stainless steel fibers are added to these mortars. Polypropylene fibers are added in order to reduce shrinkage of mortars, stainless steel fibers for improving their flexural strength. The combined use of polypropylene fibers and fine recycled material from building demolition could allow the preparation of mortars showing good performance, in particular when coupled with bricks. Furthermore, the combined use of stainless steel fibers and mortars containing brick powder seems to be an effective way to guarantee a high flexural strength.

Hail formation triggers rapid ash aggregation in volcanic plumes

USGS Publications Warehouse

Van Eaton, Alexa R.; Mastin, Larry G.; Herzog, M.; Schwaiger, Hans F.; Schneider, David J.; Wallace, Kristi; Clarke, Amanda B

2015-01-01

During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterized ‘wet’ eruption. The 2009 eruption of Redoubt Volcano in Alaska incorporated water from the surface (in this case, a glacier), which is a common occurrence during explosive volcanism worldwide. Observations from C-band weather radar, fall deposits, and numerical modeling demonstrate that volcanic hail formed rapidly in the eruption plume, leading to mixed-phase aggregation of ~95% of the fine ash and stripping much of the cloud out of the atmosphere within 30 minutes. Based on these findings, we propose a mechanism of hail-like aggregation that contributes to the anomalously rapid fallout of fine ash and the occurrence of concentrically-layered aggregates in volcanic deposits.

Hail formation triggers rapid ash aggregation in volcanic plumes.

PubMed

Van Eaton, Alexa R; Mastin, Larry G; Herzog, Michael; Schwaiger, Hans F; Schneider, David J; Wallace, Kristi L; Clarke, Amanda B

2015-08-03

During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterized 'wet' eruption. The 2009 eruption of Redoubt Volcano, Alaska, incorporated water from the surface (in this case, a glacier), which is a common occurrence during explosive volcanism worldwide. Observations from C-band weather radar, fall deposits and numerical modelling demonstrate that hail-forming processes in the eruption plume triggered aggregation of ∼95% of the fine ash and stripped much of the erupted mass out of the atmosphere within 30 min. Based on these findings, we propose a mechanism of hail-like ash aggregation that contributes to the anomalously rapid fallout of fine ash and occurrence of concentrically layered aggregates in volcanic deposits.

Hail formation triggers rapid ash aggregation in volcanic plumes

PubMed Central

Van Eaton, Alexa R.; Mastin, Larry G.; Herzog, Michael; Schwaiger, Hans F.; Schneider, David J.; Wallace, Kristi L.; Clarke, Amanda B.

2015-01-01

During explosive eruptions, airborne particles collide and stick together, accelerating the fallout of volcanic ash and climate-forcing aerosols. This aggregation process remains a major source of uncertainty both in ash dispersal forecasting and interpretation of eruptions from the geological record. Here we illuminate the mechanisms and timescales of particle aggregation from a well-characterized ‘wet' eruption. The 2009 eruption of Redoubt Volcano, Alaska, incorporated water from the surface (in this case, a glacier), which is a common occurrence during explosive volcanism worldwide. Observations from C-band weather radar, fall deposits and numerical modelling demonstrate that hail-forming processes in the eruption plume triggered aggregation of ∼95% of the fine ash and stripped much of the erupted mass out of the atmosphere within 30 min. Based on these findings, we propose a mechanism of hail-like ash aggregation that contributes to the anomalously rapid fallout of fine ash and occurrence of concentrically layered aggregates in volcanic deposits. PMID:26235052

Does mycorrhizal inoculation improve plant survival, aggregate stability, and fine root development on a coarse-grained soil in an alpine eco-engineering field experiment?

NASA Astrophysics Data System (ADS)

Bast, A.; Wilcke, W.; Graf, F.; Lüscher, P.; Gärtner, H.

2016-08-01

Steep vegetation-free talus slopes in high mountain environments are prone to superficial slope failures and surface erosion. Eco-engineering measures can reduce slope instabilities and thus contribute to risk mitigation. In a field experiment, we established mycorrhizal and nonmycorrhizal research plots and determined their biophysical contribution to small-scale soil fixation. Mycorrhizal inoculation impact on plant survival, aggregate stability, and fine root development was analyzed. Here we present plant survival (ntotal = 1248) and soil core (ntotal = 108) analyses of three consecutive years in the Swiss Alps. Soil cores were assayed for their aggregate stability coefficient (ASC), root length density (RLD), and mean root diameter (MRD). Inoculation improved plant survival significantly, but it delayed aggregate stabilization relative to the noninoculated site. Higher aggregate stability occurred only after three growing seasons. Then also RLD tended to be higher and MRD increased significantly at the mycorrhizal treated site. There was a positive correlation between RLD, ASC, and roots <0.5 mm, which had the strongest impact on soil aggregation. Our results revealed a temporal offset between inoculation effects tested in laboratory and field experiments. Consequently, we recommend to establish an intermediate to long-term field experimental monitoring before transferring laboratory results to the field.

Detecting deleterious fine particles in concrete aggregates and defining their impact.

DOT National Transportation Integrated Search

2010-10-01

This study examined the types of microfines in aggregates found in northern Wisconsin and their influence on : concrete prepared according to WisDOT specifications. Aggregates were collected from 28 sources and 69 : percent were found to contain clay...

Mechanisms of Phosphorus Removal by Recycled Crushed Concrete.

PubMed

Deng, Yihuan; Wheatley, Andrew

2018-02-17

Due to urbanisation, there are large amounts of waste concrete, particularly in rapidly industrialising countries. Currently, demolished concrete is mainly recycled as aggregate for reconstruction. This study has shown that larger sizes (2-5 mm) of recycled concrete aggregate (RCA) removed more than 90% of P from effluent when at pH 5. Analysis of the data, using equilibrium models, indicated a best fit with the Langmuir which predicated an adsorption capacity of 6.88 mg/g. Kinetic analysis indicated the equilibrium adsorption time was 12 h, with pseudo second-order as the best fit. The thermal dynamic tests showed that the adsorption was spontaneous and, together with the evidence from the sequential extraction and desorption experiments, indicated the initial mechanism was physical attraction to the surface followed by chemical reactions which prevented re-release. These results suggested that RCA could be used for both wastewater treatment and P recovery.

Optimizing the durability of the coarse fraction of porous asphalt RAP for effective recycling

NASA Astrophysics Data System (ADS)

Holleran, Irina; Wilson, Douglas J.; Black, Philippa; Holleran, Glynn; Walubita, Lubinda F.

2017-09-01

Porous asphalt (PA) durability depends not only on the binder used to manufacture the mix, but also on the aggregates chosen, particularly the coarse fraction component. Aggregates for PA should be of the highest quality and highly durable to withstand the effects of weather and traffic. To recycle PA into a new PA mix, without compromising the long-term performance, the durability of the recovered aggregates from PA-derived reclaimed asphalt pavement (RAP) should be assessed alongside the aged binder properties. In this study, the Micro-Deval (MD) Abrasion test, combined with water absorption, was found to be a good predictor of asphalt mix performance for PA. Minerology of the aggregates is an important factor when setting limits for MD loss. New Zealand (NZ) aggregates are significantly younger in geological terms, and chemically and physically less stable compared to the aggregates used in many other countries. This is especially true for greywacke, the most used aggregate in NZ for road construction. If the MD limits reported in some literature are applied to NZ PA-derived RAP aggregates, poor performing material can be erroneously incorporated in asphalt mixes. Findings from this study contributes in understanding how PA-derived RAP can be recycled into new value PA mixes.

Evaluation of the effect on aggregate properties of samples extracted using the ignition furnace.

DOT National Transportation Integrated Search

2000-04-01

The Superpave mix design system includes four consensus aggregate properties to ensure aggregate quality: coarse aggregate angularity, flat and elongated particles, fine aggregate angularity, and sand equivalent. In addition to determining these cons...

Study of the Technical Feasibility of Increasing the Amount of Recycled Concrete Waste Used in Ready-Mix Concrete Production

PubMed Central

Ferreiro-Cabello, Javier; López-González, Luis M.

2017-01-01

The construction industry generates a considerable amount of waste. Faced with this undesirable situation, the ready-mix concrete sector, in particular, has invested energy and resources into reusing its own waste in its production process as it works towards the goal of more sustainable construction. This study examines the feasibility of incorporating two types of concrete waste, which currently end up in landfill, into the production process of ready-mix concrete: the waste generated during the initial production stage (ready-mix concrete waste), and waste created when demolition waste is treated to obtain artificial aggregate. The first phase of the study’s methodology corroborates the suitability of the recycled aggregate through characterization tests. After this phase, the impact of incorporating different percentages of recycled coarse aggregate is evaluated by examining the performance of the produced concrete. The replacement rate varied between 15% and 50%. The results indicate that recycled aggregates are, indeed, suitable to be incorporated into ready-mix concrete production. The impact on the final product’s performance is different for the two cases examined herein. Incorporating aggregates from generic concrete blocks led to a 20% decrease in the produced concrete’s strength performance. On the other hand, using recycled aggregates made from the demolition waste led to a smaller decrease in the concrete’s performance: about 8%. The results indicate that with adequate management and prior treatment, the waste from these plants can be re-incorporated into their production processes. If concrete waste is re-used, concrete production, in general, becomes more sustainable for two reasons: less waste ends up as landfill and the consumption of natural aggregates is also reduced. PMID:28773183

Study of the Technical Feasibility of Increasing the Amount of Recycled Concrete Waste Used in Ready-Mix Concrete Production.

PubMed

Fraile-Garcia, Esteban; Ferreiro-Cabello, Javier; López-Ochoa, Luis M; López-González, Luis M

2017-07-18

The construction industry generates a considerable amount of waste. Faced with this undesirable situation, the ready-mix concrete sector, in particular, has invested energy and resources into reusing its own waste in its production process as it works towards the goal of more sustainable construction. This study examines the feasibility of incorporating two types of concrete waste, which currently end up in landfill, into the production process of ready-mix concrete: the waste generated during the initial production stage (ready-mix concrete waste), and waste created when demolition waste is treated to obtain artificial aggregate. The first phase of the study's methodology corroborates the suitability of the recycled aggregate through characterization tests. After this phase, the impact of incorporating different percentages of recycled coarse aggregate is evaluated by examining the performance of the produced concrete. The replacement rate varied between 15% and 50%. The results indicate that recycled aggregates are, indeed, suitable to be incorporated into ready-mix concrete production. The impact on the final product's performance is different for the two cases examined herein. Incorporating aggregates from generic concrete blocks led to a 20% decrease in the produced concrete's strength performance. On the other hand, using recycled aggregates made from the demolition waste led to a smaller decrease in the concrete's performance: about 8%. The results indicate that with adequate management and prior treatment, the waste from these plants can be re-incorporated into their production processes. If concrete waste is re-used, concrete production, in general, becomes more sustainable for two reasons: less waste ends up as landfill and the consumption of natural aggregates is also reduced.

Mechanisms of Phosphorus Removal by Recycled Crushed Concrete

PubMed Central

Wheatley, Andrew

2018-01-01

Due to urbanisation, there are large amounts of waste concrete, particularly in rapidly industrialising countries. Currently, demolished concrete is mainly recycled as aggregate for reconstruction. This study has shown that larger sizes (2–5 mm) of recycled concrete aggregate (RCA) removed more than 90% of P from effluent when at pH 5. Analysis of the data, using equilibrium models, indicated a best fit with the Langmuir which predicated an adsorption capacity of 6.88 mg/g. Kinetic analysis indicated the equilibrium adsorption time was 12 h, with pseudo second-order as the best fit. The thermal dynamic tests showed that the adsorption was spontaneous and, together with the evidence from the sequential extraction and desorption experiments, indicated the initial mechanism was physical attraction to the surface followed by chemical reactions which prevented re-release. These results suggested that RCA could be used for both wastewater treatment and P recovery. PMID:29462987

Recycled tires as coarse aggregate in concrete pavement mixtures.

DOT National Transportation Integrated Search

2013-07-01

The reuse potential of tire chips as coarse aggregates in pavement concrete was examined in this research by : investigating the effects of low- and high-volume tire chips on fresh and hardened concrete properties. One concrete : control mixture was ...

Evaluation of the engineering characteristics of RAP/Aggregate blends.

DOT National Transportation Integrated Search

2005-07-01

"This report describes results from a research program that was structured to evaluate the : suitability of using reclaimed and recycled asphalt pavement (RAP) as an additive to crushed : angular aggregate or pit run granular soils. Research and test...

Torsional Shear Device for Testing the Dynamic Properties of Recycled Material

NASA Astrophysics Data System (ADS)

Gabryś, Katarzyna; Sas, Wojciech; Soból, Emil; Głuchowski, Andrzej

2016-12-01

From the viewpoint of environmental preservation and effective utilization of resources, it is beneficial and necessary to reuse wastes, for example, concrete, as the recycled aggregates for new materials. In this work, the dynamic behavior of such aggregates under low frequency torsional loading is studied. Results show that the properties of such artificial soils match with those reported in the literature for specific natural soils.

Using recycled concrete as aggregate in concrete pavements to reduce materials cost.

DOT National Transportation Integrated Search

2013-08-01

The main objective of this project was to evaluate the effects of using aggregate produced from crushed concrete pavement as a replacement for natural (virgin) coarse aggregate in pavement mixtures. A total of ten different concrete mixtures containi...

Manufacture of reconstruction-bricks in Mexico

NASA Astrophysics Data System (ADS)

Rojas-Valencia, Ma. Neftalí; Penagos, Armando Aguilar; Rojas, Denise Y. Fernández; López, Alberto López; Gálves, David Morillón

2017-12-01

In Mexico, around 33.600 tons of construction wastes are generated every day, Mexico City contributing for around tons/day, with fewer than 1.000 tons/day being sent to be recycled. For that reason the purpose of this study was to manufacture sustainable bricks, based on three types of wastes generated in the building industry: wood cutting residues, wastes from the excavation process (From Coapa and Cuautlancingo, Puebla, Mexico) and recycled aggregates. Water was added as kneading material, and Opuntia ficus-indica (mucilage) was supplemented as natural additive to improve the workability of the mixtures. Conventional firing process was substituted by drying in a solar drying chamber. Nine mixtures were prepared using 62% excavation wastes, 4% wood cutting residues and 11%, 17% and 34% recycled aggregates. These mixtures were classified in two groups depending on their granulometry: the first one denominated cementitious recycled aggregates only having granulometry from 25.4 mm, 9.52 mm to 6.35 mm to fines and the second group denominated all in one recycled aggregates having granulometry of 6.35 mm to fines. The quality of the sustainable bricks was evaluated according to compressive strength and water absorption parameters. The results of nine mixtures showed that the reconstruction-bricks manufactured with the mixture seven consisting of 9.52 mm and 6.35 mm construction residues (all in one) fines presented the highest strength values, lowest maximum initial absorption (4 g/min) compared to the norm NMX-C-037-ONNCCE-2013 which establishes that the maximum limit for walls exposed to the outside is 5 g/min. Using a solar desiccator made from construction residues, the bricks were dried in 11 days, the maximum temperature was 76 °C and the maximum solar radiation captured was 733.4 W/m2.

Pavement Recycling Guidelines for State and Local Governments: Participant's Reference Book

DOT National Transportation Integrated Search

1998-03-01

Recycling or reuse of existing asphalt pavement materials to produce new pavement materials has the following advantages: (a) reduce costs of construction, (b) conservation of aggregate and binder, (c) preservation of the existing pavement geometrics...

Fine-scale multi-species aggregations of oceanic zooplankton

NASA Astrophysics Data System (ADS)

Haury, L. R.; Wiebe, P. H.

1982-07-01

Sixteen Longhurst-Hardy Plankton Recorder tows were taken at different depths in the northwest Atlantic for analysis of fine-scale horizontal patchiness. Abundant species were non-randomly distributed in patches with scales of tens to hundreds of meters. Positive correlations between species abundances dominated, indicating that the patches were multi-species associations. Most horizontal pattern appeared to be of biological origin.

COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway

NASA Astrophysics Data System (ADS)

Cepuritis, Rolands; Willy Danielsen, Svein

2014-05-01

COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway Rolands Cepuritis, Norcem/NTNU and Svein Willy Danielsen, SINTEF Aggregate production is a mining operation where no purification of the "ore" is necessary. Still it is extremely rare that an aggregate production plant is operating on the basis of zero-waste concept. This is since historically the fine crushed aggregate (particles with a size of less than 2, 4 or sometimes 8 mm) has been regarded as a by-product or waste of the more valuable coarse aggregate production. The reason is that the crushed coarse aggregates can easily replace coarse rounded natural stones in almost any concrete composition; while, the situation with the sand is different. The production of coarse aggregate normally yields fine fractions with rough surface texture, flaky or elongated particles an inadequate gradation. When such a material replaces smooth and rounded natural sand grains in a concrete mix, the result is usually poor and much more water and cement has to be used to achieve adequate concrete flow. The consequences are huge stockpiles of the crushed fine fractions that can't be sold (mass balance problems) for the aggregate producers, sustainability problems for the whole industry and environmental issues for society due to dumping and storing of the fine co-generated material. There have been attempts of utilising the material in concrete before; however, they have mostly ended up in failure. There have been attempts to adjust the crushed sand to the properties of the natural sand, which would still give a lot of waste, especially if the grading would have to be adjusted and the high amounts of fines abundantly present in the crushed sand would have to be removed. Another fundamental reason for failure has been that historically such attempts have mainly ended up in a research carried out by people (both industrial and academic) with aggregate background (= parties willing to find market

Impact of nonconductive powder on electrostatic separation for recycling crushed waste printed circuit board.

PubMed

Wu, Jiang; Qin, Yufei; Zhou, Quan; Xu, Zhenming

2009-05-30

The electrostatic separation is an effective and environmentally friendly method for recycling metals and nonmetals from crushed printed circuit board (PCB) wastes. However, it still confronts some problems brought by nonconductive powder (NP). Firstly, the NP is fine and liable to aggregate. This leads to an increase of middling products and loss of metals. Secondly, the stability of separation process is influenced by NP. Finally, some NPs accumulate on the surface of the corona and electrostatic electrodes during the process. These problems lead to an inefficient separation. In the present research, the impacts of NP on electrostatic separation are investigated. The experimental results show that: the separation is notably influenced when the NP content is more than 10%. With the increase of NP content, the middling products sharply increase from 1.4 g to 4.3g (increase 207.1%), while the conductive products decrease from 24.0 g to 19.1g (decrease 20.4%), and the separation process become more instable.

Evaluation of aggregate subgrade materials used as pavement subgrade/granular subbase.

DOT National Transportation Integrated Search

2015-07-01

With recent focus on sustainable construction practices and the ever-increasing transportation costs and scarcity of : natural resources, integration of large-size and marginally acceptable aggregates and recycled materials (e.g., : reclaimed asphalt...

Recycling supercapacitors based on shredding and mild thermal treatment.

PubMed

Jiang, Guozhan; Pickering, Stephen J

2016-02-01

Supercapacitors are widely used in electric and hybrid vehicles, wind farm and low-power equipment due to their high specific power density and huge number of charge-discharge cycles. Waste supercapacitors should be recycled according to EU directive 2002/96/EC on waste electric and electronic equipment. This paper describes a recycling approach for end-of-life supercapacitors based on shredding and mild thermal treatment. At first, supercapacitors are shredded using a Retsch cutting mill. The shredded mixture is then undergone thermal treatment at 200°C to recycle the organic solvent contained in the activated carbon electrodes. After the thermal treatment, the mixture is roughly separated using a fluidized bed method to remove the aluminium foil particles and paper particles from the activated carbon particles, which is subsequently put into water for a wet shredding into fine particles that can be re-used. The recycled activated carbon has a BET surface area of up to 1200m(2)/g and the recycled acetonitrile has a high purity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanical recycling of waste electric and electronic equipment: a review.

PubMed

Cui, Jirang; Forssberg, Eric

2003-05-30

The production of electric and electronic equipment (EEE) is one of the fastest growing areas. This development has resulted in an increase of waste electric and electronic equipment (WEEE). In view of the environmental problems involved in the management of WEEE, many counties and organizations have drafted national legislation to improve the reuse, recycling and other forms of recovery of such wastes so as to reduce disposal. Recycling of WEEE is an important subject not only from the point of waste treatment but also from the recovery of valuable materials.WEEE is diverse and complex, in terms of materials and components makeup as well as the original equipment's manufacturing processes. Characterization of this waste stream is of paramount importance for developing a cost-effective and environmentally friendly recycling system. In this paper, the physical and particle properties of WEEE are presented. Selective disassembly, targeting on singling out hazardous and/or valuable components, is an indispensable process in the practice of recycling of WEEE. Disassembly process planning and innovation of disassembly facilities are most active research areas. Mechanical/physical processing, based on the characterization of WEEE, provides an alternative means of recovering valuable materials. Mechanical processes, such as screening, shape separation, magnetic separation, Eddy current separation, electrostatic separation, and jigging have been widely utilized in recycling industry. However, recycling of WEEE is only beginning. For maximum separation of materials, WEEE should be shredded to small, even fine particles, generally below 5 or 10mm. Therefore, a discussion of mechanical separation processes for fine particles is highlighted in this paper. Consumer electronic equipment (brown goods), such as television sets, video recorders, are most common. It is very costly to perform manual dismantling of those products, due to the fact that brown goods contain very low

Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates.

PubMed

Klawonn, Isabell; Bonaglia, Stefano; Brüchert, Volker; Ploug, Helle

2015-06-01

Colonies of N(2)-fixing cyanobacteria are key players in supplying new nitrogen to the ocean, but the biological fate of this fixed nitrogen remains poorly constrained. Here, we report on aerobic and anaerobic microbial nitrogen transformation processes that co-occur within millimetre-sized cyanobacterial aggregates (Nodularia spumigena) collected in aerated surface waters in the Baltic Sea. Microelectrode profiles showed steep oxygen gradients inside the aggregates and the potential for nitrous oxide production in the aggregates' anoxic centres. (15)N-isotope labelling experiments and nutrient analyses revealed that N(2) fixation, ammonification, nitrification, nitrate reduction to ammonium, denitrification and possibly anaerobic ammonium oxidation (anammox) can co-occur within these consortia. Thus, N. spumigena aggregates are potential sites of nitrogen gain, recycling and loss. Rates of nitrate reduction to ammonium and N(2) were limited by low internal nitrification rates and low concentrations of nitrate in the ambient water. Presumably, patterns of N-transformation processes similar to those observed in this study arise also in other phytoplankton colonies, marine snow and fecal pellets. Anoxic microniches, as a pre-condition for anaerobic nitrogen transformations, may occur within large aggregates (⩾1 mm) even when suspended in fully oxygenated waters, whereas anoxia in small aggregates (<1 to ⩾0.1 mm) may only arise in low-oxygenated waters (⩽25 μM). We propose that the net effect of aggregates on nitrogen loss is negligible in NO(3)(-)-depleted, fully oxygenated (surface) waters. In NO(3)(-)-enriched (>1.5 μM), O(2)-depleted water layers, for example, in the chemocline of the Baltic Sea or the oceanic mesopelagic zone, aggregates may promote N-recycling and -loss processes.

Designing, producing, and constructing fine-graded hot mix asphalt on Illinois roadways.

DOT National Transportation Integrated Search

2015-04-01

Fine-graded (F-G) asphalt concrete mixtures are composed of an aggregate structure in which the fine fraction controls the : load-carrying capacity of the mix. Other states have reported benefits in using F-G mixtures, including improved compaction, ...

Recycled Portland cement concrete pavements : Part II, state-of-the art summary.

DOT National Transportation Integrated Search

1979-01-01

This report constitutes a review of the literature concerning recycling of portland cement concrete pavements by crushing the old pavement and reusing the crushed material as aggregate in a number of applications. A summary of the major projects cond...

Recycling of MSWI fly ash by means of cementitious double step cold bonding pelletization: Technological assessment for the production of lightweight artificial aggregates.

PubMed

Colangelo, Francesco; Messina, Francesco; Cioffi, Raffaele

2015-12-15

In this work, an extensive study on the recycling of municipal solid waste incinerator fly ash by means of cold bonding pelletization is presented. The ash comes from an incineration plant equipped with rotary and stoker furnaces, in which municipal, hospital and industrial wastes are treated. Fly ash from waste incineration is classified as hazardous and cannot be utilized or even landfilled without prior treatment. The pelletization process uses cement, lime and coal fly ash as components of the binding systems. This process has been applied to several mixes in which the ash content has been varied from 50% (wt.%) up to a maximum of 70%. An innovative additional pelletization step with only cementitious binder has been performed in order to achieve satisfactory immobilization levels. The obtained lightweight porous aggregates are mostly suitable for recovery in the field of building materials with enhanced sustainability properties. Density, water absorption and crushing strength ranged from 1000 to 1600 kg/m(3), 7 to 16% and 1.3 to 6.2 MPa, respectively, and the second pelletization step increased stabilization efficiency. The feasibility of the process has been analyzed by testing also concrete specimens containing the artificial aggregates, resulting in lightweight concrete of average performance. Copyright © 2015 Elsevier B.V. All rights reserved.

Bottom ash as aggregate replacement in concrete.

DOT National Transportation Integrated Search

2013-06-01

The objective of the proposed study is to evaluate bottom ash as a partial or total replacement of the fine and coarse aggregate in : concrete. This program will characterize and evaluate available bottom ash sources as potential replacement of both ...

Ultra-Fine Scale Spatially-Integrated Mapping of Habitat and Occupancy Using Structure-From-Motion.

PubMed

McDowall, Philip; Lynch, Heather J

2017-01-01

Organisms respond to and often simultaneously modify their environment. While these interactions are apparent at the landscape extent, the driving mechanisms often occur at very fine spatial scales. Structure-from-Motion (SfM), a computer vision technique, allows the simultaneous mapping of organisms and fine scale habitat, and will greatly improve our understanding of habitat suitability, ecophysiology, and the bi-directional relationship between geomorphology and habitat use. SfM can be used to create high-resolution (centimeter-scale) three-dimensional (3D) habitat models at low cost. These models can capture the abiotic conditions formed by terrain and simultaneously record the position of individual organisms within that terrain. While coloniality is common in seabird species, we have a poor understanding of the extent to which dense breeding aggregations are driven by fine-scale active aggregation or limited suitable habitat. We demonstrate the use of SfM for fine-scale habitat suitability by reconstructing the locations of nests in a gentoo penguin colony and fitting models that explicitly account for conspecific attraction. The resulting digital elevation models (DEMs) are used as covariates in an inhomogeneous hybrid point process model. We find that gentoo penguin nest site selection is a function of the topography of the landscape, but that nests are far more aggregated than would be expected based on terrain alone, suggesting a strong role of behavioral aggregation in driving coloniality in this species. This integrated mapping of organisms and fine scale habitat will greatly improve our understanding of fine-scale habitat suitability, ecophysiology, and the complex bi-directional relationship between geomorphology and habitat use.

Ultra-Fine Scale Spatially-Integrated Mapping of Habitat and Occupancy Using Structure-From-Motion

PubMed Central

McDowall, Philip; Lynch, Heather J.

2017-01-01

Organisms respond to and often simultaneously modify their environment. While these interactions are apparent at the landscape extent, the driving mechanisms often occur at very fine spatial scales. Structure-from-Motion (SfM), a computer vision technique, allows the simultaneous mapping of organisms and fine scale habitat, and will greatly improve our understanding of habitat suitability, ecophysiology, and the bi-directional relationship between geomorphology and habitat use. SfM can be used to create high-resolution (centimeter-scale) three-dimensional (3D) habitat models at low cost. These models can capture the abiotic conditions formed by terrain and simultaneously record the position of individual organisms within that terrain. While coloniality is common in seabird species, we have a poor understanding of the extent to which dense breeding aggregations are driven by fine-scale active aggregation or limited suitable habitat. We demonstrate the use of SfM for fine-scale habitat suitability by reconstructing the locations of nests in a gentoo penguin colony and fitting models that explicitly account for conspecific attraction. The resulting digital elevation models (DEMs) are used as covariates in an inhomogeneous hybrid point process model. We find that gentoo penguin nest site selection is a function of the topography of the landscape, but that nests are far more aggregated than would be expected based on terrain alone, suggesting a strong role of behavioral aggregation in driving coloniality in this species. This integrated mapping of organisms and fine scale habitat will greatly improve our understanding of fine-scale habitat suitability, ecophysiology, and the complex bi-directional relationship between geomorphology and habitat use. PMID:28076351

Air classification: Potential treatment method for optimized recycling or utilization of fine-grained air pollution control residues obtained from dry off-gas cleaning high-temperature processing systems.

PubMed

Lanzerstorfer, Christof

2015-11-01

In the dust collected from the off-gas of high-temperature processes, usually components that are volatile at the process temperature are enriched. In the recycling of the dust, the concentration of these volatile components is frequently limited to avoid operation problems. Also, for external utilization the concentration of such volatile components, especially heavy metals, is often restricted. The concentration of the volatile components is usually higher in the fine fractions of the collected dust. Therefore, air classification is a potential treatment method to deplete the coarse material from these volatile components by splitting off a fines fraction with an increased concentration of those volatile components. In this work, the procedure of a sequential classification using a laboratory air classifier and the calculations required for the evaluation of air classification for a certain application were demonstrated by taking the example of a fly ash sample from a biomass combustion plant. In the investigated example, the Pb content in the coarse fraction could be reduced to 60% by separation of 20% fines. For the non-volatile Mg the content was almost constant. It can be concluded that air classification is an appropriate method for the treatment of off-gas cleaning residues. © The Author(s) 2015.

Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates

PubMed Central

Klawonn, Isabell; Bonaglia, Stefano; Brüchert, Volker; Ploug, Helle

2015-01-01

Colonies of N2-fixing cyanobacteria are key players in supplying new nitrogen to the ocean, but the biological fate of this fixed nitrogen remains poorly constrained. Here, we report on aerobic and anaerobic microbial nitrogen transformation processes that co-occur within millimetre-sized cyanobacterial aggregates (Nodularia spumigena) collected in aerated surface waters in the Baltic Sea. Microelectrode profiles showed steep oxygen gradients inside the aggregates and the potential for nitrous oxide production in the aggregates' anoxic centres. 15N-isotope labelling experiments and nutrient analyses revealed that N2 fixation, ammonification, nitrification, nitrate reduction to ammonium, denitrification and possibly anaerobic ammonium oxidation (anammox) can co-occur within these consortia. Thus, N. spumigena aggregates are potential sites of nitrogen gain, recycling and loss. Rates of nitrate reduction to ammonium and N2 were limited by low internal nitrification rates and low concentrations of nitrate in the ambient water. Presumably, patterns of N-transformation processes similar to those observed in this study arise also in other phytoplankton colonies, marine snow and fecal pellets. Anoxic microniches, as a pre-condition for anaerobic nitrogen transformations, may occur within large aggregates (⩾1 mm) even when suspended in fully oxygenated waters, whereas anoxia in small aggregates (<1 to ⩾0.1 mm) may only arise in low-oxygenated waters (⩽25 μM). We propose that the net effect of aggregates on nitrogen loss is negligible in NO3−-depleted, fully oxygenated (surface) waters. In NO3−-enriched (>1.5 μM), O2-depleted water layers, for example, in the chemocline of the Baltic Sea or the oceanic mesopelagic zone, aggregates may promote N-recycling and -loss processes. PMID:25575306

77 FR 74006 - Polychlorinated Biphenyls (PCBs); Recycling Plastics From Shredder Residue

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-12

... show photographic identification, pass through a metal detector, and sign the EPA visitor log. All visitor bags are processed through an X-ray machine and subject to search. Visitors will be provided an... from metals recycling facilities (referred to by ISRI as automobile shredder residue (ASR) aggregate...

Characterization and environmental risk assessment of heavy metals in construction and demolition wastes from five sources (chemical, metallurgical and light industries, and residential and recycled aggregates).

PubMed

Gao, Xiaofeng; Gu, Yilu; Xie, Tian; Zhen, Guangyin; Huang, Sheng; Zhao, Youcai

2015-06-01

Total concentrations of heavy metals (Cu, Zn, Pb, Cr, Cd, and Ni) were measured among 63 samples of construction and demolition (C&D) wastes collected from chemical, metallurgical and light industries, and residential and recycled aggregates within China for risk assessment. The heavy metal contamination was primarily concentrated in the chemical and metallurgical industries, especially in the electroplating factory and zinc smelting plant. High concentrations of Cd were found in light industry samples, while the residential and recycled aggregate samples were severely polluted by Zn. Six most polluted samples were selected for deep research. Mineralogical analysis by X-ray fluorescence (XRF) spectrometry and X-ray diffraction (XRD), combined with element speciation through European Community Bureau of Reference (BCR) sequential extraction, revealed that a relatively slight corrosion happened in the four samples from electroplating plants but high transfer ability for large quantities of Zn and Cu. Lead arsenate existed in the acid extractable fraction in CI7-8 and potassium chromium oxide existed in the mobility fraction. High concentration of Cr could be in amorphous forms existing in CI9. The high content of sodium in the two samples from zinc smelter plants suggested severe deposition and erosion on the workshop floor. Large quantities of Cu existed as copper halide and most of the Zn appeared to be zinc, zinc oxide, barium zinc oxide, and zincite. From the results of the risk assessment code (RAC), the samples from the electroplating factory posed a very high risk of Zn, Cu, and Cr, a high risk of Ni, a middle risk of Pb, and a low risk of Cd. The samples from the zinc smelting plant presented a high risk of Zn, a middle risk of Cu, and a low risk of Pb, Cr, Cd, and Ni.

Laboratory evaluation of characteristics of recycled asphalt pavement in Kansas : technical summary.

DOT National Transportation Integrated Search

2011-09-01

The use of recycled asphalt pavement (RAP) has been in practice since the 1930s and is necessary to reduce the construction cost due to rising prices of virgin aggregates and binder, to conserve these rapidly depleting resources, and to minimize prob...

Recycling and reuse of chosen kinds of waste materials in a building industry

NASA Astrophysics Data System (ADS)

Ferek, B.; Harasymiuk, J.; Tyburski, J.

2016-08-01

The article describes the current state of knowledge and practice in Poland concerning recycling as a method of reuse of chosen groups of waste materials in building industry. The recycling of building scraps is imposed by environmental, economic and technological premises. The issue of usage of sewage residues is becoming a problem of ever -growing gravity as the presence of the increasing number of pernicious contaminants makes their utilization for agricultural purposes more and more limited. The strategies of using waste materials on Polish building sites were analyzed. The analysis of predispositions to salvage for a group of traditional materials, such as: timber, steel, building debris, insulation materials, plastics, and on the example of new materials, such as: artificial light aggregates made by appropriate mixing of siliceous aggregates, glass refuses and sewage residues in order to obtain a commodity which is apt for economic usage also was made in the article. The issue of recycling of waste materials originating from building operations will be presented in the context of the binding home and EU legal regulations. It was proved that the level of recycling of building wastes in Poland is considerably different from one which is achieved in the solid market economies, both in quantity and in assortment. The method of neutralization of building refuses in connection with special waste materials, which are sewage sludge that is presented in the article may be one of the alternative solutions to the problem of recycling of these wastes not only on the Polish scale.

MACROPHAGE AGGREGATES AS BIOMARKERS OF EXPOSURE: FROM FERAL POPULATIONS TO LABORATORY MODELS

EPA Science Inventory

Macrophage aggregates (MAs) are structures within the spleen, kidney and sometimes liver of teleost fishes. They are believed to function much like primitive lymph nodes in that phagocytized material is transported to these areas by macrophages, for destruction, recycling or stor...

Abrasion-Erosion Resistance of Concrete Made with Two Aggregates, Stonewall Jackson Dam, West Virginia.

DTIC Science & Technology

1983-09-01

the concrete mixtures; Mr. Dale Glass , Mr. Frank W. Dorsey, and Mr. Roger Buttner conducted the abrasion-erosion tests. Mr. Stuart Long served as the...PITT- 8 S-1, was from the Buffalo Slag Co., Franklinville, New York. This fine aggregate is classified as a glacial sand and is composed primarily of...MATERIAL Fine Aggregate ILZAI% Franklin, NY R:.rLcE- Buffalo Slag Co. sA--L.. BY ~ J2rhDst:r esne Kinzua Damn - . USED A PROCESSING BEFORE TESTING

Comparative analysis of the digestibility of sewage fine sieved fraction and hygiene paper produced from virgin fibers and recycled fibers.

PubMed

Ghasimi, Dara S M; Zandvoort, Marcel H; Adriaanse, Michiel; van Lier, Jules B; de Kreuk, Merle

2016-07-01

Sewage fine sieved fraction (FSF) is a heterogeneous substrate consisting of mainly toilet paper fibers sequestered from municipal raw sewage by a fine screen. In earlier studies, a maximum biodegradation of 62% and 57% of the sewage FSF was found under thermophilic (55°C) and mesophilic (35°C) conditions, respectively. In order to research this limited biodegradability of sewage FSF, this study investigates the biodegradation of different types of cellulosic fibers-based hygiene papers including virgin fibers based toilet paper (VTP), recycled fiber based toilet paper (RTP), virgin pulp for paper production (VPPP) as a raw material, as well as microcrystalline cellulose (MCC) as a kind of fiberless reference material. The anaerobic biodegradation or digestibility tests were conducted under thermophilic and mesophilic conditions. Results of the experiments showed different biomethane potential (BMP) values for each tested cellulose fiber-based substrate, which might be associated with the physical characteristics of the fibers, type of pulping, presence of lignin encrusted fibers, and/or the presence of additive chemicals and refractory compounds. Higher hydrolysis rates (Kh), higher specific methane production rates (SMPR) and shorter required incubation times to achieve 90% of the BMP (t90%CH4), were achieved under thermophilic conditions for all examined substrates compared to the mesophilic ones. Furthermore, the biodegradability of all employed cellulose fiber-based substrates was in the same range, 38-45%, under both conditions and less than the observed FSF biodegradability, i.e. 57-62%. MCC achieved the highest BMP and biodegradability, 86-91%, among all cellulosic substrates. Copyright © 2016 Elsevier Ltd. All rights reserved.

Waste Material Based "Terrazzo" Tiles: The Effect Of Curing Time And Extreme Environmental Conditions Over Glass Aggregate/Cement Matrix Boundary

NASA Astrophysics Data System (ADS)

Paris, E.; Radica, F.; Stabile, P.; Ansaloni, F.; Giuli, G.; Carroll, M. R.

2017-12-01

Currently, more than half of all materials extracted globally (over three billion tonnes/year in the EU only) are transformed for use in construction. Before year 2020, the EU aims to reduce the environmental impact of the construction sector by recycling or re-using large amounts of these materials, thus reducing the consumption of raw materials and helping promote the sector's economic stability. With this challenge in mind an aesthetically pleasant and fully recycled (up to 78%) pre-cast cement based tile (Terrazzo tiles) was designed by replacing raw materials with Glass Waste (GW) and Construction/Demolition Waste (CDW). Several recent studies explored the effect of the addition of GW in the manufacture of urban pavements, concluding that the use of GW can improve various phases of pavement life and structure by enhancing the structural performance, durability, environmental friendliness, and aesthetic features. In this study we extend this knowledge also to interior cement-based tiles by evaluating the technical performances of this this novel designed tile, in particular by focusing on the interface between the GW aggregates and different Portland cement based matrix at extreme environmental conditions. For this work three representative waste material based "terrazzo" tiles were selected and characterized by means of XRD and SEM imaging in order to study the boundary effect between GW aggregate and different binding materials: limestone powder, quartz powder and fine ground WG powder. A fourth additional mixture of Portland cement and CDW material was characterized. Fragments of a Limestone matrix tile were also thermally threated at -18°C and at 60°C for one week to witness the possible formation of new harmful phases at the grain-matrix boundary. Preliminary results on X-ray diffraction patterns show that 1 year after manufacture and/or thermal treatment there is no new formation of harmful phases other than the starting ones. High magnification SEM

Revisiting the effects of hydrodynamic sorting and sedimentary recycling on chemical weathering indices

NASA Astrophysics Data System (ADS)

Guo, Yulong; Yang, Shouye; Su, Ni; Li, Chao; Yin, Ping; Wang, Zhongbo

2018-04-01

Although the proxies based on elemental geochemistry of siliciclastic sediments have been well developed to indicate the intensity of chemical weathering in various catchments, their geological indications and limitations, and especially how the differentiation of minerals and sediment grain size influences the applications of these proxies needs more clarification. This paper investigates the interactive effects of weathering, hydraulic sorting and sedimentary recycling on river sediment chemistry, and further validates the application of various weathering indices by measuring mineralogical and geochemical compositions of bank sediments and suspended particulate matters (SPMs) from five rivers in East China bearing various sizes, geologic settings and climatic regimes. For a specific river, the silicate weathering intensity registered in the fine SPMs is systematically stronger than that in the coarse-grained bank sediments. Most of the weathering indices not only reflect the integrated weathering history of various catchments but also depend on hydraulic sorting effect during sediment transport and depositional processes. The correlation between CIA (chemical index of alteration) and WIP (weathering index of Parker) offers an approach to predict the weathering trends of the fine SPMs, coarse bank sediments and recycled sediments under the influence of quartz dilution. To minimize the effects of hydrodynamic sorting and sedimentary recycling, we suggest that the fine sediments (e.g. SPMs and <2 μm fraction of bank sediments) in rivers can better reflect the average of present-day weathering crust in catchments and the weathered terrigenous materials into marginal seas and oceans.

Results of physical tests of road-building aggregate.

DOT National Transportation Integrated Search

1953-01-01

This bulletin gives the results of tests on samples of ledge rock, crushed stone, gravel, blast-furnace or smelter slag, and natural or manufactured fine aggregate which were made by teh Bureau of Public Roads to January 1, 1951.

Recyclability of Concrete Pavement Incorporating High Volume of Fly Ash.

PubMed

Yoshitake, Isamu; Ishida, Takeo; Fukumoto, Sunao

2015-08-21

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

Recyclability of Concrete Pavement Incorporating High Volume of Fly Ash

PubMed Central

Yoshitake, Isamu; Ishida, Takeo; Fukumoto, Sunao

2015-01-01

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

Combined Effects of Non-Conforming Fly Ash and Recycled Masonry Aggregates on Mortar Properties

PubMed Central

Torres-Gómez, Ana Isabel; Ledesma, Enrique F.; Otero, Rocio; Fernández, José Maria; Jiménez, José Ramón; de Brito, Jorge

2016-01-01

This work evaluates the effects of using non-conforming fly ash (Nc-FA) generated in a thermoelectric power plant as filler material for mortars made with natural sand (NA) and recycled sand from masonry waste (FRMA). The incorporation of powdered recycled masonry filler (R-MF) is also tested as an alternative to siliceous filler (Si-F). Three families of mortars were designed to study: the effect of replacing Si-F with Nc-FA on mortars made with NA; the effect of replacing Si-F with Nc-FA on mortars made with 50% of NA and 50% of FRMA; and the effect of replacing Si-F with R-MF on mortars made with NA and FRMA. Replacing Si-F with Nc-FA is a viable alternative that increases the mechanical strength, the workability and durability properties and decreases the shrinkage. The use of FRMA and Nc-FA improved the mechanical strength of mortars, and it slightly increased the shrinkage. The replacement of Si-F with R-MF on mortars made with FRMA is not a good alternative, because it has a negative impact on all of the properties tested. This work can help both to reduce cement and natural resources’ consumption and to increase the recycling rate of Nc-FA and FRMA. PMID:28773849

Combined Effects of Non-Conforming Fly Ash and Recycled Masonry Aggregates on Mortar Properties.

PubMed

Torres-Gómez, Ana Isabel; Ledesma, Enrique F; Otero, Rocio; Fernández, José Maria; Jiménez, José Ramón; de Brito, Jorge

2016-08-25

This work evaluates the effects of using non-conforming fly ash (Nc-FA) generated in a thermoelectric power plant as filler material for mortars made with natural sand (NA) and recycled sand from masonry waste (FRMA). The incorporation of powdered recycled masonry filler (R-MF) is also tested as an alternative to siliceous filler (Si-F). Three families of mortars were designed to study: the effect of replacing Si-F with Nc-FA on mortars made with NA; the effect of replacing Si-F with Nc-FA on mortars made with 50% of NA and 50% of FRMA; and the effect of replacing Si-F with R-MF on mortars made with NA and FRMA. Replacing Si-F with Nc-FA is a viable alternative that increases the mechanical strength, the workability and durability properties and decreases the shrinkage. The use of FRMA and Nc-FA improved the mechanical strength of mortars, and it slightly increased the shrinkage. The replacement of Si-F with R-MF on mortars made with FRMA is not a good alternative, because it has a negative impact on all of the properties tested. This work can help both to reduce cement and natural resources' consumption and to increase the recycling rate of Nc-FA and FRMA.

Detailed Aggregate Resources Study, Dry Lake Valley, Nevada.

DTIC Science & Technology

1981-05-29

LOCAL SAND SOURCES IGENERALLY CYLINDERS. DRYING SHRINKAGE I COLLECTED WITHIN A FEW MILES OF CORRESPONDING LEDGE-ROCK SOURCES) SUPPLIED FINE MENS...COMPRESSIVE AND TENSILE STh LEDGE-ROCK SOURCES SUPPLIED COARSE AGGREGATES; LOCAL SAND SOURCES IGENERALLY CYLINDERS. DRYING SHRINKAGE COLLECTED WITHIN A FEW

Pilot-based assessment of the economics of recycling construction demolition waste.

PubMed

Srour, Issam M; Chehab, Ghassan R; El-Fadel, Mutasem; Tamraz, Sandy

2013-11-01

The significant amount of waste generated from construction demolition has become a chronic problem in many developing countries. Using data obtained from demolition contractors and various other sources, this paper proposes a framework for proper handling of construction demolition waste (CDW) to serve as a decision support tool in countries suffering from the lack of national CDW management guidelines. The framework is then demonstrated through a case study in the city of Beirut, Lebanon, and a sensitivity analysis is carried out to examine the economic feasibility of developing a recycling facility. The analysis showed that in order for a facility to be feasible, a gate fee should be charged in the presence of a market for recycled aggregates. The results confirm the significance of instigating and implementing legislation to control illegal dumping, constructing, and managing engineered landfills, and establishing markets for recycled CDW.

Evaluation of Different Mineral Filler Aggregates for Asphalt Mixtures

NASA Astrophysics Data System (ADS)

Wasilewska, Marta; Małaszkiewicz, Dorota; Ignatiuk, Natalia

2017-10-01

Mineral filler aggregates play an important role in asphalt mixtures because they fill voids in paving mix and improve the cohesion of asphalt binder. Limestone powder containing over 90% of CaCO3 is the most frequently used type of filler. Waste material from the production of coarse aggregate can be successfully used as a mineral filler aggregate for hot asphalt concrete mixtures as the limestone powder replacement. This paper presents the experimental results of selected properties of filler aggregates which were obtained from rocks with different mineral composition and origin. Five types of rocks were used as a source of the mineral filler aggregate: granite, gabbro, trachybasalt, quartz sandstone and rocks from postglacial deposits. Limestone filler was used in this study as the reference material. The following tests were performed: grading (air jet sieving), quality of fines according to methylene blue test, water content by drying in a ventilated oven, particle density using pyknometer method, Delta ring and ball test, Bitumen Number, fineness determined as Blaine specific surface area. Mineral filler aggregates showed significant differences when they were mixed with bitumen and stiffening effect in Delta ring and ball test was evaluated. The highest values were achieved when gabbro and granite fillers were used. Additionally, Scanning Electron Microscopy (SEM) analysis of grain shape and size was carried out. Significant differences in grain size and shape were observed. The highest non-homogeneity in size was determined for quartz sandstone, gabbro and granite filler. Their Blaine specific surface area was lower than 2800 cm2/g, while for limestone and postglacial fillers with regular and round grains it exceeded 3000 cm2/g. All examined mineral filler aggregates met requirements of Polish National Specification WT-1: 2014 and could be used in asphalt mixtures.

Character, mass, distribution, and origin of tephra-fall deposits from the 2009 eruption of Redoubt Volcano, Alaska: highlighting the significance of particle aggregation

USGS Publications Warehouse

Wallace, Kristi; Coombs, Michelle L; Schaefer, Janet R.

2013-01-01

Particle size data showing a preponderance of fine ash, even in the most proximal locations, along with the abundance of aggregate lapilli documented in most samples, confirms that particle aggregation played a significant role in the 2009 eruption and induced premature fallout of fine ash.

Mechanical Properties of Steel Fiber Reinforced all Lightweight Aggregate Concrete

NASA Astrophysics Data System (ADS)

Yang, Y. M.; Li, J. Y.; Zhen, Y.; Nie, Y. N.; Dong, W. L.

2018-05-01

In order to study the basic mechanical properties and failure characteristics of all lightweight aggregate concrete with different volume of steel fiber (0%, 1%, 2%), shale ceramsite is used as light coarse aggregate. The shale sand is made of light fine aggregate and mixed with different volume of steel fiber, and the mix proportion design of all lightweight aggregate concrete is carried out. The cubic compressive strength, axial compressive strength, flexural strength, splitting strength and modulus of elasticity of steel fiber all lightweight aggregate concrete were studied. Test results show that the incorporation of steel fiber can restrict the cracking of concrete, improve crack resistance; at the same time, it shows good plastic deformation ability and failure morphology. It lays a theoretical foundation for further research on the application of all lightweight aggregate concrete in structural systems.

Strength characterization of open-graded aggregates for structural backfills

DOT National Transportation Integrated Search

2015-06-01

Open-graded aggregates are common in road and bridge construction because they are easy to place, and they have the advantages of very low fine content, free-draining characteristics, low frost heave potential, and simple quality assurance testing. T...

An Investigation into the Use of Manufactured Sand as a 100% Replacement for Fine Aggregate in Concrete.

PubMed

Pilegis, Martins; Gardner, Diane; Lark, Robert

2016-06-02

Manufactured sand differs from natural sea and river dredged sand in its physical and mineralogical properties. These can be both beneficial and detrimental to the fresh and hardened properties of concrete. This paper presents the results of a laboratory study in which manufactured sand produced in an industry sized crushing plant was characterised with respect to its physical and mineralogical properties. The influence of these characteristics on concrete workability and strength, when manufactured sand completely replaced natural sand in concrete, was investigated and modelled using artificial neural networks (ANN). The results show that the manufactured sand concrete made in this study generally requires a higher water/cement (w/c) ratio for workability equal to that of natural sand concrete due to the higher angularity of the manufactured sand particles. Water reducing admixtures can be used to compensate for this if the manufactured sand does not contain clay particles. At the same w/c ratio, the compressive and flexural strength of manufactured sand concrete exceeds that of natural sand concrete. ANN proved a valuable and reliable method of predicting concrete strength and workability based on the properties of the fine aggregate (FA) and the concrete mix composition.

An Investigation into the Use of Manufactured Sand as a 100% Replacement for Fine Aggregate in Concrete

PubMed Central

Pilegis, Martins; Gardner, Diane; Lark, Robert

2016-01-01

Manufactured sand differs from natural sea and river dredged sand in its physical and mineralogical properties. These can be both beneficial and detrimental to the fresh and hardened properties of concrete. This paper presents the results of a laboratory study in which manufactured sand produced in an industry sized crushing plant was characterised with respect to its physical and mineralogical properties. The influence of these characteristics on concrete workability and strength, when manufactured sand completely replaced natural sand in concrete, was investigated and modelled using artificial neural networks (ANN). The results show that the manufactured sand concrete made in this study generally requires a higher water/cement (w/c) ratio for workability equal to that of natural sand concrete due to the higher angularity of the manufactured sand particles. Water reducing admixtures can be used to compensate for this if the manufactured sand does not contain clay particles. At the same w/c ratio, the compressive and flexural strength of manufactured sand concrete exceeds that of natural sand concrete. ANN proved a valuable and reliable method of predicting concrete strength and workability based on the properties of the fine aggregate (FA) and the concrete mix composition. PMID:28773560

Reduction in soil aggregate size distribution due to wind erosion

NASA Astrophysics Data System (ADS)

Swet, Nitzan; Katra, Itzhak

2017-04-01

Soil erosion process by wind causes emission of fine soil particles, and thus alters the topsoil's properties, fertility, and erodibility. Topsoil resistance to erosion depends on its physicochemical properties, especially on the soil aggregation. Although the key role of aggregates in soil erodibility, quantitative information on the relations between soil aggregate size distribution (ASD) and erosion is still lucking. This study focuses on ASD analyses before and after soil erosion by wind. Wind tunnel experiments and soil analyses were conducted on semiarid loess topsoils with different initial conditions of aggregation. The results show that in all initial soil conditions saltation of sand particles caused the breakdown of macro-aggregates > 500 µm, resulting in increase of micro-aggregates (63-250 µm). The micro-aggregate production increases with the wind shear velocity (up to 0.61 m s-1) for soils with available macro-aggregates. The findings highlight dynamics in soil aggregation in response to erosion process, and therefore the significance of ASD in quantifying soil degradation and soil loss potential.

Reuse of ground waste glass as aggregate for mortars.

PubMed

Corinaldesi, V; Gnappi, G; Moriconi, G; Montenero, A

2005-01-01

This work was aimed at studying the possibility of reusing waste glass from crushed containers and building demolition as aggregate for preparing mortars and concrete. At present, this kind of reuse is still not common due to the risk of alkali-silica reaction between the alkalis of cement and silica of the waste glass. This expansive reaction can cause great problems of cracking and, consequently, it can be extremely deleterious for the durability of mortar and concrete. However, data reported in the literature show that if the waste glass is finely ground, under 75mum, this effect does not occur and mortar durability is guaranteed. Therefore, in this work the possible reactivity of waste glass with the cement paste in mortars was verified, by varying the particle size of the finely ground waste glass. No reaction has been detected with particle size up to 100mum thus indicating the feasibility of the waste glass reuse as fine aggregate in mortars and concrete. In addition, waste glass seems to positively contribute to the mortar micro-structural properties resulting in an evident improvement of its mechanical performance.

Assessing a Reclaimed Concrete Up-Cycling Scheme through Life-Cycle Analysis

NASA Astrophysics Data System (ADS)

Guignot, Sylvain; Bru, Kathy; Touzé, Solène; Ménard, Yannick

The present study evaluates the environmental impacts of a recycling scheme for gravels from building concretes wastes, in which the liberated aggregates are reused in structural concretes while the residual mortar fines are sent to the raw mill of a clinker kiln.

Changes in the microstructure and properties of aspen chemithermomechanical pulp fibres during recycling.

PubMed

Fu, Yingjuan; Wang, Rongrong; Li, Dejuan; Wang, Zhaojiang; Zhang, Fengshan; Meng, Qinglin; Qin, Menghua

2015-03-06

The effects of recycling on the microstructure and properties of bleached aspen chemithermomechanical pulp (CTMP) fibres were systematically investigated. The low-temperature nitrogen adsorption and atomic force microscopy results showed that a substantial amount of large pores and most of the very small pores in the fibre wall closed and the fibre surface became less coarse and porous during recycling. The partial cocrystallisation of cellulose microfibrils took place, as reflected in the increment of the cellulose crystallinity and the width of the crystallite in the 0 0 2 lattice plane. These irreversible structural changes caused significant hornification of the recycled fibres, leading to the loss of swelling and bonding capability. The decrease of the tensile index, burst index, and tear index further demonstrated the deterioration of the fibre properties. However, the single-fibre strength considerably increased after recycling, which was mainly due to the enlarged cellulose aggregates in the fibre wall. Copyright © 2014 Elsevier Ltd. All rights reserved.

Closed-loop recycling of construction and demolition waste in Germany in view of stricter environmental threshold values.

PubMed

Weil, Marcel; Jeske, Udo; Schebek, Liselotte

2006-06-01

Recycling of construction and demolition waste contributes decisively to the saving of natural mineral resources. In Germany, processed mineral construction and demolition waste from structural engineering is used nearly exclusively in civil engineering (earthwork and road construction sector) as open-loop recycling. Due to the planned stricter limit values for the protection of soil and water, however, this recycling path in civil engineering may no longer be applicable in the future. According to some new guidelines and standards adopted recently, recycled aggregates may also be used for concrete production in the structural engineering sector (closed-loop recycling). Wastes from the structural engineering sector can thus be kept in a closed cycle, and their disposal on a landfill can be avoided. The present report focuses on the determination of maximum waste volumes that may be handled by this new recycling option. Potential adverse effects on the saving of resources and climate protection have been analysed. For this purpose, materials flow analysis and ecobalancing methods have been used.

Installation and performance of lightweight aggregate asphaltic concrete test sections.

DOT National Transportation Integrated Search

1970-01-01

In 1966 and 1968 test sections of asphaltic concrete overlays fabricated with coarse lightweight aggregate and fine limestone were installed in the Roanoke-Bedford area. The experimental mixes used were designed in an attempt to develop skid resistan...

Long-term leaching from recycled concrete aggregates applied as sub-base material in road construction.

PubMed

Engelsen, Christian J; van der Sloot, Hans A; Petkovic, Gordana

2017-06-01

In the present study, the metal leaching from recycled concrete aggregates (RCA) used in road sub-base is presented after >10years of exposure. The released levels of inorganic constituents, the effect of small variation of pH and the use of de-icing salt during winter season were studied. In addition, speciation modelling for the major elements has been provided. The pH varied from 7.5 to 8.5 for the sub-base constructed with RCA whereas the pH of around 8 was obtained for the test section not affected by the traffic and de-icing salts. Despite a small variation in pH, the leachability of Al, Ca and Mg was found to be strongly dependent on pH and fair agreement between the measured and predicted concentrations was obtained. The speciation modelling indicated that gibbsite, calcite and magnesite controlled the solubility of Al, Ca and Mg, respectively, which was in agreement with the expected carbonation products. Due to the larger pH fluctuations in the test sections exposed to the road traffic, increased concentrations were observed for the oxyanions. The same effect was not seen for the trace metal cations Cd, Cu, Ni, Pb and Zn. The distinct pH dependent leaching profile (solubility maximum in the mildly basic pH region) for vanadium could be seen after 10years of exposure. The simplified risk assessment showed that the released quantities did not exceed the chosen acceptance criteria for groundwater and fresh water. The results obtained for the test section not influenced by road dust and de-icing salts, complied with these criteria even without considering any dilution effects caused by the mixing of pore water with groundwater. Copyright © 2017 Elsevier B.V. All rights reserved.

Domestic waste recycling, collective action and economic incentive: the case in Hong Kong.

PubMed

Yau, Yung

2010-12-01

Efficacy of waste recycling is one of the key determinants of environmental sustainability of a city. Like other pro-environmental activities, waste recycling cannot be successfully accomplished by just one or two people, but only by a concerted effort of the community. The collective-action dilemma creates a common underlying difficulty in formulating workable solutions to many environmental problems. With a view to the non-excludability of the outcome, rationality drives people to free-ride efforts of others in waste recycling. To solve this free-rider problem, some scholars suggest the use of economic incentive. This article attempts to study the impacts of reward schemes on waste recycling behaviour of residents in 122 private housing estates in Hong Kong. The study is differentiable from the others as the latter mainly focus on domestic waste recycling in low-rise low-density housing while this one looks into the same in a high-rise high-density residential setting. According to the results of analyses on a set of aggregate data, reward schemes are found to have a significant positive relationship with the per-household weight of recyclables collected, keeping other things constant. The research findings suggest that economic incentives do work in promoting waste recycling in Hong Kong. Practical and policy implications follow. Copyright © 2010 Elsevier Ltd. All rights reserved.

The structure of microbial community in aggregates of a typical chernozem aggregates under contrasting variants of its agricultural use

NASA Astrophysics Data System (ADS)

Ivanova, E. A.; Kutovaya, O. V.; Tkhakakhova, A. K.; Chernov, T. I.; Pershina, E. V.; Markina, L. G.; Andronov, E. E.; Kogut, B. M.

2015-11-01

The taxonomic structure of microbiomes in aggregates of different sizes from typical chernozems was investigated using sequencing of the 16S rRNA gene. The aggregate fractions of <0.25, 2-5, and >7 mm obtained by sieving of the soil samples at natural moisture were used for analysis. The highest prokaryote biomass (bacteria, archaea) was determined in the fractions <0.25 and aggregates 2-5 mm; the bacterial and archaeal biomass decreased in the following series: fallow > permanent black fallow > permanent winter wheat. The greatest number of fungi was recorded in the fraction <0.25 mm from the soils of the permanent black fallow and in all the studied aggregate fractions in the variant with permanent wheat. The system of agricultural use affected more significantly the structure of the prokaryote community in the chernozem than the size of aggregate fractions did. The most diverse microbial community was recorded in the soil samples of the fallow; the statistically significant maximums of the Shannon diversity indices and indices of phylogenetic diversity (PD) were recorded in the fractions <0.25 and 2-5 mm from the fallow soil. On the whole, the fine soil fractions (<0.25 mm) were characterized by higher diversity indices in comparison with those of the coarser aggregate fractions.

Evaluation of cement and fly ash treated RAP and aggregates for base construction : research project capsule

DOT National Transportation Integrated Search

2009-03-01

INTRODUCTION: Many entities currently use recycled asphalt pavement (RAP) and other aggregates as base material, temporary haul roads, and in hot mix asphalt construction. Several states allow the use of RAP combined with cement for stabilized base c...

Shock fabrics in fine-grained micrometeorites

NASA Astrophysics Data System (ADS)

Suttle, M. D.; Genge, M. J.; Russell, S. S.

2017-10-01

The orientations of dehydration cracks and fracture networks in fine-grained, unmelted micrometeorites were analyzed using rose diagrams and entropy calculations. As cracks exploit pre-existing anisotropies, analysis of their orientation provides a mechanism with which to study the subtle petrofabrics preserved within fine-grained and amorphous materials. Both uniaxial and biaxial fabrics are discovered, often with a relatively wide spread in orientations (40°-60°). Brittle deformation cataclasis and rotated olivine grains are reported from a single micrometeorite. This paper provides the first evidence for impact-induced shock deformation in fine-grained micrometeorites. The presence of pervasive, low-grade shock features in CM chondrites and CM-like dust, anomalously low-density measurements for C-type asteroids, and impact experiments which suggest CM chondrites are highly prone to disruption all imply that CM parent bodies are unlikely to have remained intact and instead exist as a collection of loosely aggregated rubble-pile asteroids, composed of primitive shocked clasts.

Aggregate resource availability in the conterminous United States, including suggestions for addressing shortages, quality, and environmental concerns

USGS Publications Warehouse

Langer, William H.

2011-01-01

Although potential sources of aggregate are widespread throughout the United States, many sources may not meet certain physical property requirements, such as soundness, hardness, strength, porosity, and specific gravity, or they may contain contaminants or deleterious materials that render them unusable. Encroachment by conflicting land uses, permitting considerations, environmental issues, and societal pressures can prevent or limit development of otherwise suitable aggregate. The use of sustainable aggregate resource management can help ensure an economically viable supply of aggregate. Sustainable aggregate resource management techniques that have successfully been used include (1) protecting potential resources from encroachment; (2) using marginal-quality local aggregate for applications that do not demand a high-quality resource; (3) using substitute materials such as clinker, scoria, and recycled asphalt and concrete; and (4) using rail and water to transport aggregates from remote sources.

Motivation recycling: pre-recycling case study in Minsk, Belarus.

PubMed

Miafodzyeva, Sviatlana; Brandt, Nils; Olsson, Monika

2010-04-01

Given the aim of motivating householders to behave in a recycling-friendly manner, there is a need to understand consumers' recycling behaviour. This paper documents and analyses acceptability and awareness of a pre-recycling society, through a survey carried out in the region of Minsk, Belarus. The results show a large number of people have no strong awareness about separate collection of household waste for recycling. By analysing the pre-recycling behaviour of Minsk citizens and substantive comparison with literature studies of a more mature recycling society such as Sweden, we indicate common sociodemographic variables for both cases and determine that these sociodemographic characteristics will directly influence recycling behaviour in countries like Belarus. It is also noted that the lack of recycling habit cannot directly predict subsequent recycling behaviour on the stage of implementation the recycling system.

Combined research effort on aggregate road materials

NASA Astrophysics Data System (ADS)

Kuznetsova, Elena; Hoff, Inge; Willy Danielsen, Svein; Wigum, Børge Johannes; Fladvad, Marit; Rieksts, Karlis; Loranger, Benoit; Barbieri, Diego

2017-04-01

) mechanical and c) thermal properties, and d) frost action and susceptibility. The main goal of the PhD topic N1 is to achieve better utilization of aggregate resources through adjusting the production process according to local geological conditions and construction needs. The objective of the PhD project N2 is to look at the design stage and find the way to use these aggregates anyway by changing the road's design (e.g. increasing the thickness of asphalt layer). Fine particles content will also be harder to control due to rock type variability from site to site. Thus, PhD project N3 is going to investigate the effect of the increasing of fines and their mineralogy on frost action related problems during freezing and thawing seasons. Finally, PhD project N4 is investigating how the grading and mineralogy of the crushed rock material affects the heat exchange in road's granular layers and consequently, the frost penetration depth. Combining these PhD studies we aim to create a holistic approach for a new understanding within this very complex area.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Physical and mechanical properties of mortars containing PET and PC waste aggregates.

PubMed

Hannawi, Kinda; Kamali-Bernard, Siham; Prince, William

2010-11-01

Non-biodegradable plastic aggregates made of polycarbonate (PC) and polyethylene terephthalate (PET) waste are used as partial replacement of natural aggregates in mortar. Various volume fractions of sand 3%, 10%, 20% and 50% are replaced by the same volume of plastic. This paper investigates the physical and mechanical properties of the obtained composites. The main results of this study show the feasibility of the reuse of PC and PET waste aggregates materials as partial volume substitutes for natural aggregates in cementitious materials. Despite of some drawbacks like a decrease in compressive strength, the use of PC and PET waste aggregates presents various advantages. A reduction of the specific weight of the cementitious materials and a significant improvement of their post-peak flexural behaviour are observed. The calculated flexural toughness factors increase significantly with increasing volume fraction of PET and PC-aggregates. Thus, addition of PC and PET plastic aggregates in cementitious materials seems to give good energy absorbing materials which is very interesting for several civil engineering applications like structures subjected to dynamic or impact efforts. The present study has shown quite encouraging results and opened new way for the recycling of PC waste aggregate in cement and concrete composites. Copyright © 2010 Elsevier Ltd. All rights reserved.

Recycling.

ERIC Educational Resources Information Center

Sinker, Barbara

1986-01-01

Discusses the range of benefits resulting from recycling efforts and projects. Presents information and data related to the recycling of metals, cans, paper, fans, and plastics. Suggestions for motivating and involving youth in recycling programs are also offered. (ML)

Recycling

NASA Astrophysics Data System (ADS)

Goto, Junya; Santorelli, Michael

Recycling systems are classified into those employing typically three methods, and the progress of each method is described. In mechanical recycling, powders of phenolic materials are recovered via a mechanical process and reused as fillers or additives in virgin materials. The effects to flowability, curability, and mechanical properties of the materials are explained. In feedstock recycling, monomers, oligomers, or oils are recovered via chemical processes and reused as feedstock. Pyrolysis, solvolysis or hydrolysis, and supercritical or subcritical fluid technology will also be introduced. When using a subcritical fluid of phenol, the recycled material maintains excellent properties similar to the virgin material, and a demonstration plant has been constructed to carry out mass production development. In energy recovery, wastes of phenolic materials are used as an alternative solid fuel to coal because they are combustible and have good calorific value. Industrial wastes of these have been in practical use in a cement plant. Finally, it is suggested that the best recycling method should be selected according to the purpose or situation, because every recycling method has both strengths and weaknesses. Therefore, quantitative and objective evaluation methods in recycling are desirable and should be established.

Effects of coarse aggregate on the physical properties of Florida concrete mixes.

DOT National Transportation Integrated Search

2015-10-01

Portland cement concrete is a heterogeneous, composite material composed of coarse and fine granular material : embedded in a matrix of hardened paste. The coarse material is aggregate, which is primarily used as inexpensive filler : and comprises th...

Characterisation of excavated fine fraction and waste composition from a Swedish landfill.

PubMed

Jani, Yahya; Kaczala, Fabio; Marchand, Charlotte; Hogland, Marika; Kriipsalu, Mait; Hogland, William; Kihl, Anders

2016-12-01

The present research studies the characterisation and the physico-chemical properties of an excavated fine fraction (<10 mm) from a Swedish landfill, the Högbytorp. The results showed that the fine fraction represents 38% by mass of the total excavated wastes and it contains mainly soil-type materials and minerals. Higher concentrations of zinc, copper, barium and chromium were found with concentrations higher than the Swedish Environmental Protection Agency (EPA) for contaminated soil. The found moisture and organic contents of the fine fraction were 23.5% and 16.6%, respectively. The analysed calorific value (1.7 MJ kg -1 ), the potential of CH 4 (4.74 m 3  t -1 dry matter) and Total Organic Carbon (TOC) (5.6%) were low and offer low potential of energy. Sieving the fine fraction further showed that 80% was smaller than 2 mm. The fine represents a major fraction at any landfill (40%-70%), therefore, characterising the properties of this fraction is essential to find the potential of reusing/recycling or safely redisposing. © The Author(s) 2016.

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

PubMed

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

2013-03-01

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

Aeolian comminution experiments revealing surprising sandball mineral aggregates

NASA Astrophysics Data System (ADS)

Nørnberg, P.; Bak, E.; Finster, K.; Gunnlaugsson, H. P.; Iversen, J. J.; Jensen, S. Knak; Merrison, J. P.

2014-06-01

We have undertaken a set of wind erosion experiments on a simple and well defined mineral, quartz. In these experiments wind action is simulated by end over end tumbling of quartz grains in a sealed quartz flask. The tumbling induces collisions among the quartz grains and the walls of the flask. This process simulates wind action impact speed of ∼1.2 m/s. After several months of tumbling we observed the formation of a large number of spherical sand aggregates, which resemble small snowballs under optical microscopy. Upon mechanical load the aggregates are seen to be more elastic than quartz and their mechanical strength is comparable, though slightly lower than that of sintered silica aerogels. Aggregates of this kind have not been reported from field sites or from closed circulation systems. However, sparse occurrence might explain this, or in nature the concentration of the aggregate building particles is so low that they never meet and just appear as the most fine grained tail of the sediment particle size distribution.

Separation and recovery of fine particles from waste circuit boards using an inflatable tapered diameter separation bed.

PubMed

Duan, Chenlong; Sheng, Cheng; Wu, Lingling; Zhao, Yuemin; He, Jinfeng; Zhou, Enhui

2014-01-01

Recovering particle materials from discarded printed circuit boards can enhance resource recycling and reduce environmental pollution. Efficiently physically separating and recovering fine metal particles (-0.5 mm) from the circuit boards are a key recycling challenge. To do this, a new type of separator, an inflatable tapered diameter separation bed, was developed to study particle motion and separation mechanisms in the bed's fluid flow field. For 0.5-0.25 mm circuit board particles, metal recovery rates ranged from 87.56 to 94.17%, and separation efficiencies ranged from 87.71 to 94.20%. For 0.25-0.125 mm particles, metal recovery rates ranged from 84.76 to 91.97%, and separation efficiencies ranged from 84.74 to 91.86%. For superfine products (-0.125 mm), metal recovery rates ranged from 73.11 to 83.04%, and separation efficiencies ranged from 73.00 to 83.14%. This research showed that the inflatable tapered diameter separation bed achieved efficient particle separation and can be used to recover fine particles under a wide range of operational conditions. The bed offers a new mechanical technology to recycle valuable materials from discarded printed circuit boards, reducing environmental pollution.

Crushed aggregates for roads and their properties for frost protection

NASA Astrophysics Data System (ADS)

Kuznetsova, Elena; Willy Danielsen, Svein

2015-04-01

of the road system. According to new specification; the size of large stones for this layer should be maximum 0.5 m (longest edge) or ½ layer thickness. And minimum 30% of stones should be less than 90 mm. Fines content (<0.063 mm) should be maximum 15% of the material less than 22.4 mm. Analysing these new requirements, several questions are arising. First of all how this materials size will affect heat exchange in the layer, secondly - if the allowable fines content will make the materials frost susceptible. For calculations of frost protection layer thickness the knowledge of thermal conductivity of the aggregate layers is required. Handbook for geotechnical investigations of the soils provides this data for natural gravel which is limited by 0.7 - 1.3 W/mK. But when it comes to the crushed rocks, it can be significantly increased due to the higher conductivity of minerals (especially if they contain high amount of quartz), as well as due to higher effective conductivity. In rock-fill materials, i.e. materials with large particles and low degree of saturation, convection and radiation are the predominant heat transfer mechanisms. Convection and radiation can increase the effective conductivity by factor 2-10. Lebeau and Konrad (2007) showed that convection heat transfer could lead to the formation of undesirable permafrost conditions in toe drains of embankment dams located in Northern Quebec, i.e. in areas where there are no naturally occurring permafrost soils. In a frost design method the required parameter values of crushed rock aggregates are thermal conductivity, density and water content. The heat transfer during the freezing of natural soils is assumed proportional to thermal conductivity of the material. In a coarse-grained material with abundant pore space, convective heat transfer and radiation may be a considerable factor, sometimes even more significant than conduction. Specifications used by pavement engineers in most countries are solely based on

Comparison of recycling outcomes in three types of recycling collection units.

PubMed

Andrews, Ashley; Gregoire, Mary; Rasmussen, Heather; Witowich, Gretchen

2013-03-01

Commercial institutions have many factors to consider when implementing an effective recycling program. This study examined the effectiveness of three different types of recycling bins on recycling accuracy by determining the percent weight of recyclable material placed in the recycling bins, comparing the percent weight of recyclable material by type of container used, and examining whether a change in signage increased recycling accuracy. Data were collected over 6 weeks totaling 30 days from 3 different recycling bin types at a Midwest University medical center. Five bin locations for each bin type were used. Bags from these bins were collected, sorted into recyclable and non-recyclable material, and weighed. The percent recyclable material was calculated using these weights. Common contaminates found in the bins were napkins and paper towels, plastic food wrapping, plastic bags, and coffee cups. The results showed a significant difference in percent recyclable material between bin types and bin locations. Bin type 2 was found to have one bin location to be statistically different (p=0.048), which may have been due to lack of a trash bin next to the recycling bin in that location. Bin type 3 had significantly lower percent recyclable material (p<0.001), which may have been due to lack of a trash bin next to the recycling bin and increased contamination due to the combination of commingled and paper into one bag. There was no significant change in percent recyclable material in recycling bins post signage change. These results suggest a signage change may not be an effective way, when used alone, to increase recycling compliance and accuracy. This study showed two or three-compartment bins located next to a trash bin may be the best bin type for recycling accuracy. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cleaning and dewatering fine coal

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

Yoon, Roe-Hoan; Eraydin, Mert K.; Freeland, Chad

Fine coal is cleaned of its mineral matter impurities and dewatered by mixing the aqueous slurry containing both with a hydrophobic liquid, subjecting the mixture to a phase separation. The resulting hydrophobic liquid phase contains coal particles free of surface moisture and droplets of water stabilized by coal particles, while the aqueous phase contains the mineral matter. By separating the entrained water droplets from the coal particles mechanically, a clean coal product of substantially reduced mineral matter and moisture contents is obtained. The spent hydrophobic liquid is separated from the clean coal product and recycled. The process can also bemore » used to separate one type of hydrophilic particles from another by selectively hydrophobizing one.« less

A recycling index for food and health security: urban Taipei.

PubMed

Huang, Susana Tzy-Ying

2010-01-01

The modern food system has evolved into one with highly inefficient activities, producing waste at each step of the food pathway from growing to consumption and disposal. The present challenge is to improve recyclability in the food system as a fundamental need for food and health security. This paper develops a methodological approach for a Food Recycling Index (FRI) as a tool to assess recyclability in the food system, to identify opportunities to reduce waste production and environmental contamination, and to provide a self-assessment tool for participants in the food system. The urban Taipei framework was used to evaluate resource and nutrient flow within the food consumption and waste management processes of the food system. A stepwise approach for a FRI is described: (1) identification of the major inputs and outputs in the food chain; (2) classification of inputs and outputs into modules (energy, water, nutrients, and contaminants); (3) assignment of semi-quantitative scores for each module and food system process using a matrix; (4) assessment for recycling status and recyclability potential; (5) conversion of scores into sub-indices; (6) derivation of an aggregate FRI. A FRI of 1.24 was obtained on the basis of data for kitchen waste management in Taipei, a score which encompasses absolute and relative values for a comprehensive interpretation. It is apparent that a FRI could evolve into a broader ecosystem concept with health relevance. Community end-users and policy planners can adopt this approach to improve food and health security.

Flotation mechanisms of molybdenite fines by neutral oils

NASA Astrophysics Data System (ADS)

Lin, Qing-quan; Gu, Guo-hua; Wang, Hui; Liu, You-cai; Fu, Jian-gang; Wang, Chong-qing

2018-01-01

The flotation mechanisms of molybdenite fines by neutral oils were investigated through microflotation test, turbidity measurements, infrared spectroscopy, and interfacial interaction calculations. The results of the flotation test show that at pH 2-11, the floatability of molybdenite fines in the presence of transformer oil is markedly better than that in the presence of kerosene and diesel oil. The addition of transformer oil, which enhances the floatability of molybdenite fines, promotes the aggregation of molybdenite particles. Fourier transform infrared measurements illustrate that physical interaction dominates the adsorption mechanism of neutral oil on molybdenite. Interfacial interaction calculations indicate that hydrophobic attraction is the crucial force that acts among the oil collector, water, and molybdenite. Strong hydrophobic attraction between the oily collector and water provides the strong dispersion capability of the collector in water. Furthermore, the dispersion capability of the collector, not the interaction strength between the oily collectors and molybdenite, has a highly significant role in the flotation system of molybdenite fines. Our findings provide insights into the mechanism of molybdenite flotation.

Size-dependent distribution and inhalation cancer risk of particle-bound polycyclic aromatic hydrocarbons at a typical e-waste recycling and an urban site.

PubMed

Luo, Pei; Bao, Lian-Jun; Li, Shao-Meng; Zeng, Eddy Y

2015-05-01

Atmospheric particle size distribution of polycyclic aromatic hydrocarbons (PAHs) in a typical e-waste recycling zone and an urban site (Guangzhou) in southern China featured a unimodal peak in 0.56-1.8 μm for 4-6 ring PAHs but no obvious peak for 2-3 ring PAHs at both sites. The atmospheric deposition fluxes of PAHs were estimated at 5.4 ± 2.3 μg m(-2) d(-1) in the e-waste recycling zone and 3.1 ± 0.6 μg m(-2) d(-1) in Guangzhou. In addition, dry and wet deposition fluxes of PAHs were dominated by coarse (Dp > 1.8 μm) and fine particles (Dp < 1.8 μm), respectively. Fine particles predominated the deposition of PAHs in the lung. The results estimated by incremental inhalation cancer risk suggested that particle-bound PAHs posed serious threat to human health within the e-waste recycling zone and Guangzhou. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanical Properties of Portland Cement Concrete With Recycled Asphalt Pavement as Partial Replacement for Coarse Aggregate

DOT National Transportation Integrated Search

2016-06-01

Finding constructive uses for construction waste byproducts contributes to green engineering principles. One such plentiful material is recycled asphalt pavement (RAP). This report looks at the mechanical viability of including RAP in a high strength...

Targeting high value metals in lithium-ion battery recycling via shredding and size-based separation.

PubMed

Wang, Xue; Gaustad, Gabrielle; Babbitt, Callie W

2016-05-01

Development of lithium-ion battery recycling systems is a current focus of much research; however, significant research remains to optimize the process. One key area not studied is the utilization of mechanical pre-recycling steps to improve overall yield. This work proposes a pre-recycling process, including mechanical shredding and size-based sorting steps, with the goal of potential future scale-up to the industrial level. This pre-recycling process aims to achieve material segregation with a focus on the metallic portion and provide clear targets for subsequent recycling processes. The results show that contained metallic materials can be segregated into different size fractions at different levels. For example, for lithium cobalt oxide batteries, cobalt content has been improved from 35% by weight in the metallic portion before this pre-recycling process to 82% in the ultrafine (<0.5mm) fraction and to 68% in the fine (0.5-1mm) fraction, and been excluded in the larger pieces (>6mm). However, size fractions across multiple battery chemistries showed significant variability in material concentration. This finding indicates that sorting by cathode before pre-treatment could reduce the uncertainty of input materials and therefore improve the purity of output streams. Thus, battery labeling systems may be an important step towards implementation of any pre-recycling process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Properties of Cement Mortar by Use of Hot-Melt Polyamides as Substitute for Fine Aggregate

PubMed Central

Yuan, Xiongzhou; Xu, Weiting; Sun, Wei; Xing, Feng; Wang, Weilun

2015-01-01

This paper presents an experimental study on use of hot-melt polyamide (HMP) to prepare mortar specimens with improved crack healing and engineering properties. The role of HMP in the crack repairing of cement mortar subjected to several rounds of heat treatment was investigated. Compatibility between HMP and hydraulic cement was investigated through X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR) technology. Mortar specimens were prepared using standard cement mortar mixes with HMP at 1%, 3% and 5% (by volume) for fine aggregate substitute. After curing for 28 days, HMP specimens were subjected to heating at temperature of 160 °C for one, two, and three days and then natural cooling down to ambient temperature. Mechanical and durability properties of the heated HMP mortars were evaluated and compared with those of the corresponding mortars without heating. The microscopic observation of the interfacial transition zone (ITZ) of HMP mortar was conducted through environmental scanning electron microscopy (ESEM). Results reveal that incorporation of HMP improves the workability of the HMP/cement binder while leading to decrease in compressive strength and durability. The heated HMP mortars after exposure to heating for one, two, and three days exhibit no obvious change in compressive strength while presenting notable increase in flexural strength and durability compared with the corresponding mortars without heating. The XRD, FTIR and ESEM analyses indicate that no obvious chemical reaction occurs between HMP and hydraulic cement, and thus the self-repairing for interfacial micro-crack in HMP/cement composite system is ascribed to the physical adhesion of HMP to cement matrix rather than the chemical bonding between them.

The Beverage Can in the United States: Achieving a 100% Recycled Aluminum Can through Supply Chain Innovation

NASA Astrophysics Data System (ADS)

Buffington, Jack

2012-08-01

The purpose of this research is to analyze why recycled content is low (33-50%) in the aluminum can in the United States when it is technically possible to have a product that is made from 100% recycled material. A comprehensive literature review is conducted, followed by identification of five propositions determined with respect to the research problem. With respect to aluminum can recycling (and its research), there is a greater focus on the role of the consumer than the producer in the aluminum can supply chain system, which may impact on the role of innovation in addressing the problem. The upstream primary aluminum supply chain is vertically integrated and efficient within itself, but not integrated with the downstream secondary aluminum can market. Given the importance of the secondary aluminum market in the United States, there are significant recycling/efficiency/sustainability opportunities to address. As opposed to a dominant focus on consumers and their recycling habits, this study focuses on the aggregate aluminum can supply chain to apply innovation to the solution.

Analysis of efficiency of waste reverse logistics for recycling.

PubMed

Veiga, Marcelo M

2013-10-01

Brazil is an agricultural country with the highest pesticide consumption in the world. Historically, pesticide packaging has not been disposed of properly. A federal law requires the chemical industry to provide proper waste management for pesticide-related products. A reverse logistics program was implemented, which has been hailed a great success. This program was designed to target large rural communities, where economy of scale can take place. Over the last 10 years, the recovery rate has been very poor in most small rural communities. The objective of this study was to analyze the case of this compulsory reverse logistics program for pesticide packaging under the recent Brazilian Waste Management Policy, which enforces recycling as the main waste management solution. This results of this exploratory research indicate that despite its aggregate success, the reverse logistics program is not efficient for small rural communities. It is not possible to use the same logistic strategy for small and large communities. The results also indicate that recycling might not be the optimal solution, especially in developing countries with unsatisfactory recycling infrastructure and large transportation costs. Postponement and speculation strategies could be applied for improving reverse logistics performance. In most compulsory reverse logistics programs, there is no economical solution. Companies should comply with the law by ranking cost-effective alternatives.

Transitional grain-size-sensitive flow of milky quartz aggregates

NASA Astrophysics Data System (ADS)

Fukuda, J. I.; Holyoke, C. W., III; Kronenberg, A. K.

2014-12-01

Fine-grained (~15 μm) milky quartz aggregates exhibit reversible flow strengths in triaxial compression experiments conducted at T = 800-900oC, Pc = 1.5 GPa when strain rates are sequentially decreased (typically from 10-3.5 to 10-4.5 and 10-5.5 s-1), and then returned to the original rate (10-3.5 s-1), while samples that experience grain growth at 1000oC (to 35 μm) over the same sequence of strain rates exhibit an irreversible increase in strength. Polycrystalline quartz aggregates have been synthesized from natural milky quartz powders (ground to 5 μm) by HIP methods at T = 1000oC, Pc = 1.5 GPa and t = 24 hours, resulting in dense, fine-grained aggregates of uniform water content of ~4000 ppm (H/106Si), as indicated by a broad OH absorption band at 3400 cm-1. In experiments performed at 800o and 900oC, grain sizes of the samples are essentially constant over the duration of each experiment, though grain shapes change significantly, and undulatory extinction and deformation lamellae indicate that much of the sample shortening (to 50%) is accomplished, over the four strain-rate steps, by dislocation creep. Differential stresses measured at T = 800oC decrease from 160 to 30 MPa as strain rate is reduced from 10-4.6 to 10-5.5 s-1, and a stress of 140 MPa is measured when strain rate is returned to 10-4.5 s-1. Samples deformed at 1000o and 1100oC experience normal grain growth, with grain boundary energy-driven grain-coarsening textures superposed by undulatory extinction and deformation lamellae. Differential stresses measured at 1000oC and strain rates of 10-3.6, 10-4.6, and 10-5.5 s-1 are 185, 80, and 80 MPa, respectively, while an increased flow stress of 260 MPa is measured (following ~28 hours of prior high temperature deformation and grain growth) when strain rate is returned to 10-3.6 s-1. While all samples exhibit lattice preferred orientations, the stress exponent n inferred for the fine-grained 800oC sample is 1.5 and the stress exponent of the coarse

Bacterial density and community structure associated with aggregate size fractions of soil-feeding termite mounds.

PubMed

Fall, S; Nazaret, S; Chotte, J L; Brauman, A

2004-08-01

The building and foraging activities of termites are known to modify soil characteristics such as the heterogeneity. In tropical savannas the impact of the activity of soil-feeding termites ( Cubitermes niokoloensis) has been shown to affect the properties of the soil at the aggregate level by creating new soil microenvironments (aggregate size fractions) [13]. These changes were investigated in greater depth by looking at the microbial density (AODC) and the genetic structure (automated rRNA intergenic spacer analysis: ARISA) of the communities in the different aggregate size fractions (i.e., coarse sand, fine sand, coarse silt, fine silt, and dispersible clays) separated from compartments (internal and external wall) of three Cubitermes niokoloensis mounds. The bacterial density of the mounds was significantly higher (1.5 to 3 times) than that of the surrounding soil. Within the aggregate size fractions, the termite building activity resulted in a significant increase in bacterial density within the coarser fractions (>20 mum). Multivariate analysis of the ARISA profiles revealed that the bacterial genetic structures of unfractionated soil and soil aggregate size fractions of the three mounds was noticeably different from the savanna soil used as a reference. Moreover, the microbial community associated with the different microenvironments in the three termite mounds revealed three distinct clusters formed by the aggregate size fractions of each mound. Except for the 2-20 mum fraction, these results suggest that the mound microbial genetic structure is more dependent upon microbial pool affiliation (the termite mound) than on the soil location (aggregate size fraction). The causes of the specificity of the microbial community structure of termite mound aggregate size fractions are discussed.

Recycling Lesson Plan

ERIC Educational Resources Information Center

Okaz, Abeer Ali

2013-01-01

This lesson plan designed for grade 2 students has the goal of teaching students about the environmental practice of recycling. Children will learn language words related to recycling such as: "we can recycle"/"we can't recycle" and how to avoid littering with such words as: "recycle paper" and/or "don't throw…

Study on identically voided pervious concrete made with different sized aggregates

NASA Astrophysics Data System (ADS)

Kastro Kiran, V.; Anand, K. B.

2018-02-01

Pervious concrete (PC) is also known as no fines concrete and has been found to be a reliable stormwater management tool. As a substitution for conventional impervious pavement, PC usage has been increasing during recent years. PC made with different sized aggregate shows different void ratios and changed properties. As void ratio plays a notable role on strength and permeability of PC, this study aims to focus on properties of PC at identical void ratio of 20%, made using aggregates of three size ranges, viz., 4.75-6mm, 10-12.5mm, and 10-20mm. Appropriate alternatives were used to maintain the identical void ratio. As the permeation capacity of PC gets reduced due to the clogging tendency, the life of PC will also get reduced. Hence, to make the PC to sustain for a long time it is necessary to study the clogging behavior. This study investigates the tendency of PC for clogging and the potential for regaining the permeability through de-clogging methods. Clogging tendency of PC is studied by using two sizes (coarse and fine) of clog particles and the changes in permeability are observed. Efficiency of declogging methods like pressure washing and vacuum suction on PC with different sized aggregates are also evaluated.

Experimental Assessment of Recycled Diesel Spill-Contaminated Domestic Wastewater Treated by Reed Beds for Irrigation of Sweet Peppers

PubMed Central

Almuktar, Suhad A.A.A.N.; Scholz, Miklas

2016-01-01

The aim of this experimental study is to assess if urban wastewater treated by ten different greenhouse-based sustainable wetland systems can be recycled to irrigate Capsicum annuum L. (Sweet Pepper; California Wonder) commercially grown either in compost or sand within a laboratory environment. The design variables were aggregate diameter, contact time, resting time and chemical oxygen demand. The key objectives were to assess: (i) the suitability of different treated (recycled) wastewaters for irrigation; (ii) response of peppers in terms of growth when using recycled wastewater subject to different growth media and hydrocarbon contamination; and (iii) the economic viability of different experimental set-ups in terms of marketable yield. Ortho-phosphate-phosphorus, ammonia-nitrogen, potassium and manganese concentrations in the irrigation water considerably exceeded the corresponding water quality thresholds. A high yield in terms of economic return (marketable yield expressed in monetary value) was linked to raw wastewater and an organic growth medium, while the plants grown in organic medium and wetlands of large aggregate size, high contact and resting times, diesel-spill contamination and low inflow loading rate produced the best fruits in terms of their dimensions and fresh weights, indicating the role of diesel in reducing too high nitrogen concentrations. PMID:26861370

PRESENT CONDITION OF FOOD WASTE RECYCLING LOOP BASED ON RECYCLING PROJECT CERTIFICATION OF THE FOOD WASTE RECYCLING LAW

NASA Astrophysics Data System (ADS)

Kita, Tomoko; Kanaya, Ken

Purpose of this research is to clear present condition of food waste recycling loops based on recycling project certification of the Food Waste Recycling Law. Method of this research is questionnaire survey to companies constituting the loops. Findings of this research are as follows: 1. Proponents of the loop is most often the recycling companies. 2. Food waste recycling rate is 61% for the food retailing industry and 81% for the food service industry. These values are higher than the national average in 2006. The effect of the revision of recycling project certification is suggested.

Simple technology for recycling phosphate from wastewater to farmland in rural areas.

PubMed

Ohtake, Hisao; Okano, Kenji; Kunisada, Masashi; Takano, Hiroyuki; Toda, Masaya

2018-01-01

A simple technology for phosphate (P i ) recovery has been developed using a bifunctional adsorption-aggregation agent. The bifunctional agent was prepared by soaking calcium silicates in hydrochloric acid solution. Importantly, recyclable calcium silicates were available almost free of charge from the cement industry and also from the steel industry. The acid treatment was essential not only for enhancing the ability of calcium silicates to remove P i from aqueous solution but also for enabling the high settleability of removed P i . On-site experiments using a mobile plant showed that approximately 80% P i could be recovered from anaerobic sludge digestion liquor at a wastewater treatment plant. This technology has the potential to offer a simple, compact service for recycling P i from wastewater to farmland in rural areas.

Detecting deleterious fine particles in concrete aggregates and defining their impact : research brief.

DOT National Transportation Integrated Search

2011-02-01

As concrete hardens, it develops mechanical properties such as strength and stiffness that depend in part on the ratios of the water, cement paste and aggregate gravel that compose it. While enough water must be added to concrete so it can be mixed, ...

Environmentalism and natural aggregate mining

USGS Publications Warehouse

Drew, L.J.; Langer, W.H.; Sachs, J.S.

2002-01-01

living space has encroached on the sites of production; in other words, the act of production has engendered condemnation. Many other environmental problems that are associated with dust and noise and blasting from quarry and pit operations have been reduced through the efficient use of technology. Recycling concrete in buildings, bridges, and roads and asphaltic pavements will ultimately reduce the demand for virgin natural aggregate. The impact created by the large holes in the ground required for the mining of natural aggregate can be greatly reduced by planning their reclamation before mining begins. ?? 2002 International Association for Mathematical Geology.

Real-time imaging of Huntingtin aggregates diverting target search and gene transcription

PubMed Central

Li, Li; Liu, Hui; Dong, Peng; Li, Dong; Legant, Wesley R; Grimm, Jonathan B; Lavis, Luke D; Betzig, Eric; Tjian, Robert; Liu, Zhe

2016-01-01

The presumptive altered dynamics of transient molecular interactions in vivo contributing to neurodegenerative diseases have remained elusive. Here, using single-molecule localization microscopy, we show that disease-inducing Huntingtin (mHtt) protein fragments display three distinct dynamic states in living cells – 1) fast diffusion, 2) dynamic clustering and 3) stable aggregation. Large, stable aggregates of mHtt exclude chromatin and form 'sticky' decoy traps that impede target search processes of key regulators involved in neurological disorders. Functional domain mapping based on super-resolution imaging reveals an unexpected role of aromatic amino acids in promoting protein-mHtt aggregate interactions. Genome-wide expression analysis and numerical simulation experiments suggest mHtt aggregates reduce transcription factor target site sampling frequency and impair critical gene expression programs in striatal neurons. Together, our results provide insights into how mHtt dynamically forms aggregates and disrupts the finely-balanced gene control mechanisms in neuronal cells. DOI: http://dx.doi.org/10.7554/eLife.17056.001 PMID:27484239

Separation and Recovery of Fine Particles from Waste Circuit Boards Using an Inflatable Tapered Diameter Separation Bed

PubMed Central

Sheng, Cheng; Wu, Lingling; Zhao, Yuemin; He, Jinfeng; Zhou, Enhui

2014-01-01

Recovering particle materials from discarded printed circuit boards can enhance resource recycling and reduce environmental pollution. Efficiently physically separating and recovering fine metal particles (−0.5 mm) from the circuit boards are a key recycling challenge. To do this, a new type of separator, an inflatable tapered diameter separation bed, was developed to study particle motion and separation mechanisms in the bed's fluid flow field. For 0.5–0.25 mm circuit board particles, metal recovery rates ranged from 87.56 to 94.17%, and separation efficiencies ranged from 87.71 to 94.20%. For 0.25–0.125 mm particles, metal recovery rates ranged from 84.76 to 91.97%, and separation efficiencies ranged from 84.74 to 91.86%. For superfine products (−0.125 mm), metal recovery rates ranged from 73.11 to 83.04%, and separation efficiencies ranged from 73.00 to 83.14%. This research showed that the inflatable tapered diameter separation bed achieved efficient particle separation and can be used to recover fine particles under a wide range of operational conditions. The bed offers a new mechanical technology to recycle valuable materials from discarded printed circuit boards, reducing environmental pollution. PMID:25379546

Recycling Lesson Plans.

ERIC Educational Resources Information Center

Pennsylvania State Dept. of Environmental Resources, Harrisburg.

This document contains lesson plans about recycling for teachers in grades K-12. Titles include: (1) "Waste--Where Does It Come From? Where Does It Go?" (2) "Litter Detectives," (3) "Classroom Paper Recycling," (4) "Recycling Survey," (5) "Disposal and Recycling Costs," (6) "Composting…

Recovery of MSWI and soil washing residues as concrete aggregates.

PubMed

Sorlini, Sabrina; Abbà, Alessandro; Collivignarelli, Carlo

2011-02-01

The aim of the present work was to study if municipal solid waste incinerator (MSWI) residues and aggregates derived from contaminated soil washing could be used as alternative aggregates for concrete production. Initially, chemical, physical and geometric characteristics (according to UNI EN 12620) of municipal solid waste incineration bottom ashes and some contaminated soils were evaluated; moreover, the pollutants release was evaluated by means of leaching tests. The results showed that the reuse of pre-treated MSWI bottom ash and washed soil is possible, either from technical or environmental point of view, while it is not possible for the raw wastes. Then, the natural aggregate was partially and totally replaced with these recycled aggregates for the production of concrete mixtures that were characterized by conventional mechanical and leaching tests. Good results were obtained using the same dosage of a high resistance cement (42.5R calcareous Portland cement instead of 32.5R); the concrete mixture containing 400 kg/m(3) of washed bottom ash and high resistance cement was classified as structural concrete (C25/30 class). Regarding the pollutants leaching, all concrete mixtures respected the limit values according to the Italian regulation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Utilization of recycled cathode ray tubes glass in cement mortar for X-ray radiation-shielding applications.

PubMed

Ling, Tung-Chai; Poon, Chi-Sun; Lam, Wai-Shung; Chan, Tai-Po; Fung, Karl Ka-Lok

2012-01-15

Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when the CRT glasses were used due to the presence of lead in the glass. In addition, the radiation shielding contribution of CRT glasses was more pronounced when the mortar was subject to a higher level of X-ray energy. Copyright © 2011 Elsevier B.V. All rights reserved.

Production of lightweight aggregates from washing aggregate sludge and fly ash

NASA Astrophysics Data System (ADS)

González-Corrochano, Beatriz; Alonso-Azcárate, Jacinto; Rodas, Magdalena

2010-05-01

Increasing generation of wastes is one of the main environmental problems in industrialised countries. Heat treatment at high temperatures can convert some types of wastes into ceramic products with a wide range of microstructural features and properties (Bethanis et al., 2004). A lightweight aggregate (LWA) is a granular material with a bulk density (bd) not exceeding 1.20 g/cm3 or with a particle density not exceeding 2.00 g/cm3 (UNE-EN-13055-1, 2003). They have become a focus of interest because the low particle density and the low bulk density entail a decrease in the load transmitted to the ground, and less work and effort are required to transport them (De' Gennaro et al., 2004). The benefits associated with these low densities, which are due to the formation of voids and pores, are very good thermal and acoustic insulation and materials with a good resistance to fire (Benbow, 1987; Fakhfakh et al., 2007). The objective was to recycle fly ash, used motor oil from cars and mineral wastes from washing aggregate sludge, in order to obtain a usable material such as lightweight aggregates, and also to ensure that they are of good quality for different applications. Raw materials have been physically, chemically and mineralogically characterized. On the basis of the results obtained, they were mixed, milled to a grain size of less than 200 μm (Yasuda, 1991), formed into pellets, pre-heated for 5 min and sintered in a rotary kiln at 1150°C, 1175°C, 1200°C and 1225°C for 10 and 15 min at each temperature (Theating). Effects of raw material characteristics, heating temperature and dwell time on the following LWAs properties were determined: loss on ignition (LOI), bloating index (BI), loose bulk density (bd), apparent and dry particle density (ad, dd), voids (H), water absorption (WA24h) and compressive strength (S). The products obtained were lightweight aggregates in accordance with norm UNE-EN-13055-1 (bd ≤1.20 g/cm3 or particle density ≤2.00 g/cm3). LWAs

Initial research on recycled tyre bales for road infrastructure applications

NASA Astrophysics Data System (ADS)

Duda, Aleksander; Sobala, Dariusz

2017-12-01

The paper reviews selected surveys carried out within the R&D project, co-financed with the European Regional Development Fund, called "ReUse - Innovative Recycling Materials, Enhancing the Sustainability of Bridge Facilities" (Innotech No. K3 / IN3 / 38/228116 / NCBiR / 15). The aim of the project and conducted research is to develop and implement innovative, cheap and environmentally-friendly recycled construction material in the form of tyre bales made from compressed used car tyres. This material is likely to be applied in civil engineering, especially in transport infrastructure, geotechnical and hydraulic engineering. New material is cheap and has unique properties such as low weight, high water permeability, high vibration and noise-damping capacity, low pressure coefficient values and other parameters that technically and economically allow it to replace natural aggregates. The extensive practical application of new material will facilitate the replacement of waste management methods with the environmentally friendly ones.

Seismic performance of recycled concrete-filled square steel tube columns

NASA Astrophysics Data System (ADS)

Chen, Zongping; Jing, Chenggui; Xu, Jinjun; Zhang, Xianggang

2017-01-01

An experimental study on the seismic performance of recycled concrete-filled square steel tube (RCFST) columns is carried out. Six specimens were designed and tested under constant axial compression and cyclic lateral loading. Two parameters, replacement percentage of recycled coarse aggregate (RCA) and axial compression level, were considered in the test. Based on the experimental data, the hysteretic loops, skeleton curves, ductility, energy dissipation capacity and stiffness degradation of RCFST columns were analyzed. The test results indicate that the failure modes of RCFST columns are the local buckling of the steel tube at the bottom of the columns, and the hysteretic loops are full and their shapes are similar to normal CFST columns. Furthermore, the ductility coefficient of all specimens are close to 3.0, and the equivalent viscous damping coefficient corresponding to the ultimate lateral load ranges from 0.323 to 0.360, which demonstrates that RCFST columns exhibit remarkable seismic performance.

CCM-3/STRIPAK promotes seamless tube extension through endocytic recycling.

PubMed

Lant, Benjamin; Yu, Bin; Goudreault, Marilyn; Holmyard, Doug; Knight, James D R; Xu, Peter; Zhao, Linda; Chin, Kelly; Wallace, Evan; Zhen, Mei; Gingras, Anne-Claude; Derry, W Brent

2015-03-06

The mechanisms governing apical membrane assembly during biological tube development are poorly understood. Here, we show that extension of the C. elegans excretory canal requires cerebral cavernous malformation 3 (CCM-3), independent of the CCM1 orthologue KRI-1. Loss of ccm-3 causes canal truncations and aggregations of canaliculular vesicles, which form ectopic lumen (cysts). We show that CCM-3 localizes to the apical membrane, and in cooperation with GCK-1 and STRIPAK, promotes CDC-42 signalling, Golgi stability and endocytic recycling. We propose that endocytic recycling is mediated through the CDC-42-binding kinase MRCK-1, which interacts physically with CCM-3-STRIPAK. We further show canal membrane integrity to be dependent on the exocyst complex and the actin cytoskeleton. This work reveals novel in vivo roles of CCM-3·STRIPAK in regulating tube extension and membrane integrity through small GTPase signalling and vesicle dynamics, which may help explain the severity of CCM3 mutations in patients.

Direct Measurements of the Convective Recycling of the Upper Troposphere

NASA Technical Reports Server (NTRS)

Bertram, Timothy H.; Perring, Anne E.; Wooldridge, Paul J.; Crounse, John D.; Kwan, Alan J.; Wennberg, Paul O.; Scheuer, Eric; Dibb, Jack; Avery, Melody; Sachse, Glen;

Metamorphosis in the Porosity of Recycled Concretes Through the Use of a Recycled Polyethylene Terephthalate (PET) Additive. Correlations between the Porous Network and Concrete Properties

PubMed Central

Mendivil-Escalante, José Miguel; Gómez-Soberón, José Manuel; Almaral-Sánchez, Jorge Luis; Cabrera-Covarrubias, Francisca Guadalupe

2017-01-01

In the field of construction, sustainable building materials are currently undergoing a process of technological development. This study aims to contribute to understanding the behavior of the fundamental properties of concretes prepared with recycled coarse aggregates that incorporate a polyethylene terephthalate (PET)-based additive in their matrix (produced by synthesis and glycolysis of recycled PET bottles) in an attempt to reduce their high porosity. Techniques to measure the gas adsorption, water porosity, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to evaluate the effect of the additive on the physical, mechanical and microstructural properties of these concretes. Porosity reductions of up to 30.60% are achieved with the addition of 1%, 3%, 4%, 5%, 7% and 9% of the additive, defining a new state in the behavioral model of the additive (the overdosage point) in the concrete matrix; in addition, the porous network of these concretes and their correlation with other physical and mechanical properties are also explained. PMID:28772540

Metamorphosis in the Porosity of Recycled Concretes Through the Use of a Recycled Polyethylene Terephthalate (PET) Additive. Correlations between the Porous Network and Concrete Properties.

PubMed

Mendivil-Escalante, José Miguel; Gómez-Soberón, José Manuel; Almaral-Sánchez, Jorge Luis; Cabrera-Covarrubias, Francisca Guadalupe

2017-02-14

In the field of construction, sustainable building materials are currently undergoing a process of technological development. This study aims to contribute to understanding the behavior of the fundamental properties of concretes prepared with recycled coarse aggregates that incorporate a polyethylene terephthalate (PET)-based additive in their matrix (produced by synthesis and glycolysis of recycled PET bottles) in an attempt to reduce their high porosity. Techniques to measure the gas adsorption, water porosity, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to evaluate the effect of the additive on the physical, mechanical and microstructural properties of these concretes. Porosity reductions of up to 30.60% are achieved with the addition of 1%, 3%, 4%, 5%, 7% and 9% of the additive, defining a new state in the behavioral model of the additive (the overdosage point) in the concrete matrix; in addition, the porous network of these concretes and their correlation with other physical and mechanical properties are also explained.

Usage of Crushed Concrete Fines in Decorative Concrete

NASA Astrophysics Data System (ADS)

Pilipenko, Anton; Bazhenova, Sofia

2017-10-01

The article is devoted to the questions of usage of crushed concrete fines from concrete scrap for the production of high-quality decorative composite materials based on mixed binder. The main problem in the application of crushed concrete in the manufacture of decorative concrete products is extremely low decorative properties of crushed concrete fines itself, as well as concrete products based on them. However, crushed concrete fines could have a positive impact on the structure of the concrete matrix and could improve the environmental and economic characteristics of the concrete products. Dust fraction of crushed concrete fines contains non-hydrated cement grains, which can be opened in screening process due to the low strength of the contact zone between the hydrated and non-hydrated cement. In addition, the screening process could increase activity of the crushed concrete fines, so it can be used as a fine aggregate and filler for concrete mixes. Previous studies have shown that the effect of the usage of the crushed concrete fines is small and does not allow to obtain concrete products with high strength. However, it is possible to improve the efficiency of the crushed concrete fines as a filler due to the complex of measures prior to mixing. Such measures may include a preliminary mechanochemical activation of the binder (cement binder, iron oxide pigment, silica fume and crushed concrete fines), as well as the usage of polycarboxylate superplasticizers. The development of specific surface area of activated crushed concrete fines ensures strong adhesion between grains of binder and filler during the formation of cement stone matrix. The particle size distribution of the crushed concrete fines could achieve the densest structure of cement stone matrix and improve its resistance to environmental effects. The authors examined the mechanisms of structure of concrete products with crushed concrete fines as a filler. The results of studies of the properties of

Marshall Space Flight Center solid waste characterization and recycling improvement study

NASA Technical Reports Server (NTRS)

Eley, Michael H.; Crews, Lavonne; Johnston, Ben; Lee, David; Colebaugh, James

1995-01-01

The MSFC Facilities Office, which is responsible for disposing of all waste generated by MSFC, issued a delivery order to the University of Alabama in Huntsville (UAH) to characterize current MSFC waste streams and to evaluate their existing recycling program. The purpose of the study was to define the nature, quantity, and types of waste produced and to generate ideas for improving the present recycling program. Specifically, the following tasks were to be performed: Identify various surplus and waste materials--as identified by the Contracting Officer's Technical Representative (COTR)--by source, location, and type; Analyze MSFC's current methods for handling, storage, transport, and disposition of waste and surplussed materials; Determine the composition of various surplus and waste materials as to type and quantities from various sources and locations; Analyze different methods for the disposition of various surplus and waste materials, including quality, quantity, preparation, transport cost, and value; Study possible alternatives to current methods of handling, storage, transport, and disposition of surplus and waste materials to improve the quality and quantities recycled or sold and to reduce and minimize the quantities of surplus and waste material currently being disposed of or stored; Provide recommendations for source and centralized segregation and aggregation of materials for recycling and/or disposition; and The analysis could include identification and laboratory level evaluation of methods and/or equipment, including capital costs, operating costs, maintenance requirements, life cycle and return on investment for systems to support the waste reduction program mission.

Mechanical and Physical Performance of Concrete Including Waste Electrical Cable Rubber

NASA Astrophysics Data System (ADS)

Taner Yildirim, Salih; Pelin Duygun, Nur

2017-10-01

Solid wastes are important environmental problem all over the World. Consumption of the plastic solid waste covers big portion within the total solid waste. Although a numerous plastic material is subjected to the recycling process, it is not easy to be destroyed by nature. One of the recommended way to prevent is to utilize as an aggregate in cement-based material. There are many researches on use of recycling rubber in concrete. However, studies on recycling of waste electrical cable rubber (WECR) in concrete is insufficient although there are many research on waste tyre rubbers in concrete. In this study, fine aggregate was replaced with WECR which were 5%, 10%, and 15 % of the total aggregate volume in the concrete and researched workability, unit weight, water absorption, compressive strength, flexural strength, ultrasonic pulse velocity, modulus of elasticity, and abrasion resistance of concrete. As a result of experimental studies, increase of WECR amount in concrete increases workability due to lack of adherence between cement paste and WECR, and hydrophobic structure of WECR while it influences negatively mechanical properties of concrete. It is possible to use WECR in concrete taking into account the reduction in mechanical properties.

Production of lightweight aggregates from mining residues, heavy metal sludge, and incinerator fly ash.

PubMed

Huang, Su-Chen; Chang, Fang-Chih; Lo, Shang-Lien; Lee, Ming-Yu; Wang, Chu-Fang; Lin, Jyh-Dong

2007-06-01

In this study, artificial lightweight aggregate (LWA) manufactured from recycled resources was investigated. Residues from mining, fly ash from an incinerator and heavy metal sludge from an electronic waste water plant were mixed into raw aggregate pellets and fed into a tunnel kiln to be sintered and finally cooled rapidly. Various feeding and sintering temperatures were employed to examine their impact on the extent of vitrification on the aggregate surface. Microstructural analysis and toxicity characteristic leaching procedure (TCLP) were also performed. The results show that the optimum condition of LWA fabrication is sintering at 1150 degrees C for 15 min with raw aggregate pellets fed at 750 degrees C. The rapidly vitrified surface envelops the gas produced with the increase in internal temperature and cooling by spraying water prevents the aggregates from binding together, thus forming LWA with specific gravity of 0.6. LWA produced by sintering in tunnel kiln shows good vitrified surface, low water absorption rate below 5%, and low cylindrical compressive strength of 4.3 MPa. In addition, only trace amounts of heavy metals were detected, making the LWA non-hazardous for construction use.

Physical and chemical effects of grain aggregates on the Palos Verdes margin, southern California

USGS Publications Warehouse

Drake, D.E.; Eganhouse, R.; McArthur, W.

2002-01-01

Large discharges of wastewater and particulate matter from the outfalls of the Los Angeles County Sanitation Districts onto the Palos Verdes shelf since 1937 have produced an effluent-affected sediment deposit characterized by low bulk density, elevated organic matter content, and a high percentage of fine silt and clay particles relative to underlying native sands and sandy silts. Comparison of the results of grain-size analyses using a gentle wet-sieving technique that preserves certain grain aggregates to the results of standard size analyses of disaggregated particles shows that high percentages (up to 50%) of the silt and clay fractions of the effluent-affected mud are incorporated in aggregates having intermediate diameters in the fine-to-medium sand size range (63-500 ??m), Scanning electron microscope images of the aggregates show that they are predominantly oval fecal pellets or irregularly shaped fragments of pellets. Deposit-feeding polychaete worms such as Capitella sp. and Mediomastus sp., abundant in the mud-rich effluent-affected sediment on Palos Verdes shelf, are probably responsible for most of the grain aggregates through fecal pellet production. Particle settling rates and densities, and the concentrations of organic carbon and p,p???-DDE, a metabolite of the hydrophobic pesticide DDT, were determined for seven grain-size fractions in the effluent-affected sediment. Fecal pellet grain densities ranged from about 1.2 to 1.5 g/cc, and their average settling rates were reduced to the equivalent of about one phi size relative to spherical quartz grains of the same diameter. However, repackaging of fine silt and clay grains into the sand-sized fecal pellets causes an effective settling rate increase of up to 3 orders of magnitude for the smallest particles incorporated in the pellets. Moreover, organic carbon and p,p???-DDE exhibit a bimodal distribution with relatively high concentrations in the finest size fraction (0-20 ??m), as expected, and a

Concanavalin-A conjugated fine-multiple emulsion loaded with 6-mercaptopurine.

PubMed

Khopade, A J; Jain, N K

2000-01-01

Fine-multiple (water-in-oil-in-water) emulsions were prepared by two-step emulsification using sonication. They were coated with concanavalin-A (Con-A) by three methods. The one involving covalent coupling of Con-A to the multiple emulsion incorporated anchor was better compared with lipid derivatized Con-A anchoring or the glutaraldehyde-based cross-linking method, as shown by the faster rate of dextran-induced aggregation. The selected multiple emulsions were characterized by physical properties such as droplet size, encapsulation efficiency, and zeta potential. Stability parameters such as droplet size, creaming, leakage, and aggregation as a function of relative turbidity were monitored over a 1-month period, which revealed good stability of the formulations. The release profile of 6-mercaptopurine followed zero-order kinetics. Pharmacokinetic studies showed an increase in half-life and bioavailability from multiple emulsion formulations administered intravenously. There was prolonged retention of drug in various tissues of rats when treated with Con-A-coated multiple emulsion as compared with uncoated one. Our study demonstrates the suitability of fine-multiple emulsion for intravenous administration and the potential for prolonged retention of drugs and targeting in biological systems.

Characterization of Fine Metal Particles Derived from Shredded WEEE Using a Hyperspectral Image System: Preliminary Results

PubMed Central

Candiani, Gabriele; Picone, Nicoletta; Pompilio, Loredana; Pepe, Monica; Colledani, Marcello

2017-01-01

Waste of electric and electronic equipment (WEEE) is the fastest-growing waste stream in Europe. The large amount of electric and electronic products introduced every year in the market makes WEEE disposal a relevant problem. On the other hand, the high abundance of key metals included in WEEE has increased the industrial interest in WEEE recycling. However, the high variability of materials used to produce electric and electronic equipment makes key metals’ recovery a complex task: the separation process requires flexible systems, which are not currently implemented in recycling plants. In this context, hyperspectral sensors and imaging systems represent a suitable technology to improve WEEE recycling rates and the quality of the output products. This work introduces the preliminary tests using a hyperspectral system, integrated in an automatic WEEE recycling pilot plant, for the characterization of mixtures of fine particles derived from WEEE shredding. Several combinations of classification algorithms and techniques for signal enhancement of reflectance spectra were implemented and compared. The methodology introduced in this study has shown characterization accuracies greater than 95%. PMID:28505070

Utilization of power plant bottom ash as aggregates in fiber-reinforced cellular concrete.

PubMed

Lee, H K; Kim, H K; Hwang, E A

2010-02-01

Recently, millions tons of bottom ash wastes from thermoelectric power plants have been disposed of in landfills and coastal areas, regardless of its recycling possibility in construction fields. Fiber-reinforced cellular concrete (FRCC) of low density and of high strength may be attainable through the addition of bottom ash due to its relatively high strength. This paper focuses on evaluating the feasibility of utilizing bottom ash of thermoelectric power plant wastes as aggregates in FRCC. The flow characteristics of cement mortar with bottom ash aggregates and the effect of aggregate type and size on concrete density and compressive strength were investigated. In addition, the effects of adding steel and polypropylene fibers for improving the strength of concrete were also investigated. The results from this study suggest that bottom ash can be applied as a construction material which may not only improve the compressive strength of FRCC significantly but also reduce problems related to bottom ash waste.

Hydrophobization of Concrete Using Granular Nanostructured Aggregate

NASA Astrophysics Data System (ADS)

Ogurtsova, Y. N.; Strokova, V. V.; Labuzova, M. V.

2017-11-01

The possibility of giving hydrophobical properties to the fine-grained concrete matrix by using a granular nanostructured aggregate (GNA) with a hydrophobizing additive is investigated in this work. GNA is obtained by granulating the silica raw material with an alkaline component. The introduction of a hydrophobizing additive into the raw mix of GNA allows to encapsulate it reducing the negative effect on hydration processes, the intensity of migration of moisture and efflorescence in concrete and, consequently, improving the performance characteristics of fine-grained concrete products. The hydrophobizing ability of a solution of sodium polysilicates formed in the core of GNA during concrete heat and moisture treatment is proved. The analysis of IR spectra after the impregnation of cement stone samples with a solution of sodium polysilicates showed an increase in the degree of hydration and the formation of framework water aluminosilicates. Atmospheric processes modelling showed that the use of GNA on the basis of gaize with calcium stearate and on the basis of fly ash with GKZh-11 makes it possible to increase the resistance of fine-grained concrete to the atmospheric effect of the medium, namely, the outwashing of readily soluble compounds.

[Experimental-morphological study of morphogenetic potencies of homogeneous aggregates of different types of cells from the freshwater sponge Ephydatia fluviatilis (L.)].

PubMed

Nikitin, N S

1977-01-01

The morphogenetic potencies of somatic cells of the fresh-water sponge Ephydatia fluviatilis in the developing aggregates depend on their initial specialization and the number of cells in the aggregate. The aggregates of nucleolar amoebocytes consisting of 500 or more cells have the highest morphogenetic potencies. All main cell types can arise in the developing homogeneous aggregates of nucleolar amoebocytes. The fine structure of nucleolar amoebocytes at different stages of development of the homogeneous aggregates was studied by means of electron microscopy. The structural rearrangements are described which accompany the process of redifferentiation of the nucleolar amoebocytes in other cell types.

Freeze/thaw stress induces organelle remodeling and membrane recycling in cryopreserved human mature oocytes.

PubMed

Nottola, Stefania Annarita; Albani, Elena; Coticchio, Giovanni; Palmerini, Maria Grazia; Lorenzo, Caterina; Scaravelli, Giulia; Borini, Andrea; Levi-Setti, Paolo Emanuele; Macchiarelli, Guido

2016-12-01

Our aim was to evaluate the ultrastructure of human metaphase II oocytes subjected to slow freezing and fixed after thawing at different intervals during post-thaw rehydration. Samples were studied by light and transmission electron microscopy. We found that vacuolization was present in all cryopreserved oocytes, reaching a maximum in the intermediate stage of rehydration. Mitochondria-smooth endoplasmic reticulum (M-SER) aggregates decreased following thawing, particularly in the first and intermediate stages of rehydration, whereas mitochondria-vesicle (MV) complexes augmented in the same stages. At the end of rehydration, vacuoles and MV complexes both diminished and M-SER aggregates increased again. Cortical granules (CGs) were scarce in all cryopreserved oocytes, gradually diminishing as rehydration progressed. This study also shows that such a membrane remodeling is mainly represented by a dynamic process of transition between M-SER aggregates and MV complexes, both able of transforming into each other. Vacuoles and CG membranes may take part in the membrane recycling mechanism.

Life Cycle Assessment of Completely Recyclable Concrete.

PubMed

De Schepper, Mieke; Van den Heede, Philip; Van Driessche, Isabel; De Belie, Nele

2014-08-21

Since the construction sector uses 50% of the Earth's raw materials and produces 50% of its waste, the development of more durable and sustainable building materials is crucial. Today, Construction and Demolition Waste (CDW) is mainly used in low level applications, namely as unbound material for foundations, e.g., in road construction. Mineral demolition waste can be recycled as crushed aggregates for concrete, but these reduce the compressive strength and affect the workability due to higher values of water absorption. To advance the use of concrete rubble, Completely Recyclable Concrete (CRC) is designed for reincarnation within the cement production, following the Cradle-to-Cradle (C2C) principle. By the design, CRC becomes a resource for cement production because the chemical composition of CRC will be similar to that of cement raw materials. If CRC is used on a regular basis, a closed concrete-cement-concrete material cycle will arise, which is completely different from the current life cycle of traditional concrete. Within the research towards this CRC it is important to quantify the benefit for the environment and Life Cycle Assessment (LCA) needs to be performed, of which the results are presented in a this paper. It was observed that CRC could significantly reduce the global warming potential of concrete.

Life Cycle Assessment of Completely Recyclable Concrete

PubMed Central

De Schepper, Mieke; Van den Heede, Philip; Van Driessche, Isabel; De Belie, Nele

2014-01-01

Since the construction sector uses 50% of the Earth’s raw materials and produces 50% of its waste, the development of more durable and sustainable building materials is crucial. Today, Construction and Demolition Waste (CDW) is mainly used in low level applications, namely as unbound material for foundations, e.g., in road construction. Mineral demolition waste can be recycled as crushed aggregates for concrete, but these reduce the compressive strength and affect the workability due to higher values of water absorption. To advance the use of concrete rubble, Completely Recyclable Concrete (CRC) is designed for reincarnation within the cement production, following the Cradle-to-Cradle (C2C) principle. By the design, CRC becomes a resource for cement production because the chemical composition of CRC will be similar to that of cement raw materials. If CRC is used on a regular basis, a closed concrete-cement-concrete material cycle will arise, which is completely different from the current life cycle of traditional concrete. Within the research towards this CRC it is important to quantify the benefit for the environment and Life Cycle Assessment (LCA) needs to be performed, of which the results are presented in a this paper. It was observed that CRC could significantly reduce the global warming potential of concrete. PMID:28788174

A long-term study on the effect of magnetite supplementation in continuous anaerobic digestion of dairy effluent - Magnetic separation and recycling of magnetite.

PubMed

Baek, Gahyun; Jung, Heejung; Kim, Jaai; Lee, Changsoo

2017-10-01

Promotion of direct interspecies electron transfer (DIET) between exoelectrogenic bacteria and electron-utilizing methanogens has recently been discussed as a new method for enhanced biomethanation. This study evaluated the effect of magnetite-promoted DIET in continuous anaerobic digestion of dairy effluent and tested the magnetic separation and recycling of magnetite to avoid continuous magnetite addition. The applied magnetite recycling method effectively supported enhanced DIET activity and biomethanation performance over a long period (>250days) without adding extra magnetite. DIET via magnetite particles as electrical conduits was likely the main mechanism for the enhanced biomethanation. Magnetite formed complex aggregate structures with microbes, and magnetite recycling also helped retain more biomass in the process. Methanosaeta was likely the major methanogen group responsible for DIET-based methanogenesis, in association with Proteobacteria and Chloroflexi populations as syntrophic partners. The recycling approach proved robust and effective, highlighting the potential of magnetite recycling for high-rate biomethanation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interactions between extracellular polymeric substances and clay minerals affect soil aggregation

NASA Astrophysics Data System (ADS)

Vogel, Cordula; Rehschuh, Stephanie; Kemi Olagoke, Folasade; Redmile Gordon, Marc; Kalbiltz, Karsten

2017-04-01

Soil aggregation is crucial for carbon (C) sequestration and microbial processes have been recognised as important control of aggregate turnover (formation, stability, and destruction). However, how microorganisms contribute to these processes is still a matter of debate. An enthralling mechanism determining aggregate turnover and therefore C sequestration may be the excretion of extracellular polymeric substances (EPS) as microbial glue, but effects of EPS on aggregation is largely unknown. Moreover, interdependencies between important aggregation factors like the amount of fine-sized particles (clay content), the decomposability of organic matter and the microbial community (size and composition, as well as the excretion of EPS) are still poorly understood. Therefore, we studied the complex interactions between these factors and their role in aggregate turnover. It was hypothesized that an increase in microbial activity, induced by the input of organic substrates, will stimulate EPS production and therefore the formation and stability of aggregates. To test this hypothesis, an incubation experiment has been conducted across a gradient of clay content (montmorillonite) and substrate decomposability (starch and glucose) as main drivers of the microbial activity. A combination of aggregate separation and stability tests were applied. This results will be examined with respect to the obtained microbial parameters (amount and composition of EPS, CO2 emission, microbial biomass, phospholipid fatty acid), to disentangle the mechanisms and factors controlling aggregate turnover affected by soil microorganisms. This study is expected to provide insights on the role of EPS in the stability of aggregates. Thus, the results of this study will provide an improved understanding of the underlying processes of aggregate turnover in soils, which is necessary to implement strategies for enhanced C sequestration in agricultural soils.

Flocculation kinetics and aggregate structure of kaolinite mixtures in laminar tube flow.

PubMed

Vaezi G, Farid; Sanders, R Sean; Masliyah, Jacob H

2011-03-01

Flocculation is commonly used in various solid-liquid separation processes in chemical and mineral industries to separate desired products or to treat waste streams. This paper presents an experimental technique to study flocculation processes in laminar tube flow. This approach allows for more realistic estimation of the shear rate to which an aggregate is exposed, as compared to more complicated shear fields (e.g. stirred tanks). A direct sampling method is used to minimize the effect of sampling on the aggregate structure. A combination of aggregate settling velocity and image analysis was used to quantify the structure of the aggregate. Aggregate size, density, and fractal dimension were found to be the most important aggregate structural parameters. The two methods used to determine aggregate fractal dimension were in good agreement. The effects of advective flow through an aggregate's porous structure and transition-regime drag coefficient on the evaluation of aggregate density were considered. The technique was applied to investigate the flocculation kinetics and the evolution of the aggregate structure of kaolin particles with an anionic flocculant under conditions similar to those of oil sands fine tailings. Aggregates were formed using a well controlled two-stage aggregation process. Detailed statistical analysis was performed to investigate the establishment of dynamic equilibrium condition in terms of aggregate size and density evolution. An equilibrium steady state condition was obtained within 90 s of the start of flocculation; after which no further change in aggregate structure was observed. Although longer flocculation times inside the shear field could conceivably cause aggregate structure conformation, statistical analysis indicated that this did not occur for the studied conditions. The results show that the technique and experimental conditions employed here produce aggregates having a well-defined, reproducible structure. Copyright © 2011

Geotechnical valorisation of large recycling concrete in FezMeknes region (Morocco)

NASA Astrophysics Data System (ADS)

Demehati, A.; Abidi, A.; El Qandil, M.

2018-05-01

The growing and accelerated development of agglomerations is resulting in increasing pressure on deposits of materials as natural resources. This results in shortages of aggregates including sand. Situation in the different regions of Morocco, including that of FezMeknes. In addition, the threat to the stability or durability of buildings in general and road works and their annexes in particular is often started either from the surface of the grounds or from areas vulnerable to their geotechnical contact as seating materials surrounding them. The large concrete with recycles aggregates filling or protective mask provides adequate solutions. According to the results of our research, it offers a well-adapted physical and mechanical characterization in transition between conventional concretes, whether or not they are armed, and their support. Its use of protection against the effects of erosion or scouring and against the seismic movements further strengthens its potential field employment.

Protein aggregation induced during glass bead lysis of yeast

PubMed Central

Papanayotou, Irene; Sun, Beimeng; Roth, Amy F.; Davis, Nicholas G.

2013-01-01

Yeast cell lysates produced by mechanical glass bead disruption are widely used in a variety of applications, including for the analysis of native function, e.g. protein–protein interaction, enzyme assays and membrane fractionations. Below, we report a striking case of protein denaturation and aggregation that is induced by this lysis protocol. Most of this analysis focuses on the type 1 casein kinase Yck2, which normally tethers to the plasma membrane through C-terminal palmitoylation. Surprisingly, when cells are subjected to glass bead disruption, non-palmitoylated, cytosolic forms of the kinase denature and aggregate, while membrane-associated forms, whether attached through their native palmitoyl tethers or through a variety of artificial membrane-tethering sequences, are wholly protected from denaturation and aggregation. A wider look at the yeast proteome finds that, while the majority of proteins resist glass bead-induced aggregation, a significant subset does, in fact, succumb to such denaturation. Thus, yeast researchers should be aware of this potential artifact when embarking on biochemical analyses that employ glass bead lysates to look at native protein function. Finally, we demonstrate an experimental utility for glass bead-induced aggregation, using its fine discrimination of membrane-associated from non-associated Yck2 forms to discern fractional palmitoylation states of Yck2 mutants that are partially defective for palmitoylation. PMID:20641011

New Engineering Solutions in Creation of Mini-BOF for Metallic Waste Recycling

NASA Astrophysics Data System (ADS)

Eronko, S. P.; Gorbatyuk, S. M.; Oshovskaya, E. V.; Starodubtsev, B. I.

2017-12-01

New engineering solutions used in design of the mini melting unit capable of recycling industrial and domestic metallic waste with high content of harmful impurities are provided. High efficiency of the process technology implemented with its use is achieved due to the possibility of the heat and mass transfer intensification in the molten metal bath, controlled charge into it of large amounts of reagents in lumps and in fines, and cut-off of remaining process slag during metal tapping into the teeming ladle.

Principles for problem aggregation and assignment in medium scale multiprocessors

NASA Technical Reports Server (NTRS)

Nicol, David M.; Saltz, Joel H.

1987-01-01

One of the most important issues in parallel processing is the mapping of workload to processors. This paper considers a large class of problems having a high degree of potential fine grained parallelism, and execution requirements that are either not predictable, or are too costly to predict. The main issues in mapping such a problem onto medium scale multiprocessors are those of aggregation and assignment. We study a method of parameterized aggregation that makes few assumptions about the workload. The mapping of aggregate units of work onto processors is uniform, and exploits locality of workload intensity to balance the unknown workload. In general, a finer aggregate granularity leads to a better balance at the price of increased communication/synchronization costs; the aggregation parameters can be adjusted to find a reasonable granularity. The effectiveness of this scheme is demonstrated on three model problems: an adaptive one-dimensional fluid dynamics problem with message passing, a sparse triangular linear system solver on both a shared memory and a message-passing machine, and a two-dimensional time-driven battlefield simulation employing message passing. Using the model problems, the tradeoffs are studied between balanced workload and the communication/synchronization costs. Finally, an analytical model is used to explain why the method balances workload and minimizes the variance in system behavior.

A novel approach to a fine particle coating using porous spherical silica as core particles.

PubMed

Ishida, Makoto; Uchiyama, Jumpei; Isaji, Keiko; Suzuki, Yuta; Ikematsu, Yasuyuki; Aoki, Shigeru

2014-08-01

Abstract The applicability of porous spherical silica (PSS) was evaluated as core particles for pharmaceutical products by comparing it with commercial core particles such as mannitol (NP-108), sucrose and microcrystalline cellulose spheres. We investigated the physical properties of core particles, such as particle size distribution, flow properties, crushing strength, plastic limit, drying rate, hygroscopic property and aggregation degree. It was found that PSS was a core particle of small particle size, low friability, high water adsorption capacity, rapid drying rate and lower occurrence of particle aggregation, although wettability is a factor to be carefully considered. The aggregation and taste-masking ability using PSS and NP-108 as core particles were evaluated at a fluidized-bed coating process. The functional coating under the excess spray rate shows different aggregation trends and dissolution profiles between PSS and NP-108; thereby, exhibiting the formation of uniform coating under the excess spray rate in the case of PSS. This expands the range of the acceptable spray feed rates to coat fine particles, and indicates the possibility of decreasing the coating time. The results obtained in this study suggested that the core particle, which has a property like that of PSS, was useful in overcoming such disadvantages as large particle size, which feels gritty in oral cavity; particle aggregation; and the long coating time of the particle coating process. These results will enable the practical fine particle coating method by increasing the range of optimum coating conditions and decreasing the coating time in fluidized bed technology.

Rethink, Rework, Recycle.

ERIC Educational Resources Information Center

Wrhen, Linda; DiSpezio, Michael A.

1991-01-01

Information about the recycling and reuse of plastics, aluminum, steel, glass, and newspapers is presented. The phases of recycling are described. An activity that allows students to separate recyclable materials is included. The objectives, a list of needed materials, and procedure are provided. (KR)

Concrete with onyx waste aggregate as aesthetically valued structural concrete

NASA Astrophysics Data System (ADS)

Setyowati E., W.; Soehardjono, A.; Wisnumurti

2017-09-01

The utillization of Tulungagung onyx stone waste as an aggregate of concrete mixture will improve the economic value of the concrete due to the brighter color and high aesthetic level of the products. We conducted the research of 75 samples as a test objects to measure the compression stress, splits tensile stress, flexural tensile stress, elasticity modulus, porosity modulus and also studied 15 test objects to identify the concrete micro structures using XRD test, EDAX test and SEM test. The test objects were made from mix designed concrete, having ratio cement : fine aggregate : coarse aggregate ratio = 1 : 1.5 : 2.1, and W/C ratio = 0.4. The 28 days examination results showed that the micro structure of Tulungagung onyx waste concrete is similar with normal concrete. Moreover, the mechanical test results proved that Tulungagung onyx waste concretes also have a qualified level of strength to be used as a structural concrete with higher aesthetic level.

Recycling at Penn State's Beaver Stadium. "Recycle on the Go" Success Story

ERIC Educational Resources Information Center

US Environmental Protection Agency, 2009

2009-01-01

With a 13-year-old recycling program, The Pennsylvania State University's (Penn State) Beaver Stadium in the past diverted nearly 30 tons of recyclables per year from local landfills. A new initiative to promote recycling in the stadium's tailgating area has helped Penn State more than triple its old recycling record, collecting 112 tons in 2008.…

Mercury recycling in the United States in 2000

USGS Publications Warehouse

Brooks, William E.; Matos, Grecia R.

2005-01-01

Reclamation and recycling of mercury from used mercury- containing products and treatment of byproduct mercury from gold mining is vital to the continued, though declining, use of this metal. Mercury is reclaimed from mercury-containing waste by treatment in multistep high-temperature retorts-the mercury is volatized and then condensed for purification and sale. Some mercury-containing waste, however, may be landfilled, and landfilled material represents loss of a recyclable resource and a threat to the environment. Related issues include mercury disposal and waste management, toxicity and human health, and regulation of mercury releases in the environment. End-users of mercury-containing products may face fines and prosecution if these products are improperly recycled or not recycled. Local and State environmental regulations require adherence to the Resource Conservation and Recovery Act and the Comprehensive Environmental Response, Compensation, and Liability Act to regulate generation, treatment, and disposal of mercury-containing products. In the United States, several large companies and a number of smaller companies collect these products from a variety of sources and then reclaim and recycle the mercury. Because mercury has not been mined as a principal product in the United States since 1992, mercury reclamation from fabricated products has become the main source of mercury. Principal product mercury and byproduct mercury from mining operations are considered to be primary materials. Mercury may also be obtained as a byproduct from domestic or foreign gold-processing operations. In the early 1990s, U.S. manufacturers used an annual average that ranged from 500 to 600 metric tons of recycled and imported mercury for fabrication of automobile convenience switches, dental amalgam, fluorescent lamps, medical uses and thermometers, and thermostats. The amount now used for fabrication is estimated to be 200 metric tons per year or less. Much of the data on

Recycling of nonmetallics

USGS Publications Warehouse

Amey, E.B.; Kelly, T.D.

1996-01-01

The first factor determining recyclability is the composition of the material itself. Metals, for example, can be reused with little or no loss in quality. Paper and rubber, by this criterion, are less recyclable. Each time paper is recycled, some cellulose fibers are broken. Shorter fibers can mean weaker paper of perceived lower quality and value. Vulcanizing is an irreversible chemical process that precludes recycling rubber in its original form. Both materials may be reused in other applications often of lower value than the original one. To be recyclable, the discarded material must have a collection infrastructure at the source of waste generation, at a central collection site, or at curbside. The recovered material must also have a market. If it is priced noncompetitively or no market exists, if it does not meet specifications, or if it requires special technology investments which cannot be recovered through future sales, the recovered material may be stockpiled or discarded rather than recycled. ?? 1996 International Association for Mathematical Geology.

Analysis of the vibronic fine structure in circularly polarized emission spectra from chiral molecular aggregates.

PubMed

Spano, Frank C; Zhao, Zhen; Meskers, Stefan C J

2004-06-08

Using a Frenkel-exciton model, the degree of circular polarization of the luminescence (g(lum)) from one-dimensional, helical aggregates of chromophoric molecules is investigated theoretically. The coupling between the electronic excitation and a local, intramolecular vibrational mode is taken into account. Analytical expressions for the fluorescence band shape and g(lum) are presented for the case of strong and weak electronic coupling between the chromophoric units. Results are compared to those from numerical calculations obtained using the three particle approximation. g(lum) for the 0-0 vibronic band is found to be independent of the relative strength of electronic coupling between chromophores and excitation-vibration coupling. It depends solely on the number of coherently coupled molecules. In contrast, for the higher vibronic transitions[g(lum)] decreases with decreasing strength of the electronic coupling. In the limit of strong electronic coupling, [g(lum)] is almost constant throughout the series of vibronic transitions but for weak coupling [g(lum)] becomes vanishingly small for all vibronic transitions except for the 0-0 transition. The results are interpreted in terms of dynamic localization of the excitation during the zero point vibrational motion in the excited state of the aggregate. It is concluded that circular polarization measurements provide an independent way to determine the coherence size and bandwidth of the lowest exciton state for chiral aggregates. (c) 2004 American Institute of Physics.

Downcycling versus recycling of construction and demolition waste: Combining LCA and LCC to support sustainable policy making.

PubMed

Di Maria, Andrea; Eyckmans, Johan; Van Acker, Karel

2018-05-01

Urgent solutions are needed in Europe to deal with construction and demolition waste (CDW). EU policy has contributed to significantly reducing the amount of CDW going to landfill, but most of the effort has been put in downcycling practices. Therefore, further policies are needed to stimulate high-quality recycling of CDW. The present paper presents a combined life cycle assessment (LCA) and life cycle costing (LCC) methodologies to analyse the environmental and the economic drivers in four alternative CDW end-of-life scenarios in the region of Flanders, in Belgium. The four analysed alternatives are (i) landfilling, (ii) downcycling, (iii) advanced recycling and (iv) recycling after selective demolition. LCA results show that landiflling is the scenario having the highest environmental impacts in terms of person equivalent (PE), followed by downcycling and recycling (-36%) and recycling after selective demolition (-59%). The decrease in environmental impacts is mostly due to the avoided landfilling of CDW and the recovery of materials from selective demolition. LCC results indicate that landfilling is the scenario bearing the highest total economic costs. This is due to the high landfill tax in Flanders. The recycling after selective demolition bears the second highest cost. The increase of high-quality CDW recycling can significantly reduce the overall environmental impact of the system. Implementing a high landfill tax, increasing the gate fee to the recycling plant, and boosting the sales price of recycled aggregates are the most effective drivers to facilitate a transition towards a more sustainable CDW management system. The paper demonstrates that the combined LCA and LCC results can highlight the environmental and economic drivers in CDW management. The results of the combined analysis can help policymakers to promote the aspects contributing to sustainability and to limit the ones creating a barrier. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biological role of bacterial inclusion bodies: a model for amyloid aggregation.

PubMed

García-Fruitós, Elena; Sabate, Raimon; de Groot, Natalia S; Villaverde, Antonio; Ventura, Salvador

2011-07-01

Inclusion bodies are insoluble protein aggregates usually found in recombinant bacteria when they are forced to produce heterologous protein species. These particles are formed by polypeptides that cross-interact through sterospecific contacts and that are steadily deposited in either the cell's cytoplasm or the periplasm. An important fraction of eukaryotic proteins form inclusion bodies in bacteria, which has posed major problems in the development of the biotechnology industry. Over the last decade, the fine dissection of the quality control system in bacteria and the recognition of the amyloid-like architecture of inclusion bodies have provided dramatic insights on the dynamic biology of these aggregates. We discuss here the relevant aspects, in the interface between cell physiology and structural biology, which make inclusion bodies unique models for the study of protein aggregation, amyloid formation and prion biology in a physiologically relevant background. © 2011 The Authors Journal compilation © 2011 FEBS.

Recycling production designs: the value of coordination and flexibility in aluminum recycling operations

NASA Astrophysics Data System (ADS)

Brommer, Tracey H.

The growing motivation for aluminum recycling has prompted interest in recycling alternative and more challenging secondary materials. The nature of these alternative secondary materials necessitates the development of an intermediate recycling facility that can reprocess the secondary materials into a liquid product Two downstream aluminum remelters will incorporate the liquid products into their aluminum alloy production schedules. Energy and environmental benefits result from delivering the products as liquid but coordination challenges persist because of the energy cost to maintain the liquid. Further coordination challenges result from the necessity to establish a long term recycling production plan in the presence of long term downstream aluminum remelter production uncertainty and inherent variation in the daily order schedule of the downstream aluminum remelters. In this context a fundamental question arises, considering the metallurgical complexities of dross reprocessing, what is the value of operating a coordinated set of by-product reprocessing plants and remelting cast houses? A methodology is presented to calculate the optimal recycling center production parameters including 1) the number of recycled products, 2) the volume of recycled products, 3) allocation of recycled materials across recycled products, 4) allocation of recycled products across finished alloys, 4) the level of flexibility for the recycling center to operate. The methods implemented include, 1) an optimization model to describe the long term operations of the recycling center, 2) an uncertainty simulation tool, 3) a simulation optimization method, 4) a dynamic simulation tool with four embedded daily production optimization models of varying degrees of flexibility. This methodology is used to quantify the performance of several recycling center production designs of varying levels of coordination and flexibility. This analysis allowed the identification of the optimal recycling

Measuring the gypsum content of C&D debris fines.

PubMed

Musson, Stephen E; Xu, Qiyong; Townsend, Timothy G

2008-11-01

Construction and demolition (C&D) debris recycling facilities often produce a screened material intended for use as alternative daily cover (ADC) at active landfills or for shaping and grading at closed landfills. This product contains soil and small pieces of wood, concrete, gypsum drywall, shingles and other components of C&D debris. Concerns have been raised over the contribution of gypsum drywall in C&D debris fines to odor problems at landfills where the product is used. To address such concerns, limitations may be placed on the percentage of gypsum (or sulfate) that can occur, and standardized testing procedures are required to permit valid compliance testing. A test procedure was developed for measuring the gypsum content in C&D debris fines. The concentration of sulfate leached in an aqueous solution was used to estimate the initial gypsum content of the sample. The impact of sample size and leaching time were evaluated. Precision and accuracy increased with increasing gypsum content. Results from replicate samples had an average relative standard deviation of 9%. The gypsum content of fines obtained from different facilities in the US varied widely from 1% to over 25%. These variations not only occurred between differing facilities, but within batches produced within a single facility.

Green Science: Revisiting Recycling

ERIC Educational Resources Information Center

Palliser, Janna

2011-01-01

Recycling has been around for a long time--people have reused materials and refashioned them into needed items for thousands of years. More recently, war efforts encouraged conservation and reuse of materials, and in the 1970s recycling got its official start when recycling centers were created. Now, curbside recycling programs and recycling…

Microstructural Analysis and Rheological Modeling of Asphalt Mixtures Containing Recycled Asphalt Materials.

PubMed

Falchetto, Augusto Cannone; Moon, Ki Hoon; Wistuba, Michael P

2014-09-02

The use of recycled materials in pavement construction has seen, over the years, a significant increase closely associated with substantial economic and environmental benefits. During the past decades, many transportation agencies have evaluated the effect of adding Reclaimed Asphalt Pavement (RAP), and, more recently, Recycled Asphalt Shingles (RAS) on the performance of asphalt pavement, while limits were proposed on the amount of recycled materials which can be used. In this paper, the effect of adding RAP and RAS on the microstructural and low temperature properties of asphalt mixtures is investigated using digital image processing (DIP) and modeling of rheological data obtained with the Bending Beam Rheometer (BBR). Detailed information on the internal microstructure of asphalt mixtures is acquired based on digital images of small beam specimens and numerical estimations of spatial correlation functions. It is found that RAP increases the autocorrelation length (ACL) of the spatial distribution of aggregates, asphalt mastic and air voids phases, while an opposite trend is observed when RAS is included. Analogical and semi empirical models are used to back-calculate binder creep stiffness from mixture experimental data. Differences between back-calculated results and experimental data suggest limited or partial blending between new and aged binder.

Microstructural Analysis and Rheological Modeling of Asphalt Mixtures Containing Recycled Asphalt Materials

PubMed Central

Cannone Falchetto, Augusto; Moon, Ki Hoon; Wistuba, Michael P.

2014-01-01

The use of recycled materials in pavement construction has seen, over the years, a significant increase closely associated with substantial economic and environmental benefits. During the past decades, many transportation agencies have evaluated the effect of adding Reclaimed Asphalt Pavement (RAP), and, more recently, Recycled Asphalt Shingles (RAS) on the performance of asphalt pavement, while limits were proposed on the amount of recycled materials which can be used. In this paper, the effect of adding RAP and RAS on the microstructural and low temperature properties of asphalt mixtures is investigated using digital image processing (DIP) and modeling of rheological data obtained with the Bending Beam Rheometer (BBR). Detailed information on the internal microstructure of asphalt mixtures is acquired based on digital images of small beam specimens and numerical estimations of spatial correlation functions. It is found that RAP increases the autocorrelation length (ACL) of the spatial distribution of aggregates, asphalt mastic and air voids phases, while an opposite trend is observed when RAS is included. Analogical and semi empirical models are used to back-calculate binder creep stiffness from mixture experimental data. Differences between back-calculated results and experimental data suggest limited or partial blending between new and aged binder. PMID:28788190

Historical spatial reconstruction of a spawning-aggregation fishery.

PubMed

Buckley, Sarah M; Thurstan, Ruth H; Tobin, Andrew; Pandolfi, John M

2017-12-01

Aggregations of individual animals that form for breeding purposes are a critical ecological process for many species, yet these aggregations are inherently vulnerable to exploitation. Studies of the decline of exploited populations that form breeding aggregations tend to focus on catch rate and thus often overlook reductions in geographic range. We tested the hypothesis that catch rate and site occupancy of exploited fish-spawning aggregations (FSAs) decline in synchrony over time. We used the Spanish mackerel (Scomberomorus commerson) spawning-aggregation fishery in the Great Barrier Reef as a case study. Data were compiled from historical newspaper archives, fisher knowledge, and contemporary fishery logbooks to reconstruct catch rates and exploitation trends from the inception of the fishery. Our fine-scale analysis of catch and effort data spanned 103 years (1911-2013) and revealed a spatial expansion of fishing effort. Effort shifted offshore at a rate of 9.4 nm/decade, and 2.9 newly targeted FSAs were reported/decade. Spatial expansion of effort masked the sequential exploitation, commercial extinction, and loss of 70% of exploited FSAs. After standardizing for improvements in technological innovations, average catch rates declined by 90.5% from 1934 to 2011 (from 119.4 to 11.41 fish/vessel/trip). Mean catch rate of Spanish mackerel and occupancy of exploited mackerel FSAs were not significantly related. Our study revealed a special kind of shifting spatial baseline in which a contraction in exploited FSAs occurred undetected. Knowledge of temporally and spatially explicit information on FSAs can be relevant for the conservation and management of FSA species. © 2017 Society for Conservation Biology.

Fining of Red Wine Monitored by Multiple Light Scattering.

PubMed

Ferrentino, Giovanna; Ramezani, Mohsen; Morozova, Ksenia; Hafner, Daniela; Pedri, Ulrich; Pixner, Konrad; Scampicchio, Matteo

2017-07-12

This work describes a new approach based on multiple light scattering to study red wine clarification processes. The whole spectral signal (1933 backscattering points along the length of each sample vial) were fitted by a multivariate kinetic model that was built with a three-step mechanism, implying (1) adsorption of wine colloids to fining agents, (2) aggregation into larger particles, and (3) sedimentation. Each step is characterized by a reaction rate constant. According to the first reaction, the results showed that gelatin was the most efficient fining agent, concerning the main objective, which was the clarification of the wine, and consequently the increase in its limpidity. Such a trend was also discussed in relation to the results achieved by nephelometry, total phenols, ζ-potential, color, sensory, and electronic nose analyses. Also, higher concentrations of the fining agent (from 5 to 30 g/100 L) or higher temperatures (from 10 to 20 °C) sped up the process. Finally, the advantage of using the whole spectral signal vs classical univariate approaches was demonstrated by comparing the uncertainty associated with the rate constants of the proposed kinetic model. Overall, multiple light scattering technique showed a great potential for studying fining processes compared to classical univariate approaches.

Production of mineral aggregates in quartz tumbling experiments

NASA Astrophysics Data System (ADS)

Nørnberg, Per; Finster, Kai; Pall Gunnlaugsson, Haraldur; Knak Jensen, Svend; Merrison, Jonathan Peter

2013-04-01

Introduction Tumbling experiments with quartz sand with the purpose of tracing the effect of broken bonds in mineral surfaces resulted in an unexpected production of aggregates. These aggregates are a few microns in diameter, spherical and resembling tiny white "snowballs." Particle comminution by aeolian and other natural weathering processes are known in soil science and is often seen as an increase of fine particles towards the top of soil profiles (Nørnberg, P. 1987, 1988, 2002, J.S. Wright 2007). When mineral grains collide in aeolian processes they break up along weakness zones in the crystal lattice. This mechanism causes broken bonds between atoms in the crystal lattice and results in reactive groups in the mineral surface. This mechanism provides the background for experiments to investigate the oxidation processes of magnetite on the planet Mars. The primary magnetic iron oxide phase on Mars is to day known to be magnetite and the colour of the dust on Mars is most likely due to hematite. To investigate if the oxidation process could take place without going over dissolution and precipitation in water, experiments with tumbling of quartz grains in sealed glass containers along with magnetite were started. The idea was that activated bonds at the surface of quartz could oxidize magnetite and convert it to hematite over time. This proved to be the case (Merrison, J.P. et al. 2010). However, in these experiments we observed the formation of the white aggregates which has been the subject of the study that we present here. Results of tumbling experiments Commercially available quarts (Merck) was sieved to obtain the fraction between 125 and 1000 µm. This fraction was tumbled in glass containers for months and resulted in production of a significant amount of fine grained material (Merrison, J.P et al. 2010). A part of this fine fraction consists of the "snowball"-like aggregates which is a fragile element with relatively high specific surface. The physical

Value-added utilisation of recycled concrete in hot-mix asphalt

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

Wong, Yiik Diew; Sun, Darren Delai; Lai, Dickson

2007-07-01

The feasibility of partial substitution of granite aggregate in hot-mix asphalt (HMA) with waste concrete aggregate was investigated. Three hybrid HMA mixes incorporating substitutions of granite fillers/fines with 6%, 45% untreated, and 45% heat-treated concrete were evaluated by the Marshall mix design method; the optimum binder contents were found to be 5.3%, 6.5% and 7.0% of grade Pen 60/70 bitumen, respectively. All three hybrid mixes satisfied the Marshall criteria of the Singapore Land Transport Authority (LTA) W3B wearing course specification. The hybrid mix with 6% concrete fillers gave comparable resilient modulus and creep resistance as the conventional W3B mix, whilemore » hybrid mixes with higher concrete substitutions achieved better performance. X-ray diffraction (XRD) showed the distinct presence of free lime in the heat-treated concrete, while the scanning electron microscope (SEM) provided an in-depth perspective of the concrete grains in the HMA matrix. The results suggest feasible use of waste concrete as partial aggregate substitution in HMA.« less

Value-added utilisation of recycled concrete in hot-mix asphalt.

PubMed

Wong, Yiik Diew; Sun, Darren Delai; Lai, Dickson

2007-01-01

The feasibility of partial substitution of granite aggregate in hot-mix asphalt (HMA) with waste concrete aggregate was investigated. Three hybrid HMA mixes incorporating substitutions of granite fillers/fines with 6%, 45% untreated, and 45% heat-treated concrete were evaluated by the Marshall mix design method; the optimum binder contents were found to be 5.3%, 6.5% and 7.0% of grade Pen 60/70 bitumen, respectively. All three hybrid mixes satisfied the Marshall criteria of the Singapore Land Transport Authority (LTA) W3B wearing course specification. The hybrid mix with 6% concrete fillers gave comparable resilient modulus and creep resistance as the conventional W3B mix, while hybrid mixes with higher concrete substitutions achieved better performance. X-ray diffraction (XRD) showed the distinct presence of free lime in the heat-treated concrete, while the scanning electron microscope (SEM) provided an in-depth perspective of the concrete grains in the HMA matrix. The results suggest feasible use of waste concrete as partial aggregate substitution in HMA.

Financing electronic waste recycling Californian households' willingness to pay advanced recycling fees.

PubMed

Nixon, Hilary; Saphores, Jean-Daniel M

2007-09-01

The growth of electronic waste (e-waste) is of increasing concern because of its toxic content and low recycling rates. The e-waste recycling infrastructure needs to be developed, yet little is known about people's willingness to fund its expansion. This paper examines this issue based on a 2004 mail survey of California households. Using an ordered logit model, we find that age, income, beliefs about government and business roles, proximity to existing recycling facilities, community density, education, and environmental attitudes are significant factors for explaining people's willingness to pay an advanced recycling fee (ARF) for electronics. Most respondents are willing to support a 1% ARF. Our results suggest that policymakers should target middle-aged and older adults, improve programs in communities with existing recycling centers or in rural communities, and consider public-private partnerships for e-waste recycling programs.

The fast-recycling receptor Megalin defines the apical recycling pathway of epithelial cells

PubMed Central

Perez Bay, Andres E.; Schreiner, Ryan; Benedicto, Ignacio; Paz Marzolo, Maria; Banfelder, Jason; Weinstein, Alan M.; Rodriguez-Boulan, Enrique J.

2016-01-01

The basolateral recycling and transcytotic pathways of epithelial cells were previously defined using markers such as transferrin (TfR) and polymeric IgA (pIgR) receptors. In contrast, our knowledge of the apical recycling pathway remains fragmentary. Here we utilize quantitative live-imaging and mathematical modelling to outline the recycling pathway of Megalin (LRP-2), an apical receptor with key developmental and renal functions, in MDCK cells. We show that, like TfR, Megalin is a long-lived and fast-recycling receptor. Megalin enters polarized MDCK cells through segregated apical sorting endosomes and subsequently intersects the TfR and pIgR pathways at a perinuclear Rab11-negative compartment termed common recycling endosomes (CRE). Whereas TfR recycles to the basolateral membrane from CRE, Megalin, like pIgR, traffics to subapical Rab11-positive apical recycling endosomes (ARE) and reaches the apical membrane in a microtubule- and Rab11-dependent manner. Hence, Megalin defines the apical recycling pathway of epithelia, with CRE as its apical sorting station. PMID:27180806

Aggregate nanostructures of organic molecular materials.

PubMed

Liu, Huibiao; Xu, Jialiang; Li, Yongjun; Li, Yuliang

2010-12-21

Conjugated organic molecules are interesting materials because of their structures and their electronic, electrical, magnetic, optical, biological, and chemical properties. However, researchers continue to face great challenges in the construction of well-defined organic compounds that aggregate into larger molecular materials such as nanowires, tubes, rods, particles, walls, films, and other structural arrays. Such nanoscale materials could serve as direct device components. In this Account, we describe our recent progress in the construction of nanostructures formed through the aggregation of organic conjugated molecules and in the investigation of the optical, electrical, and electronic properties that depend on the size or morphology of these nanostructures. We have designed and synthesized functional conjugated organic molecules with structural features that favor assembly into aggregate nanostructures via weak intermolecular interactions. These large-area ordered molecular aggregate nanostructures are based on a variety of simpler structures such as fullerenes, perylenes, anthracenes, porphyrins, polydiacetylenes, and their derivatives. We have developed new methods to construct these larger structures including organic vapor-solid phase reaction, natural growth, association via self-polymerization and self-organization, and a combination of self-assembly and electrochemical growth. These methods are both facile and reliable, allowing us to produce ordered and aligned aggregate nanostructures, such as large-area arrays of nanowires, nanorods, and nanotubes. In addition, we can synthesize nanoscale materials with controlled properties. Large-area ordered aggregate nanostructures exhibit interesting electrical, optical, and optoelectronic properties. We also describe the preparation of large-area aggregate nanostructures of charge transfer (CT) complexes using an organic solid-phase reaction technique. By this process, we can finely control the morphologies and

Characterization of Size-Fractionated Airborne Particles Inside an Electronic Waste Recycling Facility and Acute Toxicity Testing in Mice.

PubMed

Kim, Yong Ho; Wyrzykowska-Ceradini, Barbara; Touati, Abderrahmane; Krantz, Q Todd; Dye, Janice A; Linak, William P; Gullett, Brian; Gilmour, M Ian

2015-10-06

Disposal of electronic waste (e-waste) in landfills, incinerators, or at rudimentary recycling sites can lead to the release of toxic chemicals into the environment and increased health risks. Developing e-waste recycling technologies at commercial facilities can reduce the release of toxic chemicals and efficiently recover valuable materials. While these e-waste operations represent a vast improvement over previous approaches, little is known about environmental releases, workplace exposures, and potential health impacts. In this study, airborne particulate matter (PM) was measured at various locations within a modern U.S.-based e-waste recycling facility that utilized mechanical processing. In addition, composite size fractionated PM (coarse, fine and ultrafine) samples were collected, extracted, chemically analyzed, and given by oropharyngeal aspiration to mice or cultured with lung slices for lung toxicity tests. Indoor total PM concentrations measured during the study ranged from 220 to 1200 μg/m(3). In general, the coarse PM (2.5-10 μm) was 3-4 times more abundant than fine/ultrafine PM (<2.5 μm). The coarse PM contained higher levels of Ni, Pb, and Zn (up to 6.8 times) compared to the fine (0.1-2.5 μm) and ultrafine (<0.1 μm) PM. Compared to coarse PM measurements from a regional near-roadway study, Pb and Ni were enriched 170 and 20 times, respectively, in the indoor PM, with other significant enrichments (>10 times) observed for Zn and Sb, modest enrichments (>5 times) for Cu and Sr, and minor enrichments (>2 times) for Cr, Cd, Mn, Ca, Fe, and Ba. Negligible enrichment (<2 times) or depletion (<1 time) were observed for Al, Mg, Ti, Si, and V. The coarse PM fraction elicited significant pro-inflammatory responses in the mouse lung at 24 h postexposure compared to the fine and ultrafine PM, and similar toxicity outcomes were observed in the lung slice model. We conclude that exposure to coarse PM from the facility caused substantial inflammation in the

Bacterial cell-wall recycling

PubMed Central

Johnson, Jarrod W.; Fisher, Jed F.; Mobashery, Shahriar

2012-01-01

Many Gram-negative and Gram-positive bacteria recycle a significant proportion of the peptidoglycan components of their cell walls during their growth and septation. In many—and quite possibly all—bacteria, the peptidoglycan fragments are recovered and recycled. While cell-wall recycling is beneficial for the recovery of resources, it also serves as a mechanism to detect cell-wall–targeting antibiotics and to regulate resistance mechanisms. In several Gram-negative pathogens, anhydro-MurNAc-peptide cell-wall fragments regulate AmpC β-lactamase induction. In some Gram-positive organisms, short peptides derived from the cell wall regulate the induction of both β-lactamase and β-lactam-resistant penicillin-binding proteins. The involvement of peptidoglycan recycling with resistance regulation suggests that inhibitors of the enzymes involved in the recycling might synergize with cell-wall-targeted antibiotics. Indeed, such inhibitors improve the potency of β-lactams in vitro against inducible AmpC β-lactamase-producing bacteria. We describe the key steps of cell-wall remodeling and recycling, the regulation of resistance mechanisms by cell-wall recycling, and recent advances toward the discovery of cell-wall recycling inhibitors. PMID:23163477

An Assessment of Recycled Refractory Material Performance After Two Years of Service in a Carbon Bake Furnace

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

Schubert, N.; Bennett, J.P.; Kwong, K.S.

1999-10-27

Material removed from carbon bake furnaces used to manufacture anodes for the production of aluminum metal has historically been disposed by landfill. This material is composed primarily of 50% alumina refractory. in 1997, Alcoa completed a highly successful program to reuse the spent refractories in castables for carbon bake furnace headwalls and flooring, as roadbed aggregate, and in other internal applications. This program recycled/reused 11,000 metric tons of used refractory material (99% of the material removed from the carbon bake furnace) and saved Alcoa over 3.8 of the 9.6 million dollar projected furnace rebuild costs. As assessment is made ofmore » the performance of the recycled refractory components after two years of service.« less

Treatments for clays in aggregates used to produce cement concrete, bituminous materials, and chip seals : technical report.

DOT National Transportation Integrated Search

2013-07-01

The clay contamination of coarse and fine aggregates and its effects on pavement performance of portland cement concrete, bituminous mixes and chip seals is a major concern for Texas Department of Transportation. We proposed (i) to determine what typ...

Quantitative Analysis of Endocytic Recycling of Membrane Proteins by Monoclonal Antibody-Based Recycling Assays.

PubMed

Blagojević Zagorac, Gordana; Mahmutefendić, Hana; Maćešić, Senka; Karleuša, Ljerka; Lučin, Pero

2017-03-01

In this report, we present an analysis of several recycling protocols based on labeling of membrane proteins with specific monoclonal antibodies (mAbs). We analyzed recycling of membrane proteins that are internalized by clathrin-dependent endocytosis, represented by the transferrin receptor, and by clathrin-independent endocytosis, represented by the Major Histocompatibility Class I molecules. Cell surface membrane proteins were labeled with mAbs and recycling of mAb:protein complexes was determined by several approaches. Our study demonstrates that direct and indirect detection of recycled mAb:protein complexes at the cell surface underestimate the recycling pool, especially for clathrin-dependent membrane proteins that are rapidly reinternalized after recycling. Recycling protocols based on the capture of recycled mAb:protein complexes require the use of the Alexa Fluor 488 conjugated secondary antibodies or FITC-conjugated secondary antibodies in combination with inhibitors of endosomal acidification and degradation. Finally, protocols based on the capture of recycled proteins that are labeled with Alexa Fluor 488 conjugated primary antibodies and quenching of fluorescence by the anti-Alexa Fluor 488 displayed the same quantitative assessment of recycling as the antibody-capture protocols. J. Cell. Physiol. 232: 463-476, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Recycling Mentors: an intergenerational, service-learning program to promote recycling and environmental awareness.

PubMed

D'abundo, Michelle L; Fugate-Whitlock, Elizabeth I; Fiala, Kelly A

2011-01-01

The purpose of Recycling Mentors was to implement an intergenerational, service-learning program focused on promoting recycling and environmental awareness among students enrolled in Community Health (HEA 301) and Current Issues in Gerontology (GRN 440/540) and adults older than 60 years. Recycling Mentors was conducted in New Hanover County (NHC), North Carolina, where a moderate climate and coastal location attracts many tourists, retirees, and college students. A community like NHC is a good place to implement service-learning that educates both students and older adults about the benefits of recycling to individual health and the environment. During the Fall 2009 semester, undergraduate and graduate students completed institutional review board training and then conducted the program with older adults. The education component of Recycling Mentors included a pre/post survey, brochure, and scheduled visits. Overall, Recycling Mentors was positive service-learning experience with students identifying salient outcomes such as learning about recycling and the environment and working with older adults. In addition, teaching the education component of Recycling Mentors was good practice for students who will be the future health professionals. While service-learning and environmentally themed projects are common, a program that combines the 2 like Recycling Mentors is unique and has the potential to motivate individual change while positively impacting the local community and the environment.

Development of design guidelines for proper selection of graded aggregate base in Maryland state highways : [research summary].

DOT National Transportation Integrated Search

2015-01-01

Millions of tons of graded aggregate base (GAB) materials are used in construction of : highway base layers in Maryland due to their satisfactory mechanical properties. The : fines content of a GAB material is highly variable and is often related to ...

Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

NASA Astrophysics Data System (ADS)

Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

2015-04-01

(about 10 mm in size) selected per treatment (mulched or conventional tillage) and crop (apricot, citrus and wheat). In this case, every set of aggregates was randomly divided in three groups (n = 30) for assessing stability to slaking, WR and OC, respectively. OC content in the fine earth fraction of soils under different crops did not show important variations, although it increased significantly from conventionally tilled to mulched soils. The distribution of OC content in aggregates with different size varied among soils under different crops, generally increasing with decreasing size. At the intra-aggregate level, OC concentrated preferably in the exterior layer of differently sized aggregates and of aggregate coatings and interior from conventionally tilled soils, probably because of recent organic inputs or leachates. In the case of mulched soils, higher concentrations were observed, but no significant differences among aggregate regions were found. The intensity of water repellency, determined by the ethanol method, did not show great variations among differently sized aggregates under different crops in the 0-10 cm layer, but increased significantly from conventionally tilled to mulched soils. Coarser aggregates were generally wettable, while finer aggregates showed slight water repellency. Regardless of variations in the distribution of OC in different layers of aggregate from conventionally tilled soils, great or significant differences in the distribution of water repellency at the intra-aggregate level were not found. In case of mulched soils such differences were not significant. Finally, the intensity of water repellency was much more important than the concentration of OC in the stability to slaking of aggregates.

Recycle Alaska: Reduce, Reuse, Recycle. Activities Handbook, Teacher's Guide, and Student Worksheets.

ERIC Educational Resources Information Center

Alaska State Dept. of Education, Juneau.

Recycling is a very important aspect of conserving the environment for future generations. This guide addresses the topic of litter prevention for the Alaskan environment and contains 42 activities. Activity topics covered include Natural Cycles, Human Interruption of Natural Cycles, Reduce, Reuse, Recycle and Recycled Classroom. Grade level,…

Influence of increasing amount of recycled concrete powder on mechanical properties of cement paste

NASA Astrophysics Data System (ADS)

Topič, Jaroslav; Prošek, Zdeněk; Plachý, Tomáš

2017-09-01

This paper deals with using fine recycled concrete powder in cement composites as micro-filler and partial cement replacement. Binder properties of recycled concrete powder are given by exposed non-hydrated cement grains, which can hydrate again and in small amount replace cement or improve some mechanical properties. Concrete powder used in the experiments was obtained from old railway sleepers. Infrastructure offer more sources of old concrete and they can be recycled directly on building site and used again. Experimental part of this paper focuses on influence of increasing amount of concrete powder on mechanical properties of cement paste. Bulk density, shrinkage, dynamic Young’s modulus, compression and flexural strength are observed during research. This will help to determine limiting amount of concrete powder when decrease of mechanical properties outweighs the benefits of cement replacement. The shrinkage, dynamic Young’s modulus and flexural strength of samples with 20 to 30 wt. % of concrete powder are comparable with reference cement paste or even better. Negative effect of concrete powder mainly influenced the compression strength. Only a 10 % cement replacement reduced compression strength by about 25 % and further decrease was almost linear.

Parameterizing Aggregation Rates: Results of cold temperature ice-ash hydrometeor experiments

NASA Astrophysics Data System (ADS)

Courtland, L. M.; Dufek, J.; Mendez, J. S.; McAdams, J.

2014-12-01

Recent advances in the study of tephra aggregation have indicated that (i) far-field effects of tephra sedimentation are not adequately resolved without accounting for aggregation processes that preferentially remove the fine ash fraction of volcanic ejecta from the atmosphere as constituent pieces of larger particles, and (ii) the environmental conditions (e.g. humidity, temperature) prevalent in volcanic plumes may significantly alter the types of aggregation processes at work in different regions of the volcanic plume. The current research extends these findings to explore the role of ice-ash hydrometeor aggregation in various plume environments. Laboratory experiments utilizing an ice nucleation chamber allow us to parameterize tephra aggregation rates under the cold (0 to -50 C) conditions prevalent in the upper regions of volcanic plumes. We consider the interaction of ice-coated tephra of variable thickness grown in a controlled environment. The ice-ash hydrometers interact collisionally and the interaction is recorded by a number of instruments, including high speed video to determine if aggregation occurs. The electric charge on individual particles is examined before and after collision to examine the role of electrostatics in the aggregation process and to examine the charge exchange process. We are able to examine how sticking efficiency is related to both the relative abundance of ice on a particle as well as to the magnitude of the charge carried by the hydrometeor. We here present preliminary results of these experiments, the first to constrain aggregation efficiency of ice-ash hydrometeors, a parameter that will allow tephra dispersion models to use near-real-time meteorological data to better forecast particle residence time in the atmosphere.

Generation of urban road dust from anti-skid and asphalt concrete aggregates.

PubMed

Tervahattu, Heikki; Kupiainen, Kaarle J; Räisänen, Mika; Mäkelä, Timo; Hillamo, Risto

2006-04-30

Road dust forms an important component of airborne particulate matter in urban areas. In many winter cities the use of anti-skid aggregates and studded tires enhance the generation of mineral particles. The abrasion particles dominate the PM10 during springtime when the material deposited in snow is resuspended. This paper summarizes the results from three test series performed in a test facility to assess the factors that affect the generation of abrasion components of road dust. Concentrations, mass size distribution and composition of the particles were studied. Over 90% of the particles were aluminosilicates from either anti-skid or asphalt concrete aggregates. Mineral particles were observed mainly in the PM10 fraction, the fine fraction being 12% and submicron size being 6% of PM10 mass. The PM10 concentrations increased as a function of the amount of anti-skid aggregate dispersed. The use of anti-skid aggregate increased substantially the amount of PM10 originated from the asphalt concrete. It was concluded that anti-skid aggregate grains contribute to pavement wear. The particle size distribution of the anti-skid aggregates had great impact on PM10 emissions which were additionally enhanced by studded tires, modal composition, and texture of anti-skid aggregates. The results emphasize the interaction of tires, anti-skid aggregate, and asphalt concrete pavement in the production of dust emissions. They all must be taken into account when measures to reduce road dust are considered. The winter maintenance and springtime cleaning must be performed properly with methods which are efficient in reducing PM10 dust.

Spatiotemporal & Ecological Processes Associated With Goliath Grouper Aggregations in Southeastern Florida

NASA Astrophysics Data System (ADS)

Binder, B. M.; Boswell, K. M.

2016-02-01

The formation of Fish Spawning Aggregations (FSAs) is vital to the life history of many reef fishes, representing the only reproductive opportunity for many species. Unfortunately FSAs present a lucrative target for exploitation which has led to cases of decline and regional extirpation. However, the integration of stakeholders into the design of fisheries management strategies has led to the protection of several species throughout the Greater Caribbean; including the goliath grouper, which has shown evidence of recovery since the moratorium on harvest in 1990. Since the closure, user based and researcher driven initiatives have investigated the recovery, biology, and life history of goliath grouper, but fine scale spatiotemporal and community level aspects of aggregation formation have not been specifically addressed. Thus, we developed a novel two-tiered survey approach using scientific echosounders and diver visual surveys to characterize the spatiotemporal aspects of goliath grouper aggregations, along with the community response to aggregations at six aggregation sites near Jupiter, Florida. Acoustic transects and diver surveys were performed near peak lunar phases throughout the spawning season to quantify fluctuations in goliath grouper density and abundance during the season; and to characterize changes in local community structure in response to aggregation formation. The results from this study are being used to inform the development of resource management plans in South Florida; and addressing these questions will generate a framework to apply a novel research technique in other regions where knowledge of reproductive behavior is absent from the peer-reviewed literature.

The effect of switchable water additives on clay settling.

PubMed

Chen, Chien-Shun; Lau, Ying Yin; Mercer, Sean M; Robert, Tobias; Horton, J Hugh; Jessop, Philip G

2013-01-01

The recycling of process water from strip mining extractions is a very relevant task both industrially and environmentally. The sedimentation of fine tailings during such processes, however, can often require long periods of time and/or the addition of flocculants which make later water recycling difficult. We propose the use of switchable water additives as reversible flocculants for clay/water suspensions. Switchable water additives are compounds such as diamines that make it possible to reversibly control the ionic strength of an aqueous solution. Addition of CO(2) to such an aqueous solution causes the ionic strength to rise dramatically, and the change is reversed upon removal of the CO(2). These additives, while in the presence of CO(2), promote the aggregation of clay tailings, reduce settling times, and greatly increase the clarity of the liberated water. The removal of CO(2) from the liberated water regenerates a low ionic strength solution that does not promote clay aggregation and settling until CO(2) is added again. Such reversible behavior would be useful in applications such as oil sands separations in which the recycled water must not promote aggregation. When added to kaolinite and montmorillonite clay suspensions, switchable water provided process waters of lower turbidity than those additives from inorganic salts or by CO(2)-treatment alone. When recollected, the switchable water supernatant was shown to be recyclable over three cycles for enhanced settling of kaolinite. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integrated and holistic suitability assessment of recycling options for masonry rubble

NASA Astrophysics Data System (ADS)

Herbst, T.; Rübner, K.; Meng, B.

2012-04-01

Our industrial society depends on continuous mining and consumption of raw materials and energy. Besides, the building sector causes one of the largest material streams in Germany. On the one hand, the building sector is connected with a high need in material and energetic resources as well as financial expenditures. On the other hand, nearly 50 % of the volume of waste arises from the building industry. During the last years, the limitation of natural resources, increasing negative environmental consequences as well as rising prices and shortages of dump space have led to a change in thinking in the building and waste industry to a closed substance cycle waste management. In consideration of the production figures of the main kinds of masonry units (clay bricks, sand-lime bricks, autoclaved aerated concrete brick, concrete blocks), a not unimportant quantity of masonry rubble (including gypsum plaster boards, renders, mortars and mineral insulating materials) of more than 20 million tons per year is generated in the medium term. With regard to a sustainable closed substance cycle waste management, these rest masses have to be recycled if possible. Processed aggregates made from masonry rubble can be recycled in the production of new masonry units under certain conditions. Even carefully deconstructed masonry units can once more re-used as masonry units, particularly in the area of the preservation of monuments and historical buildings. In addition, masonry rubble in different processing qualities is applied in earth and road construction, horticulture and scenery construction as well as concrete production. The choice of the most suitable recycling option causes technical, economical and ecological questions. At present, a methodology for a comprehensive suitability assessment with a passable scope of work does not exist. Basic structured and structuring information on the recycling of masonry rubble is absent up to now. This as well as the economic and technical

Compression Molding of Composite of Recycled HDPE and Recycled Tire Particles

NASA Technical Reports Server (NTRS)

Liu, Ping; Waskom, Tommy L.; Chen, Zhengyu; Li, Yanze; Peng, Linda

1996-01-01

Plastic and rubber recycling is an effective means of reducing solid waste to the environment and preserving natural resources. A project aimed at developing a new composite material from recycled high density polyethylene (HDPE) and recycled rubber is currently being conducted at Eastern Illinois University. The recycled plastic pellets with recycled rubber particles are extruded into some HDPE/rubber composite strands. The strand can be further cut into pellets that can be used to fabricate other material forms or products. This experiment was inspired by the above-mentioned research activity. In order to measure Durometer hardness of the extruded composite, a specimen with relatively large dimensions was needed. Thus, compression molding was used to form a cylindrical specimen of 1 in. diameter and 1 in. thickness. The initial poor quality of the molded specimen prompted a need to optimize the processing parameters such as temperature, holding time, and pressure. Design of experiment (DOE) was used to obtain optimum combination of the parameters.

America Recycles Day

NASA Image and Video Library

2017-11-17

In the parking lot of the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, a member of Goodwill Industries loads used household material for recycling. During the two-day event, employees dropped off items as part of America Recycles Day. The center partnered with Goodwill Industries and several other local organizations to collect items for reprocessing. The annual event is a program of Keep America Beautiful, dedicated to promoting and celebrating recycling.

Rab15 Effector Protein: A Novel Protein for Receptor Recycling from the Endocytic Recycling CompartmentD⃞

PubMed Central

Strick, David J.; Elferink, Lisa A.

2005-01-01

Sorting endosomes and the endocytic recycling compartment are critical intracellular stores for the rapid recycling of internalized membrane receptors to the cell surface in multiple cell types. However, the molecular mechanisms distinguishing fast receptor recycling from sorting endosomes and slow receptor recycling from the endocytic recycling compartment remain poorly understood. We previously reported that Rab15 differentially regulates transferrin receptor trafficking through sorting endosomes and the endocytic recycling compartment, suggesting a role for distinct Rab15-effector interactions at these endocytic compartments. In this study, we identified the novel protein Rab15 effector protein (REP15) as a binding partner for Rab15-GTP. REP15 is compartment specific, colocalizing with Rab15 and Rab11 on the endocytic recycling compartment but not with Rab15, Rab4, or early endosome antigen 1 on sorting endosomes. REP15 interacts directly with Rab15-GTP but not with Rab5 or Rab11. Consistent with its localization, REP15 overexpression and small interfering RNA-mediated depletion inhibited transferrin receptor recycling from the endocytic recycling compartment, without affecting receptor entry into or recycling from sorting endosomes. Our data identify REP15 as a compartment-specific protein for receptor recycling from the endocytic recycling compartment, highlighting that the rapid and slow modes of transferrin receptor recycling are mechanistically distinct pathways. PMID:16195351

Size-dependent enrichment of waste slag aggregate fragments abraded from asphalt concrete.

PubMed

Takahashi, Fumitake; Shimaoka, Takayuki; Gardner, Kevin; Kida, Akiko

2011-10-30

Authors consider the environmental prospects of using melted waste slag as the aggregate for asphalt pavement. In particular, the enrichment of slag-derived fragments in fine abrasion dust particles originated from slag asphalt concrete and its size dependency were concerned. A series of surface abrasion tests for asphalt concrete specimens, containing only natural aggregates as reference or 30 wt% of substituted slag aggregates, were performed. Although two of three slag-asphalt concretes generated 1.5-3.0 times larger amount of abrasion dust than the reference asphalt concrete did, it could not be explained only by abrasion resistance of slag. The enrichment of slag-derived fragments in abrasion dust, estimated on the basis of the peak intensity of quartz and heavy metal concentrations, had size dependency for all slag-asphalt concretes. Slag-derived fragments were enriched in abrasion dust particles with diameters of 150-1000 μm. Enrichment factors were 1.4-2.1. In contrast, there was no enrichment in abrasion dust particles with diameter less than 75 μm. This suggests that prior airborne-size fragmentation of substituted slag aggregates does not need to be considered for tested slag aggregates when environmental risks of abrasion dust of slag-asphalt pavement are assessed. Copyright © 2011 Elsevier B.V. All rights reserved.

Biosolids increase soil aggregation and protection of soil carbon five years after application on a crested wheatgrass pasture.

PubMed

Wallace, Brian M; Krzic, Maja; Forge, Tom A; Broersma, Klaas; Newman, Reg F

2009-01-01

Biosolids application to rangelands and pastures recycles nutrients and organic matter back to soils. The effects of biosolids (20 and 60 dry Mg ha(-)(1)) and N+P fertilizer on soil aggregate stability, bulk density, aeration porosity, and total C and N of stable aggregates were evaluated 4 and 5 yr after surface application to a crested wheatgrass [Agropyron cristatum (L.) Gaertn.] pasture in the southern interior of British Columbia (BC). The experiment was established in 2001 in a randomized complete block design with four replications. The 60 Mg ha(-1) biosolids treatment (Bio 60) had a greater aggregate mean weight diameter (MWD) and proportion of water-stable soil aggregates > 1 mm relative to the control and fertilizer treatments. Temporal variation in aggregate stability was attributed to seasonal variations in soil water content. Surface application of 60 Mg ha(-1) of biosolids increased C concentrations within water-stable aggregates relative to the control from 29 to 104, 24 to 79, and 12 to 38 g kg(-1) for the 2 to 6, 1 to 2, and 0.25 to 1 mm size fractions, respectively. The concentration of N within aggregates increased in similar proportions to C. Neither soil bulk density, nor aeration porosity were affected by biosolids application. Increased aggregation and the accumulation of soil C within aggregates following biosolids application creates a potential for better soil C storage, soil water retention, nutrient availability, and ultimately the overall health of semiarid perennial pastures.

Certified Electronics Recyclers

EPA Pesticide Factsheets

Learn how EPA encourages all electronics recyclers become certified by demonstrating to an accredited, independent third-party auditor and that they meet specific standards to safely recycle and manage electronics.

2016 America's Recycle Day

NASA Image and Video Library

2016-11-15

Members of the Sustainability team at NASA's Kennedy Space Center in Florida look over appliances donated for reuse or recycling in conjunction with America Recycles Day. America Recycles Day is a nationally recognized initiative dedicated to promoting recycling in the United States. Kennedy partnered with several organizations in order to donate as many of the items as possible to those who could use them the most in the Space Coast community. Space center personnel brought in electronic waste, gently used household goods, clothing and more.

2016 America's Recycle Day

NASA Image and Video Library

2016-11-15

Members of the Sustainability team at NASA's Kennedy Space Center in Florida sort through items donated for reuse or recycling in conjunction with America Recycles Day. America Recycles Day is a nationally recognized initiative dedicated to promoting recycling in the United States. Kennedy partnered with several organizations in order to donate as many of the items as possible to those who could use them the most in the Space Coast community. Space center personnel brought in electronic waste, gently used household goods, clothing and more.

Cell phone recycling experiences in the United States and potential recycling options in Brazil.

PubMed

Silveira, Geraldo T R; Chang, Shoou-Yuh

2010-11-01

This paper presents an overview of cell phone recycling programs currently available in the United States. At the same time, it also provides analyses of the current recycling situation and possible recycling alternatives for Brazil. Although there are several recycling options in the United States, collection rates are still only 10% of all potential devices because customers are not aware of these possibilities. The whole system is financially based on reselling refurbished cell phones and recycled materials to developing countries which represent an effective and strong market. Several recyclers offer funds to collection partners who are either charities or who work with charities while obtaining the materials that they need in order to run their operations. A mobile phone recycling system for Brazil considering the United States experience and the Extended Producer Responsibility (EPR) principle is suggested. A deposit/refund/advance-recycling fee is proposed which might be implemented as a voluntary industrial initiative managed by PRO Brazil, a producer responsibility organization. One widespread public-private agreement will integrate all mobile phone stakeholders, and environmental education actions and promotional events will promote citizen's participation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Effect of Soil Water Content on the Distribution of Diuron into Organomineral Aggregates of Highly Weathered Tropical Soils.

PubMed

Regitano, Jussara B; Rocha, Wadson S D; Bonfleur, Eloana J; Milori, Debora; Alleoni, Luís R F

2016-05-25

We evaluated the effects of soil water content on the retention of diuron and its residual distribution into organomineral aggregates in four Brazilian oxisols. (14)C-Diuron was incubated for days at 25, 50, and 75% of maximum water-holding capacity for each soil. After 42 days, the physical fractionation method was used to obtain >150, 53-150, 20-53, 2-20, and <2 μm aggregate sizes. Diuron retention increased with increasing soil water content for all soils. At lower soil water content, diuron's retention was higher in the sandier soil. It was mostly retained in the fine (<20 μm) aggregates of sandier soil, and for clayed soils, retention was higher in the coarse aggregates (>53 μm). The sorption coefficients (Kd and Koc) generated by batch studies should be carefully used because they do not provide information about aggregation and diffusion effects on pesticides soil sorption.

Soil Aggregates and Associated Organic Matter under Conventional Tillage, No-Tillage, and Forest Succession after Three Decades

PubMed Central

Devine, Scott; Markewitz, Daniel; Hendrix, Paul; Coleman, David

2014-01-01

Impacts of land use on soil organic C (SOC) are of interest relative to SOC sequestration and soil sustainability. The role of aggregate stability in SOC storage under contrasting land uses has been of particular interest relative to conventional tillage (CT) and no-till (NT) agriculture. This study compares soil structure and SOC fractions at the 30-yr-old Horseshoe Bend Agroecosystem Experiment (HSB). This research is unique in comparing NT and CT with adjacent land concurrently undergoing forest succession (FS) and in sampling to depths (15–28 cm) previously not studied at HSB. A soil moving experiment (SME) was also undertaken to monitor 1-yr changes in SOC and aggregation. After 30 years, enhanced aggregate stability under NT compared to CT was limited to a depth of 5 cm, while enhanced aggregate stability under FS compared to CT occurred to a depth of 28 cm and FS exceeded NT from 5–28 cm. Increases in SOC concentrations generally followed the increases in stability, except that no differences in SOC concentration were observed from 15–28 cm despite greater aggregate stability. Land use differences in SOC were explained equally by differences in particulate organic carbon (POC) and in silt-clay associated fine C. Enhanced structural stability of the SME soil was observed under FS and was linked to an increase of 1 Mg SOC ha−1 in 0–5 cm, of which 90% could be attributed to a POC increase. The crushing of macroaggregates in the SME soil also induced a 10% reduction in SOC over 1 yr that occurred under all three land uses from 5–15 cm. The majority of this loss was in the fine C fraction. NT and FS ecosystems had greater aggregation and carbon storage at the soil surface but only FS increased aggregation below the surface, although in the absence of increased carbon storage. PMID:24465460

Characterization of Mechanical and Bactericidal Properties of Cement Mortars Containing Waste Glass Aggregate and Nanomaterials

PubMed Central

Sikora, Pawel; Augustyniak, Adrian; Cendrowski, Krzysztof; Horszczaruk, Elzbieta; Rucinska, Teresa; Nawrotek, Pawel; Mijowska, Ewa

2016-01-01

The recycling of waste glass is a major problem for municipalities worldwide. The problem concerns especially colored waste glass which, due to its low recycling rate as result of high level of impurity, has mostly been dumped into landfills. In recent years, a new use was found for it: instead of creating waste, it can be recycled as an additive in building materials. The aim of the study was to evaluate the possibility of manufacturing sustainable and self-cleaning cement mortars with use of commercially available nanomaterials and brown soda-lime waste glass. Mechanical and bactericidal properties of cement mortars containing brown soda-lime waste glass and commercially available nanomaterials (amorphous nanosilica and cement containing nanocrystalline titanium dioxide) were analyzed in terms of waste glass content and the effectiveness of nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50%, 75% and 100% by weight. Study has shown that waste glass can act as a successful replacement for sand (up to 100%) to produce cement mortars while nanosilica is incorporated. Additionally, a positive effect of waste glass aggregate for bactericidal properties of cement mortars was observed. PMID:28773823

Characterization of Mechanical and Bactericidal Properties of Cement Mortars Containing Waste Glass Aggregate and Nanomaterials.

PubMed

Sikora, Pawel; Augustyniak, Adrian; Cendrowski, Krzysztof; Horszczaruk, Elzbieta; Rucinska, Teresa; Nawrotek, Pawel; Mijowska, Ewa

2016-08-18

The recycling of waste glass is a major problem for municipalities worldwide. The problem concerns especially colored waste glass which, due to its low recycling rate as result of high level of impurity, has mostly been dumped into landfills. In recent years, a new use was found for it: instead of creating waste, it can be recycled as an additive in building materials. The aim of the study was to evaluate the possibility of manufacturing sustainable and self-cleaning cement mortars with use of commercially available nanomaterials and brown soda-lime waste glass. Mechanical and bactericidal properties of cement mortars containing brown soda-lime waste glass and commercially available nanomaterials (amorphous nanosilica and cement containing nanocrystalline titanium dioxide) were analyzed in terms of waste glass content and the effectiveness of nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50%, 75% and 100% by weight. Study has shown that waste glass can act as a successful replacement for sand (up to 100%) to produce cement mortars while nanosilica is incorporated. Additionally, a positive effect of waste glass aggregate for bactericidal properties of cement mortars was observed.

2016 America's Recycle Day

NASA Image and Video Library

2016-11-15

A sign tells NASA Kennedy Space Center employees they have come to the right place to donate items for reuse or recycling in conjunction with America Recycles Day. America Recycles Day is a nationally recognized initiative dedicated to promoting recycling in the United States. Kennedy partnered with several organizations in order to donate as many of the items as possible to those who could use them the most in the Space Coast community. Space center personnel brought in electronic waste, gently used household goods, clothing and more. The two-day event was sponsored by Kennedy's Sustainability team.

2016 America's Recycle Day

NASA Image and Video Library

2016-11-15

Members of the Sustainability team at NASA's Kennedy Space Center in Florida set up giveaway items and sort through donations for reuse or recycling in conjunction with America Recycles Day. America Recycles Day is a nationally recognized initiative dedicated to promoting recycling in the United States. Kennedy partnered with several organizations in order to donate as many of the items as possible to those who could use them the most in the Space Coast community. Space center personnel brought in electronic waste, gently used household goods, clothing and more. The two-day event was sponsored by Kennedy's Sustainability team.

Adjusting particle-size distributions to account for aggregation in tephra-deposit model forecasts

USGS Publications Warehouse

Mastin, Larry G.; Van Eaton, Alexa; Durant, A.J.

2016-01-01

Volcanic ash transport and dispersion (VATD) models are used to forecast tephra deposition during volcanic eruptions. Model accuracy is limited by the fact that fine-ash aggregates (clumps into clusters), thus altering patterns of deposition. In most models this is accounted for by ad hoc changes to model input, representing fine ash as aggregates with density ρagg, and a log-normal size distribution with median μagg and standard deviation σagg. Optimal values may vary between eruptions. To test the variance, we used the Ash3d tephra model to simulate four deposits: 18 May 1980 Mount St. Helens; 16–17 September 1992 Crater Peak (Mount Spurr); 17 June 1996 Ruapehu; and 23 March 2009 Mount Redoubt. In 192 simulations, we systematically varied μagg and σagg, holding ρagg constant at 600 kg m−3. We evaluated the fit using three indices that compare modeled versus measured (1) mass load at sample locations; (2) mass load versus distance along the dispersal axis; and (3) isomass area. For all deposits, under these inputs, the best-fit value of μagg ranged narrowly between  ∼  2.3 and 2.7φ (0.20–0.15 mm), despite large variations in erupted mass (0.25–50 Tg), plume height (8.5–25 km), mass fraction of fine ( <  0.063 mm) ash (3–59 %), atmospheric temperature, and water content between these eruptions. This close agreement suggests that aggregation may be treated as a discrete process that is insensitive to eruptive style or magnitude. This result offers the potential for a simple, computationally efficient parameterization scheme for use in operational model forecasts. Further research may indicate whether this narrow range also reflects physical constraints on processes in the evolving cloud.

Cross-linked enzyme aggregates of phenylalanine ammonia lyase: novel biocatalysts for synthesis of L-phenylalanine.

PubMed

Cui, Jian-Dong; Zhang, Si; Sun, Li-Mei

2012-06-01

Cross-linked enzyme aggregates of phenylalanine ammonia lyase (PAL-CLEAs) from Rhodotorula glutinis were prepared. The effects of the type of aggregating agent, its concentration, and that of cross-linking agent were studied. PAL-CLEAs production was most effective using ammonium sulfate (40 % saturation), followed by cross-linking for 1 h with 0.2 % (v/v) glutaraldehyde. Moreover, the storage and operational stability of the resulting PAL-CLEAs were also investigated. Compared to the free enzyme, the PAL-CLEAs exhibited the expected increased stability of the enzyme against various deactivating conditions such as pH, temperature, denaturants, and organic solvents and showed higher storage stability than its soluble counterpart. Additionally, the reusability of PAL-CLEAs with respect to the biotransformation of L-phenylalanine was evaluated. PAL-CLEAs could be recycled at least for 12 consecutive batch reactions without dramatic activity loss, which should dramatically increase the commercial potential of PAL for synthesis of L: -phenylalanine. To the best of our knowledge, this is the first report of immobilization of PAL as cross-linked enzyme aggregates.

Impact of ozonation on particle aggregation in mature fine tailings.

PubMed

Liang, Jiaming; Tumpa, Fahmida; Pérez Estrada, Leonidas; Gamal El-Din, Mohamed; Liu, Yang

2014-12-15

The extraction of bitumen from the oil sands in Canada generates tonnes of mature fine tailings (MFT), consisting of a mineral matrix of sand, clay, and water, which without treatment requires thousands of years to fully consolidate. We assessed the performance of a novel ozonation method designed to enhance the settling of MFT and explored the mechanisms involved. The solid content of MFT obtained from oil sands tailings was adjusted to 1, 3, 5 wt % with water before applying 15, 30, and 60 min of ozonation. MFT settled after a short (15 min) ozonation treatment, resulting in a sample with clear released water on the top and condensed sludge at the bottom. The water chemistry characteristics, particles' surface charge and chemical bonding were measured. Ozonation led to the increased organic acids concentrations in MFT suspension through converting of organic matter from high to low molecular weight, and detaching organic coating on MFT particles. The pH and the concentrations of ions in the MFT suspension were changed significantly, an association of metal ions with MFT particles was promoted, and the surface charges of MFT particles were neutralized. Consequently, the MFT suspension was destabilized and MFT particle precipitation was observed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recycling at Camp.

ERIC Educational Resources Information Center

Cummins, William M.

1988-01-01

Outlines a Michigan summer camp's efforts to reduce solid waste disposal by recycling cardboard, tin, glass, aluminum, and plastic milk containers. Points out variables affecting the success of such efforts. Discusses Michigan state funding for the development of recycling programs. (SV)

Characteristic features and biotechnological applications of cross-linked enzyme aggregates (CLEAs).

PubMed

Sheldon, Roger A

2011-11-01

Cross-linked enzyme aggregates (CLEAs) have many economic and environmental benefits in the context of industrial biocatalysis. They are easily prepared from crude enzyme extracts, and the costs of (often expensive) carriers are circumvented. They generally exhibit improved storage and operational stability towards denaturation by heat, organic solvents, and autoproteolysis and are stable towards leaching in aqueous media. Furthermore, they have high catalyst productivities (kilograms product per kilogram biocatalyst) and are easy to recover and recycle. Yet another advantage derives from the possibility to co-immobilize two or more enzymes to provide CLEAs that are capable of catalyzing multiple biotransformations, independently or in sequence as catalytic cascade processes.

Tire Recycling

NASA Technical Reports Server (NTRS)

1997-01-01

Cryopolymers, Inc. tapped NASA expertise to improve a process for recycling vehicle tires by converting shredded rubber into products that can be used in asphalt road beds, new tires, hoses, and other products. In conjunction with the Southern Technology Applications Center and Stennis Space Center, NASA expertise in cryogenic fuel-handling needed for launch vehicle and spacecraft operations was called upon to improve the recycling concept. Stennis advised Cryopolymers on the type of equipment required, as well as steps to reduce the amount of liquid nitrogen used in the process. They also guided the company to use more efficient ways to control system hardware. It is estimated that more than 300 million tires nationwide are produced per year. Cryopolymers expects to reach a production rate of 5,000 tires recycled per day.

Auditing an intensive care unit recycling program.

PubMed

Kubicki, Mark A; McGain, Forbes; O'Shea, Catherine J; Bates, Samantha

2015-06-01

The provision of health care has significant direct environmental effects such as energy and water use and waste production, and indirect effects, including manufacturing and transport of drugs and equipment. Recycling of hospital waste is one strategy to reduce waste disposed of as landfill, preserve resources, reduce greenhouse gas emissions, and potentially remain fiscally responsible. We began an intensive care unit recycling program, because a significant proportion of ICU waste was known to be recyclable. To determine the weight and proportion of ICU waste recycled, the proportion of incorrect waste disposal (including infectious waste contamination), the opportunity for further recycling and the financial effects of the recycling program. We weighed all waste and recyclables from an 11-bed ICU in an Australian metropolitan hospital for 7 non-consecutive days. As part of routine care, ICU waste was separated into general, infectious and recycling streams. Recycling streams were paper and cardboard, three plastics streams (polypropylene, mixed plastics and polyvinylchloride [PVC]) and commingled waste (steel, aluminium and some plastics). ICU waste from the waste and recycling bins was sorted into those five recycling streams, general waste and infectious waste. After sorting, the waste was weighed and examined. Recycling was classified as achieved (actual), potential and total. Potential recycling was defined as being acceptable to hospital protocol and local recycling programs. Direct and indirect financial costs, excluding labour, were examined. During the 7-day period, the total ICU waste was 505 kg: general waste, 222 kg (44%); infectious waste, 138 kg (27%); potentially recyclable waste, 145 kg (28%). Of the potentially recyclable waste, 70 kg (49%) was actually recycled (14% of the total ICU waste). In the infectious waste bins, 82% was truly infectious. There was no infectious contamination of the recycling streams. The PVC waste was 37% contaminated

Reduction of Leaching Impacts by Applying Biomass Bottom Ash and Recycled Mixed Aggregates in Structural Layers of Roads

PubMed Central

Cabrera, Manuel; Galvin, Adela P.; Agrela, Francisco; Beltran, Manuel G.; Ayuso, Jesus

2016-01-01

This research is focused on analyzing the environmental pollution potential of biomass bottom ashes as individual materials, as mixtures manufactured with biomass bottom ashes and granular construction aggregates, and these mixtures treated with cement. For the environmental assessment of all of the samples and materials mentioned, the following leaching procedures have been performed: the compliance batch test of UNE-EN 12457-3:2003 for aggregates and bottom ashes; the column test according to NEN 7343:1994 for the mixtures prepared in the laboratory; and the tank test by EA NEN 7375:2004 for analyzing the behavior of mixtures after their solidification/stabilization with 5% cement. After the discussion of the data, the reduction of the pollution load of the most hazardous biomass bottom ashes after their combination with different aggregates can be confirmed, which implies their possible application in civil infrastructures, such as filler embankments and road construction layers, without negatively impacting the environment. In addition, the positive effect of the stabilization/solidification of the cement-treated mixtures with a reduction of the heavy metals that were released at the highest levels, namely As, Hg Cr, Ni, Cu, Se and Mo, was proven. PMID:28773352

Comparison Pore Aggregate Levels After Extraction With Solvents Pertamax Plus And Gasoline

NASA Astrophysics Data System (ADS)

Anggraini, Muthia

2017-12-01

Loss of asphalt content extraction results become problems in Field Work For implementing parties. The use of solvents with high octane (pertamax plus) for the extraction, dissolving the asphalt more than gasoline. By comparing the levels of aggregate pores after using solvent extraction pertamax plus compared to gasoline could answer that pertamax plus more solvent dissolves the bitumen compared to gasoline. This study aims to obtain comparative levels of porous aggregate mix AC-WC after using solvent extraction pertamax plus compared to gasoline. This study uses the aggregate that has been extracted from the production of asphalt mixtures, when finisher and after compaction field. The method used is the assay of coarse and fine aggregate pores, extraction of bitumen content to separate the aggregate with bitumen. Results of testing the total absorption after extraction using a solvent preta max plus in the production of asphalt mixtures 0.80%, while gasoline solvent 0.67% deviation occurs 0.13%. In the finisher after the solvent extraction preta max plus 0.77%, while 0.67% gasoline solvent occurs deviation of 0.1%. At the core after extraction and solvent pertamax plus 0.71%, while gasoline solvent 0.60% 0.11% deviation occurs. The total water absorption after extraction using a solvent pertamax plus greater than gasoline. This proves that the solvent dissolves pertamax plus more asphalt than gasoline.

The Utilisation of Shredded PET as Aggregate Replacement for Interlocking Concrete Block

NASA Astrophysics Data System (ADS)

Mokhtar, M.; Kaamin, M.; Sahat, S.; Hamid, N. B.

2018-03-01

The consumption of plastic has grown substantially all over the world in recent years and this has created huge quantities of plastic-based waste. Plastic waste is now a serious environmental threat to the modern way of living, although steps were taken to reduce its consumption. This creates substantial garbage every day, which is much unhealthy. Plastic bottles such as Polyethylene terephthalate (PET) was use as the partially component in this making of interlocking blocks concrete. This project investigates the strength and workability of the interlocking block concrete by replacing course aggregate with % PET. The suitability of recycled plastics (PET) as course aggregate in interlocking block concrete and its advantages are discussed here. Moreover, there were more benefits when using interlocking block than using conventional block such as it easy for construction because they are aligning, easy to place, high speed stacking and they offer more resistance to shear and buildings would be even stronger. Based on the test perform, the failure parameter were discussed .From the compressive strength test result, it shows that the strength of concrete block decreased with increased of PET used. From the results, it shows that higher compressive strength was found with 5% natural course aggregate replaced with PET compared to other percentages.

A tale of five cities: Using recycling frameworks to analyse inclusive recycling performance.

PubMed

Scheinberg, Anne; Simpson, Michael

2015-11-01

'Recycling' is a source of much confusion, particularly when comparing solid waste systems in high-income countries with those in low- and middle-income countries. Few analysts can explain why the performance and structure of recycling appears to be so different in rich countries from poor ones, nor why well-meaning efforts to implement recycling so often fail. The analysis of policy drivers, and the Integrated Sustainable Waste Management (ISWM) framework, come close to an explanation.This article builds on these earlier works, focusing in on five cities profiled in the 2010 UN-Habitat publication (Scheinberg A, Wilson DC and Rodic L (2010) Solid Waste Management in the World's Cities. UN-Habitat's Third Global Report on the State of Water and Sanitation in the World's Cities. Newcastle-on-Tyne, UK: Earthscan Publications). Data from these cities and others provides the basis for developing a new tool to analyse inclusive recycling performance. The points of departure are the institutional and economic relationships between the service chain, the public obligation to remove waste, pollution, and other forms of disvalue, and the value chain, a system of private enterprises trading valuable materials and providing markets for recyclables. The methodological innovation is to use flows of materials and money as indicators of institutional relationships, and is an extension of process flow diagramming.The authors are using the term 'recycling framework analysis' to describe this new form of institutional analysis. The diagrams increase our understanding of the factors that contribute to high-performance inclusive recycling. By focusing on institutional relationships, the article seeks to improve analysis, planning, and ultimately, outcomes, of recycling interventions. © The Author(s) 2015.

Flocculation characteristics of freshly eroded aggregates

NASA Astrophysics Data System (ADS)

Manning, Andrew; Wendling, Valentin; Gratiot, Nicolas; Legout, Cedric; Michallet, Herve

2014-05-01

In Europe, 260,000 square kms of soils already suffer erosion by water. This worrying level of land degradation is expected to increase in the context of climate change, with situations particularly critical in mountainous environments. This study aims at improving sediment transport parameterisation, by examining the kinetics of fine soil aggregates (size D, settling velocity Ws, density), once immersed in a turbulent flow. Thus observing the changing state, as soil aggregates become suspended sediment floc/aggregates. Particle properties of two Mediterranean materials (black marl and molasse, both sampled in badlands) were tested in grid stirred experiments. Hydrodynamic properties were monitored with ADV and turbidity sensors. For each soil, three suspended sediment concentration (SSC) loads (1.5; 5; 10 g/l) representative of flood conditions were tested. Aggregate properties were obtained at four depths above the grid, using the video LabSFLOC technique and laser techniques. These acquisition heights are associated with the corresponding turbulence dissipation rates G of 1.5, 3, 7 and 19 s^-1. Once particles were injected in the tank, a quasi-equilibrium state was rapidly reached, after one to two minutes. The floc/aggregate properties did not vary with sediment load. The median diameter D_50 was measured to be around 60 microns for the clay loam soil and around 15 microns for the two badlands materials. Examining the molasse samples, we see that the SSC at 1, 5, 10, 20 and 40 minute intervals were all +12 g/l at distances 10 cm and 15 cm above the nominal vertical mid-stroke grid position for the experimental SSC ranges. At the less turbulent zone, a 2 g/l base SSC reduced by 80% and at a nominal 10 g/l the SSC dipped by two orders of magnitude from the base concentration. If we consider the population distribution for molasse at a base SSC of 10 g/l sampled 15cm above the grid after 40 minutes, D ranged from 39 - 273 microns. A small microfloc cluster only

Resource Efficient Metal and Material Recycling

NASA Astrophysics Data System (ADS)

Reuter, Markus A.; van Schaik, Antoinette

Metals enable sustainability through their use and their recyclability. However, various factors can affect the Resource Efficiency of Metal Processing and Recycling. Some typical factors that enable Resource Efficiency include and arranged under the drivers of sustainability: Environment (Maximize Resource Efficiency — Energy, Recyclates, Materials, Water, Sludges, Emissions, Land); Economic Feasibility (BAT & Recycling Systems Simulation / Digitalization, Product vis-à-vis Material Centric Recycling); and Social — Licence to Operate (Legislation, consumer, policy, theft, manual labour.). In order to realize this primary production has to be linked systemically with typical actors in the recycling chain such as Original Equipment Manufacturers (OEMs), Recyclers & Collection, Physical separation specialists as well as process metallurgical operations that produce high value metals, compounds and products that recycle back to products. This is best done with deep knowledge of multi-physics, technology, product & system design, process control, market, life cycle management, policy, to name a few. The combination of these will be discussed as Design for Sustainability (DfS) and Design for Recycling (DfR) applications.

Carbon quantum dots-based recyclable real-time fluorescence assay for alkaline phosphatase with adenosine triphosphate as substrate.

PubMed

Qian, Zhaosheng; Chai, Lujing; Tang, Cong; Huang, Yuanyuan; Chen, Jianrong; Feng, Hui

2015-03-03

A convenient, reliable, and highly sensitive real-time assay for alkaline phosphatase (ALP) activity in the continuous and recyclable way is established on the basis of aggregation and disaggregation of carbon quantum dots (CQDs) through the competitive assay approach. CQDs and adenosine triphosphate (ATP) were used as the fluorescent indicator and substrate for ALP activity assessment, respectively. Richness of carboxyl groups on the surface of CQDs enables their severe aggregation triggered by cerium ions, which results in effective fluorescence quenching. Under the catalytic hydrolysis of ALP, ATP can be rapidly transformed to phosphate ions. Stronger affinity of phosphate ions to cerium ions than carboxyl groups is taken advantage of to achieve fluorescence recovery induced by redispersion of CQDs in the presence of ALP and ATP. Quantitative evaluation of ALP activity in a broad range from 4.6 to 383.3 U/L with the detection limit of 1.4 U/L can be realized in this way, which endows the assay with high enough sensitivity for practical detection in human serum. The assay can be used in a recyclable way for more than three times since the generated product CePO4 as a precipitate can be easily removed from the standard assay system. This strategy broadens the sensing application of fluorescent CQDs with excellent biocompatibility and provides an example based on disaggregation in optical probe development.

Mesoscale behavior study of collector aggregations in a wet dust scrubber.

PubMed

Li, Xiaochuan; Wu, Xiang; Hu, Haibin; Jiang, Shuguang; Wei, Tao; Wang, Dongxue

2018-01-01

In order to address the bottleneck problem of low fine-particle removal efficiency of self-excited dust scrubbers, this paper is focused on the influence of the intermittent gas-liquid two-phase flow on the mesoscale behavior of collector aggregations. The latter is investigated by the application of high-speed dynamic image technology to the self-excited dust scrubber experimental setup. The real-time-scale monitoring of the dust removal process is provided to clarify its operating mechanism at the mesoscale level. The results obtained show that particulate capturing in self-excited dust scrubber is provided by liquid droplets, liquid films/curtains, bubbles, and their aggregations. Complex spatial and temporal structures are intrinsic to each kind of collector morphology, and these are considered as the major factors controlling the dust removal mechanism of self-excited dust scrubbers. For the specific parameters of gas-liquid two-phase flow under study, the evolution patterns of particular collectors reflect the intrinsic, intermittent, and complex characteristics of the temporal structure. The intermittent initiation of the collector and the air hole formation-collapse cyclic processes provide time and space for the fine dust to escape from being trapped by the collectors. The above mesoscale experimental data provide more insight into the factors reducing the dust removal efficiency of self-excited dust scrubbers. This paper focuses on the reconsideration of the capturer aggregations of self-excited dust scrubbers from the mesoscale. Complex structures in time and space scales exist in each kind of capturer morphology. With changes of operating parameters, the morphology and spatial distributions of capturers diversely change. The change of the capturer over time presents remarkable, intermittent, and complex characteristics of the temporal structure.

Carbon dioxide recycling

EPA Science Inventory

The recycling of carbon dioxide to methanol and dimethyl ether is seen to offer a substantial route to renewable and environmentally carbon neutral fuels. One of the authors has championed the “Methanol Economy" in articles and a book. By recycling ambient CO2, the authors argue ...

Printability of papers recycled from toner and inkjet-printed papers after deinking and recycling processes.

PubMed

Karademir, Arif; Aydemir, Cem; Tutak, Dogan; Aravamuthan, Raja

2018-04-01

In our contemporary world, while part of the fibers used in the paper industry is obtained from primary fibers such as wood and agricultural plants, the rest is obtained from secondary fibers from waste papers. To manufacture paper with high optical quality from fibers of recycled waste papers, these papers require deinking and bleaching of fibers at desired levels. High efficiency in removal of ink from paper mass during recycling, and hence deinkability, are especially crucial for the optical and printability quality of the ultimate manufactured paper. In the present study, deinkability and printability performance of digitally printed paper with toner or inkjet ink were compared for the postrecycling product. To that end, opaque 80 g/m 2 office paper was digitally printed under standard printing conditions with laser toner or inkjet ink; then these sheets of paper were deinked by a deinking process based on the INGEDE method 11 p. After the deinking operation, the optical properties of the obtained recycled handsheets were compared with unprinted (reference) paper. Then the recycled paper was printed on once again under the same conditions as before with inkjet and laser printers, to monitor and measure printing color change before and after recycling, and differences in color universe. Recycling and printing performances of water-based inkjet and toner-based laser printed paper were obtained. The outcomes for laser-printed recycled paper were better than those for inkjet-printed recycled paper. Compared for luminosity Y, brightness, CIE a* and CIE b* values, paper recycled from laser-printed paper exhibited higher value than paper recycled from inkjet-printed paper.

Effect of surrogate aggregates on the thermal conductivity of concrete at ambient and elevated temperatures.

PubMed

Yun, Tae Sup; Jeong, Yeon Jong; Youm, Kwang-Soo

2014-01-01

The accurate assessment of the thermal conductivity of concretes is an important part of building design in terms of thermal efficiency and thermal performance of materials at various temperatures. We present an experimental assessment of the thermal conductivity of five thermally insulated concrete specimens made using lightweight aggregates and glass bubbles in place of normal aggregates. Four different measurement methods are used to assess the reliability of the thermal data and to evaluate the effects of the various sensor types. The concrete specimens are also assessed at every 100 °C during heating to ~800 °C. Normal concrete is shown to have a thermal conductivity of ~2.25 W m(-1) K(-1). The surrogate aggregates effectively reduce the conductivity to ~1.25 W m(-1) K(-1) at room temperature. The aggregate size is shown not to affect thermal conduction: fine and coarse aggregates each lead to similar results. Surface contact methods of assessment tend to underestimate thermal conductivity, presumably owing to high thermal resistance between the transducers and the specimens. Thermogravimetric analysis shows that the stages of mass loss of the cement paste correspond to the evolution of thermal conductivity upon heating.

Effect of Surrogate Aggregates on the Thermal Conductivity of Concrete at Ambient and Elevated Temperatures

PubMed Central

Yun, Tae Sup; Jeong, Yeon Jong; Youm, Kwang-Soo

2014-01-01

The accurate assessment of the thermal conductivity of concretes is an important part of building design in terms of thermal efficiency and thermal performance of materials at various temperatures. We present an experimental assessment of the thermal conductivity of five thermally insulated concrete specimens made using lightweight aggregates and glass bubbles in place of normal aggregates. Four different measurement methods are used to assess the reliability of the thermal data and to evaluate the effects of the various sensor types. The concrete specimens are also assessed at every 100°C during heating to ~800°C. Normal concrete is shown to have a thermal conductivity of ~2.25 W m−1 K−1. The surrogate aggregates effectively reduce the conductivity to ~1.25 W m−1 K−1 at room temperature. The aggregate size is shown not to affect thermal conduction: fine and coarse aggregates each lead to similar results. Surface contact methods of assessment tend to underestimate thermal conductivity, presumably owing to high thermal resistance between the transducers and the specimens. Thermogravimetric analysis shows that the stages of mass loss of the cement paste correspond to the evolution of thermal conductivity upon heating. PMID:24696666

16 CFR 260.12 - Recyclable claims.

Code of Federal Regulations, 2013 CFR

2013-01-01

... established recycling program for reuse or use in manufacturing or assembling another item. (b) Marketers... the availability of recycling programs and collection sites to consumers. (1) When recycling..., means at least 60 percent. (2) When recycling facilities are available to less than a substantial...

16 CFR 260.12 - Recyclable claims.

Code of Federal Regulations, 2014 CFR

2014-01-01

... established recycling program for reuse or use in manufacturing or assembling another item. (b) Marketers... the availability of recycling programs and collection sites to consumers. (1) When recycling..., means at least 60 percent. (2) When recycling facilities are available to less than a substantial...

MX Siting Investigation. Geotechnical Evaluation. Aggregate Resources Study, Lake Valley, Nevada.

DTIC Science & Technology

1981-02-27

KILOMETERS Mx SITING INVESTIGATION IGURE IPARTMENT OF TNt Ag1 FORCE - GMO 2 -_ONiO NATIONAL INC. FlU It FN-TR-37-f 5 2. Aerial and ground reconnaissance...fine, or crushed rock) and potential construction use ( con - crete and/or road base). TOM. FN-TR -37-f 6 2.0 STUDY APPROACH 2.1 EXISTING DATA Collection...2 the southwestern part of Lake Valley. This formation also pro - vides Class I crushed rock aggregate material in the southern White Rock Mountains

Nature and origin of the resistant carbonaceous polymorphs involved the fossilization of biogenic soil-aggregates

NASA Astrophysics Data System (ADS)

Courty, M.-A.

2012-04-01

The rare occurrence of organic-rich surface horizons in soil archives is widely accepted to resulting from their rapid degradation. We intend here to further elucidate how pedogenic signatures that initially formed at the soil surface could resist over long timescales to burial processes. We focus on the structural evolution of the biogenic soil aggregates that is controlled by the complex interaction of bioturbation, root colonization, microbial decomposition, chemical weathering and physical processes. The nature and origin of carbonaceous components that could possibly contribute to the long term preservation of biogenic soil-aggregates is particularly examined. The study is based on the comparison of pedogenic aggregated microfacies from present-day situations and the ones encountered in soil archives from contrasting edaphic conditions: Arctic Holocene soils from Spitsbergen, hyper-arid soils from the Moche valley (Peru), Holocene semi-arid Mediterranean soils from Northern Syria, late Pleistocene paleosols from lake Mungo (South Wales Australia) and late Pleistocene paleosols from the Ardeche valley (France). The assemblage and composition of biogenic soil-aggregated horizons has been characterized under the binocular microscope and in thin sections. The basic components have been separated by water sieving. A typology of carbonaceous polymorphs and associated composite materials has been established under the binocular. They have been characterized by SEM-EDS, Raman spectrometry, X-ray diffraction and TEM. The comparative study shows that all the biogenic soil-aggregates from the soil archives contain a high amount of similar exotic components that contrast from the parent materials by their fresh aspect and their hydrophobic properties. This exotic assemblage comprises various types of aliphatic carbonaceous polymorphs (filaments, agglutinates, spherules) and aromatic ones (vitrous char, graphite), carbon cenospheres, fine grained sandstones and rock clasts

You're a "What"? Recycling Coordinator

ERIC Educational Resources Information Center

Torpey, Elka Maria

2011-01-01

Recycling coordinators supervise curbside and dropoff recycling programs for municipal governments or private firms. Today, recycling is mandatory in many communities. And advancements in collection and processing methods have helped to increase the quantity of materials for which the recycling coordinator is responsible. In some communities,…

Approaching Moisture Recycling Governance

NASA Astrophysics Data System (ADS)

Keys, Patrick; Wang-Erlandsson, Lan; Gordon, Line; Galaz, Victor; Ebbesson, Jonas

2017-04-01

The spatial and temporal dynamics of water resources are a continuous challenge for effective and sustainable national and international governance. Despite the surface watershed being the typical unit of water management, recent advances in hydrology have revealed 'atmospheric watersheds' - otherwise known as precipitationsheds. Also, recent research has demonstrated that water flowing within a precipitationshed may be modified by land-use change in one location, while the effect of this modification could be felt in a different province, nation, or continent. Notwithstanding these insights, the major legal and institutional implications of modifying moisture recycling have remained unexplored. In this presentation, we examine potential approaches to moisture recycling governance. We first identify a set of international study regions, and then develop a typology of moisture recycling relationships within these regions ranging from bilateral moisture exchange to more complex networks. This enables us to classify different types of legal and institutional governance principles. Likewise, we relate the moisture recycling types to existing land and water governance frameworks and management practices. The complexity of moisture recycling means institutional fit will be difficult to generalize for all moisture recycling relationships, but our typology allows the identification of characteristics that make effective governance of these normally ignored water flows more tenable.

The Three Rs: Reduce, Reuse, Recycle.

ERIC Educational Resources Information Center

Science Activities, 1991

1991-01-01

A student hand-out for a recycling unit defines the terms reduce, recycle, and reuse as they relate to solid waste management. Presents the characteristics of recyclable items such as yard wastes, metals, glass, and paper. Lists organizations through which more information about recycling can be obtained. (MCO)

UV-Vis Spectroscopy and Dynamic Light Scattering Study of Gold Nanorods Aggregation

PubMed Central

Kanjanawarut, Roejarek; Yuan, Bo

2013-01-01

Gold nanorods (AuNRs) were used as spectroscopic sensing elements to detect specific DNA sequences with a single-base mismatch sensitivity. The assay was based on the observation that the stabilizing repulsive forces between CTA+-coated AuNRs can be removed by citrate ions, which causes aggregation among AuNRs; whereas nucleic acids of different structures[ i.e., peptide nucleic acid (PNA), single-stranded DNA (ssDNA), PNA-DNA complex, and double-stranded DNA (dsDNA)] can retard the aggregation. Moreover, the dsDNA PNA-DNA duplexes provide larger retardation than that by unhybridized ssDNA and PNA probe. This assay can differentiate single-base mismatched targets with base substitution at different locations (center and end) with AuNRs of a larger aspect ratio. Besides ultraviolet–visable spectroscopy measurement of particle assembly-induced plasmonic coupling that in turn provides a spectroscopic detection of the specific DNA, dynamic light scattering and transmission electron microscope (TEM) were used to measure smaller degree of aggregation that can reveal sodium citrate– and dsDNA–AuNRs interactions in fine detail. PMID:23902360

UV-vis spectroscopy and dynamic light scattering study of gold nanorods aggregation.

PubMed

Kanjanawarut, Roejarek; Yuan, Bo; XiaoDi, Su

2013-08-01

Gold nanorods (AuNRs) were used as spectroscopic sensing elements to detect specific DNA sequences with a single-base mismatch sensitivity. The assay was based on the observation that the stabilizing repulsive forces between CTA(+)-coated AuNRs can be removed by citrate ions, which causes aggregation among AuNRs; whereas nucleic acids of different structures[ i.e., peptide nucleic acid (PNA), single-stranded DNA (ssDNA), PNA-DNA complex, and double-stranded DNA (dsDNA)] can retard the aggregation. Moreover, the dsDNA PNA-DNA duplexes provide larger retardation than that by unhybridized ssDNA and PNA probe. This assay can differentiate single-base mismatched targets with base substitution at different locations (center and end) with AuNRs of a larger aspect ratio. Besides ultraviolet-visable spectroscopy measurement of particle assembly-induced plasmonic coupling that in turn provides a spectroscopic detection of the specific DNA, dynamic light scattering and transmission electron microscope (TEM) were used to measure smaller degree of aggregation that can reveal sodium citrate- and dsDNA-AuNRs interactions in fine detail.

Recycling steel. Conducting a waste audit.

PubMed

Crawford, G

1996-01-01

This is the second in a series of three articles regarding steel can recycling from foodservice operations of healthcare facilities. This article highlights the basic methods of recycling steel cans, and includes information on conducting a waste audit and negotiating with a hauler regarding the benefits of recycling. The previous article discussed how steel is recycled across the country. The next article will convey a case history of actual foodservice recycling practice from a healthcare facility.

Reuse, Reduce, Recycle.

ERIC Educational Resources Information Center

Briscoe, Georgia

1991-01-01

Discussion of recycling paper in law libraries is also applicable to other types of libraries. Results of surveys of law libraries that investigated recycling practices in 1987 and again in 1990 are reported, and suggestions for reducing the amount of paper used and reusing as much as possible are offered. (LRW)

Treatment of nanowaste via fast crystal growth: with recycling of nano-SnO2 from electroplating sludge as a study case.

PubMed

Zhuang, Zanyong; Xu, Xinjiang; Wang, Yongjing; Wang, Yandi; Huang, Feng; Lin, Zhang

2012-04-15

The treatment of industrial sludge containing amorphous/nanophase metal oxides or hydroxides is one of the vital issues in hazardous waste disposal. In this work, we developed a strategy to recycle nano-SnO(2) from tinplate electroplating sludge. It revealed that the major components of this sludge were acid soluble Sn and Fe amorphous phases. By introducing NaOH as a mineralizer, a fast growth of amorphous Sn compound into acid-insoluble SnO(2) nanowires was achieved selectively. Thus, the as-formed nano-SnO(2) could be recycled via dissolving other solid compositions in the sludge by using acid. The role of NaOH on accelerating both the Oriented Attachment (OA) and Ostwald Ripening (OR) growth of SnO(2) was discussed, which was regarded as a critical factor for treating the sludge. A pilot-scale experiment was conducted to treat 2.3 kg original sludge and the recycling of about 90 g nano-SnO(2) was achieved. We anticipate this work can provide a good example for the recycling of valuable metals from industrial sludge containing fine metal oxides or hydroxides. Copyright © 2011 Elsevier B.V. All rights reserved.

Recycled tire crumb rubber anodes for sustainable power production in microbial fuel cells

NASA Astrophysics Data System (ADS)

Wang, Heming; Davidson, Matthew; Zuo, Yi; Ren, Zhiyong

One of the greatest challenges facing microbial fuel cells (MFCs) in large scale applications is the high cost of electrode material. We demonstrate here that recycled tire crumb rubber coated with graphite paint can be used instead of fine carbon materials as the MFC anode. The tire particles showed satisfactory conductivity after 2-4 layers of coating. The specific surface area of the coated rubber was over an order of magnitude greater than similar sized graphite granules. Power production in single chamber tire-anode air-cathode MFCs reached a maximum power density of 421 mW m -2, with a coulombic efficiency (CE) of 25.1%. The control graphite granule MFC achieved higher power density (528 mW m -2) but lower CE (15.6%). The light weight of tire particle could reduce clogging and maintenance cost but posts challenges in conductive connection. The use of recycled material as the MFC anodes brings a new perspective to MFC design and application and carries significant economic and environmental benefit potentials.

Physical pretreatment of biogenic-rich trommel fines for fast pyrolysis.

PubMed

Eke, Joseph; Onwudili, Jude A; Bridgwater, Anthony V

2017-12-01

Energy from Waste (EfW) technologies such as fluidized bed fast pyrolysis, are beneficial for both energy generation and waste management. Such technologies, however face significant challenges due to the heterogeneous nature, particularly the high ash contents of some municipal solid waste types e.g. trommel fines. A study of the physical/mechanical and thermal characteristics of these complex wastes is important for two main reasons; (a) to inform the design and operation of pyrolysis systems to handle the characteristics of such waste; (b) to control/modify the characteristics of the waste to fit with existing EFW technologies via appropriate feedstock preparation methods. In this study, the preparation and detailed characterisation of a sample of biogenic-rich trommel fines has been carried out with a view to making the feedstock suitable for fast pyrolysis based on an existing fluidized bed reactor. Results indicate that control of feed particle size was very important to prevent problems of dust entrainment in the fluidizing gas as well as to prevent feeder hardware problems caused by large stones and aggregates. After physical separation and size reduction, nearly 70wt% of the trommel fines was obtained within the size range suitable for energy recovery using the existing fast pyrolysis system. This pyrolyzable fraction could account for about 83% of the energy content of the 'as received' trommel fines sample. Therefore there was no significant differences in the thermochemical properties of the raw and pre-treated feedstocks, indicating that suitably prepared trommel fines samples can be used for energy recovery, with significant reduction in mass and volume of the original waste. Consequently, this can lead to more than 90% reduction in the present costs of disposal of trommel fines in landfills. In addition, the recovered plastics and textile materials could be used as refuse derived fuel. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Hang-Ups on Recycling

ERIC Educational Resources Information Center

Environmental Science and Technology, 1975

1975-01-01

While all seem to agree that recycling will alleviate solid waste problems and energy and mineral shortages, recycling is, at present, bogged down by the thin market for recycled materials, the recessionary business picture, the vertical integration of many companies, unfavorable tax laws, and high rail freight rates. (BT)

Across species-pool aggregation alters grassland productivity and diversity.

PubMed

McKenna, Thomas P; Yurkonis, Kathryn A

2016-08-01

Plant performance is determined by the balance of intra- and interspecific neighbors within an individual's zone of influence. If individuals interact over smaller scales than the scales at which communities are measured, then altering neighborhood interactions may fundamentally affect community responses. These interactions can be altered by changing the number (species richness), abundances (species evenness), and positions (species pattern) of the resident plant species, and we aimed to test whether aggregating species at planting would alter effects of species richness and evenness on biomass production at a common scale of observation in grasslands. We varied plant species richness (2, 4, or 8 species and monocultures), evenness (0.64, 0.8, or 1.0), and pattern (planted randomly or aggregated in groups of four individuals) within 1 × 1 m plots established with transplants from a pool of 16 tallgrass prairie species and assessed plot-scale biomass production and diversity over the first three growing seasons. As expected, more species-rich plots produced more biomass by the end of the third growing season, an effect associated with a shift from selection to complementarity effects over time. Aggregating conspecifics at a 0.25-m scale marginally reduced biomass production across all treatments and increased diversity in the most even plots, but did not alter biodiversity effects or richness-productivity relationships. Results support the hypothesis that fine-scale species aggregation affects diversity by promoting species coexistence in this system. However, results indicate that inherent changes in species neighborhood relationships along grassland diversity gradients may only minimally affect community (meter) - scale responses among similarly designed biodiversity-ecosystem function studies. Given that species varied in their responses to local aggregation, it may be possible to use such species-specific results to spatially design larger-scale grassland

Inactive Mineral Filler as a Stiffness Modulus Regulator in Foamed Bitumen-Modified Recycled Base Layers

NASA Astrophysics Data System (ADS)

Buczyński, Przemyslaw; Iwański, Marek

2017-10-01

The article presents the results of a cold recycled mix test with a foam bitumen including the addition of the inactive mineral filler as a dust of basalt. Basalt dust was derived from dedusting system by extraction of aggregates in the mine. Assessment of the impact of a basalt dust on the properties of a recycled base layer was carried out in terms of the amount of mineral filler (basalt) in the composition of the mineral mixture. This experiment involved a dosing of mineral filler in range from 5 to 20% with steps of 7.5% in the mineral mixture composition. The foamed bitumen was performed at optimum foaming process settings (ie. bitumen temperature, air pressure) and at 2.5% of the water content. The amount of a hydraulic binder as a Portland cement was 2.0%. The evaluation of rheological properties allowed to determine whether the addition of inactive mineral fillers can act as a stiffness modulus controller in the recycled base layer. The analysis of the rheological properties of a recycled base layer in terms of the amount of inactive fillers was performed in accordance with given standard EN 12697-26 Annex D. The study was carried out according to the direct tension-compression test methodology on cylindrical samples. The sample was subjected to the oscillatory sinusoidal strain ε0 < 25με. Studies carried out at a specific temperature set-points: - 7°C, 5°C, 13°C, 25°C and 40°C and at the frequency 0.1 Hz, 0.3 Hz, 1 Hz, 3 Hz, 10 Hz and 20 Hz. The obtained results allow to conclude that the use of an inactive filler can reduce the stiffness of an appropriate designed mixes of the cold recycled foundation. In addition, the analysis of the relation E‧-E″ showed a similar behaviour of a recycled base, regardless of the amount of inactive fillers in the mix composition, at high temperatures/high frequency of induced load.

Precipitation recycling in the Amazon basin

NASA Technical Reports Server (NTRS)

Eltahir, E. A. B.; Bras, R. L.

1994-01-01

Precipitation recycling is the contribution of evaporation within a region to precipitation in that same region. The recycling rate is a diagnostic measure of the potential for interactions between land surface hydrology and regional climate. In this paper we present a model for describing the seasonal and spatial variability of the recycling process. The precipitation recycling ratio, rho, is the basic variable in describing the recycling process. Rho is the fraction of precipitation at a certain location and time which is contributed by evaporation within the region under study. The recycling model is applied in studyiing the hydrologic cycle in the Amazon basin. It is estimated that about 25% of all the rain that falls in the Amazon basin is contributed by evaporation within the basin. This estimate is based on analysis of a data set supplied by the European Centre for Medium-range Weather Forecasts (ECMWF). The same analysis is repeated using a different data set from the Geophysical Fluid Dynamics Laboratory (GFDL). Based on this data set, the recycling ratio is estimated to be 35%. The seasonal variability of the recycling ratio is small compared with the yearly average. The new estimates of the recycling ratio are compared with results of previous studies, and the differences are explained.

Analyzing effective municipal solid waste recycling programs: the case of county-level MSW recycling performance in Florida, USA.

PubMed

Park, Seejeen; Berry, Frances S

2013-09-01

Municipal solid waste (MSW) recycling performance, both nationally and in Florida, USA, has shown little improvement during the past decade. This research examines variations in the MSW recycling program performance in Florida counties in an attempt to identify effective recycling programs. After reviewing trends in the MSW management literature, we conducted an empirical analysis using cross-sectional multiple regression analysis. The findings suggest that the convenience-based hypothesis was supported by showing that curbside recycling had a positive effect on MSW recycling performance. Financial (cost-saving) incentive-based hypotheses were partially supported meaning that individual level incentives can influence recycling performance. Citizen environmental concern was found to positively affect the amount of county recycling, while education and political affiliation yielded no significant results. In conclusion, this article discusses the implications of the findings for both academic research and practice of MSW recycling programs.

Wee Recyclers Resources.

ERIC Educational Resources Information Center

Wisconsin State Dept. of Natural Resources, Madison.

Hands-on activities in this guide are designed to help preschool children (ages 3-5) understand that reducing, reusing, and recycling preserves natural resources and prolongs the life of landfills. Children sort, match and compare recyclable items and learn to separate some items by number and color. The 29 activities are divided into units that…

Text Recycling in Scientific Writing.

PubMed

Moskovitz, Cary

2018-03-15

Text recycling, often called "self-plagiarism", is the practice of reusing textual material from one's prior documents in a new work. The practice presents a complex set of ethical and practical challenges to the scientific community, many of which have not been addressed in prior discourse on the subject. This essay identifies and discusses these factors in a systematic fashion, concluding with a new definition of text recycling that takes these factors into account. Topics include terminology, what is not text recycling, factors affecting judgements about the appropriateness of text recycling, and visual materials.

Global Warming Implications of the Use of By-Products and Recycled Materials in Western Australia’s Housing Sector

PubMed Central

Lawania, Krishna; Sarker, Prabir; Biswas, Wahidul

2015-01-01

Western Australia’s housing sector is growing rapidly and around half a million houses are expected to be built by 2030, which not only will result in increased energy and resources demand but will have socio-economic impacts. Majority of Western Australians live in detached houses made of energy intensive clay bricks, which have a high potential to generate construction and demolition (C&D) waste. Therefore, there is a need to look into the use of alternative materials and construction methods. Due to Western Australia’s temperate climate, concrete could not only offer a comfortable living space but an operational energy saving also can be achieved. This paper has assessed the global warming implications of cast in-situ concrete sandwich wall system as an alternative to clay brick walls (CBW) with partial replacement of cement in concrete with by-products such as fly ash (FA) and ground granulated blast furnace slag (GGBFS), natural aggregate (NA) with recycled crushed aggregate (RCA), natural sand (NS) with manufactured sand (MS) and, polyethylene terephthalate (PET) foam core as a replacement to polystyrene core for construction of a typical 4 × 2 × 2 detached house in Perth. Life cycle management (LCM) approach has been used to determine global warming reduction benefits due to the use of available by-products and recycled materials in Western Australian houses.

Recycling Behavior: A Multidimensional Approach

ERIC Educational Resources Information Center

Meneses, Gonzalo Diaz; Palacio, Asuncion Beerli

2005-01-01

This work centers on the study of consumer recycling roles to examine the sociodemographic and psychographic profile of the distribution of recycling tasks and roles within the household. With this aim in mind, an empirical work was carried out, the results of which suggest that recycling behavior is multidimensional and comprises the undertaking…

2016 America's Recycle Day