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Sample records for recycle aggregate concrete

  1. Studies on recycled aggregates-based concrete.

    PubMed

    Rakshvir, Major; Barai, Sudhirkumar V

    2006-06-01

    Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design.

  2. Reusing recycled aggregates in structural concrete

    NASA Astrophysics Data System (ADS)

    Kou, Shicong

    The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

  3. 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.

  4. Aspects Concerning the Use of Recycled Concrete Aggregates

    NASA Astrophysics Data System (ADS)

    Robu, I.; Mazilu, C.; Deju, R.

    2016-11-01

    Natural aggregates (gravel and crushed) are essential non-renewable resources which are used for infrastructure works and civil engineering. Using recycled concrete aggregates (RCA) is a matter of high priority in the construction industry worldwide. This paper presents a study on the use of recycled aggregates, from a concrete of specified class, to acquire new cement concrete with different percentages of recycled aggregates.

  5. Concrete Waste Recycling Process for High Quality Aggregate

    SciTech Connect

    Ishikura, Takeshi; Fujii, Shin-ichi

    2008-01-15

    Large amount of concrete waste generates during nuclear power plant (NPP) dismantling. Non-contaminated concrete waste is assumed to be disposed in a landfill site, but that will not be the solution especially in the future, because of decreasing tendency of the site availability and natural resources. Concerning concrete recycling, demand for roadbeds and backfill tends to be less than the amount of dismantled concrete generated in a single rural site, and conventional recycled aggregate is limited of its use to non-structural concrete, because of its inferior quality to ordinary natural aggregate. Therefore, it is vital to develop high quality recycled aggregate for general uses of dismantled concrete. If recycled aggregate is available for high structural concrete, the dismantling concrete is recyclable as aggregate for industry including nuclear field. Authors developed techniques on high quality aggregate reclamation for large amount of concrete generated during NPP decommissioning. Concrete of NPP buildings has good features for recycling aggregate; large quantity of high quality aggregate from same origin, record keeping of the aggregate origin, and little impurities in dismantled concrete such as wood and plastics. The target of recycled aggregate in this development is to meet the quality criteria for NPP concrete as prescribed in JASS 5N 'Specification for Nuclear Power Facility Reinforced Concrete' and JASS 5 'Specification for Reinforced Concrete Work'. The target of recycled aggregate concrete is to be comparable performance with ordinary aggregate concrete. The high quality recycled aggregate production techniques are assumed to apply for recycling for large amount of non-contaminated concrete. These techniques can also be applied for slightly contaminated concrete dismantled from radiological control area (RCA), together with free release survey. In conclusion: a technology on dismantled concrete recycling for high quality aggregate was developed

  6. 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.

  7. Assessing relationships among properties of demolished concrete, recycled aggregate and recycled aggregate concrete using regression analysis.

    PubMed

    Tam, Vivian W Y; Wang, K; Tam, C M

    2008-04-01

    Recycled demolished concrete (DC) as recycled aggregate (RA) and recycled aggregate concrete (RAC) is generally suitable for most construction applications. Low-grade applications, including sub-base and roadwork, have been implemented in many countries; however, higher-grade activities are rarely considered. This paper examines relationships among DC characteristics, properties of their RA and strength of their RAC using regression analysis. Ten samples collected from demolition sites are examined. The results show strong correlation among the DC samples, properties of RA and RAC. It should be highlighted that inferior quality of DC will lower the quality of RA and thus their RAC. Prediction of RAC strength is also formulated from the DC characteristics and the RA properties. From that, the RAC performance from DC and RA can be estimated. In addition, RAC design requirements can also be developed at the initial stage of concrete demolition. Recommendations are also given to improve the future concreting practice.

  8. Microstructural characterization of concrete prepared with recycled aggregates.

    PubMed

    Guedes, Mafalda; Evangelista, Luís; de Brito, Jorge; Ferro, Alberto C

    2013-10-01

    Several authors have reported the workability, mechanical properties, and durability of concrete produced with construction waste replacing the natural aggregate. However, a systematic microstructural characterization of recycled aggregate concrete has not been reported. This work studies the use of fine recycled aggregate to replace fine natural aggregate in the production of concrete and reports the resulting microstructures. The used raw materials were natural aggregate, recycled aggregate obtained from a standard concrete, and Portland cement. The substitution extent was 0, 10, 50, and 100 vol%; hydration was stopped at 9, 24, and 96 h and 28 days. Microscopy was focused on the cement/aggregate interfacial transition zone, enlightening the effect of incorporating recycled aggregate on the formation and morphology of the different concrete hydration products. The results show that concretes with recycled aggregates exhibit typical microstructural features of the transition zone in normal strength concrete. Although overall porosity increases with increasing replacement, the interfacial bond is apparently stronger when recycled aggregates are used. An addition of 10 vol% results in a decrease in porosity at the interface with a corresponding increase of the material hardness. This provides an opportunity for development of increased strength Portland cement concretes using controlled amounts of concrete waste.

  9. Determination of the dynamic elastic constants of recycled aggregate concrete

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Nowadays, construction and demolition waste constitutes a major portion of the total solid waste production in the world. Due to both environmental and economical reasons, an increasing interest concerning the use of recycled aggregate to replace aggregate from natural sources is generated. This paper presents an investigation on the properties of recycled aggregate concrete. Concrete mixes are prepared using recycled aggregates at a substitution level between 0 and 100% of the total coarse aggregate. The influence of this replacement on strengthened concrete's properties is being investigated. The properties estimated are: density and dynamic modulus of elasticity at the age of both 7 and 28 days. Also, flexural strength of 28 days specimens is estimated. The determination of the dynamic elastic modulus was made using the ultrasonic pulse velocity method. The results reveal that the existence of recycled aggregates affects the properties of concrete negatively; however, in low levels of substitution the influence of using recycled aggregates is almost negligible. Concluding, the controlled use of recycled aggregates in concrete production may help solve a vital environmental issue apart from being a solution to the problem of inadequate concrete aggregates.

  10. Comparative environmental assessment of natural and recycled aggregate concrete.

    PubMed

    Marinković, S; Radonjanin, V; Malešev, M; Ignjatović, I

    2010-11-01

    Constant and rapid increase in construction and demolition (C&D) waste generation and consumption of natural aggregate for concrete production became one of the biggest environmental problems in the construction industry. Recycling of C&D waste represents one way to convert a waste product into a resource but the environment benefits through energy consumption, emissions and fallouts reductions are not certain. The main purpose of this study is to determine the potentials of recycled aggregate concrete (concrete made with recycled concrete aggregate) for structural applications and to compare the environmental impact of the production of two types of ready-mixed concrete: natural aggregate concrete (NAC) made entirely with river aggregate and recycled aggregate concrete (RAC) made with natural fine and recycled coarse aggregate. Based on the analysis of up-to-date experimental evidence, including own tests results, it is concluded that utilization of RAC for low-to-middle strength structural concrete and non-aggressive exposure conditions is technically feasible. The Life Cycle Assessment (LCA) is performed for raw material extraction and material production part of the concrete life cycle including transport. Assessment is based on local LCI data and on typical conditions in Serbia. Results of this specific case study show that impacts of aggregate and cement production phases are slightly larger for RAC than for NAC but the total environmental impacts depend on the natural and recycled aggregates transport distances and on transport types. Limit natural aggregate transport distances above which the environmental impacts of RAC can be equal or even lower than the impacts of NAC are calculated for the specific case study. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Compressive strength and hydration processes of concrete with recycled aggregates

    SciTech Connect

    Koenders, Eduardus A.B.; Pepe, Marco; Martinelli, Enzo

    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 heat 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.

  12. 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.

  13. Properties of concrete blocks prepared with low grade recycled aggregates.

    PubMed

    Poon, Chi-Sun; Kou, Shi-cong; Wan, Hui-wen; Etxeberria, Miren

    2009-08-01

    Low grade recycled aggregates obtained from a construction waste sorting facility were tested to assess the feasibility of using these in the production of concrete blocks. The characteristics of the sorted construction waste are significantly different from that of crushed concrete rubbles that are mostly derived from demolition waste streams. This is due to the presence of higher percentages of non-concrete components (e.g. >10% soil, brick, tiles etc.) in the sorted construction waste. In the study reported in this paper, three series of concrete block mixtures were prepared by using the low grade recycled aggregates to replace (i) natural coarse granite (10mm), and (ii) 0, 25, 50, 75 and 100% replacement levels of crushed stone fine (crushed natural granite <5mm) in the concrete blocks. Test results on properties such as density, compressive strength, transverse strength and drying shrinkage as well as strength reduction after exposure to 800 degrees C are presented below. The results show that the soil content in the recycled fine aggregate was an important factor in affecting the properties of the blocks produced and the mechanical strength deceased with increasing low grade recycled fine aggregate content. But the higher soil content in the recycled aggregates reduced the reduction of compressive strength of the blocks after exposure to high temperature due probably to the formation of a new crystalline phase. The results show that the low grade recycled aggregates obtained from the construction waste sorting facility has potential to be used as aggregates for making non-structural pre-cast concrete blocks.

  14. Use of recycled fine aggregate in concretes with durable requirements.

    PubMed

    Zega, Claudio Javier; Di Maio, Angel Antonio

    2011-11-01

    The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete.

  15. Chemical-mineralogical characterisation of coarse recycled concrete aggregate

    SciTech Connect

    Limbachiya, M.C. . E-mail: m.limbachiya@kingston.ac.uk; Marrocchino, E.; Koulouris, A.

    2007-07-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO{sub 2}, Al{sub 2}O{sub 3} and CaO) of concrete, but thereafter there was a marginal decrease in SiO{sub 2} and increase in Al{sub 2}O{sub 3} and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition.

  16. Chemical-mineralogical characterisation of coarse recycled concrete aggregate.

    PubMed

    Limbachiya, M C; Marrocchino, E; Koulouris, A

    2007-01-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO2, Al2O3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO2 and increase in Al2O3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition.

  17. 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.

  18. 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.

  19. Experimental study on the effect of volcanic residue on the performance of recycled lightweight aggregate concrete

    NASA Astrophysics Data System (ADS)

    Xiao, Li-guang; Li, Ji-heng; Liu, Qing-shun

    2017-08-01

    Recycled lightweight aggregate concrete prepared with waste brick recycled light aggregate has high water absorption, large apparent density and poor frost resistance. The technical measures of regen-erating lightweight aggregate concrete with modified waste bricks from volcanic slag are put forward. The effects of volcanic slag on the properties of waste lightweight aggregate concrete were studied. The experi-mental results show that volcanic slag can significantly reduce the apparent density of recycled lightweight aggregate concrete and improve its frost resistance.

  20. 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.

  1. 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

  2. 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.

  3. Influence of recycled aggregate quality and proportioning criteria on recycled concrete properties.

    PubMed

    López-Gayarre, F; Serna, P; Domingo-Cabo, A; Serrano-López, M A; López-Colina, C

    2009-12-01

    This paper presents the results of experimental research using concrete produced by substituting part of the natural coarse aggregates with recycled aggregates from concrete demolition. The influence of the quality of the recycled aggregate (amount of declassified and source of aggregate), the percentage of replacement on the targeted quality of the concrete to be produced (strength and workability) has been evaluated. The granular structure of concrete and replacement criteria were analyzed in this study, factors which have not been analyzed in other studies. The following properties of recycled concretes were analyzed: density, absorption, compressive strength, elastic modulus, amount of occluded air, penetration of water under pressure and splitting tensile strength. A simplified test program was designed to control the costs of the testing while still producing sufficient data to develop reliable conclusions in order to make the number of tests viable whilst guaranteeing the reliability of the conclusions. Several factors were analyzed including the type of aggregate, the percentage of replacement, the type of sieve curve, the declassified content, the strength of concrete and workability of concrete and the replacement criteria. The type of aggregate and the percentage of replacement were the only factors that showed a clear influence on most of the properties. Compressive strength is clearly affected by the quality of recycled aggregates. If the water-cement ratio is kept constant and the loss of workability due to the effect of using recycled aggregate is compensated for with additives, the percentage of replacement of the recycled aggregate will not affect the compressive strength. The elastic modulus is affected by the percentage of replacement. If the percentage of replacement does not exceed 50%, the elastic modulus will only change slightly.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Applicability of recycled aggregates in concrete piles for soft soil improvement.

    PubMed

    Medeiros-Junior, Ronaldo A; Balestra, Carlos Et; Lima, Maryangela G

    2017-01-01

    The expressive generation of construction and demolition waste is stimulating several studies for reusing this material. The improvement of soft soils by concrete compaction piles has been widely applied for 40 years in some Brazilian cities. This technique is used to improve the bearing capacity of soft soils, allowing executing shallow foundations instead of deep foundations. The compaction piles use a high volume of material. This article explored the possibility of using recycled aggregates from construction waste to replace the natural aggregates in order to improve the bearing capacity of the soft soil, regarding its compressive strength. Construction wastes from different stages of a construction were used in order to make samples of concrete with recycled aggregates. The strength of concretes with natural aggregates was compared with the strength of concretes with recycled (fine and coarse) aggregates. Results show that all samples met the minimum compressive strength specified for compaction piles used to improve the bearing capacity of soft soils. The concrete with recycled aggregate from the structural stage had even higher resistances than the concrete with natural aggregates. This behaviour was attributed to the large amount of cementitious materials in the composition of this type of concrete. It was also observed that concrete with recycled fine aggregate has a superior resistance to concrete with recycled coarse aggregate.

  9. Recycling of PET bottles as fine aggregate in concrete

    SciTech Connect

    Frigione, Mariaenrica

    2010-06-15

    An attempt to substitute in concrete the 5% by weight of fine aggregate (natural sand) with an equal weight of PET aggregates manufactured from the waste un-washed PET bottles (WPET), is presented. The WPET particles possessed a granulometry similar to that of the substituted sand. Specimens with different cement content and water/cement ratio were manufactured. Rheological characterization on fresh concrete and mechanical tests at the ages of 28 and 365 days were performed on the WPET/concretes as well as on reference concretes containing only natural fine aggregate in order to investigate the influence of the substitution of WPET to the fine aggregate in concrete. It was found that the WPET concretes display similar workability characteristics, compressive strength and splitting tensile strength slightly lower that the reference concrete and a moderately higher ductility.

  10. Recycling of PET bottles as fine aggregate in concrete.

    PubMed

    Frigione, Mariaenrica

    2010-06-01

    An attempt to substitute in concrete the 5% by weight of fine aggregate (natural sand) with an equal weight of PET aggregates manufactured from the waste un-washed PET bottles (WPET), is presented. The WPET particles possessed a granulometry similar to that of the substituted sand. Specimens with different cement content and water/cement ratio were manufactured. Rheological characterization on fresh concrete and mechanical tests at the ages of 28 and 365days were performed on the WPET/concretes as well as on reference concretes containing only natural fine aggregate in order to investigate the influence of the substitution of WPET to the fine aggregate in concrete. It was found that the WPET concretes display similar workability characteristics, compressive strength and splitting tensile strength slightly lower that the reference concrete and a moderately higher ductility.

  11. Evaluation of Fracture in Concrete with Recycled Aggregate by Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Nishibata, Sayaka; Watanabe, Takeshi; Hashimoro, Chikanori; Kohno, Kiyoshi

    This research revealed fracture behavior of concrete in using recycled aggregates by Acoustic Emission as one of the Non-destructive Inspection. The phenomenon of acoustic emission (AE) is the propagation of elastic waves generated from a source, known as a micro-crack in an elastic material. There were taken to use low-treated recycled aggregate, crushed returned ready mixed concrete for aggregate and normal aggregate. Examination measured AE under the uniaxial compression test. The condition of load is repeated loading. As a result, fracture behavior due to low treated recycled aggregate was detected by AE. It is clarified that AE of concrete with low treated recycled aggregate appeared in low stress level. It has been understood that difference of aggregates becomes clear from Kaiser effect in repeated loading. In relation between RA value and average frequency, it has been understood the adhesion properties of the cement paste in recycled aggregate are appreciable.

  12. Evaluation of recycled concrete aggregates for their suitability in construction activities: An experimental study.

    PubMed

    Puthussery, Joseph V; Kumar, Rakesh; Garg, Anurag

    2017-02-01

    Construction and demolition waste disposal is a major challenge in developing nations due to its ever increasing quantities. In this study, the recycling potential of waste concrete as aggregates in construction activities was studied. The metal leaching from the recycled concrete aggregates (RCA) collected from the demolition site of a 50year old building, was evaluated by performing three different leaching tests (compliance, availability and Toxic Characteristic Leaching Procedure). The metal leaching was found mostly within the permissible limit except for Hg. Several tests were performed to determine the physical and mechanical properties of the fine and coarse aggregates produced from recycled concrete. The properties of recycled aggregates were found to be satisfactory for their utilization in road construction activities. The suitability of using recycled fine and coarse aggregates with Portland pozzolanic cement to make a sustainable and environmental friendly concrete mix design was also analyzed. No significant difference was observed in the compressive strength of various concrete mixes prepared by natural and recycled aggregates. However, only the tensile strength of the mix prepared with 25% recycled fine aggregates was comparable to that of the control concrete. For other mixes, the tensile strength of the concrete was found to drop significantly. In summary, RCA should be considered seriously as a building material for road construction, mass concrete works, lightly reinforced sections, etc. The present work will be useful for the waste managers and policy makers particularly in developing nations where proper guidelines are still lacking. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. 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.

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

    PubMed

    Sim, Jongsung; Park, Cheolwoo

    2011-11-01

    Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. 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.

  16. Environmental performance and mechanical analysis of concrete containing recycled asphalt pavement (RAP) and waste precast concrete as aggregate.

    PubMed

    Erdem, Savaş; Blankson, Marva Angela

    2014-01-15

    The overall objective of this research project was to investigate the feasibility of incorporating 100% recycled aggregates, either waste precast concrete or waste asphalt planning, as replacements for virgin aggregates in structural concrete and to determine the mechanical and environmental performance of concrete containing these aggregates. Four different types of concrete mixtures were designed with the same total water cement ratio (w/c=0.74) either by using natural aggregate as reference or by totally replacing the natural aggregate with recycled material. Ground granulated blast furnace slag (GGBS) was used as a mineral addition (35%) in all mixtures. The test results showed that it is possible to obtain satisfactory performance for strength characteristics of concrete containing recycled aggregates, if these aggregates are sourced from old precast concrete. However, from the perspective of the mechanical properties, the test results indicated that concrete with RAP aggregate cannot be used for structural applications. In terms of leaching, the results also showed that the environmental behaviour of the recycled aggregate concrete is similar to that of the natural aggregate concrete.

  17. The influence of retained moisture in aggregates from recycling on the properties of new hardened concrete

    SciTech Connect

    Barra de Oliveira, M.; Vazquez, E.

    1996-12-31

    In this study the influence of retained moisture in recycled aggregates on the mechanical properties and durability of new concrete is determined experimentally and analyzed. The effects of three different moisture conditions from the recycled aggregate are compared (dry, saturated and semi-saturated). A slight decrease is to be observed in the compressive strength of the concrete made from dry and saturated recycled aggregates respectively. The decrease is especially noticeable in flexural strength in the concrete with the saturated aggregates. The bad resistance to freeze-thaw of concretes with saturated and dry recycled aggregates and the good results of those made with semi-saturated aggregates can be explained as being due to the different quality of the interfaces formed in each case.

  18. Application of orthogonal test method in mix proportion design of recycled lightweight aggregate concrete

    NASA Astrophysics Data System (ADS)

    Zhao, Zhanshan; An, Le; Zhang, Yijing; Yuan, Jie

    2017-03-01

    Recycled lightweight aggregate concrete was made with construction waste and ceramsite brick mainly including brick. Using the orthogonal test method, the mix proportion of recycled lightweight aggregate concrete was studied, and the Influence regularity and significance of water binder ratio, fly ash, sand ratio, the amount of recycled aggregate proportion on the compressive strength of concrete, the strong influence of mass ratio, slump expansion degree was studied. Through the mean and range analysis of the test results, the results show that the water binder ratio has the greatest influence on the 28d intensity of recycled lightweight aggregate concrete. Secondly, the fly ash content, the recycled aggregate replacement rate and the sand ratio have little influence. For the factors of expansion: the proportion of fly ash = water binder ratio sand >sand rate> recycled aggregate replacement rate. When the content of fly ash is about 30%, the expanded degree of recycled lightweight aggregate concrete is the highest, and the workability of that is better and the strength of concrete with 28d and 56d are the highest. When the content of brickbat is about 40% brick particles, the strength of concrete reaches the highest.

  19. The effect of recycled concrete aggregate properties on the bond strength between RCA concrete and steel reinforcement

    SciTech Connect

    Butler, L. West, J.S.; Tighe, S.L.

    2011-10-15

    The purpose of this study was to investigate the influence that replacing natural coarse aggregate with recycled concrete aggregate (RCA) has on concrete bond strength with reinforcing steel. Two sources of RCA were used along with one natural aggregate source. Numerous aggregate properties were measured for all aggregate sources. Two types of concrete mixture proportions were developed replacing 100% of the natural aggregate with RCA. The first type maintained the same water-cement ratios while the second type was designed to achieve the same compressive strengths. Beam-end specimens were tested to determine the relative bond strength of RCA and natural aggregate concrete. On average, natural aggregate concrete specimens had bond strengths that were 9 to 19% higher than the equivalent RCA specimens. Bond strength and the aggregate crushing value seemed to correlate well for all concrete types.

  20. Increased Durability of Concrete Made with Fine Recycled Concrete Aggregates Using Superplasticizers

    PubMed Central

    Cartuxo, Francisco; de Brito, Jorge; Evangelista, Luis; Jiménez, José Ramón; Ledesma, Enrique F.

    2016-01-01

    This paper evaluates the influence of two superplasticizers (SP) on the durability properties of concrete made with fine recycled concrete aggregate (FRCA). For this purpose, three families of concrete were tested: concrete without SP, concrete made with a regular superplasticizer and concrete made with a high-performance superplasticizer. Five volumetric replacement ratios of natural sand by FRCA were tested: 0%, 10%, 30%, 50% and 100%. Two natural gravels were used as coarse aggregates. All mixes had the same particle size distribution, cement content and amount of superplasticizer. The w/c ratio was calibrated to obtain similar slump. The results showed that the incorporation of FRCA increased the water absorption by immersion, the water absorption by capillary action, the carbonation depth and the chloride migration coefficient, while the use of superplasticizers highly improved these properties. The incorporation of FRCA jeopardized the SP’s effectiveness. This research demonstrated that, from a durability point of view, the simultaneous incorporation of FRCA and high-performance SP is a viable sustainable solution for structural concrete production. PMID:28787905

  1. Increased Durability of Concrete Made with Fine Recycled Concrete Aggregates Using Superplasticizers.

    PubMed

    Cartuxo, Francisco; de Brito, Jorge; Evangelista, Luis; Jiménez, José Ramón; Ledesma, Enrique F

    2016-02-08

    This paper evaluates the influence of two superplasticizers (SP) on the durability properties of concrete made with fine recycled concrete aggregate (FRCA). For this purpose, three families of concrete were tested: concrete without SP, concrete made with a regular superplasticizer and concrete made with a high-performance superplasticizer. Five volumetric replacement ratios of natural sand by FRCA were tested: 0%, 10%, 30%, 50% and 100%. Two natural gravels were used as coarse aggregates. All mixes had the same particle size distribution, cement content and amount of superplasticizer. The w/c ratio was calibrated to obtain similar slump. The results showed that the incorporation of FRCA increased the water absorption by immersion, the water absorption by capillary action, the carbonation depth and the chloride migration coefficient, while the use of superplasticizers highly improved these properties. The incorporation of FRCA jeopardized the SP's effectiveness. This research demonstrated that, from a durability point of view, the simultaneous incorporation of FRCA and high-performance SP is a viable sustainable solution for structural concrete production.

  2. 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%.

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

    PubMed

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

    2014-09-01

    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.

  4. 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

  5. Integrating service-life modeling and life-cycle assessment for recycled-aggregate concrete

    NASA Astrophysics Data System (ADS)

    Bergman, Todd Lee

    The development and implementation of one-dimensional (a) analytical and (b) numerical service-life models for chloride-induced corrosion of reinforced concrete containing both recycled-aggregates and supplementary cementitious materials (SCMs) are presented in this work. Both the analytical and numerical models account for initial chloride contamination levels due to previous applications. The effects of aggregate type (e.g., virgin, recycled aggregate, recycled mortar), aggregate replacement ratio, severity of chloride contamination levels, severity of in-service chloride exposure, reinforcement cover depth, SCM type (e.g., fly ash, slag, slice fume, metakaolin), and SCM replacement ratio on the expected service life of recycled-aggregate reinforced concrete were investigated. Results illustrated trends between concrete mixes and life cycle costs, which were employed to make conclusions on the trade-offs presented by cost, sustainability, and service life.

  6. Performance of concrete pavements containing recycled concrete aggregate. Interim report, October 1993-October 1996

    SciTech Connect

    Wade, M.J.; Cuttell, G.D.; Vandenbossche, J.M.; Yu, H.T.; Smith, K.D.

    1997-03-01

    This interim report documents the field performance of nine concrete pavement projects that incorporate recycled concrete aggregate (RCA) in the construction of the pavement. Multiple sections were evaluated on many of the nine projects, due to perceived differences in performance levels or variations in pavement design (such as the use of virgin aggregate or the inclusion of dowel bars). All told, a total of 17 sections (of which 12 contain RCA) were subjected to an extensive field testing program, consisting of pavement condition surveys, drainage surveys, falling weight deflectometer (FWD) testing, coring, and serviceability assessments. A minimum of eight cores were retrieved from each section for laboratory evaluation of compressive strength, split tensile strength, dynamic elastic modulus, static elastic modulus, and thermal coefficient of expansion, as well as for volumetric surface testing and petrographic analyses.

  7. Impact of aging on leaching characteristics of recycled concrete aggregate.

    PubMed

    Abbaspour, Aiyoub; Tanyu, Burak F; Cetin, Bora

    2016-10-01

    The focus of this study was to evaluate the effects of stockpiling (aging) on leaching of elements in recycled concrete aggregate (RCA) that may contribute to tufaceous constituent formation. Speciation and leaching controlling mechanisms of these elements were identified via geochemical modeling. The effects of stockpiling were simulated by comparing freshly produced RCA with RCA aged as part of this study for 1 year both in the laboratory and in the field. Leachate samples were generated following batch water leach test (WLT) and US Geological Survey leach test (USGSLT) methods. USGSLTs were conducted both on the laboratory and field samples while WLT was only conducted on laboratory samples. During the laboratory aging, it is observed that the carbonate content of RCA, measured as calcite equivalent, increased 20 % (i.e., from ∼100 to 120 mg/g) within a year time frame. The leachate extracted from RCA showed minor changes in pH and more significant decreases in electrical conductivity (i.e., ∼300 to 100 μS/cm). A comparison between laboratory and field samples revealed that the RCA aged much slower in the field than in the laboratory within a year. Comparisons between two leach extraction methods on the laboratory conditions showed that the total leached concentrations (TLCs) of most of the constituents from USGSLT were appreciably lower than the ones measured via WLT method. The results of geochemical modeling analyses showed that Al, Si, Fe, Ca, Mg, and Cu exist in their oxidized forms as Al(3+), Fe(3+), Si(4+), Ca(2+), Mg(2+), and Cu(2+) and results revealed that these elements are primarily controlled by the solubility of gibbsite, hematite, silica gel, calcite, magnesite, and tenorite solid phases, respectively. One of the significant findings of the study was to identify the changes in leaching behavior of Ca, Si, Mg, Al, Fe, and Cu due to carbonation.

  8. 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

  9. 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

  10. 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).

  11. Microstructure and mechanical properties of recycled aggregate concrete in seawater environment.

    PubMed

    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.

  12. 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

  13. Bonding Behavior of Deformed Steel Rebars in Sustainable Concrete Containing both Fine and Coarse Recycled Aggregates

    PubMed Central

    Kim, Sun-Woo; Park, Wan-Shin; Jang, Young-Il; Jang, Seok-Joon; Yun, Hyun-Do

    2017-01-01

    In order to assess the bond behavior of deformed steel rebars in recycled-aggregate concrete (RAC) incorporating both fine and coarse recycled aggregate, pull-out tests were carried out in this study on 16-mm diameter deformed steel rebars embedded concentrically in RAC. The concrete was designed using equivalently mixed proportions of both recycled coarse aggregate and recycled fine aggregate. The tests employed five types of recycled aggregate replacement combinations and three types of rebar placement orientation (i.e., vertical bars and two-tiered and three-tiered horizontal bars). Based on the pull-out test results, the maximum bond strength tended to decrease and the slip at the maximum bond strength increased as the average water absorption of the aggregate increased, irrespective of the rebar orientation or placement location within the concrete member. The pull-out test results for the horizontal steel rebars embedded in RAC indicate that the casting position effect could be determined from the mid-depth of the concrete member, irrespective of the member’s height. The normalized bond versus slip relationship between the deformed rebar and the RAC could be predicted using an empirical model based on regression analysis of the experimental data. PMID:28906441

  14. Bonding Behavior of Deformed Steel Rebars in Sustainable Concrete Containing both Fine and Coarse Recycled Aggregates.

    PubMed

    Kim, Sun-Woo; Park, Wan-Shin; Jang, Young-Il; Jang, Seok-Joon; Yun, Hyun-Do

    2017-09-14

    In order to assess the bond behavior of deformed steel rebars in recycled-aggregate concrete (RAC) incorporating both fine and coarse recycled aggregate, pull-out tests were carried out in this study on 16-mm diameter deformed steel rebars embedded concentrically in RAC. The concrete was designed using equivalently mixed proportions of both recycled coarse aggregate and recycled fine aggregate. The tests employed five types of recycled aggregate replacement combinations and three types of rebar placement orientation (i.e., vertical bars and two-tiered and three-tiered horizontal bars). Based on the pull-out test results, the maximum bond strength tended to decrease and the slip at the maximum bond strength increased as the average water absorption of the aggregate increased, irrespective of the rebar orientation or placement location within the concrete member. The pull-out test results for the horizontal steel rebars embedded in RAC indicate that the casting position effect could be determined from the mid-depth of the concrete member, irrespective of the member's height. The normalized bond versus slip relationship between the deformed rebar and the RAC could be predicted using an empirical model based on regression analysis of the experimental data.

  15. A closed-loop life cycle assessment of recycled aggregate concrete utilization in China.

    PubMed

    Ding, Tao; Xiao, Jianzhuang; Tam, Vivian W Y

    2016-10-01

    This paper studies the potential environmental impact of recycled coarse aggregate (RCA) for concrete production in China. According to the cradle-to-cradle theory, a closed-loop life cycle assessment (LCA) on recycled aggregate concrete (RAC) utilization in China with entire local life cycle inventory (LCI) is performed, regarding the environmental influence of cement content, aggregate production, transportation and waste landfilling. Special attention is paid on the primary resource and energy conservation, as well as climate protection induced by RAC applications. Environmental impact between natural aggregate concrete (NAC) and RAC are also compared. It is shown that cement proportion and transportation are the top two contributors for carbon dioxide (CO2) emissions and energy consumption for both NAC and RAC. Sensitivity analysis also proves that long delivery distances for natural coarse aggregate (NCA) leave a possible opportunity for lowering environmental impact of RAC in China. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. 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.

  17. Study on conversion relationships of compressive strength indexes for recycled lightweight aggregate concrete

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang-gang; Yang, Jian-hui; Kuang, Xiao-mei

    2017-01-01

    In order to study cube compressive strength and axial compressive strength of recycled lightweight aggregate concrete(RLAC), and conversion relationship between the two, with the replacement rate of recycled lightweight coarse aggregate as change parameters, 15 standard cube test specimens and 15 standard prism test specimens were produced to carry out the test. Then compressive strength of test specimens were measured, and the law of different replacement rate of recycled lightweight coarse aggregate influencing compressive strength of RLAC was analyzed, as the method of statistical regression adopted, the conversion relationships between of cube compressive strength and axial compressive strength of RLAC was obtained. It is shown that compressive strength of RLAC are lower than compressive strength of ordinary concrete; and that compressive strength of RLAC gradually decreases as replacement rate of recycled lightweight coarse aggregate increases; as well as, the conversion relationship between axial compressive strength and cube compressive strength of RLAC is different from ordinary concrete; based on the experimental data, conversion relationship formula between compressive strength indexes of RLAC was established. It is suggested that the replacement rate of recycled lightweight aggregate should be controlled within 25%.

  18. Evaluation of the environmental, material, and structural performance of recycled aggregate concrete

    NASA Astrophysics Data System (ADS)

    Michaud, Katherine Sarah

    Concrete is the most commonly used building material in the construction industry, and contributes to 52% of construction and demolition waste in Canada. Recycled concrete aggregate (RCA) is one way to reduce this impact. To evaluate the performance of coarse and granular (fine and coarse) RCA in structural concrete applications, four studies were performed: an environmental assessment, a material testing program, a shear performance study, and a flexural performance study. To determine the environmental benefits of recycled aggregate concrete (RAC), three case studies were investigated using different populations and proximities to city centres. Environmental modelling suggested that RCA replacement could result in energy savings and greenhouse gas emission reductions, especially in remote areas. Tests were performed to determine if the volumetric replacement of up to 30% coarse RCA and 20% granular RCA is suitable for structural concrete applications in Canada. Fresh, hardened, and durability properties were evaluated. All five (5) of the RCA mixes showed equivalent material performance to the control mixes and met the requirements for a structural concrete mix. The five (5) RAC mixes were also used in structural testing. One-way reinforced concrete slab specimens were tested to failure to evaluate the shear and flexural performance of the RAC members. Peak capacities of and crack formation within each member were analyzed to evaluate the performance of RAC compared to conventional concrete. The shear capacity of specimens made from four (4) of the five (5) RAC mixtures was higher or equivalent to the control specimens. Specimens of the concrete mixture containing the highest content of recycled aggregate, 20% volumetric replacement of granular RCA, had shear capacities 14.1% lower, and exhibited cracking at lower loads than the control. The average flexural capacities of all RAC specimens were within 3.7% of the control specimens. Results from this research

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. Photocatalytic activity of titanium dioxide modified concrete materials - influence of utilizing recycled glass cullets as aggregates.

    PubMed

    Chen, Jun; Poon, Chi-Sun

    2009-08-01

    Combining the use of photocatalysts with cementitious materials is an important development in the field of photocatalytic air pollution mitigation. This paper presents the results of a systematic study on assessing the effectiveness of pollutant degradation by concrete surface layers that incorporate a photocatalytic material - Titanium Dioxide. The photocatalytic activity of the concrete samples was determined by photocatalytic oxidation of nitric oxide (NO) in the laboratory. Recycled glass cullets, derived from crushed waste beverage bottles, were used to replace sand in preparing the concrete surface layers. Factors, which may affect the pollutant removal performance of the concrete layers including glass color, aggregate size and curing age, were investigated. The results show a significant enhancement of the photocatalytic activity due to the use of glass cullets as aggregates in the concrete layers. The samples fabricated with clear glass cullets exhibited threefold NO removal efficiency compared to the samples fabricated with river sand. The light transmittance property of glass was postulated to account for the efficiency improvement, which was confirmed by a separate simulation study. But the influence of the size of glass cullets was not evident. In addition, the photocatalytic activity of concrete surface layers decreased with curing age, showing a loss of 20% photocatalytic activity after 56-day curing.

  8. 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

  9. 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

  10. 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.

  11. Utilization of municipal solid waste bottom ash and recycled aggregate in concrete.

    PubMed

    Juric, B; Hanzic, L; Ilić, R; Samec, N

    2006-01-01

    In the combustion process of municipal solid waste (MSW), bottom ash (BA) represents the major portion of the solid residue. Since BA is composed of oxides, especially SiO(2) and CaO, the feasibility of its application in concrete as a substitute for cement was tested. It was found that at the age of 28 days, the flexural and compressive strengths of the binder linearly decrease at the rate of 0.03 and 0.02 MPa per wt% of BA in the binder, respectively. According to the results it may be recommended to replace up to 15 wt% of cement by BA and to use such binder where a low strength of concrete elements is required. Furthermore, the aggregate used for low strength concrete need not be of a very good quality. Therefore, gravel aggregate was partially replaced by recycled aggregate (RA). Consistency measured by slump was significantly reduced (>50%) when BA or/and RA were introduced into the mixture. However, concrete density and compressive strength were not affected and were approximately 2300 kg/m(3) and approximately 40 MPa, respectively.

  12. Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete

    PubMed Central

    Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

    2016-01-01

    This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber—polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance. PMID:28773256

  13. Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete.

    PubMed

    Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

    2016-02-26

    This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber-polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance.

  14. Use of Nano-SiO2 to Improve Microstructure and Compressive Strength of Recycled Aggregate Concretes

    NASA Astrophysics Data System (ADS)

    Hosseini, P.; Booshehrian, A.; Delkash, M.; Ghavami, S.; Zanjani, M. K.

    The purpose of this paper is to provide new type of recycled aggregate concrete (RAC) incorporating nano-SiO2. In particular, we investigate the effects of colloidal nano-silica solution on the properties of fresh and hardened concrete. The main variables included the dosage of nano-silica (including 0%, 1.5%, and 3% of cement content) and the cement content of the concrete (including 400 and 450 kg/m3). Results were compared with plain concretes. Tests were conducted to determine the mechanical properties (compressive strength) and microstructure (SEM test) of the concretes.

  15. 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.

  16. Effect of Stress Amplitude on the Damping of Recycled Aggregate Concrete

    PubMed Central

    Liang, Chaofeng; Liu, Tiejun; Xiao, Jianzhuang; Zou, Dujian; Yang, Qiuwei

    2015-01-01

    Damping characterizes the energy dissipation capacity of materials and structures, and it is affected by several external factors such as vibrating frequency, stress history, temperature, and stress amplitude. This study investigates the relationship between the damping and the stress amplitude of environment-friendly recycled aggregate concrete (RAC). First, a function model of a member’s loss factor and stress amplitude was derived based on Lazan’s damping-stress function. Then, the influence of stress amplitude on the loss tangent of RAC was experimentally investigated. Finally, parameters used to determine the newly derived function were obtained by numerical fitting. It is shown that the member’s loss factor is affected not only by the stress amplitude but also by factors such as the cross section shapes, boundary conditions, load types, and loading positions. The loss tangent of RAC increases with the stress amplitude, even at low stress amplitude. The damping energy exponent of RAC is not identically equal to 2.0, indicating that the damping is nonlinear. It is also found that the energy dissipation capacity of RAC is superior to that of natural aggregate concrete (NAC), and the energy dissipation capacity can be further improved by adding modified admixtures. PMID:28793505

  17. Effect of Stress Amplitude on the Damping of Recycled Aggregate Concrete.

    PubMed

    Liang, Chaofeng; Liu, Tiejun; Xiao, Jianzhuang; Zou, Dujian; Yang, Qiuwei

    2015-08-14

    Damping characterizes the energy dissipation capacity of materials and structures, and it is affected by several external factors such as vibrating frequency, stress history, temperature, and stress amplitude. This study investigates the relationship between the damping and the stress amplitude of environment-friendly recycled aggregate concrete (RAC). First, a function model of a member's loss factor and stress amplitude was derived based on Lazan's damping-stress function. Then, the influence of stress amplitude on the loss tangent of RAC was experimentally investigated. Finally, parameters used to determine the newly derived function were obtained by numerical fitting. It is shown that the member's loss factor is affected not only by the stress amplitude but also by factors such as the cross section shapes, boundary conditions, load types, and loading positions. The loss tangent of RAC increases with the stress amplitude, even at low stress amplitude. The damping energy exponent of RAC is not identically equal to 2.0, indicating that the damping is nonlinear. It is also found that the energy dissipation capacity of RAC is superior to that of natural aggregate concrete (NAC), and the energy dissipation capacity can be further improved by adding modified admixtures.

  18. Study of the seismic response of a recycled aggregate concrete frame structure

    NASA Astrophysics Data System (ADS)

    Wang, Changqing; Xiao, Jianzhuang

    2013-12-01

    Based on six-degree-of-freedom three-dimensional shaking table tests, the seismic response of a recycled aggregate concrete (RAC) frame was obtained. The analysis results indicate that the maximum story shear force and overturning moment reduce proportionally along the height of the model under the same earthquake wave. The story shear force, base shear coefficient and overturning moment of the structure increase progressively as the acceleration amplitude increases. The base shear coefficient is primarily controlled by the peak ground acceleration (PGA). The relationships between the PGA and the shear coefficient as well as between the PGA and the dynamic amplification factor are obtained by mathematical fitting. The dynamic amplification factor decreases rapidly at the elastic-plastic stage, but decreases slowly with the development of the elastic-plasticity stage. The results show that the RAC frame structure has reasonable deformability when compared with natural aggregate concrete frame structures. The maximum inter-story drift ratios of the RAC frame model under frequent and rare intensity 8 test phases are 1/266 and 1/29, respectively, which are larger than the allowable value of 1/500 and 1/50 according to Chinese seismic design requirements. Nevertheless, the RAC frame structure does not collapse under base excitations with PGAs from 0.066 g up to 1.170 g.

  19. Recycling of waste glass as a partial replacement for fine aggregate in concrete.

    PubMed

    Ismail, Zainab Z; Al-Hashmi, Enas A

    2009-02-01

    Waste glass creates serious environmental problems, mainly due to the inconsistency of waste glass streams. With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal. The properties of concretes containing waste glass as fine aggregate were investigated in this study. The strength properties and ASR expansion were analyzed in terms of waste glass content. An overall quantity of 80 kg of crushed waste glass was used as a partial replacement for sand at 10%, 15%, and 20% with 900 kg of concrete mixes. The results proved 80% pozzolanic strength activity given by waste glass after 28 days. The flexural strength and compressive strength of specimens with 20% waste glass content were 10.99% and 4.23%, respectively, higher than those of the control specimen at 28 days. The mortar bar tests demonstrated that the finely crushed waste glass helped reduce expansion by 66% as compared with the control mix.

  20. Release of major elements from recycled concrete aggregates and geochemical modelling

    SciTech Connect

    Engelsen, Christian J. Sloot, Hans A. van der; Wibetoe, Grethe; Petkovic, Gordana; Stoltenberg-Hansson, Erik; Lund, Walter

    2009-05-15

    The pH dependent leaching characteristics were assessed for different types of recycled concrete aggregates, including real construction debris and crushed fresh concrete samples prepared in laboratory. Carbonation effects were identified from the characteristic pH dependent leaching patterns for the major constituents Al, Ca, Fe, Mg, Si and SO{sub 4}{sup 2-}. The original particle size ranges were different for the samples investigated and this factor influenced the cement paste content in the samples which in turn controlled the leachable contents. Cement paste contents for concrete samples with fine particle size fractions (0-4 mm) were found to be higher than the originally present amount in the hardened concrete. Geochemical speciation modelling was applied over the entire pH range using the speciation and transport modelling framework ORCHESTRA, for which mineral saturation, solution speciation and sorption processes can be calculated based on equilibrium models and thermodynamic data. The simulated equilibrium concentrations by this model agreed well with the respective measured concentrations. The main differences between the fresh and aged materials were quantified, described and predicted by the ORCHESTRA. Solubility controlling mineral phase assemblages were calculated by the model as function of pH. Cement hydrate phases such as calcium silicate hydrate, calcium aluminate hydrate (AFm and AFt) and hydrogarnet were predominating at the material pH. The concentration of carboaluminates was found to be strongly dependent on the available carbonates in the samples. As the pH was decreased these phases decomposed to more soluble species or precipitates were formed including iron- and aluminium hydroxides, wairakite and amorphous silica. In the most acid region most phases dissolved, and the major elements were approaching maximum leachability, which was determined by the amount of cement paste.

  1. 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.

  2. Properties of concrete made with north carolina recycled coarse and fine aggregates. Final report, 1 July 1994-30 June 1996

    SciTech Connect

    Ahmad, S.H.; Fisher, D.G.; Sackett, K.W.

    1996-06-30

    Reconstruction of roadways generates large quantities of waste material and requires considerable amounts of aggregate. The recycling of concrete from old deteriorated pavements into aggregates for construction of new pavements reduces disposal costs as well as providing a source of aggregates to replace natural supplies. In this study, recycled coarse and fine aggregates were obtained from a portion of concrete pavement which was removed from Interstate 40 in North Carolina. Various amounts of recycled coarse and fine aggregates were volumerically substituted for natural coarse and fine aggregates of a control mixture. A relatively higher cement factor was used for the control mix, compared to NCDOT standard. The effects on plastic and hardened concrete properties were investigated.

  3. Effects of extraction methods and factors on leaching of metals from recycled concrete aggregates.

    PubMed

    Bestgen, Janile O; Cetin, Bora; Tanyu, Burak F

    2016-07-01

    Leaching of metals (calcium (Ca), chromium (Cr), copper, (Cu), iron (Fe), and zinc (Zn)) of recycled concrete aggregates (RCAs) were investigated with four different leachate extraction methods (batch water leach tests (WLTs), toxicity leaching procedure test (TCLP), synthetic precipitation leaching procedure test (SPLP), and pH-dependent leach tests). WLTs were also used to perform a parametric study to evaluate factors including (i) effects of reaction time, (ii) atmosphere, (iii) liquid-to-solid (L/S) ratio, and (iv) particle size of RCA. The results from WLTs showed that reaction time and exposure to atmosphere had impact on leaching behavior of metals. An increase in L/S ratio decreased the effluent pH and all metal concentrations. Particle size of the RCA had impact on some metals but not all. Comparison of the leached concentrations of metals from select RCA samples with WLT method to leached concentrations from TCLP and SPLP methods revealed significant differences. For the same RCA samples, the highest metal concentrations were obtained with TCLP method, followed by WLT and SPLP methods. However, in all tests, the concentrations of all four (Cr, Cu, Fe, and Zn) metals were below the regulatory limits determined by EPA MCLs in all tests with few exceptions. pH-dependent batch water leach tests revealed that leaching pattern for Ca is more cationic whereas for other metals showed more amphoteric. The results obtained from the pH-dependent tests were evaluated with geochemical modeling (MINTEQA2) to estimate the governing leaching mechanisms for different metals. The results indicated that the releases of the elements were solubility-controlled except Cr.

  4. 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

  5. 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.

  6. 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

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

    DTIC Science & Technology

    2008-05-27

    process additive in foundry and scrap metal 3 operations before the toxic dust is collected in a bag house. Due to its high alkalinity, Bantox® can...assist in achieving concrete that does not have the toxicity characteristic for lead. Based on the information from available literature and industrial ...as percent (by weight) sodium oxide (Na2O). 3.2 Concrete Mixing and Curing A LWD Lancaster pan concrete mixer (Kercher Industries , Inc., Lebanon

  8. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

    PubMed Central

    Garach, Laura; López, Mónica; Agrela, Francisco; Ordóñez, Javier; Alegre, Javier; Moya, José Antonio

    2015-01-01

    Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term. PMID:28793747

  9. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base.

    PubMed

    Garach, Laura; López, Mónica; Agrela, Francisco; Ordóñez, Javier; Alegre, Javier; Moya, José Antonio

    2015-12-16

    Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term.

  10. 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.

  11. The feasibility of recycling contaminated concrete

    SciTech Connect

    Ayers, K.W,; Corroon, W.; Parker, F.L.

    1999-07-01

    The changing mission of the Department of Energy along with the aging of many of its facilities has resulted in renewed emphasis on decontaminating and decommissioning surplus structures. Currently DOE is decontaminating some concrete and sending the clean material to C and D disposal facilities. In other instance, DOE is sending contaminated concrete to LLW disposal facilities. This paper examines the economic feasibility of decontaminating the concrete and recycling the rubble as clean aggregate. A probabilistic cost model was used to examine six potential recycling and disposal scenarios. The model predicted potential costs saving across the DOE complex of nearly one billion dollars. The ability of local markets to assimilate the recycled material was estimated for Washington, Idaho, Tennessee, New Mexico, and South Carolina. The relationships between a number of the economic model's variables were examined to develop operating ranges for initial managerial evaluation of recycling.

  12. The cause and influence of self-cementing properties of fine recycled concrete aggregates on the properties of unbound sub-base

    SciTech Connect

    Poon, C.-S. . E-mail: cecspoon@polyu.edu.hk; Qiao, X.C.; Chan, Dixon

    2006-07-01

    The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete aggregates (FRCA) as sub-base materials has been widely studied. Although research results indicate that it is feasible to employ both CRCA and FRCA as granular sub-base, the influence of the unhydrated cement in the adhered mortar of the RCA on the properties of the sub-base materials has not been thoroughly studied. Generally, it is known that the strength of the sub-base materials prepared with RCA increases over time. However, this mechanism, known as the self-cementing properties, is not well understood and is believed to be governed by the properties of the fine portion of the RCA (<5 mm). This paper presents an investigation on the cause of the self-cementing properties by measuring X-ray diffraction patterns, pH values, compressive strength and permeability of various size fractions of the FRCA obtained from a commercially operated construction and demolition waste recycling plant. Their influence on the overall sub-base materials was determined. The results indicate that the size fractions of <0.15 and 0.3-0.6 mm (active fractions) were most likely to be the principal cause of the self-cementing properties of the FRCA. However, the effects on the properties of the overall RCA sub-base materials were minimal if the total quantity of the active fractions was limited to a threshold by weight of the total fine aggregate.

  13. The cause and influence of self-cementing properties of fine recycled concrete aggregates on the properties of unbound sub-base.

    PubMed

    Poon, Chi-Sun; Qiao, X C; Chan, Dixon

    2006-01-01

    The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete aggregates (FRCA) as sub-base materials has been widely studied. Although research results indicate that it is feasible to employ both CRCA and FRCA as granular sub-base, the influence of the unhydrated cement in the adhered mortar of the RCA on the properties of the sub-base materials has not been thoroughly studied. Generally, it is known that the strength of the sub-base materials prepared with RCA increases over time. However, this mechanism, known as the self-cementing properties, is not well understood and is believed to be governed by the properties of the fine portion of the RCA (<5mm). This paper presents an investigation on the cause of the self-cementing properties by measuring X-ray diffraction patterns, pH values, compressive strength and permeability of various size fractions of the FRCA obtained from a commercially operated construction and demolition waste recycling plant. Their influence on the overall sub-base materials was determined. The results indicate that the size fractions of <0.15 and 0.3-0.6mm (active fractions) were most likely to be the principal cause of the self-cementing properties of the FRCA. However, the effects on the properties of the overall RCA sub-base materials were minimal if the total quantity of the active fractions was limited to a threshold by weight of the total fine aggregate.

  14. High performance polyester concrete using recycled PET

    SciTech Connect

    Rebeiz, K.S.

    1995-10-01

    Recycled polyethylene terephthalate (PET) plastic wastes could be used in production of unsaturated polyester resins. In turn, these resins could be mixed with inorganic aggregates to produce polymer concrete (PC). Unsaturated polyesters based on recycled PET might be a potentially lower source cost of resins for producing useful PC based-products. The advantage of recycling PET in PC is that the PET materials do not have to be purified, including removal of colors, to the same extent as other PET recycling applications, which should facilitate the recycling operation and minimize its cost. The recycling of PET in PC could also help save energy and allow the long term disposal of the PET waste, an important advantage in recycling applications.

  15. Experimental study on dynamic splitting of recycled concrete using SHPB

    NASA Astrophysics Data System (ADS)

    Lu, Yubin; Yu, Shuisheng; Cai, Yong

    2015-09-01

    To study the recycled concrete splitting tensile properties and fracture state with various recycled coarse aggregate replacement percentage (i.e. 0%, 25%, 50%, 75% and 100%), the dynamic splitting test of recycled concrete was carried out using large diameter (75 mm) split Hopkinson pressure bar (SHPB). The results show that the recycled concrete splitting tensile strength increases with the increase of loading rate, and the loading rate also affects the recycled concrete fracture state, which indicates that the recycled concrete has obvious rate sensitivity. The damage state of the recycled concrete is not only the destruction of the interface between coarse aggregate and cement mortar, but also associates with the fracture damage of aggregates. Under the same water cement ratio, when the replacement percentage of coarse aggregates is around 50%-75%, the gradation of natural and recycled coarse aggregate is optimal, and thus the splitting tensile strength is the largest. This study offers theoretical basis for the engineering applications of recycled concrete.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Evaluation of properties of recycled asphalt concrete hot mix

    SciTech Connect

    Brown, E.R.

    1983-01-01

    This study was undertaken to evaluate the laboratory performance of recycled asphalt concrete mixtures and to compare these results to those measured for conventional asphalt concrete mixtures. To make these comparisons, samples of aged asphalt concrete were obtained from three locations where recycling was planned. These samples were blended with new aggregate and new asphalt materials to produce six different recycled mixtures. Two aggregate types, a crushed gravel and a crushed limestone, were used to produce two conventional mixtures and to blend with the reclaimed asphalt pavement to produce the six recycled mixtures. Three asphalt materials which were obtained to produce the various mixtures being evaluated consisted of AC-20 for preparing the conventional mixtures and AC-5 and a recycling agent for preparing the recycled mixtures. The Shell BISAR computer program was used to predict the stesses and strains for two typical pavement sections under a given loading conditions. The computed stresses and strains were then analyzed along with the laboratory fatigue tests to predict the fatigue performance of the various mixtures. The results of this study indicated a satisfactory comparison between laboratory performance of recycled mixtures and conventional mixtures. Fatigue analysis indicated that the conventional mixtures would provide the greatest fatigue resistance in thick asphalt concrete layers at lower temperatures while the recycled mixtures would provide the greatest fatigue resistance in thin asphalt layers at higher temperatures.

  4. Recycling of portland cement concrete pavement, Johnson County. Final report, 1986-1995

    SciTech Connect

    Wojakowski, J.B.; Fager, G.A.; Catron, M.A.

    1995-08-01

    In recent years there has been increasing interest in recycling construction materials. Surface courses of bituminous pavements are currently being actively recycled all over Kansas. The recycling of portland cement concrete pavements (PCCP) can help alleviate any material disposal problems during construction, especially in urban areas and reduce the consumption or importation of virgin aggregate into aggregate poor areas. Two test sections using the coarser fraction from the original crushed portland cement concrete pavement were placed on K-7 in 1985. One section incorporated a recycled base and standard PCCP construction, another section was designed as a recycled base and recycled PCCP. Two other sections were control sections constructed with regular aggregate.

  5. Shaking table experimental study of recycled concrete frame-shear wall structures

    NASA Astrophysics Data System (ADS)

    Zhang, Jianwei; Cao, Wanlin; Meng, Shaobin; Yu, Cheng; Dong, Hongying

    2014-06-01

    In this study, four 1/5 scaled shaking table tests were conducted to investigate the seismic performance of recycled concrete frame-shear wall structures with different recycled aggregates replacement rates and concealed bracing detail. The four tested structures included one normal concrete model, one recycled coarse aggregate concrete model, and two recycled coarse and fine aggregate concrete models with or without concealed bracings inside the shear walls. The dynamic characteristics, dynamic response and failure mode of each model were compared and analyzed. Finite element models were also developed and nonlinear time-history response analysis was conducted. The test and analysis results show that the seismic performance of the recycled coarse aggregate concrete frame-shear wall structure is slightly worse than the normal concrete structure. The seismic resistance capacity of the recycled concrete frame-shear wall structure can be greatly improved by setting up concealed bracings inside the walls. With appropriate design, the recycled coarse aggregate concrete frame-shear wall structure and recycled concrete structure with concealed bracings inside the walls can be applied in buildings.

  6. Mechanical properties of GFRP tube confined recycled concrete under axial compression

    NASA Astrophysics Data System (ADS)

    Wang, Xiaogang; Liang, Chaofeng; Zhou, Zechenglong; Dong, Lanqi; Ding, Kewei; Huang, Jialun

    2015-07-01

    This article outlines the recycled aggregate replacement rate and thick-diameter rate of GFRP tube confined in recycled concrete, which has an important impact on the material's compressive strength. Overall, under the same conditions of using recycled concrete, the bearing capacity of short concrete columns can be improved by using broader GFRP tubes. There is a four-fold increase in the bearing capacity of short concrete columns compared to the short column without the restriction of a GFRP tube. The bearing capacity of a short column crafted by recycled coarse aggregate is much lower (about 30%). than those made by common concrete column Additionally, the bearing capacity of short columns made by recycled fine aggregates is also lower than those made by common concrete (approximately 20%). Finally, we find that there is no significant difference between experimental and theoretical data.

  7. Recycling of Portland Cement Concrete Airport Pavements - A State-of-the-Art Study,

    DTIC Science & Technology

    1981-04-01

    Urban Roads, Mar 1980, pp 70-71. 2. Waterways Experiment Station. Miscellaneous Paper C-72-14: Recycled Concrete, by A. D. Buck. Vicksburg, Miss., May...1972. 3. . Miscellaneous Paper C-72-14 (Report 2): Recycled Concrete - Additional Investigations, by A. D. Buck. Vicksburg, Miss., Apr 1976. 4...Miscellaneous Paper C-76-2: Recycled Concrete as a Source of Aggregate, by A. D. Buck. Vicksburg, Miss., Apr 1976. ! " . Institute of Technology (IOef 5

  8. 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

  9. 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.

  10. 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.

  11. Economic analysis of recycling contaminated concrete

    SciTech Connect

    Stephen, A.; Ayers, K.W.; Boren, J.K.; Parker, F.L.

    1997-02-01

    Decontamination and Decommissioning activities in the DOE complex generate large volumes of radioactively contaminated and uncontaminated concrete. Currently, this concrete is usually decontaminated, the contaminated waste is disposed of in a LLW facility and the decontaminated concrete is placed in C&D landfills. A number of alternatives to this practice are available including recycling of the concrete. Cost estimates for six alternatives were developed using a spreadsheet model. The results of this analysis show that recycling alternatives are at least as economical as current practice.

  12. Eco-efficient concretes: the effects of using recycled ceramic material from sanitary installations on the mechanical properties of concrete.

    PubMed

    Guerra, I; Vivar, I; Llamas, B; Juan, A; Moran, J

    2009-02-01

    The aim of this research was to investigate some of the physical and mechanical properties of concrete mixed under laboratory conditions, where different proportions of coarse aggregate materials were substituted by porcelain from sanitary installations. The results of the tests show that the concrete produced has the same mechanical characteristics as conventional concrete, thus opening a door to selective recycling of sanitary porcelain and its use in the production of concrete.

  13. 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.

  14. Recycled lightweight concrete made from footwear industry waste and CDW.

    PubMed

    Lima, Paulo Roberto Lopes; Leite, Mônica Batista; Santiago, Ediela Quinteiro Ribeiro

    2010-06-01

    In this paper two types of recycled aggregate, originated from construction and demolition waste (CDW) and ethylene vinyl acetate (EVA) waste, were used in the production of concrete. The EVA waste results from cutting off the EVA expanded sheets used to produce insoles and innersoles of shoes in the footwear industry. The goal of this study was to evaluate the influence of the use of these recycled aggregates as replacements of the natural coarse aggregate, upon density, compressive strength, tensile splitting strength and flexural behavior of recycled concrete. The experimental program was developed with three w/c ratios: 0.49, 0.63 and 0.82. Fifteen mixtures were produced with different aggregate substitution rates (0%, 50% EVA, 50% CDW, 25% CDW-25% EVA and 50% CDW-50% EVA), by volume. The results showed that it is possible to use the EVA waste and CDW to produce lightweight concrete having semi-structural properties. Copyright 2010 Elsevier Ltd. All rights reserved.

  15. Innovative process routes for a high-quality concrete recycling.

    PubMed

    Menard, Y; Bru, K; Touze, S; Lemoign, A; Poirier, J E; Ruffie, G; Bonnaudin, F; Von Der Weid, F

    2013-06-01

    This study presents alternative methods for the processing of concrete waste. The mechanical stresses needed for the embrittlement of the mortar matrix and further selective crushing of concrete were generated by either electric impulses or microwaves heating. Tests were carried out on lab-made concrete samples representative of concrete waste from concrete mixer trucks and on concrete waste collected on a French demolition site. The results obtained so far show that both techniques can be used to weaken concrete samples and to enhance aggregate selective liberation (that is the production of cement paste-free aggregates) during crushing and grinding. Electric pulses treatment seems to appear more efficient, more robust and less energy consuming (1-3 kWh t(-1)) than microwave treatment (10-40 kWh t(-1)) but it can only be applied on samples in water leading to a major drawback for recycling aggregates or cement paste in the cement production process. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Materials development and field demonstration of high-recycled-content concrete for energy-efficient building construction

    SciTech Connect

    Ostowari, Ken; Nosson, Ali

    2000-09-30

    The project developed high-recycled-content concrete material with balanced structural and thermal attributes for use in energy-efficient building construction. Recycled plastics, tire, wool, steel and concrete were used as replacement for coarse aggregates in concrete and masonry production. With recycled materials the specific heat and thermal conductivity of concrete could be tailored to enhance the energy-efficiency of concrete buildings. A comprehensive field project was implemented which confirmed the benefits of high-recycled-content concrete for energy-efficient building construction.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Stabilized fiber-reinforced pavement base course with recycled aggregate

    NASA Astrophysics Data System (ADS)

    Sobhan, Khaled

    This study evaluates the benefits to be gained by using a composite highway base course material consisting of recycled crushed concrete aggregate, portland cement, fly ash, and a modest amount of reinforcing fibers. The primary objectives of this research were to (a) quantify the improvement that is obtained by adding fibers to a lean concrete composite (made from recycled aggregate and low quantities of Portland cement and/or fly ash), (b) evaluate the mechanical behavior of such a composite base course material under both static and repeated loads, and (c) utilize the laboratory-determined properties with a mechanistic design method to assess the potential advantages. The split tensile strength of a stabilized recycled aggregate base course material was found to be exponentially related to the compacted dry density of the mix. A lean mix containing 4% cement and 4% fly ash (by weight) develops sufficient unconfined compressive, split tensile, and flexural strengths to be used as a high quality stabilized base course. The addition of 4% (by weight) of hooked-end steel fibers significantly enhances the post-peak load-deformation response of the composite in both indirect tension and static flexure. The flexural fatigue behavior of the 4% cement-4% fly ash mix is comparable to all commonly used stabilized materials, including regular concrete; the inclusion of 4% hooked-end fibers to this mix significantly improves its resistance to fatigue failure. The resilient moduli of stabilized recycled aggregate in flexure are comparable to the values obtained for traditional soil-cement mixes. In general, the fibers are effective in retarding the rate of fatigue damage accumulation, which is quantified in terms of a damage index defined by an energy-based approach. The thickness design curves for a stabilized recycled aggregate base course, as developed by using an elastic layer approach, is shown to be in close agreement with a theoretical model (based on Westergaard

  5. 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.

  6. Radiation shielding concrete made of Basalt aggregates.

    PubMed

    Alhajali, S; Yousef, S; Kanbour, M; Naoum, B

    2013-04-01

    In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield.

  7. Assessment of the recycling potential of fresh concrete waste using a factorial design of experiments.

    PubMed

    Correia, S L; Souza, F L; Dienstmann, G; Segadães, A M

    2009-11-01

    Recycling of industrial wastes and by-products can help reduce the cost of waste treatment prior to disposal and eventually preserve natural resources and energy. To assess the recycling potential of a given waste, it is important to select a tool capable of giving clear indications either way, with the least time and work consumption, as is the case of modelling the system properties using the results obtained from statistical design of experiments. In this work, the aggregate reclaimed from the mud that results from washout and cleaning operations of fresh concrete mixer trucks (fresh concrete waste, FCW) was recycled into new concrete with various water/cement ratios, as replacement of natural fine aggregates. A 3(2) factorial design of experiments was used to model fresh concrete consistency index and hardened concrete water absorption and 7- and 28-day compressive strength, as functions of FCW content and water/cement ratio, and the resulting regression equations and contour plots were validated with confirmation experiments. The results showed that the fresh concrete workability worsened with the increase in FCW content but the water absorption (5-10 wt.%), 7-day compressive strength (26-36 MPa) and 28-day compressive strength (32-44 MPa) remained within the specified ranges, thus demonstrating that the aggregate reclaimed from FCW can be recycled into new concrete mixtures with lower natural aggregate content.

  8. Charge-based fractionation of oxyanion-forming metals and metalloids leached from recycled concrete aggregates of different degrees of carbonation: a comparison of laboratory and field leaching tests.

    PubMed

    Mulugeta, Mesay; Engelsen, Christian J; Wibetoe, Grethe; Lund, Walter

    2011-02-01

    The release and charge-based fractionation of As, Cr, Mo, Sb, Se and V were evaluated in leachates generated from recycled concrete aggregates (RCA) in a laboratory and at a field site. The leachates, covering the pH range 8.4-12.6, were generated from non-carbonated, and artificially and naturally carbonated crushed concrete samples. Comparison between the release of the elements from the non-carbonated and carbonated samples indicated higher solubility of the elements from the latter. The laboratory leaching tests also revealed that the solubility of the elements is low at the "natural pH" of the non-carbonated materials and show enhancement when the pH is decreased. The charge-based fractionation of the elements was determined by ion-exchange solid phase extraction (SPE); it was found that all the target elements predominantly existed as anions in both the laboratory and field leachates. The high fraction of the anionic species of the elements in the leachates from the carbonated RCA materials verified the enhanced solubility of the oxyanionic species of the elements as a result of carbonation. The concentrations of the elements in the leachates and SPE effluents were determined by inductively coupled plasma mass spectrometry (ICP-MS). Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. Grout Impregnation of Pre-Placed Recycled Concrete Pavement (RCP) for Rapid Repair of Deteriorated Portland Cement Concrete Airfield Pavement

    DTIC Science & Technology

    2007-04-01

    aggregates in the repair hole, and the voids are filled with a rapid-setting, flowable grout. The results of this study will be used to provide...the repair of spalls involve filling the damaged area with some type of flowable substance which hardens to provide a material that has comparable... filled with Recycled Concrete Pavement (RCP)........................................................................ 53 7 Mixing Pavemend™ material

  10. Research on Durability of Recycled Ceramic Powder Concrete

    NASA Astrophysics Data System (ADS)

    Chen, M. C.; Fang, W.; Xu, K. C.; Xie, L.

    2017-06-01

    Ceramic was ground into powder with 325 mesh and used to prepare for concrete. Basic mechanical properties, carbonation and chloride ion penetration of the concrete tests were conducted. In addition, 6-hour electric fluxes of recycled ceramic powder concrete were measured under loading. The results showed that the age strength of ceramics powder concrete is higher than that of the ordinary concrete and the fly ash concrete. The ceramic powder used as admixture would reduce the strength of concrete under no consideration of its impact factor; under consideration of the impact factor for ceramic powder as admixture, the carbonation resistance of ceramic powder concrete was significantly improved, and the 28 day carbonation depth of the ceramic powder concrete was only 31.5% of ordinary concrete. The anti-chloride-permeability of recycled ceramic powder concrete was excellent.

  11. 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.

  12. 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.

  13. Influence of recycled fine aggregates on the resistance of mortars to magnesium sulfate attack

    SciTech Connect

    Lee, Seung-Tae

    2009-08-15

    The influence of recycled fine aggregates, which had been reclaimed from field-demolished concretes, on the resistance of mortar specimens to magnesium sulfate attack was investigated. Mortar specimens were prepared with recycled fine aggregates at different replacement levels (0%, 25%, 50%, 75% and 100% of natural fine aggregate by mass). The mortar specimens were exposed to 4.24% magnesium sulfate solution for about 1 year at ambient temperature, and regularly monitored for visual appearance, compressive strength loss and expansion. Additionally, in order to identify products of magnesium sulfate attack, mortar samples incorporating 0%, 25% and 100% replacement levels of the recycled fine aggregates were examined by X-ray diffraction (XRD) technique. Experimental results confirmed that the use of recycled fine aggregates up to a maximum 50% replacement level is effective under severe magnesium sulfate environment, irrespective of type of recycled fine aggregates. However, the worse performance was observed in mortar specimens incorporating 100% replacement level. It was found that the water absorption of recycled fine aggregates affected deterioration of mortar specimens, especially at a higher replacement level. XRD results indicated that the main cause of deterioration of the mortar specimens was primarily due to the formation of gypsum and thaumasite by magnesium sulfate attack. In addition, it appeared that the conversion of C-S-H into M-S-H by the attack probably influenced mechanical deterioration of mortar specimens with recycled fine aggregates.

  14. Asphalt-Aggregate Interactions in Hot Recycling.

    DTIC Science & Technology

    1987-07-01

    showed that recycled systems resisted the action of water better than virgin systems. Bonding energy measurements indicated that asphalt-aggregate mixtures...Mexico Powders and Granular Materials Laboratory for surface area/porosity measurements and discussion of results John Husler and Les Mcfadden at the...FORMUJLA MIXTURE RESULTS.................. 70 22 F VALUES DERIVED FROM THE TWO-WAY ANOVA................. 79 23 BONDING ENERGY MEASUREMENTS FOR - #16 + #50

  15. 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

  16. Hyperspectral imaging applied to end-of-life concrete recycling

    NASA Astrophysics Data System (ADS)

    Serranti, Silvia; Bonifazi, Giuseppe

    2014-03-01

    In this paper a new technology, based on HyperSpectral Imaging (HSI) sensors, and related detection architectures, is investigated in order to develop suitable and low cost strategies addressed to: i) preliminary detection and characterization of the composition of the structure to dismantle and ii) definition and implementation of innovative smart detection engines for sorting and/or demolition waste flow stream quality control. The proposed sensing architecture is fast, accurate, affordable and it can strongly contribute to bring down the economic threshold above which recycling is cost efficient. Investigations have been carried out utilizing an HSI device working in the range 1000-1700 nm: NIR Spectral Camera™, embedding an ImSpector™ N17E (SPECIM Ltd, Finland). Spectral data analysis was carried out utilizing the PLS_Toolbox (Version 6.5.1, Eigenvector Research, Inc.) running inside Matlab® (Version 7.11.1, The Mathworks, Inc.), applying different chemometric techniques, selected depending on the materials under investigation. The developed procedure allows assessing the characteristics, in terms of materials identification, such as recycled aggregates and related contaminants, as resulting from end-of-life concrete processing. A good classification of the different classes of material was obtained, being the model able to distinguish aggregates from other materials (i.e. glass, plastic, tiles, paper, cardboard, wood, brick, gypsum, etc.).

  17. 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.

  18. 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.

  19. Economics and risks of recycling radioactively contaminated concrete

    SciTech Connect

    Parker, F.L.; Ayers, K.W.

    1997-12-31

    As Decontamination and Decommissioning activities proceed within the DOE complex, tremendous volumes of both radioactively contaminated and non-contaminated concrete will be processed for disposal. Current practice is to decontaminate the concrete, dispose of the contamination at LLW facilities and ship the concrete rubble to C & D landfills for disposal. This study evaluates the economic, health and safety, legal, and social aspects of recycling radioactively contaminated concrete. Probabilistic models were used to estimate costs and risks. The model indicates that the radioactively contaminated concrete can be recycled at the same or lower cost than current or alternative practices. The risks associated with recycling were consistently less than or equal to the other alternatives considered.

  20. Polymer concrete reinforced with recycled-tire fibers: Mechanical properties

    NASA Astrophysics Data System (ADS)

    Martínez-Cruz, E.; Martínez-Barrera, G.; Martínez-López, M.

    2013-06-01

    Polymer Concrete was reinforced with recycled-tire fibers in order to improve the compressive and flexural strength. Polymer concrete specimens were prepared with 70% of silicious sand, 30% of polyester resin and various fiber concentrations (0.3, 0.6, 0.9 and 1.2 vol%). The results show increment of 50% in average of the compressive and flexural strength as well as on the deformation when adding 1.2 vol% of recycled-fibers.

  1. Material property assessment and crack identification of recycled concrete with embedded smart cement modules

    NASA Astrophysics Data System (ADS)

    Qiao, Pizhong; Fan, Wei; Chen, Fangliang

    2011-04-01

    In this paper, the material property assessment and crack identification of concrete using embedded smart cement modules are presented. Both the concrete samples with recycled aggregates (RA) and natural aggregates (NA) were prepared. The smart cement modules were fabricated and embedded in concrete beams to serve as either the actuators or sensors, and the elastic wave propagation-based technique was developed to detect the damage (crack) in the recycled aggregate concrete (RAC) beams and monitor the material degradation of RAC beams due to the freeze/thaw (F/T) conditioning cycles. The damage detection results and elastic modulus reduction monitoring data demonstrate that the proposed smart cement modules and associated damage detection and monitoring techniques are capable of identifying crack-type damage and monitoring material degradation of the RAC beams. Both the RAC and natural aggregate concrete (NAC) beams degrade with the increased F/T conditioning cycles. Though the RAC shows a lower reduction percentage of the modulus of elasticity from both the dynamic modulus and wave propagation tests at the given maximum F/T conditioning cycle (i.e., 300 in this study), the RAC tends to degrade faster after the 180 F/T cycles. As observed in this study, the material properties and degradation rate of RAC are comparable to those of NAC, thus making the RAC suitable for transportation construction. The findings in development of damage detection and health monitoring techniques using embedded smart cement modules resulted from this study promote the widespread application of recycled concrete in transportation construction and provide viable and effective health monitoring techniques for concrete structures in general.

  2. High Modulus Asphalt Concrete with Dolomite Aggregates

    NASA Astrophysics Data System (ADS)

    Haritonovs, V.; Tihonovs, J.; Smirnovs, J.

    2015-11-01

    Dolomite is one of the most widely available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1,000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality, mainly, its LA index (The Los Angeles abrasion test). Therefore, mostly the imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used, which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue, and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance with EN 13108-1 standard.

  3. Concrete using waste oil palm shells as aggregate

    SciTech Connect

    Basri, H.B.; Mannan, M.A.; Zain, M.F.M.

    1999-04-01

    Concrete with oil palm shells (OPS) as coarse aggregate was investigated for its workability, density, and compressive strength development over 56 days under three curing conditions. The effect of fly ash as partial cement replacement was also studied. Fresh OPS concrete was found to have better workability while its 28-day air-dry density was 19--20% lower than ordinary concrete. Compressive strength after 56 days was found to be 41--50% lower than ordinary concrete. These results were still within the normal range for structural lightweight concrete. Fly ash was found to lower the compressive strength of OPS concrete, which was the opposite of its effect on normal concrete.

  4. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method.

    PubMed

    Kim, Haseog; Park, Sangki; Kim, Hayong

    2016-07-29

    There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5.

  5. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method

    PubMed Central

    Kim, Haseog; Park, Sangki; Kim, Hayong

    2016-01-01

    There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5. PMID:27483298

  6. Design guidelines for steel-reinforced polymer concrete using resins based on recycled PET

    SciTech Connect

    Rebeiz, K.S.; Fowler, D.W.

    1996-10-01

    Very little research has been done on the structural behavior of steel-reinforced polymer concrete (PC). In all the previous studies, it was generally assumed that the structural behavior of reinforced PC is similar to the structural behavior of reinforced portland cement concrete because both are composite materials consisting of a binder and inorganic aggregates. However, the design equations developed for steel-reinforced portland cement concrete yield very conservative results when applied to reinforced PC. The objective of this paper is to recommend simple, yet effective design guidelines in shear and flexure for steel-reinforced PC. The recommended design procedures are mostly based on test results performed on PC beams using resins based on recycled poly(ethyleneterephthalate), PET, plastic waste (the PET waste is mainly recovered from used beverage bottles). Previous studies have shown that polyester resins based on recycled PET can produce very good quality PC at a potentially lower cost.

  7. 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).

  8. Study of Bond Characteristics of Reinforced Waste Glass Aggregate Concrete

    NASA Astrophysics Data System (ADS)

    Rajagopalan, P.; Balaji, V.; Unnikrishnan, N.; Jainul Haq, T.; Bhuvaneshwari, P.

    2017-07-01

    The conformity of properties of waste glass aggregate with conventional aggregate was found out. Nine cubes (150mm x 150mm x 150mm) were cast out of which three were used for control concrete, three were fully replaced with waste glass as coarse aggregate, three were partially replaced(50%) with waste glass as fine aggregate. Six cylinders (150mm x 300mm) were cast out of which two for control concrete, two cylinders with coarse aggregate fully replaced with waste glass aggregate(WGA) and remaining two cylinders with partially replaced (50%) fine aggregate with waste glass aggregate. Cured specimens were subjected to compression and split-tensile test to ascertain the characteristic compressive strength and split tensile strength. Since the surface of the coarse aggregate plays a significant role in bonding of the rebar in reinforced concrete, pull-out test on both control and Waste Glass Aggregate (WGA) cube specimens (150mm x 150mm with 20mm diameter steel rods) were conducted. Scanning Electron Microscopy (SEM) analysis has been done for better understanding of bonding properties in waste glass fine aggregate(WGFA) and waste glass coarse aggregate(WGCA) concrete. Comparison of the results with that of control specimens showed that waste glass could be effectively used as aggregates in reinforced concrete construction.

  9. Carbonation around near aggregate regions of old hardened concrete cement paste

    SciTech Connect

    Tam, Vivian W.Y. . E-mail: tam.vivian@student.cityu.edu.hk; Gao, X.F.; Tam, C.M. . E-mail: bctam@cityu.edu.hk

    2005-06-01

    Analogous with most modern cities, waste disposal is a pressing issue due to limited landfill and public filling (land reclamation) areas in Hong Kong in which construction and demolition (C and D) waste forms the major source. Concrete, apportioning the largest portion of C and D waste, has the greatest potential for recycling. However, the knowledge on micro-structural behavior of concrete waste is immature to give adequate details on the macro-behavior of concrete waste. This paper attempts to examine the problems of recycling old concrete by investigating the microstructure and phase transformation of the concrete samples collected from buildings with 46 and 37 years of services. From the results of Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) examination, it is found that there are a lot of pores at the near layers of aggregate where carbonation of the hardened cement paste (HCP) is high. The pores may be generated as a result of poor workmanship such as insufficient concrete mixing time, trapping of air voids beneath coarse aggregate, inappropriate water to cement ratio, and the microclimate conditions such as humidity that affects the demand on water from the aggregate during mixing.

  10. RESEARCH INTO A METHOD FOR IMPROVING THE QUALITY OF RECYCLED FINE AGGREGATE BY SELECTIVELY REMOVING THE BRITTLE DEFECTS

    NASA Astrophysics Data System (ADS)

    Ogawa, Hideo; Nawa, Toyoharu; Ohya, Kazu; Yamamoto, Kazuo

    Recycled aggregates have brittle defects such as cracks, pores, and voids, which comes from the residue of paste in original concrete. This report presents a method of improving the quality of recycled fine aggregate by a producing method of selectively removing the defects. Fourteen different kinds of recycled fine aggregates were manufactured by three different griding machines: joe crusher, ball mill and granulator. The influences of the characters on the recycled fine aggregates on the flowability and strength of the recycled mortar was evaluated using multiple linear regression analysis. From the results obtained in this study, it is clear that the flowability was mainly affected by both the filling fraction of recycled fine aggregate and the amount of fine powder, whereas both the compressive strength and bending strength of mortars were affected not by the filling fraction, but by the fraction of defects and the surface smoothness of the aggregates. Compareing the properties of mortar with grinding machine, it is evident that the polishing action, which is such as the ball mill or the granulator is effective both to increase the filling fraction of recycled fine aggregate and to reduce the fraction of defects in the aggregate. It was also found that the surface of grain was more irregular when the granulator was used compared with the ball mill, and hence the strength of the recycled mortar was increased.

  11. User's guide: Hot-mix recycling of asphalt concrete pavements

    NASA Astrophysics Data System (ADS)

    Shoenberger, James E.

    1993-05-01

    This guide provides the technical information required to implement the application of hot-mix recycling of asphalt concrete pavements. Included are details on application, benefits/advantages, limitations/disadvantages, and costs associated with this technology. Information is provided on three demonstration sites at Fort Gillem, Georgia; Fort Leavenworth, Kansas; and Fort Benjamin Harrison, Indiana. Also provided is information concerning funding, procurement, maintenance, and performance monitoring. A fact sheet on recycling, contract specification example, and references are provided in the appendices.

  12. 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.

  13. Use of recycled plastic in concrete: A review

    SciTech Connect

    Siddique, Rafat Khatib, Jamal; Kaur, Inderpreet

    2008-07-01

    Numerous waste materials are generated from manufacturing processes, service industries and municipal solid wastes. The increasing awareness about the environment has tremendously contributed to the concerns related with disposal of the generated wastes. Solid waste management is one of the major environmental concerns in the world. With the scarcity of space for landfilling and due to its ever increasing cost, waste utilization has become an attractive alternative to disposal. Research is being carried out on the utilization of waste products in concrete. Such waste products include discarded tires, plastic, glass, steel, burnt foundry sand, and coal combustion by-products (CCBs). Each of these waste products has provided a specific effect on the properties of fresh and hardened concrete. The use of waste products in concrete not only makes it economical, but also helps in reducing disposal problems. Reuse of bulky wastes is considered the best environmental alternative for solving the problem of disposal. One such waste is plastic, which could be used in various applications. However, efforts have also been made to explore its use in concrete/asphalt concrete. The development of new construction materials using recycled plastics is important to both the construction and the plastic recycling industries. This paper presents a detailed review about waste and recycled plastics, waste management options, and research published on the effect of recycled plastic on the fresh and hardened properties of concrete. The effect of recycled and waste plastic on bulk density, air content, workability, compressive strength, splitting tensile strength, modulus of elasticity, impact resistance, permeability, and abrasion resistance is discussed in this paper.

  14. Use of recycled plastic in concrete: a review.

    PubMed

    Siddique, Rafat; Khatib, Jamal; Kaur, Inderpreet

    2008-01-01

    Numerous waste materials are generated from manufacturing processes, service industries and municipal solid wastes. The increasing awareness about the environment has tremendously contributed to the concerns related with disposal of the generated wastes. Solid waste management is one of the major environmental concerns in the world. With the scarcity of space for landfilling and due to its ever increasing cost, waste utilization has become an attractive alternative to disposal. Research is being carried out on the utilization of waste products in concrete. Such waste products include discarded tires, plastic, glass, steel, burnt foundry sand, and coal combustion by-products (CCBs). Each of these waste products has provided a specific effect on the properties of fresh and hardened concrete. The use of waste products in concrete not only makes it economical, but also helps in reducing disposal problems. Reuse of bulky wastes is considered the best environmental alternative for solving the problem of disposal. One such waste is plastic, which could be used in various applications. However, efforts have also been made to explore its use in concrete/asphalt concrete. The development of new construction materials using recycled plastics is important to both the construction and the plastic recycling industries. This paper presents a detailed review about waste and recycled plastics, waste management options, and research published on the effect of recycled plastic on the fresh and hardened properties of concrete. The effect of recycled and waste plastic on bulk density, air content, workability, compressive strength, splitting tensile strength, modulus of elasticity, impact resistance, permeability, and abrasion resistance is discussed in this paper.

  15. 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

  16. 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.

  17. An evaluation of concrete recycling and reuse practices

    SciTech Connect

    Nakhjiri, K.S.; MacKinney, J.

    1997-02-01

    Nuclear facilities operated by the Department of Energy (DOE), Department of Defense (DOD), and NRC licensees contain many concrete structures that are contaminated with radioactivity. Dismantling these structures will result in significant quantities of waste materials, both contaminated and uncontaminated. Bartlett estimates the total volume of waste from demolition of concrete structures to be on the order of 4 million cubic meters, but that only 20,000 cubic meters would be contaminated with radioactivity. Other studies suggest that as much as 5% of the concrete in these facilities would be contaminated with radioactivity. While the actual quantity of contaminated material should be fixed with greater precision, the fact that so much uncontaminated concrete exists (over 95% of the total 4 million cubic meters) suggests that a program that recycles concrete could produce substantial savings for both government agencies (DOE, DOD) and private companies (NRC licensees). This paper presents a fundamental discussion of (1) various methods of processing concrete, (2) demolition methods, especially those compatible with recycling efforts, and (3) state-of-the-art concrete dismantlement techniques.

  18. Performance of recycled asphalt concrete airport pavement surfaces

    NASA Astrophysics Data System (ADS)

    Cline, G. D.; Hironaka, M. C.

    1986-10-01

    The objective of this research was to make an assessment of the relative performance of recycled versus new asphalt concrete pavement surfaces constructed for airport facilities. To make this assessment, pavement condition index (PCI) surveys and tests on core samples from the hot-mix recycled pavements located on the airports at Needles, California, and Valley City, North Dakota were conducted. Both pavements have a condition rating of very good. The survey and test data were compared with those for recycled highway and virgin material Navy airfield pavements. The recycle pavement at Needles is performing as good as those Navy pavements constructed with virgin material. The recycled pavement at Valley City has a higher deterioration rate than the Navy pavements but this could be attributed to the harsh climate found in North Dakota. The results of this study show that hot-mix recycling was successful at these airports but additional studies are required to determine the applicability of Asphalt Concrete (AC) recycling for reconstruction at all airports.

  19. Innovative technologies for recycling contaminated concrete and scrap metal

    SciTech Connect

    Bossart, S.J.; Moore, J.

    1993-09-01

    Decontamination and decommissioning of US DOE`s surplus facilities will generate enormous quantities of concrete and scrap metal. A solicitation was issued, seeking innovative technologies for recycling and reusing these materials. Eight proposals were selected for award. If successfully developed, these technologies will enable DOE to clean its facilities by 2019.

  20. Washington Gas makes switch to recycled concrete bedding

    SciTech Connect

    Gunther, K.M. . Materials Testing Lab.)

    1993-08-01

    Washington Gas Light Co., following extensive testing, is successfully using recycled concrete as bedding with plastic pipe that has produced cost savings and environmental benefits. The search for new bedding material for use with plastic pipe started in the mid-1970's, when the traditionally used sand was becoming increasingly more difficult to purchase at any price. Sand bedding has been used with plastic services and mains because it provided maximum scratch and rock impingement protection. Although it added to installation cost, sand was accepted as a necessary expense. Decision to use recycled concrete followed studies conducted in 1990. It was discovered that polyethylene was not severely scratched by the concrete or even some of the materials that were rejected during testing in 1976. Toughness improvements in modern polyethylenes explains the difference in the results and proved safe for use with virtually any commercial backfill material.

  1. 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.

  2. Mechanical properties of recycled concrete in marine environment.

    PubMed

    Wang, Jianxiu; Huang, Tianrong; Liu, Xiaotian; Wu, Pengcheng; Guo, Zhiying

    2013-01-01

    Experimental work was carried out to develop information about mechanical properties of recycled concrete (RC) in marine environment. By using the seawater and dry-wet circulation to simulate the marine environment, specimens of RC were tested with different replacement percentages of 0%, 30%, and 60% after immersing in seawater for 4, 8, 12, and 16 months, respectively. Based on the analysis of the stress-strain curves (SSCs) and compressive strength, it is revealed that RC' peak value and elastic modulus decreased with the increase of replacement percentage and corroding time in marine environment. And the failure of recycled concrete was speeded up with more obvious cracks and larger angles of 65° to 85° in the surface when compared with normal concrete. Finally, the grey model (GM) with equal time intervals was constructed to investigate the law of compressive strength of recycled concrete in marine environment, and it is found that the GM is accurate and feasible for the prediction of RC compressive strength in marine environment.

  3. Mechanical Properties of Recycled Concrete in Marine Environment

    PubMed Central

    Wang, Jianxiu; Huang, Tianrong; Liu, Xiaotian; Wu, Pengcheng; Guo, Zhiying

    2013-01-01

    Experimental work was carried out to develop information about mechanical properties of recycled concrete (RC) in marine environment. By using the seawater and dry-wet circulation to simulate the marine environment, specimens of RC were tested with different replacement percentages of 0%, 30%, and 60% after immersing in seawater for 4, 8, 12, and 16 months, respectively. Based on the analysis of the stress-strain curves (SSCs) and compressive strength, it is revealed that RC' peak value and elastic modulus decreased with the increase of replacement percentage and corroding time in marine environment. And the failure of recycled concrete was speeded up with more obvious cracks and larger angles of 65° to 85° in the surface when compared with normal concrete. Finally, the grey model (GM) with equal time intervals was constructed to investigate the law of compressive strength of recycled concrete in marine environment, and it is found that the GM is accurate and feasible for the prediction of RC compressive strength in marine environment. PMID:23766707

  4. Cross-cultural comparison of concrete recycling decision-making and implementation in construction industry.

    PubMed

    Tam, Vivian W Y; Tam, Leona; Le, Khoa N

    2010-02-01

    Waste management is pressing very hard with alarming signals in construction industry. Concrete waste constituents major proportions of construction and demolition waste of 81% in Australia. To minimize concrete waste generated from construction activities, recycling concrete waste is one of the best methods to conserve the environment. This paper investigates concrete recycling implementation in construction. Japan is a leading country in recycling concrete waste, which has been implementing 98% recycling and using it for structural concrete applications. Hong Kong is developing concrete recycling programs for high-grade applications. Australia is making relatively slow progress in implementing concrete recycling in construction. Therefore, empirical studies in Australia, Hong Kong, and Japan were selected in this paper. A questionnaire survey and structured interviews were conducted. Power spectrum was used for analysis. It was found that "increasing overall business competitiveness and strategic business opportunities" was considered as the major benefit for concrete recycling from Hong Kong and Japanese respondents, while "rising concrete recycling awareness such as selecting suitable resources, techniques and training and compliance with regulations" was considered as the major benefit from Australian respondents. However, "lack of clients' support", "increase in management cost" and "increase in documentation workload, such as working documents, procedures and tools" were the major difficulties encountered from Australian, Hong Kong, and Japanese respondents, respectively. To improve the existing implementation, "inclusion of concrete recycling evaluation in tender appraisal" and "defining clear legal evaluation of concrete recycling" were major recommendations for Australian and Hong Kong, and Japanese respondents, respectively.

  5. Cross-cultural comparison of concrete recycling decision-making and implementation in construction industry

    SciTech Connect

    Tam, Vivian W.Y.; Tam, Leona; Le, Khoa N.

    2010-02-15

    Waste management is pressing very hard with alarming signals in construction industry. Concrete waste constituents major proportions of construction and demolition waste of 81% in Australia. To minimize concrete waste generated from construction activities, recycling concrete waste is one of the best methods to conserve the environment. This paper investigates concrete recycling implementation in construction. Japan is a leading country in recycling concrete waste, which has been implementing 98% recycling and using it for structural concrete applications. Hong Kong is developing concrete recycling programs for high-grade applications. Australia is making relatively slow progress in implementing concrete recycling in construction. Therefore, empirical studies in Australia, Hong Kong, and Japan were selected in this paper. A questionnaire survey and structured interviews were conducted. Power spectrum was used for analysis. It was found that 'increasing overall business competitiveness and strategic business opportunities' was considered as the major benefit for concrete recycling from Hong Kong and Japanese respondents, while 'rising concrete recycling awareness such as selecting suitable resources, techniques and training and compliance with regulations' was considered as the major benefit from Australian respondents. However, 'lack of clients' support', 'increase in management cost' and 'increase in documentation workload, such as working documents, procedures and tools' were the major difficulties encountered from Australian, Hong Kong, and Japanese respondents, respectively. To improve the existing implementation, 'inclusion of concrete recycling evaluation in tender appraisal' and 'defining clear legal evaluation of concrete recycling' were major recommendations for Australian and Hong Kong, and Japanese respondents, respectively.

  6. Recycling concrete: An undiscovered source of ultrafine particles

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Morawska, Lidia

    2014-06-01

    While concrete recycling is practiced worldwide, there are many unanswered questions in relation to ultrafine particle (UFP; Dp < 100 nm) emissions and exposure around recycling sites. In particular: (i) Does recycling produce UFPs and in what quantities? (ii) How do they disperse around the source? (iii) What impact does recycling have on ambient particle number concentrations (PNCs) and exposure? (iv) How effective are commonly used dust respirators to limit exposure? We measured size-resolved particles in the 5-560 nm range at five distances between 0.15 and 15.15 m that were generated by an experimentally simulated concrete recycling source and found that: (i) the size distributions were multimodal, with up to ˜93% of total PNC in the UFP size range; and (ii) dilution was a key particle transformation mechanism. UFPs showed a much slower decay rate, requiring ˜62% more distance to reach 10% of their initial concentration compared with their larger counterparts in the 100-560 nm size range. Compared with typical urban exposure during car journeys, exposure decay profiles showed up to ˜5 times higher respiratory deposition within 10 m of the source. Dust respirators were found to remove half of total PNC; however the removal factor for UFPs was only ˜57% of that observed in the 100-560 nm size range. These findings highlight a need for developing an understanding of the nature of the particles as well as for better control measures to limit UFP exposure.

  7. Use of recycled glass for concrete masonry blocks. Final report

    SciTech Connect

    Meyer, C.; Baxter, S.

    1997-11-01

    A two-year research project was conducted to study the technical and economic feasibility of using mixed-color crushed waste glass for concrete masonry. From a technical standpoint, two problems had to be confronted. First, it was known that the silica in glass is highly reactive in the alkaline environment of portland cement concrete. Second, there was the possibility of strength loss, as crushed glass particles with smooth surfaces were substituted for regular aggregate. Both problems were solved in the course of this research. It was found that waste glass ground to mesh size No. 30 or smaller does not exhibit any expansion due to alkali-silica reaction (ASR). Another significant research finding was that very finely ground glass exhibits pozzolanic properties and therefore is suitable as a partial replacement for portland cement. The economic feasibility of concrete block masonry with glass both as aggregate and cement substitution was evaluated and found to be encouraging.

  8. 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

  9. 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.

  10. 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

  11. Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

    NASA Astrophysics Data System (ADS)

    al-Swaidani, Aref M.; Baddoura, Mohammad K.; Aliyan, Samira D.; Choeb, Walid

    2015-11-01

    The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction). Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289) and accelerated mortar bar test (ASTM C1260) have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida'a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete.

  12. Laboratory-scale sodium-carbonate aggregate concrete interactions. [LMFBR

    SciTech Connect

    Westrich, H.R.; Stockman, H.W.; Suo-Anttila, A.

    1983-09-01

    A series of laboratory-scale experiments was made at 600/sup 0/C to identify the important heat-producing chemical reactions between sodium and carbonate aggregate concretes. Reactions between sodium and carbonate aggregate were found to be responsible for the bulk of heat production in sodium-concrete tests. Exothermic reactions were initiated at 580+-30/sup 0/C for limestone and dolostone aggregates as well as for hydrated limestone concrete, and at 540+-10/sup 0/C for dehydrated limestone concrete, but were ill-defined for dolostone concrete. Major reaction products included CaO, MgO, Na/sub 2/CO/sub 3/, Na/sub 2/O, NaOH, and elemental carbon. Sodium hydroxide, which forms when water is released from cement phases, causes slow erosion of the concrete with little heat production. The time-temperature profiles of these experiments have been modeled with a simplified version of the SLAM computer code, which has allowed derivation of chemical reaction rate coefficients.

  13. Recycling of spent abrasive media in nonstructural concrete

    SciTech Connect

    Webster, M.T.; Loehr, R.C.

    1996-09-01

    Spent abrasive media from bridge repainting operations contain metals which may result in the media being classified as hazardous under the Environmental Protection Agency (EPA) Toxicity Characteristic (TC) criteria. The management of spent abrasive media by recycling it as a component of nonstructural concrete was investigated. Success was measured with respect to the TC criteria for leaching and a compressive strength requirement of 6.9 MPa (1,000 psi). Portland cement, with and without the additives used, successfully immobilized the metals present in the media. However, not all of the mixes prepared set, indicating that there is a limit to the amount of media that can be recycled in a concrete product. Mixes incorporating 100% unseparated spent abrasive sand and dust or slag in place of clean sand successfully met the project criteria. Mixes containing up to 25% addition of separated spent abrasive dust met the project criteria with the inclusion of appropriate mix additives. Based on results from this and earlier studies, the Texas Department of Transportation has begun to recycle spent abrasive media using Portland cement.

  14. Recycling of harbor sediment as lightweight aggregate.

    PubMed

    Wei, Yu-Ling; Yang, Jing-Chiang; Lin, Yong-Yang; Chuang, Shih-Yu; Wang, H Paul

    2008-01-01

    Sediment sampled from Taichung Harbor was mixed with local reservoir sediment at different weight ratios to prepare lightweight aggregate at 1050, 1100, and 1150 degrees C. A pressure of 3000 or 5000 psi was used to shape the powder mixtures into pellets before the heating processes. The results indicate that the leaching levels of trace metals from the lightweight aggregate samples are considerably reduced to levels less than Taiwan Environmental Protection Administration regulatory limits. Increasing final process temperature tends to reduce the bulk density and crushing intensity of lightweight aggregate with a concomitant increase in water sorption capability. Lightweight aggregate with the lowest bulk density, 0.49 g cm(-3) for the 5000 psi sample, was obtained with the heating process to 1150 degrees C. Based on the X-ray absorption near edge structure results, FeSO(4) decomposition with a concomitant release of SO(x) (x = 2,3) is suggested to play an important role for the bloating process in present study.

  15. 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.

  16. Damage assessment for seismic response of recycled concrete filled steel tube columns

    NASA Astrophysics Data System (ADS)

    Huang, Yijie; Xiao, Jianzhuang; Shen, Luming

    2016-09-01

    A model for evaluating structural damage of recycled aggregate concrete filled steel tube (RCFST) columns under seismic effects is proposed in this paper. The proposed model takes the lateral deformation and the effect of repeated cyclic loading into account. Available test results were collected and utilized to calibrate the parameters of the proposed model. A seismic test for six RCFST columns was also performed to validate the proposed damage assessment model. The main test parameters were the recycled coarse aggregate (RCA) replacement percentage and the bond-slip property. The test results indicated that the seismic performance of the RCFST member depends on the RCA contents and their damage index increases as the RCA replacement percentage increases. It is also indicated that the damage degree of RCFST changes with the variation of the RCA replacement percentage. Finally, comparisons between the RCA contents, lateral deformation ratio and damage degree were implemented. It is suggested that an improvement procedure should be implemented in order to compensate for the performance difference between the RCFST and normal concrete filled steel tubes (CFST).

  17. Spall Strength Measurements of Concrete for Varying Aggregate Sizes

    SciTech Connect

    Chhabildas, Lalit C.; Kipp, Marlin E.; Reinhart, William D.; Wilson, Leonard T.

    1999-05-05

    Controlled impact experiments have been performed to determine the spall strength of four different concrete compositions. The four concrete compositions are identified as, `SAC-5, CSPC', ("3/4") large, and ("3/8") small, Aggregate. They differ primarily in aggregate size but with average densities varying by less than five percent. Wave profiles from sixteen experiments, with shock amplitudes of 0.07 to 0.55 GPa, concentrate primarily within the elastic regime. Free-surface particle velocity measurements indicate consistent pullback signals in the release profiles, denoting average span strength of approximately 40 MPa. It is the purpose of this paper to present spall measurements under uniaxial strain loading. Notwithstanding considerable wave structure that is a unique characteristic to the heterogeneous nature of the scaled concrete, the spall amplitudes appear reproducible and consistent over the pressure range reported in this study.

  18. Constituents of aggregates for radiation-shielding concrete

    SciTech Connect

    Not Available

    1981-01-01

    The nomenclature is intended to give accurate descriptions of some common or important naturally occurring and synthetic constituents of aggregates that are not common or important constituents of concrete aggregates in general use. Heavy or high density aggregates that are described include hematite, hematite ores, ilmenite, ilmenite ores, lepidocrocite, geothite, geothite ores, limonite, magnetite, magnetite ores, witherite, barite, and ferrophosphorus. Minerals and synthetic glasses of substantial boron content that are particularly effective in absorbing thermal neutrons without producing highly penetrating gamma rays include paigeite and tourmaline. Boron-Frit glasses are included because of their frequent use. (JMT)

  19. 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.

  20. Use of waste plastic in concrete mixture as aggregate replacement.

    PubMed

    Ismail, Zainab Z; Al-Hashmi, Enas A

    2008-11-01

    Industrial activities in Iraq are associated with significant amounts of non-biodegradable solid waste, waste plastic being among the most prominent. This study involved 86 experiments and 254 tests to determine the efficiency of reusing waste plastic in the production of concrete. Thirty kilograms of waste plastic of fabriform shapes was used as a partial replacement for sand by 0%, 10%, 15%, and 20% with 800 kg of concrete mixtures. All of the concrete mixtures were tested at room temperature. These tests include performing slump, fresh density, dry density, compressive strength, flexural strength, and toughness indices. Seventy cubes were molded for compressive strength and dry density tests, and 54 prisms were cast for flexural strength and toughness indices tests. Curing ages of 3, 7, 14, and 28 days for the concrete mixtures were applied in this work. The results proved the arrest of the propagation of micro cracks by introducing waste plastic of fabriform shapes to concrete mixtures. This study insures that reusing waste plastic as a sand-substitution aggregate in concrete gives a good approach to reduce the cost of materials and solve some of the solid waste problems posed by plastics.

  1. Effects of maximum aggregate size on UPV of brick aggregate concrete.

    PubMed

    Mohammed, Tarek Uddin; Mahmood, Aziz Hasan

    2016-07-01

    Investigation was carried out to study the effects of maximum aggregate size (MAS) (12.5mm, 19.0mm, 25.0mm, 37.5mm, and 50.0mm) on ultrasonic pulse velocity (UPV) of concrete. For investigation, first class bricks were collected and broken to make coarse aggregate. The aggregates were tested for specific gravity, absorption capacity, unit weight, and abrasion resistance. Cylindrical concrete specimens were made with different sand to aggregate volume ratio (s/a) (0.40 and 0.45), W/C ratio (0.45, 0.50, and 0.55), and cement content (375kg/m(3) and 400kg/m(3)). The specimens were tested for compressive strength and Young's modulus. UPV through wet specimen was measured using Portable Ultrasonic Non-destructive Digital Indicating Tester (PUNDIT). Results indicate that the pulse velocity through concrete increases with an increase in MAS. Relationships between UPV and compressive strength; and UPV and Young's modulus of concrete are proposed for different maximum sizes of brick aggregate.

  2. Experimental Study on the Seismic Performance of Recycled Concrete Brick Walls Embedded with Vertical Reinforcement

    PubMed Central

    Cao, Wanlin; Zhang, Yongbo; Dong, Hongying; Zhou, Zhongyi; Qiao, Qiyun

    2014-01-01

    Recycled concrete brick (RCB) is manufactured by recycled aggregate processed from discarded concrete blocks arising from the demolishing of existing buildings. This paper presents research on the seismic performance of RCB masonry walls to assess the applicability of RCB for use in rural low-rise constructions. The seismic performance of a masonry wall is closely related to the vertical load applied to the wall. Thus, the compressive performance of RCB masonry was investigated firstly by constructing and testing eighteen RCB masonry compressive specimens with different mortar strengths. The load-bearing capacity, deformation and failure characteristic were analyzed, as well. Then, a quasi-static test was carried out to study the seismic behavior of RCB walls by eight RCB masonry walls subjected to an axial compressive load and a reversed cyclic lateral load. Based on the test results, equations for predicting the compressive strength of RCB masonry and the lateral ultimate strength of an RCB masonry wall were proposed. Experimental values were found to be in good agreement with the predicted values. Meanwhile, finite element analysis (FEA) and parametric analysis of the RCB walls were carried out using ABAQUS software. The elastic-plastic deformation characteristics and the lateral load-displacement relations were studied. PMID:28788170

  3. Experimental Study on the Seismic Performance of Recycled Concrete Brick Walls Embedded with Vertical Reinforcement.

    PubMed

    Cao, Wanlin; Zhang, Yongbo; Dong, Hongying; Zhou, Zhongyi; Qiao, Qiyun

    2014-08-19

    Recycled concrete brick (RCB) is manufactured by recycled aggregate processed from discarded concrete blocks arising from the demolishing of existing buildings. This paper presents research on the seismic performance of RCB masonry walls to assess the applicability of RCB for use in rural low-rise constructions. The seismic performance of a masonry wall is closely related to the vertical load applied to the wall. Thus, the compressive performance of RCB masonry was investigated firstly by constructing and testing eighteen RCB masonry compressive specimens with different mortar strengths. The load-bearing capacity, deformation and failure characteristic were analyzed, as well. Then, a quasi-static test was carried out to study the seismic behavior of RCB walls by eight RCB masonry walls subjected to an axial compressive load and a reversed cyclic lateral load. Based on the test results, equations for predicting the compressive strength of RCB masonry and the lateral ultimate strength of an RCB masonry wall were proposed. Experimental values were found to be in good agreement with the predicted values. Meanwhile, finite element analysis (FEA) and parametric analysis of the RCB walls were carried out using ABAQUS software. The elastic-plastic deformation characteristics and the lateral load-displacement relations were studied.

  4. 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.

  5. Reliable classification of moving waste materials with LIBS in concrete recycling.

    PubMed

    Xia, Han; Bakker, M C M

    2014-03-01

    Effective discrimination between different waste materials is of paramount importance for inline quality inspection of recycle concrete aggregates from demolished buildings. The moving targeted materials in the concrete waste stream are wood, PVC, gypsum block, glass, brick, steel rebar, aggregate and cement paste. For each material, up to three different types were considered, while thirty particles of each material were selected. Proposed is a reliable classification methodology based on integration of the LIBS spectral emissions in a fixed time window, starting from the deployment of the laser shot. PLS-DA (multi class) and the hybrid combination PCA-Adaboost (binary class) were investigated as efficient classifiers. In addition, mean centre and auto scaling approaches were compared for both classifiers. Using 72 training spectra and 18 test spectra per material, each averaged by ten shots, only PLS-DA achieved full discrimination, and the mean centre approach made it slightly more robust. Continuing with PLS-DA, the relation between data averaging and convergence to 0.3% average error was investigated using 9-fold cross-validations. Single-shot PLS-DA presented the highest challenge and most desirable methodology, which converged with 59 PC. The degree of success in practical testing will depend on the quality of the training set and the implications of the possibly remaining false positives.

  6. User's guide: Cold-mix recycling of asphalt concrete pavements. Final report

    SciTech Connect

    Shoenberger, J.E.

    1992-09-01

    This guide provides the technical information required to implement the application of cold-mix recycling of asphalt concrete pavements. Included are details on areas on application, benefits/advantages, limitations/disadvantages, and costs associated with this technology. Information is provided on two demonstration sites at Fort Gillem, Georgia, and Fort Leavenworth, Kansas. Also provided is information concerning funding, procurement, maintenance, and performance monitoring. A fact sheet on recycling, contract specification example, and references are provided in the appendixes.... Asphalt pavement recycling, Emulsified asphalt cement, Cold milling, In-place cold-mix asphalt recycling, Cold-mix asphalt recycling, Recycling of asphalt.

  7. Alkali-aggregate reaction in concrete containing high-alkali cement and granite aggregate

    SciTech Connect

    Owsiak, Z

    2004-01-01

    The paper discusses results of the research into the influence of high-alkali Portland cement on granite aggregate. The deformation of the concrete structure occurred after 18 months. The research was carried out by means of a scanning electron microscope equipped with a high-energy dispersive X-ray analyzer that allowed observation of unpolished sections of concrete bars exhibiting the cracking pattern typical of the alkali-silica reaction. Both the microscopic observation and the X-ray elemental analysis confirm the presence of alkali-silica gel and secondary ettringite in the cracks.

  8. 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.

  9. Use of plastic waste (poly-ethylene terephthalate) in asphalt concrete mixture as aggregate replacement.

    PubMed

    Hassani, Abolfazl; Ganjidoust, Hossein; Maghanaki, Amir Abedin

    2005-08-01

    One of the environmental issues in most regions of Iran is the large number of bottles made from poly-ethylene terephthalate (PET) deposited in domestic wastes and landfills. Due to the high volume of these bottles, more than 1 million m3 landfill space is needed for disposal every year. The purpose of this experimental study was to investigate the possibility of using PET waste in asphalt concrete mixes as aggregate replacement (Plastiphalt) to reduce the environmental effects of PET disposal. For this purpose the mechanical properties of plastiphalt mixes were compared with control samples. This study focused on the parameters of Marshall stability, flow, Marshall quotient (stability-to-flow ratio) and density. The waste PET used in this study was in the form of granules of about 3 mm diameter which would replace (by volume) a portion of the mineral coarse aggregates of an equal size (2.36-4.75 mm). In all prepared mixes the determined 6.6% optimum bitumen content was used. In this investigation, five different percentages of coarse aggregate replacement were used. The results showed that the aggregate replacement of 20% by volume with PET granules would result in a reduction of 2.8% in bulk compacted mix density. The value of flow in the plastiphalt mix was lower than that of the control samples. The results also showed that when PET was used as partial aggregate replacement, the corresponding Marshall stability and Marshall quotient were almost the same as for the control samples. According to most of specification requirement, these results introduce an asphalt mix that has properties that makes it suitable for practical use and furthermore, the recycling of PET for asphalt concrete roads helps alleviate an environmental problem and saves energy.

  10. Crushed cement concrete substitution for construction aggregates; a materials flow analysis

    USGS Publications Warehouse

    Kelly, Thomas

    1998-01-01

    An analysis of the substitution of crushed cement concrete for natural construction aggregates is performed by using a materials flow diagram that tracks all material flows into and out of the cement concrete portion of the products made with cement concrete: highways, roads, and buildings. Crushed cement concrete is only one of the materials flowing into these products, and the amount of crushed cement concrete substituted influences the amount of other materials in the flow. Factors such as availability and transportation costs, as well as physical properties, that can affect stability and finishability, influence whether crushed cement concrete or construction aggregates should be used or predominate for a particular end use.

  11. Influence of aggregate pre-wetting and fly ash on mechanical properties of lightweight concrete.

    PubMed

    Lo, T Y; Cui, H Z; Li, Z G

    2004-01-01

    This study has examined the mechanical properties of lightweight aggregate concrete with a density of 1800 kg/m3. The effects of the following parameters on the concrete properties have been analyzed: the pre-wetting time of the lightweight aggregate and the percentage of pulverized fly ash used as cementitious replacement material. The strength of the lightweight aggregate was found to be the primary factor controlling the strength of high-strength lightweight concrete. An increase in the cementitious content from 420 to 450 kg/m3 does not significantly increase the strength of lightweight aggregate concrete. The relationship between the flexural and compressive strength at 28 days can be represented by the equation fr=0.69/fck. The elastic modulus was found to be much lower than that of normal weight concrete, ranging from 15.0 to 20.3 GPa. The addition of PFA increases the slump and density of lightweight aggregate concrete.

  12. An Exploratory Compressive Strength Of Concrete Containing Modified Artificial Polyethylene Aggregate (MAPEA)

    NASA Astrophysics Data System (ADS)

    Hadipramana, J.; Mokhatar, S. N.; Samad, A. A. A.; Hakim, N. F. A.

    2016-11-01

    Concrete is widely used in the world as building and construction material. However, the constituent materials used in concrete are high cost when associated with the global economic recession. This exploratory aspires to have an alternative source of replacing natural aggregate with plastic wastes. An investigation of the Modified Artificial Polyethylene Aggregate (MAPEA) as natural aggregate replacement in concrete through an experimental work was conducted in this study. The MAPEA was created to improve the bonding ability of Artificial Polyethylene Aggregate (APEA) with the cement paste. The concrete was mixed with 3%, 6%, 9%, and 12% of APEA and MAPEA for 14 and 28 curing days, respectively. Furthermore, the compressive strength test was conducted to find out the optimum composition of MAPEA in concrete and compared to the APEA concrete. Besides, this study observed the influence and behaviour of MAPEA in concrete. Therefore, the Scanning Electron Microscopy was applied to observe the microstructure of MAPEA and APEA concrete. The results showed the use of high composition of an artificial aggregate resulted inferior strength on the concrete and 3% MAPEA in the concrete mix was highest compressive strength than other content. The modification of APEA (MAPEA) concrete increased its strength due to its surface roughness. However, the interfacial zone cracking was still found and decreased the strength of MAPEA concrete especially when it was age 28 days.

  13. Mechanical and Physical Properties of Hydrophobized Lightweight Aggregate Concrete with Sewage Sludge

    PubMed Central

    Suchorab, Zbigniew; Barnat-Hunek, Danuta; Franus, Małgorzata; Łagód, Grzegorz

    2016-01-01

    This article is focused on lightweight aggregate-concrete modified by municipal sewage sludge and lightweight aggregate-concrete obtained from light aggregates. The article presents laboratory examinations of material physical parameters. Water absorptivity of the examined material was decreased by the admixture of water emulsion of reactive polysiloxanes. Water transport properties were determined using Time Domain Reflectometry, an indirect technique for moisture detection in porous media. Together with basic physical parameters, the heat conductivity coefficient λ was determined for both types of lightweight aggregate-concrete. Analysis of moisture and heat properties of the examined materials confirmed the usefulness of light aggregates supplemented with sewage sludge for prospective production. PMID:28773442

  14. Mechanical and Physical Properties of Hydrophobized Lightweight Aggregate Concrete with Sewage Sludge.

    PubMed

    Suchorab, Zbigniew; Barnat-Hunek, Danuta; Franus, Małgorzata; Łagód, Grzegorz

    2016-04-27

    This article is focused on lightweight aggregate-concrete modified by municipal sewage sludge and lightweight aggregate-concrete obtained from light aggregates. The article presents laboratory examinations of material physical parameters. Water absorptivity of the examined material was decreased by the admixture of water emulsion of reactive polysiloxanes. Water transport properties were determined using Time Domain Reflectometry, an indirect technique for moisture detection in porous media. Together with basic physical parameters, the heat conductivity coefficient λ was determined for both types of lightweight aggregate-concrete. Analysis of moisture and heat properties of the examined materials confirmed the usefulness of light aggregates supplemented with sewage sludge for prospective production.

  15. A study on engineering characteristics of asphalt concrete using filler with recycled waste lime.

    PubMed

    Sung Do, Hwang; Hee Mun, Park; Suk keun, Rhee

    2008-01-01

    This study focuses on determining the engineering characteristics of asphalt concrete using mineral fillers with recycled waste lime, which is a by-product of the production of soda ash (Na(2)CO(3)). The materials tested in this study were made using a 25%, 50%, 75%, and 100% mixing ratio based on the conventional mineral filler ratio to analyze the possibility of using recycled waste lime. The asphalt concretes, made of recycled waste lime, hydrated lime, and conventional asphalt concrete, were evaluated through their fundamental engineering properties such as Marshall stability, indirect tensile strength, resilient modulus, permanent deformation characteristics, moisture susceptibility, and fatigue resistance. The results indicate that the application of recycled waste lime as mineral filler improves the permanent deformation characteristics, stiffness and fatigue endurance of asphalt concrete at the wide range of temperatures. It was also determined that the mixtures with recycled waste lime showed higher resistance against stripping than conventional asphalt concrete. It was concluded from various test results that a waste lime can be used as mineral filler and, especially, can greatly improve the resistance of asphalt concrete to permanent deformation at high temperatures.

  16. Effect of lightweight fly ash aggregate microstructure on the strength of concretes

    SciTech Connect

    Wasserman, R.; Bentur, A.

    1997-04-01

    The structure and properties of sintered fly ash lightweight aggregate was modified by heat and polymer treatments to obtain aggregates different in their strength, absorption and pozzolanic activity. These properties of the aggregates were accounted for by changes in their microstructure. The strength of concretes of equal effective water/cement ratio prepared from these aggregates was determined at different ages to resolve the influence of the aggregate properties. It was shown that the strength of the concrete could not be accounted for by the strength of the aggregates only, and it is suggested that the absorption and pozzolanic activity of the aggregates can have an influence on the strength developed.

  17. Quality control of lightweight aggregate concrete based on initial and final water absorption tests

    NASA Astrophysics Data System (ADS)

    Maghfouri, M.; Shafigh, P.; Ibrahim, Z. Binti; Alimohammadi, V.

    2017-06-01

    Water absorption test is used to evaluate overall performance of concrete in terms of durability. The water absorption of lightweight concrete might be considerably higher than the conventional concrete due to higher rate of pores in concrete and lightweight aggregate. Oil palm shell is a bio-solid waste in palm oil industry, which could be used as lightweight aggregate in the concrete mixture. The present study aims to measure the initial and final water absorption and compressive strength of oil palm shell lightweight concrete in order to evaluation of quality control and durability performance. Total normal coarse aggregates were substituted with coarse oil palm shell in a high strength concrete mixture. The quality of concrete was then evaluated based on the compressive strength and water absorption rates. The results showed that fully substitution of normal coarse aggregates with oil palm shell significantly reduced the compressive strength. However, this concrete with the 28-day compressive strength of 40 MPa still can be used as structural concrete. The initial and final water absorption test results also showed that this concrete is not considered as a good concrete in terms of durability. Therefore, it is recommended that both compressive strength and waster absorption tests must be performed for quality control of oil palm shell concretes.

  18. 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.

  19. Standard descriptive nomenclature of constituents of aggregates for radiation-shielding concrete. ASTM standard

    SciTech Connect

    1992-05-01

    This nomenclature is under the jurisdiction of ASTM Committee C-9 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.41 on Concrete for Radiation Shielding. Current edition approved Mar. 15, 1992 and published May 1992. Originally published as C 638-73. Last previous edition was C 638-84(1990). It was reapproved 1997.

  20. Study on performance of concrete with over-burnt bricks aggregates and micro-silica admixture

    NASA Astrophysics Data System (ADS)

    Praveen, K.; Sathyan, Dhanya; Mini, K. M.

    2016-09-01

    Concrete is made by mixing cement, sand, aggregates and water in required proportion, where aggregates occupy the major volume. Addition of aggregates in concrete improves properties of concrete. With the natural resources depleting rapidly, limiting the use of natural resources and enhancing the use of waste materials is very important for sustainable development. Over-burnt bricks are a waste material which cannot be used in construction directly because of their irregular shape and dark colour. Use of over-burnt bricks helps to preserve natural aggregate source. The present study focuses on the effects of microsilica at various percentages as a partial cement replacement in concrete with over-burnt bricks as coarse aggregates. The mechanical properties of hardened concrete such as splitting tensile strength, flexural strength and compressive strength are studied and analyzed.

  1. The Properties and Characteristics of Concretes Containing Calcium Carbonate (CaCO3) and Synthetic Lightweight Aggregate

    NASA Astrophysics Data System (ADS)

    Ramos, Matthew J.

    The purpose of this study was to investigate the efficacy of precipitated calcium carbonate as a means for enhancing the mechanical and environmental favorability of concretes containing synthetic lightweight aggregates (SLA), which are comprised of recycled mixed plastic and fly ash. Compressive strength tests show that 2% calcium carbonate additions are able to mitigate strength decreases induced by SLA as well as decrease concrete density when compared to NWA concretes. SLA concretes containing 5% calcium carbonate do not show the same trend. Instead, strength decreases and density increases are observed. Furthermore, increases in aluminum trisulphate (AFt) phase mineralization are observed through scanning electron microscopy. Results suggest that calcium carbonate additions increase early hydration and stabilize AFt minerals thaumasite and ettringite throughout hydration. It is proposed that increased AFt phase mineralization causes reductions in concrete density. However, a limit to this relationship was observed as additions of greater than 2% calcium carbonate exceed the potential for increased hydration, causing a threshold effect that resulted in calcium carbonate acting as filler, which increases density. Improved mechanical properties and the ability to stabilize waste plastics, fly ash, and CO2 emissions make the use of 2% calcium carbonate in conjunction with SLA a favorable alternative to ordinary concretes.

  2. Computational investigation of the neutron shielding and activation characteristics of borated concrete with polyethylene aggregate

    NASA Astrophysics Data System (ADS)

    Park, S. J.; Jang, J. G.; Lee, H. K.

    2014-09-01

    This paper presents the result of a computational study to investigate the neutron shielding and activation characteristics of concretes containing boron carbide and polyethylene. Various mixes were considered with changes in the contents of boron carbide and polyethylene aggregate. The Monte Carlo simulation code MCNP-5 was utilized to determine the transmission of neutron through concrete at different energies from 0.1 eV to 1 MeV, and ORIGEN-S code was then used to predict activation characteristics of the concretes. It was shown that the replacement of polyethylene in borated concrete greatly enhanced the shielding efficiency of the concrete, and total activity levels of the concrete were considerably decreased with this replacement. Furthermore, double-layered structures having the first layer of polyethylene aggregate-replaced concrete and the second layer of 2 wt% borated concrete are shown to improve shielding efficiency more significantly than monolithic structures.

  3. Use of recycled glass and fly ash for precast concrete. Final report

    SciTech Connect

    Meyer, C.; Baxter, S.

    1998-10-01

    An 18-month research project was conducted to study the technical and economic feasibility of using crushed waste glass and chemically self-activated fly ash, a byproduct of coal-burning power plants, to produce precast concrete products. The crushed glass is used as substitute for the aggregate, and the fly ash is substituted for Portland cement as binder. Technically, the important problem of alkali-silica reaction (ASR) had to be addressed and was partially solved in a separate research program funded by NYSERDA. In the present project, additional knowledge was obtained about this important phenomenon, especially in cases where the glass is sorted by color, larger aggregate sizes are desirable, and glass constitutes up to 100% of the aggregate. The primary goal of this research was to develop a material with a particularly attractive appearance that would be suitable for architectural and decorative applications. The use of this material, tentatively called `glascrete`, has been shown to be technically and economically feasible to the point that it is ready for commercial exploitation, provided regular portland cement is used as the binder. Extensive efforts have been made, in conjunction with a project supported by the New York State Department of Economic Development, to spur private parties to product glascrete products commercially. The use of chemically self-activated fly ash as cement replacement is technically feasible by not yet commercially viable. Efforts to search for less costly chemical activators are continuing. If these efforts are successful, the end result could be a material that consists almost entirely of recycled components namely crush waste glass and fly ash.

  4. An Investigation of Techniques for Achieving Exposed Aggregate Surfaces for Site-Cast Concrete

    DTIC Science & Technology

    1975-06-01

    obtaining concrete structures free of placement defects is the use of cast- in-place exposed aggregate . Objective. The objective of this investigation...7 AD-A012 110 AN INVESTIGATION OF TECHNIQUES FOR ACHIEVING EXPOSED AGGREGATE SURFACES FOR SITE-CAST CONCRETE Daniel J. Naus, et...research laboratory TECHNICAL REPORT M-61 (RevlMd) June 1975 w AN INVESTIGATION OF TECHNIQUES FOR ACHIEVING EXPOSED AGGREGATE SURFACES FOR SITE

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

    SciTech Connect

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

    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. 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.

  6. 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.

  7. Assessing hydration disturbances from concrete aggregates with radiation shielding properties by isothermal calorimetry

    NASA Astrophysics Data System (ADS)

    Wadsö, Lars; Cooper-Jensen, Carsten P.; Bentley, Phillip M.

    2017-04-01

    Spallation sources create a large amount of neutrons with energies up to the GeV range. To shield for these neutrons, steel and concrete are important materials. By adding different aggregates to normal concrete, one can improve the shielding effect of the concrete. Some of these aggregates can influence the rate of hydration (reaction) of the cement or even completely inhibit the hydration. It is thus good practice to start the investigation of new shielding concretes by assessing the rate of cement hydration in the presence of new aggregates. This is preferably made with isothermal (heat conduction) calorimetry. In this paper we describe such tests made with a large number of different potential aggregates for a shielding concrete. We found a full range of influence on the hydration, from no influence to severely disturbed. In some cases smaller particles gave more disturbance.

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

    SciTech Connect

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

    1999-11-01

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

  9. Hot in-place recycling of asphalt concrete. Final report

    SciTech Connect

    Button, J.W.; Little, D.N.; Estakhri, C.K.; Mason, L.S.

    1994-01-01

    ;Contents: Hot in place recycling processes and equipment; HIPR as a tool for asphalt pavement rehabilitation; Mixture design for HIPR processes; Relative performance of HIPR pavements; Guidelines for effective use of HIPR; and Conclusions and recommendations.

  10. The effect of fly ash on the mechanical properties of cinder lightweight aggregate concrete

    NASA Astrophysics Data System (ADS)

    Xiao, Liguang; Jiang, Dawei

    2017-04-01

    The volcanic cinder is a kind of porous rock with good performance and is formed by the cooling of the volcanic eruption. This paper studies the effect of fly ash on the mechanical properties of cinder lightweight aggregate concrete. Results show the mechanical properties of cinder lightweight aggregate concrete is significantly improved with fly ash, and it has a maximum strength value when the dosage is 35%; the early strength of lightweight aggregate concrete is greatly improved, when we extend the grinding time of fly ash, decrease the particle size and increase the activity.

  11. Aggregates: Waste and recycled materials; new rapid evaluation technology. Soils, geology, and foundations; materials and construction. Transportation research record

    SciTech Connect

    Not Available

    1994-01-01

    ;Contents: Engineering Properties of Shredded Tires in Lightweight Fill Applications; Using Recovered Glass as Construction Aggregate Feedstock; Utilization of Phosphogypsum-Based Slag Aggregate in Portland Cement Concrete Mixtures; Waste Foundry Sand in Asphalt Concrete; Toward Automating Size-Gradation Analysis of Mineral Aggregate; Evaluation of Fine Aggregate Angularity Using National Aggregate Association Flow Test; Siliceous Content Determination of Sands Using Automatic Image Analysis; and Methodology for Improvement of Oxide Residue Models for Estimation of Aggregate Performance Using Stoichiometric Analysis.

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

    SciTech Connect

    Wong, Yiik Diew; Sun, Darren Delai . E-mail: ddsun@ntu.edu.sg; 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, 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.

  13. 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.

  14. Influence of Aggregate Coated with Modified Sulfur on the Properties of Cement Concrete

    PubMed Central

    Lee, Swoo-Heon; Hong, Ki-Nam; Park, Jae-Kyu; Ko, Jung

    2014-01-01

    This paper proposes the mixing design of concrete having modified sulfur-coated aggregate (MSCA) to enhance the durability of Portland cement concrete. The mechanical properties and durability of the proposed MSCA concrete were evaluated experimentally. Melting-modified sulfur was mixed with aggregate in order to coat the aggregate surface at a speed of 20 rpm for 120 s. The MSCA with modified sulfur corresponding to 5% of the cement weight did not significantly affect the flexural strength in a prism concrete beam specimen, regardless of the water-cement ratio (W/C). However, a dosage of more than 7.5% decreased the flexural strength. On the other hand, the MSCA considerably improved the resistance to the sulfuric acid and the freezing-thawing, regardless of the sulfur dosage in the MSCA. The coating modified sulfur of 5% dosage consequently led to good results for the mechanical properties and durability of MSCA concrete. PMID:28788703

  15. Investigation of micro-structural phenomena at aggregate level in concretes using DEM

    NASA Astrophysics Data System (ADS)

    Nitka, Michał; Tejchman, Jacek

    2017-06-01

    This paper presents numerical analyses of concrete beams under three-point bending. The discrete element methods (DEM) was used to calculate fracture at the aggregate level. Concrete was described as a four-phase material, which was composed of aggregate, cement matrix, interfacial transitional zones (ITZs) and macro-voids. The beam micro-structure was directly taken from our experiments using x-ray micro-tomography. Simulations were carried out with real aggregate modelled as sphere clusters. Numerical results were compared with laboratory outcomes. The special attention was laid on the fracture propagation and some micro-structural phenomena at the aggregate level.

  16. The use of the chrysotile cement waste as the secondary aggregate for the concrete

    NASA Astrophysics Data System (ADS)

    Semenov, V.; Pligina, A.; Rozovskaya, T.

    2015-01-01

    The article presents the results of research on the effective concrete with secondary chrysotile cement aggregate. One of the important problems of modern science of construction materials is the use of secondary resources for the production of construction materials, and a considerable part of them are the chrysotile cement waste and scrapped chrysotile cement products. The aim of presented research is the development of effective concrete for the production of foundation wall blocks with the use of crushed chrysotile cement products as a secondary aggregate. The main characteristics of the secondary chrysotile cement aggregate have been determined. The concrete with different compositions and with different content of secondary chrysotile cement rubble has been studied. The dependences of the strength and the specific strength of concrete with a constant W/C ratio and constant binder consumption on the consumption of the secondary aggregate have been obtained. It is stated that the introduction of secondary chrysotile cement aggregate does not significantly effect the water resistance and frost resistance of the concrete. It is shown that the variation of the fractions of secondary aggregates and the binder makes it possible to obtain the effective concrete with a wide range of strength values.

  17. Evaluation of Properties of Recycled Asphalt Concrete Hot Mix.

    DTIC Science & Technology

    1984-02-01

    the literature, it is difti ult to compare test results among the various laboratories. Whitcomb evaluated a simplified method of mix design for...proposed ASTM test method under jurisdiction of ASTM Subcom- mittee D04.20). A nomograph was used to select the type of recycling agent needed to...in viscosity with aging. The thin-film oven test and rolling thin-film oven test have been used in durability tests . These two test methods are used

  18. Acoustic absorption modeling of porous concrete considering the gradation and shape of aggregates and void ratio

    NASA Astrophysics Data System (ADS)

    Kim, H. K.; Lee, H. K.

    2010-03-01

    The results of acoustic absorption modeling of porous concrete considering the gradation and shape of aggregates and void ratio are presented. To model the void texture of porous concrete, the multi-layered micro-perforated rigid panel model considering air gaps [1,2] is adopted. The parameters used in this acoustic absorption modeling are determined by a geometrical and experimental approach considering the gradation and shape of aggregates and void ratio. The predicted acoustic absorption spectra are compared with experimental results to verify the proposed acoustic absorption modeling approach. Finally, a parametric study is conducted to investigate the influence of design factors on the acoustic absorption properties of porous concrete.

  19. Effect of coarse aggregate type on mechanical properties of concretes with different strengths

    SciTech Connect

    Oezturan, T.; Cecen, C.

    1997-02-01

    Tests were carried out to study the effect of the type of coarse aggregate on the compressive, flexural and splitting tensile strength on concrete produced at different strength levels. Concretes with 28 day target compressive strengths of 30, 60 and 90 MPa were produced using basalt, limestone and gravel coarse aggregates. The gravel aggregate concrete with 90 MPa target strength was also replicated by using a cement of higher strength, keeping the other parameters same. Twenty eight day test results have indicated that, in high strength concrete, basalt produced the highest, whereas gravel gave the lowest compressive strengths. Normal strength concretes made with basalt and gravel gave similar compressive strengths while the concrete containing limestone attained somewhat higher strength. Higher tensile strengths were obtained with crushed basalt and limestone compared to the gravel aggregate when used in high strength concrete. In the replicate mixture, approximately 30 percent increase in flexural and splitting tensile strengths were obtained as a result of using a stronger cement, while the compressive strength was not affected at all.

  20. Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

    NASA Astrophysics Data System (ADS)

    Khatib, Jamal; Jefimiuk, Adrian; Khatib, Sammy

    2015-12-01

    The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand) replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume) expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

  1. Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

    NASA Astrophysics Data System (ADS)

    Khatib, Jamal; Jefimiuk, Adrian; Khatib, Sammy

    2015-12-01

    The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand) replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume) expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

  2. Thermochemical degradation of limestone aggregate concrete on exposure to sodium fire

    NASA Astrophysics Data System (ADS)

    Premila, M.; Sivasubramanian, K.; Amarendra, G.; Sundar, C. S.

    2008-04-01

    Limestone aggregate concrete blocks were subjected to sodium fire conforming to a realistic scenario in order to qualify them as protective sacrificial layers over structural concrete flooring in liquid metal-cooled fast breeder reactors. Mid infrared absorption measurements were carried out on these sodium fire-exposed samples as a function of depth from the affected surface. Definite signatures of thermochemical degradation indicating dehydration and structural modification of the limestone concrete have been obtained. Control runs were carried out to delineate the thermal effects of sodium fires from that of the chemical interaction effects. Measurements on limestone aggregate samples treated with fused NaOH provided direct evidence of the exact mechanism of the sodium attack on concrete. The observed degradation effects were correlated to the mechanical strength of the concrete blocks and to the intensity of the sodium fire experienced.

  3. Fatal and nonfatal risk associated with recycle of D&D-generated concrete

    SciTech Connect

    Boren, J.K.; Ayers, K.W.; Parker, F.L.

    1997-02-01

    As decontamination and decommissioning activities proceed within the U.S. Department of Energy Complex, vast volumes of uncontaminated and contaminated concrete will be generated. The current practice of decontaminating and landfilling the concrete is an expensive and potentially wasteful practice. Research is being conducted at Vanderbilt University to assess the economic, social, legal, and political ramifications of alternate methods of dealing with waste concrete. An important aspect of this research work is the assessment of risk associated with the various alternatives. A deterministic risk assessment model has been developed which quantifies radiological as well as non-radiological risks associated with concrete disposal and recycle activities. The risk model accounts for fatal as well as non-fatal risks to both workers and the public. Preliminary results indicate that recycling of concrete presents potentially lower risks than the current practice. Radiological considerations are shown to be of minor importance in comparison to other sources of risk, with conventional transportation fatalities and injuries dominating. Onsite activities can also be a major contributor to non-fatal risk.

  4. Recycling of tailings from Korea Molybdenum Corporation as admixture for high-fluidity concrete.

    PubMed

    Jung, Moon Young; Choi, Yun Wang; Jeong, Jae Gwon

    2011-01-01

    The main objective of this study is to develop an eco-friendly and a large recycling technique of flotation Tailings from korea (TK) from metal mines as construction materials such as admixtures for high-fluidity concrete (HFC). TK used in this study was obtained from the Korea Molybdenum Corporation in operation. TK was used as the alternative material to adjust flowability and viscosity of HFC in the form of powder agent which enables adjustment of concrete compressive strength. In this study, we have performed concrete rheological tests and concrete flowability tests to obtain the quality characteristics of TK for using as the admixture in producing HFC. The results indicated that the adequate mix ratio of cement to TK should be 8:2 (vol%). It is more effective to use the TK as admixture to control flowability, viscosity and strength of HFC than the normal concrete. It was found that TK could be recycled construction materials in bulk such as admixture for HFC, in terms of the economic and eco-friendly aspects.

  5. Recycled and virgin plastics in fiber reinforced concrete. Final report, October 1994--August 1997

    SciTech Connect

    Tawfiq, K.S.

    1998-08-30

    The primary objectives of this study is to conduct a laboratory investigation to evaluate the intrinsic stress that can cause cracking of concrete mixed recommended by the Florida Department of Transportation with the addition of monofilament and fibrillated polypropylene and monofilament polyolefin fibers, subjected to highly cyclic loading. In addition, the flexural behavior of concrete reinforced with recycled post-consumer in-house made fibers will be study and Finite Element Methods (FEM) following laboratory work would be used to establish comparable numerical models for the flexural test and pavement overlays.

  6. Eco-friendly porous concrete using bottom ash aggregate for marine ranch application.

    PubMed

    Lee, Byung Jae; Prabhu, G Ganesh; Lee, Bong Chun; Kim, Yun Yong

    2016-03-01

    This article presents the test results of an investigation carried out on the reuse of coal bottom ash aggregate as a substitute material for coarse aggregate in porous concrete production for marine ranch applications. The experimental parameters were the rate of bottom ash aggregate substitution (30%, 50% and 100%) and the target void ratio (15%, 20% and 25%). The cement-coated granular fertiliser was substituted into a bottom ash aggregate concrete mixture to improve marine ranch applications. The results of leaching tests revealed that the bottom ash aggregate has only a negligible amount of the ten deleterious substances specified in the Ministry of Environment - Enforcement Regulation of the Waste Management Act of Republic Korea. The large amount of bubbles/air gaps in the bottom ash aggregate increased the voids of the concrete mixtures in all target void ratios, and decreased the compressive strength of the porous concrete mixture; however, the mixture substituted with 30% and 10% of bottom ash aggregate and granular fertiliser, respectively, showed an equal strength to the control mixture. The sea water resistibility of the bottom ash aggregate substituted mixture was relatively equal to that of the control mixture, and also showed a great deal of improvement in the degree of marine organism adhesion compared with the control mixture. No fatality of fish was observed in the fish toxicity test, which suggested that bottom ash aggregate was a harmless material and that the combination of bottom ash aggregate and granular fertiliser with substitution rates of 30% and 10%, respectively, can be effectively used in porous concrete production for marine ranch application.

  7. The influence of recycled expanded polystyrene (EPS) on concrete properties: Influence on flexural strength, water absorption and shrinkage

    NASA Astrophysics Data System (ADS)

    Elsalah, Jamaleddin; Al-Sahli, Yosra; Akish, Ahmed; Saad, Omar; Hakemi, Abdurrahman

    2013-12-01

    Expanded polystyrene waste in a granular form was used as a lightweight aggregate in order to produce lightweight concretë Lightweight EPS concrete composites were produced by replacing the coarse aggregate, either partially or fully with equal volume of EPS aggregates. The coarse aggregate replacements levels used were 25, 50, 75, and 100%, which corresponded to (9.20, 18.40, 27.60, and 36.8%) from total volume. The investigation is directed towards the development and performance evaluation of the concrete composites containing EPS aggregates, without addition of either bonding additives, or super-plasticizers on some concrete properties such as flexure strength, water absorption and change in length (or shrinkage). Experimental results showed that a density reduction of 12% caused flexure strength to decrease by 25.3% at a replacement level of 25% EPS. However, the reduction percentage strongly depends upon the replacement level of EPS granules. Moreover, the lower strength concretes showed a higher water absorption values compared to higher strength concrete, i.e., increasing the volume percentage of EPS increases the water absorption as well as the negative strain (shrinkage). The negative strain was higher at concretes of lower density (containing a high amount of EPS aggregate). The water to cement ratio of EPS aggregate concrete is found to be slightly lower than that of conventional concrete.

  8. Asphalt-aggregate interactions in hot recycling. Final report, April 1985-March 1987

    SciTech Connect

    Kiggundu, B.M.; Newman, J.K.

    1987-07-01

    This report summarizes results of an investigation of asphalt-aggregate interactions in hot recycled systems. Materials used in the research included a severe stripping aggregate and a nonstripping aggregate. Both were evaluated using the Lottman 70% retained tensile-strength criteria. Additional materials included a 40/60 RAP new aggregate system, one virgin asphalt, two RAP recovered binders, one modifier or recycling agent, and two blends. The modifier was selected using a recently developed specification involving physical, composition, and solubility properties. Aggregates were evaluated for surface area, bulk composition, water-soluble ions, cation exchange capacity, gradation, and specific gravities. Binders were tested for physical properties and composition properties using a modified Clay-Gel procedure, and compatibility properties using a modified Heithaus procedure.

  9. Study on the mechanical and environmental properties of concrete containing cathode ray tube glass aggregate.

    PubMed

    Romero, Diego; James, Jacqueline; Mora, Rodrigo; Hays, Carol D

    2013-07-01

    Cathode ray tube (CRT) glass is considered a hazardous material due to its lead toxicity. In addition, current disposal practices are being phased out due to their adverse environmental impacts. In this project, CRT glass was used as a fine aggregate replacement in concrete. Life-cycle material characterization was conducted by evaluating the durability and strength of the CRT-Concrete. Leaching tests were also conducted to investigate whether the material meets drinking water limits for Pb. Test results show that the plastic state of the CRT-Concrete was affected by the angularity of the glass particles. Moreover, the compressive strength of CRT-Concrete met and exceeded that of the control specimen. However, CRT-Concrete was susceptible to expansive alkali-silica reactions when more than 10% CRT replacement was used. Environmental leaching results show that lead concentrations from CRT-Concrete are below the drinking water limits depending on the CRT volume replacement and if biopolymers are used.

  10. Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars.

    PubMed

    Abdul-Majid, S; Othman, F

    1994-03-01

    Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples.

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

    PubMed

    Kockal, Niyazi Ugur; Ozturan, Turan

    2010-07-15

    Influence of different lightweight fly ash aggregates on the behavior of concrete mixtures was discussed. The performance characteristics of lightweight concretes (LWCs) and normalweight concrete (NWC) were investigated through compressive strength, modulus of elasticity and splitting tensile strength representing the mechanical behavior; through rapid chloride permeability representing the transport properties and through rapid freezing and thawing cycling representing the durability of concrete. In order to investigate the aggregate-cement paste interfacial transition zone (ITZ), SEM observations were performed. Regression and graphical analysis of the experimental data obtained were also performed. An increase in compressive strength was observed with the increase in oven-dry density. The ratios of splitting tensile strength to compressive strength of lightweight aggregate concretes were found to be similar to that of normalweight concrete. All the 28- and 56-day concrete specimens had a durability factor greater than 85 and 90, respectively, which met the requirement for freezing and thawing durability. 2010 Elsevier B.V. All rights reserved.

  12. The Feasibility of Palm Kernel Shell as a Replacement for Coarse Aggregate in Lightweight Concrete

    NASA Astrophysics Data System (ADS)

    Itam, Zarina; Beddu, Salmia; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Issa Ayash, Usama

    2016-03-01

    Implementing sustainable materials into the construction industry is fast becoming a trend nowadays. Palm Kernel Shell is a by-product of Malaysia’s palm oil industry, generating waste as much as 4 million tons per annum. As a means of producing a sustainable, environmental-friendly, and affordable alternative in the lightweight concrete industry, the exploration of the potential of Palm Kernel Shell to be used as an aggregate replacement was conducted which may give a positive impact to the Malaysian construction industry as well as worldwide concrete usage. This research investigates the feasibility of PKS as an aggregate replacement in lightweight concrete in terms of compressive strength, slump test, water absorption, and density. Results indicate that by using PKS for aggregate replacement, it increases the water absorption but decreases the concrete workability and strength. Results however, fall into the range acceptable for lightweight aggregates, hence it can be concluded that there is potential to use PKS as aggregate replacement for lightweight concrete.

  13. 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.

  14. Effect of Different Coarse Aggregate Sizes on the Strength Characteristics of Laterized Concrete

    NASA Astrophysics Data System (ADS)

    Salau, M. A.; Busari, A. O.

    2015-11-01

    The high cost of conventional concrete materials is a major factor affecting housing delivery in developing countries such as Nigeria. Since Nigeria is blessed with abundant locally available materials like laterite, researchers have conducted comprehensive studies on the use of laterite to replace river sand partially or fully in the concrete. However, the works did not consider the optimum use of coarse aggregate to possibly improve the strength of the laterized concrete, since it is normally lower than that of normal concrete. The results of the tests showed that workability, density and compressive strength at constant water-cement ratio increase with the increase in the coarse aggregate particle size and also with curing age. As the percentage of laterite increases, there was a reduction in all these characteristics even with the particle size of coarse aggregate reduction due to loss from the aggregate-paste interface zone. Also, when sand was replaced by 25% of laterite, the 19.5mm and 12.5mm coarse aggregate particle sizes gave satisfactory results in terms of workability and compressive strength respectively at 28 days of curing age, compared to normal concrete. However, in case of 50% up to 100% laterite contents, the workability and compressive strength values were very low.

  15. 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.

  16. TOPICAL REVIEW: Smart aggregates: multi-functional sensors for concrete structures—a tutorial and a review

    NASA Astrophysics Data System (ADS)

    Song, Gangbing; Gu, Haichang; Mo, Yi-Lung

    2008-06-01

    This paper summarizes the authors' recent pioneering research work in piezoceramic-based smart aggregates and their innovative applications in concrete civil structures. The basic operating principle of smart aggregates is first introduced. The proposed smart aggregate is formed by embedding a waterproof piezoelectric patch with lead wires into a small concrete block. The proposed smart aggregates are multi-functional and can perform three major tasks: early-age concrete strength monitoring, impact detection and structural health monitoring. The proposed smart aggregates are embedded into the desired location before the casting of the concrete structure. The concrete strength development is monitored by observing the high frequency harmonic wave response of the smart aggregate. Impact on the concrete structure is detected by observing the open-circuit voltage of the piezoceramic patch in the smart aggregate. For structural health monitoring purposes, a smart aggregate-based active sensing system is designed for the concrete structure. Wavelet packet analysis is used as a signal-processing tool to analyze the sensor signal. A damage index based on the wavelet packet analysis is used to determine the structural health status. To better describe the time-history and location information of damage, two types of damage index matrices are proposed: a sensor-history damage index matrix and an actuator-sensor damage index matrix. To demonstrate the multi-functionality of the proposed smart aggregates, different types of concrete structures have been used as test objects, including concrete bridge bent-caps, concrete cylinders and a concrete frame. Experimental results have verified the effectiveness and the multi-functionality of the proposed smart aggregates. The multi-functional smart aggregates have the potential to be applied to the comprehensive monitoring of concrete structures from their earliest stages and throughout their lifetime.

  17. The shakeout scenario: Meeting the needs for construction aggregates, asphalt, and concrete

    USGS Publications Warehouse

    Langer, W.H.

    2011-01-01

    An Mw 7.8 earthquake as described in the ShakeOut Scenario would cause significantdamage to buildings and infrastructure. Over 6 million tons of newly mined aggregate would be used for emergency repairs and for reconstruction in the five years following the event. This aggregate would be applied mostly in the form of concrete for buildings and bridges, asphalt or concrete for pavement, and unbound gravel for applications such as base course that goes under highway pavement and backfilling for foundations and pipelines. There are over 450 aggregate, concrete, and asphalt plants in the affected area, some of which would be heavily damaged. Meeting the increased demand for construction materials would require readily available permitted reserves, functioning production facilities, a supply of cement and asphalt, a source of water, gas, and electricity, and a trained workforce. Prudent advance preparations would facilitate a timely emergency response and reconstruction following such an earthquake. ?? 2011, Earthquake Engineering Research Institute.

  18. Experience-based training of students on concretes reinforced by recycled carbon fibers

    NASA Astrophysics Data System (ADS)

    Cosgun, Cumhur; Patlolla, Vamsidhar R.; Alzahrani, Naif; Zeineddine, Hatim F.; Asmatulu, Eylem

    2017-04-01

    Fiber reinforcement increases many properties of the concretes, such as toughness, strength, abrasion, and resistance to corrosion. Use of recycled carbon fibers from industrial waste offers many advantages because it will reduce the waste, contribute the economy, protect natural resources and improve the property of structural units. The City of Wichita, KS is known to be "Air Capital of the World" where many aircraft companies have been producing aircraft, parts and components. Due to the superior properties of composites (e.g., light weight, low density, high impact resistance), they have been highly used by aircraft industry. Prepreg is the most preferred combination of the fiber and resin due to the easy application, but it has a limited shelf life (e.g., three months to one year at most) and scrap has no use after all in the same industry. Every year tons of un-used prepreg or after use scrap are being collected in Wichita, KS. Recycling prepreg from the post-consumer waste offers great advantages of waste reduction and resource conservation in the city. Reusing the carbon fibers obtained from outdated prepreg composites for concrete reinforcement will offer double advantages for our environment and concrete structures. In this study, recycled carbon fibers of the outdated prepreg composites were collected, and then incorporated with concretes at different ratios prior to the molding and mechanical testing. An undergraduate student was involved in the project and observed all the process during the laboratory studies, as well as data collection, analysis and presentation. We believe that experience based learning will enhance the students' skills and interest into the scientific and engineering studies.

  19. 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

  20. Structural use of polymer concrete made with resins based on recycled PET

    SciTech Connect

    Rebeiz, K.S.; Fowler, D.W.

    1995-08-01

    Recycled poly(ethylene terephthalate), PET, plastic waste can be used to produce unsaturated polyester resins. The PET waste is typically found in used beverage bottles that are collected after use in many localities. This research investigated the use of suitable unsaturated polyester resins based on recycled PET for the production of polymer concrete (PC) materials. The properties and structural behavior of unreinforced and steel-reinforced PC materials using resins based on recycled PET were found to be comparable to those obtained with PC materials using virgin resins. Resins based on recycled PET can also relatively easily be altered to achieve a wide variety of properties and performances in the PC. An experimental design also showed that the effect of the level of PET in the resin did not adversely affect the neat resin and the PC mechanical properties. Resins based on recycled PET help in decreasing the cost of PC products, saving energy, and alleviating an environmental problem posed by plastics waste.

  1. 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.

  2. 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

  3. Utilization of recycled glass as aggregate in controlled low-strength material (CLSM)

    SciTech Connect

    Ohlheiser, T.R.

    1998-10-01

    Incoming glass from curbside recycling programs is successfully being utilized as aggregate replacements. The colored glass that can not be used by local bottle manufacturers is crushed to a {1/2} in. (12.5 mm) material and used in various construction projects. The most successful use of processed glass aggregate (PGA) to date, has been in replacing up to 100% of the aggregate in controlled low-strength material (CLSM). It has proven to be successful and has gained acceptance by contractors in the Boulder, Colorado area.

  4. An investigation on the use of shredded waste PET bottles as aggregate in lightweight concrete

    SciTech Connect

    Akcaoezoglu, Semiha; Atis, Cengiz Duran; Akcaoezoglu, Kubilay

    2010-02-15

    In this work, the utilization of shredded waste Poly-ethylene Terephthalate (PET) bottle granules as a lightweight aggregate in mortar was investigated. Investigation was carried out on two groups of mortar samples, one made with only PET aggregates and, second made with PET and sand aggregates together. Additionally, blast-furnace slag was also used as the replacement of cement on mass basis at the replacement ratio of 50% to reduce the amount of cement used and provide savings. The water-binder (w/b) ratio and PET-binder (PET/b) ratio used in the mixtures were 0.45 and 0.50, respectively. The size of shredded PET granules used in the preparation of mortar mixtures were between 0 and 4 mm. The results of the laboratory study and testing carried out showed that mortar containing only PET aggregate, mortar containing PET and sand aggregate, and mortars modified with slag as cement replacement can be drop into structural lightweight concrete category in terms of unit weight and strength properties. Therefore, it was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete. The use of shredded waste PET granules due to its low unit weight reduces the unit weight of concrete which results in a reduction in the death weight of a structural concrete member of a building. Reduction in the death weight of a building will help to reduce the seismic risk of the building since the earthquake forces linearly dependant on the dead-weight. Furthermore, it was also concluded that the use of industrial wastes such as PET granules and blast-furnace slag in concrete provides some advantages, i.e., reduction in the use of natural resources, disposal of wastes, prevention of environmental pollution, and energy saving.

  5. An investigation on the use of shredded waste PET bottles as aggregate in lightweight concrete.

    PubMed

    Akçaözoğlu, Semiha; Atiş, Cengiz Duran; Akçaözoğlu, Kubilay

    2010-02-01

    In this work, the utilization of shredded waste Poly-ethylene Terephthalate (PET) bottle granules as a lightweight aggregate in mortar was investigated. Investigation was carried out on two groups of mortar samples, one made with only PET aggregates and, second made with PET and sand aggregates together. Additionally, blast-furnace slag was also used as the replacement of cement on mass basis at the replacement ratio of 50% to reduce the amount of cement used and provide savings. The water-binder (w/b) ratio and PET-binder (PET/b) ratio used in the mixtures were 0.45 and 0.50, respectively. The size of shredded PET granules used in the preparation of mortar mixtures were between 0 and 4 mm. The results of the laboratory study and testing carried out showed that mortar containing only PET aggregate, mortar containing PET and sand aggregate, and mortars modified with slag as cement replacement can be drop into structural lightweight concrete category in terms of unit weight and strength properties. Therefore, it was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete. The use of shredded waste PET granules due to its low unit weight reduces the unit weight of concrete which results in a reduction in the death weight of a structural concrete member of a building. Reduction in the death weight of a building will help to reduce the seismic risk of the building since the earthquake forces linearly dependent on the dead-weight. Furthermore, it was also concluded that the use of industrial wastes such as PET granules and blast-furnace slag in concrete provides some advantages, i.e., reduction in the use of natural resources, disposal of wastes, prevention of environmental pollution, and energy saving.

  6. Thermal properties of light-weight concrete with waste polypropylene aggregate

    NASA Astrophysics Data System (ADS)

    Záleská, Martina; Pokorný, Jaroslav; Pavlíková, Milena; Pavlík, Zbyšek

    2017-07-01

    Thermal properties of a sustainable light-weight concrete incorporating high volume of waste polypropylene as partial substitution of natural aggregate were studied in the paper. Glass fiber reinforced polypropylene (GFPP), a by-product of PP tubes production, partially substituted fine natural silica aggregate in 10, 20, 30, 40, and 50 mass%. In order to quantify the effect of GFPP use on concrete properties, a reference concrete mix without plastic waste was studied as well. For the applied GFPP, bulk density, matrix density, and particle size distribution were measured. Specific attention was paid to thermal transport and storage properties of GFPP that were examined in dependence on compaction time. For the developed light-weight concrete, thermal properties were accessed using transient impulse technique, whereas the measurement was done in dependence on moisture content, from the dry state to fully water saturated state. Additionally, the investigated thermal properties were plotted as function of porosity. The tested light-weight concrete was found to be prospective construction material possessing improved thermal insulation function. Moreover, the reuse of waste plastics in concrete composition was beneficial both from the environmental and financial point of view considering plastics low biodegradability and safe disposal.

  7. Microscopic analysis of alkali-aggregate reaction products in a 50-year-old concrete

    SciTech Connect

    Fernandes, Isabel . E-mail: ifernand@fc.up.pt; Noronha, Fernando . E-mail: fmnoronh@fc.up.pt; Teles, Madalena . E-mail: mteles@fe.up.pt

    2004-11-15

    Fifty-year-old concrete from a large dam was examined in the scope of an investigation program concerning the properties of granite as aggregate material for concrete. Site inspection, which was developed in order to detect possible signs of deterioration of the concrete, revealed the existence of efflorescence and exudations. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analyses were attempted to identify the composition of these materials and their morphology. From the analyses, it was concluded that some of the exudations were composed by alkali-silica gel. In these samples, an interesting behavior was observed in different moments after a 3-month interval. It was noticed that the initially noncrystalline alkali-silica gel transformed into sodium-rich needles and tablets after a few months kept in a desiccator in the laboratory. Therefore, it was concluded that the materials identified corresponded to different stages of evolution of an alkali-aggregate reaction product.

  8. Specimen and aggregate size effect on the fracture behavior of concrete

    NASA Astrophysics Data System (ADS)

    Islam, Md. Shahidul

    2000-12-01

    Fracture in concrete has been a subject of extensive research for the past thirty years. Although much has been accomplished, concrete still remains the least known of the engineering materials with respect to its fracture behavior. The objective of this research was to study the influence of micro-structural parameters, such as aggregate size, and macroscopic parameters, such as specimen size, on the fracture toughness of concrete. In addition, the effect of notch-depth ratio on the fracture behavior of concrete was studied. Over 300 concrete specimens of various sizes were prepared with various maximum aggregate sizes. There is a well pronounced trend observed in all groups of specimens tested. Critical energy release rate of concrete in the presence of compressive force increases with crack length, i.e., exhibits a typical R-curve behavior. For fixed specimen size, toughness (energy release rate or fracture energy) increases with an increase in maximum aggregate size. Fracture surface interaction, i.e., interlocking, bridging, etc. is more pronounced in the specimens with larger maximum size aggregates. For specimens with fixed maximum aggregate size, toughness increases with an increase in specimen size. For geometrically similar specimens, i.e., the shape and all dimensionless parameters are the same, the toughness evaluated for larger specimens is noticeably higher than that for smaller specimens. Energy release rates for long-notch specimens were relatively lower than those for short-notch specimens. Fracture energy for short-notch specimen is higher than that for long notch specimen. Concrete surfaces exhibit fractal characteristics over the range of scales studied. Fractal dimension increases with an increase in maximum aggregate size and specimen size as well. The fractal dimension correlates very well with surface roughness. The rougher the surface, the higher the fractal dimension. A good correlation also exits between the fractal dimension and fracture

  9. Comparative performance of various smart aggregates during strength gain and damage states of concrete

    NASA Astrophysics Data System (ADS)

    Jothi Saravanan, T.; Balamonica, K.; Bharathi Priya, C.; Likhith Reddy, A.; Gopalakrishnan, N.

    2015-08-01

    Information regarding the early strength gain of fresh concrete determines the time for the removal of form work and the transfer of pre-stressing forces for pre-stressed concrete. An ultrasonic based non-destructive evaluation of early strength gain may not work for concrete in fluid and semi-solid phases. A possible alternative is a lead zirconate titanate (PZT)-based smart aggregate embedded in concrete, which can evaluate the micro-structural and rheological properties right from the fluid phase. A set of five smart aggregates embedded in a concrete cube were investigated for their suitability to evaluate electromechanical impedance (EMI) signatures. Cubes were loaded to failure and the EMI during progressive strength loss under compressive loads was studied. To show the generalized applicability of this, experimental results for the performance of typical smart aggregates on a larger specimen, namely a concrete beam, are also discussed. Different statistical metrics were examined computationally on a three peak admittance curve with a parametric variation of stiffness, damping and simple scaling. The root mean square deviation (RMSD), mean absolute percentage deviation (MAPD), cross correlation (CC) and modified cross correlation (MCC) were investigated, in addition to the rate of change of the RMSD. Variations between the reference and modified states were studied. Both stiffness and mass gains occur for the smart aggregates, resulting in an increase or decrease of frequency and amplitude peaks due to progressive C-S-H gel formation. The trend of increasing stiffness and the consequent rightward shift of the resonant peaks and decrease of damping, with the consequent upward shift of amplitudes that happens during curing and strength gain, was observed to be reversed during the application of damaging loads.

  10. Using a centrifuge for quality control of pre-wetted lightweight aggregate in internally cured concrete

    NASA Astrophysics Data System (ADS)

    Miller, Albert E.

    Early age shrinkage of cementitious systems can result in an increased potential for cracking which can lead to a reduction in service life. Early age shrinkage cracking can be particularly problematic for high strength concretes, which are often specified due to their high strength and low permeability. However, these high strength concretes frequently exhibit a reduction in the internal relative humidity (RH) due to the hydration reaction (chemical shrinkage) and self-desiccation which results in a bulk shrinkage, termed autogenous shrinkage, which is substantial at early ages. Due to the low permeability of these concretes, standard external curing is not always efficient in addressing this reduction in internal RH since the penetration of water can be limited. Internal curing has been developed to reduce autogenous shrinkage. Internally cured mixtures use internal reservoirs filled with fluid (generally water) that release this fluid at appropriate times to counteract the effects of self-desiccation thereby maintaining a high internal RH. Internally cured concrete is frequently produced in North America using pre-wetted lightweight aggregate. One important aspect associated with preparing quality internally cured concrete is being able to determine the absorbed moisture and surface moisture associated with the lightweight aggregate which enables aggregate moisture corrections to be made for the concrete mixture. This thesis represents work performed to develop a test method using a centrifuge to determine the moisture state of pre-wetted fine lightweight aggregate. The results of the test method are then used in a series of worksheets that were developed to assist field technicians when performing the tests and applying the results to a mixture design. Additionally, research was performed on superabsorbent polymers to assess their ability to be used as an internal curing reservoir.

  11. Patterns of gravity induced aggregate migration during casting of fluid concretes

    SciTech Connect

    Spangenberg, J.; Roussel, N.; Hattel, J.H.; Sarmiento, E.V.; Zirgulis, G.; Geiker, M.R.

    2012-12-15

    In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.

  12. The study of pervious concrete mix proportion by the method of specific surface area of aggregate

    NASA Astrophysics Data System (ADS)

    Xiao, Liguang; Jiang, Dawei

    2017-09-01

    The purpose of this paper is to solve the shortcoming of the mix proportion of pervious concrete. So we have done the research on the measurement of the specific surface area of aggregate, and the research on the volume change of cement after hydration, and the research on the best water-binder ratio and thickness of gelled material package. The experimental results show that the equivalent method is more accurate for measuring the specific surface area of aggregate. It can better reflect the specific surface area of aggregate. Moreover, the calculation method of the mix proportion of the cementing material can improve the utilization ratio of material and the quality of pervious concrete.

  13. 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.

  14. Effects of Aggregate Microfines and Potassium Acetate Interactions on Concrete Performance

    NASA Astrophysics Data System (ADS)

    Silva, Jessica Marie Sanfilippo

    The principal objective of this research is to elucidate the role that microfines from coarse and fine aggregates play in the development of the Alkali Silica Reaction (ASR) related distress observed in airport pavements subject to anti-icing agents. As a secondary objective, it was proposed to identify other potential impacts of microfines and deicers on concrete durability. It was determined that combinations of microfines at less than 5% of the total aggregate weight and potassium acetate deicer (KAC Deicer) exposure caused significant deterioration of concrete that may be mistaken for ASR cracking and expansion. However, our analyses suggest it was not ASR, at least as traditionally diagnosed through the presence of ASR gel and reaction rims around aggregates. Expansions in modified ASTM C1293 produced expansions from 0.05% to 0.70% at one year depending on the type of microfine. Expansions of specimens containing microfines but not exposed to KAc Deicer produced negligible expansion. Expansions were larger with base aggregate known to be prone to ASR, but significant expansions (up to 0.50% at one year) also occurred in specimens with unreactive aggregates. Degradation combined with the reduction in entrained air content led to dramatic loss of freeze-thaw durability. These degradations were associated with specific mineralogical profiles of microfines in the presence of KAc Deicer and these profiles consistently were associated with corresponding levels of degradation. The KAc Deicer transformed in the concrete pore solutions to form potassium sulfate and calcium-bearing potassium sulfate compounds. During the transformation of the potassium acetate the level of hydroxide increases dramatically in the pore solution and can lead to reformation of silica species released by the microfines and the aggregates. While these reactions do not appear to be the classical alkali silica reaction, they may exhibit some similarity and create an environment where expansion

  15. 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.

  16. Role of alkalis of aggregate origin in the deterioration of CAC concrete

    SciTech Connect

    Blanco-Varela, M.T.

    2005-09-01

    Both hexagonal and cubic calcium aluminate cement (CAC) hydrates react with atmospheric CO{sub 2}, bringing about mineralogical changes in concrete, which may, on occasion, lead to loss of mechanical strength. Alkaline hydrolysis or carbonation in the presence of alkalis is a highly destructive process. The purpose of the study was to determine what caused CAC concrete deterioration in a prestressed beam that had suffered intense external damage and showed signs of alkaline hydrolysis or a reaction between the aggregate and the cement. Samples of the internal (sound) and external (damaged) parts of the concrete were studied using XRF, XRD, FTIR, OM, SEM/EDX, and BSE techniques, and mechanical strength was measured on microspecimens extracted from both zones. The conclusion drawn from these analyses was that alkaline hydrolysis took place on or near the surface of the concrete. The white deposits observed around the alkali-containing aggregate were found to consist primarily of bayerite whose very loose consistency undermined the aggregate-matrix bond, greatly weakening the material.

  17. Residual Mechanical Properties of Concrete Made with Crushed Clay Bricks and Roof Tiles Aggregate after Exposure to High Temperatures.

    PubMed

    Miličević, Ivana; Štirmer, Nina; Banjad Pečur, Ivana

    2016-04-19

    This paper presents the residual mechanical properties of concrete made with crushed bricks and clay roof tile aggregates after exposure to high temperatures. One referent mixture and eight mixtures with different percentages of replacement of natural aggregate by crushed bricks and roof tiles are experimentally tested. The properties of the concrete were measured before and after exposure to 200, 400, 600 and 800 °C. In order to evaluate the basic residual mechanical properties of concrete with crushed bricks and roof tiles after exposure to high temperatures, ultrasonic pulse velocity is used as a non-destructive test method and the results are compared with those of a destructive method for validation. The mixture with the highest percentage of replacement of natural aggregate by crushed brick and roof tile aggregate has the best physical, mechanical, and thermal properties for application of such concrete in precast concrete elements exposed to high temperatures.

  18. Residual Mechanical Properties of Concrete Made with Crushed Clay Bricks and Roof Tiles Aggregate after Exposure to High Temperatures

    PubMed Central

    Miličević, Ivana; Štirmer, Nina; Banjad Pečur, Ivana

    2016-01-01

    This paper presents the residual mechanical properties of concrete made with crushed bricks and clay roof tile aggregates after exposure to high temperatures. One referent mixture and eight mixtures with different percentages of replacement of natural aggregate by crushed bricks and roof tiles are experimentally tested. The properties of the concrete were measured before and after exposure to 200, 400, 600 and 800 °C. In order to evaluate the basic residual mechanical properties of concrete with crushed bricks and roof tiles after exposure to high temperatures, ultrasonic pulse velocity is used as a non-destructive test method and the results are compared with those of a destructive method for validation. The mixture with the highest percentage of replacement of natural aggregate by crushed brick and roof tile aggregate has the best physical, mechanical, and thermal properties for application of such concrete in precast concrete elements exposed to high temperatures. PMID:28773420

  19. Multiscale imaging and characterization of the effect of mixing temperature on asphalt concrete containing recycled components.

    PubMed

    Cavalli, M C; Griffa, M; Bressi, S; Partl, M N; Tebaldi, G; Poulikakos, L D

    2016-10-01

    When producing asphalt concrete mixture with high amounts of reclaimed asphalt pavement (RAP), the mixing temperature plays a significant role in the resulting spatial distribution of the components as well as on the quality of the resulting mixture, in terms of workability during mixing and compaction as well as in service mechanical properties. Asphalt concrete containing 50% RAP was investigated at mixing temperatures of 140, 160 and 180°C, using a multiscale approach. At the microscale, using energy dispersive X-ray spectroscopy the RAP binder film thickness was visualized and measured. It was shown that at higher mixing temperatures this film thickness was reduced. The reduction in film thickness can be attributed to the loss of volatiles as well as the mixing of RAP binder with virgin binder at higher temperatures. X-ray computer tomography was used to characterize statistically the distribution of the RAP and virgin aggregates geometric features: volume, width and shape anisotropy. In addition using X-ray computer tomography, the packing and spatial distribution of the RAP and virgin aggregates was characterized using the nearest neighbour metric. It was shown that mixing temperature may have a positive effect on the spatial distribution of the aggregates but did not affect the packing. The study shows a tendency for the RAP aggregates to be more likely distributed in clusters at lower mixing temperatures. At higher temperatures, they were more homogeneously distributed. This indicates a higher degree of blending both at microscale (binder film) and macroscale (spatial distribution) between RAP and virgin aggregates as a result of increasing mixing temperatures and the ability to quantify this using various imaging techniques. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  20. Intermediate-scale tests of sodium interactions with calcite and dolomite aggregate concretes. [LMFBR

    SciTech Connect

    Randich, E.; Acton, R.U.

    1983-09-01

    Two intermediate-scale tests were performed to compare the behavior of calcite and dolomite aggregate concretes when attacked by molten sodium. The tests were performed as part of an interlaboratory comparison between Sandia National Laboratories and Hanford Engineering Development Laboratories. Results of the tests at Sandia National Laboratories are reported here. The results show that both concretes exhibit similar exothermic reactions with molten sodium. The large difference in reaction vigor suggested by thermodynamic considerations of CO/sub 2/ release from calcite and dolomite was not realized. Penetration rates of 1.4 to 1.7 mm/min were observed for short periods of time with reaction zone temperatures in excess of 800/sup 0/C during the energetic attack. The penetration was not uniform over the entire sodium-concrete contact area. Rapid attack may be localized due to inhomogeneities in the concrete. The chemical reaction zone is less then one cm thick for the calcite concrete but is about seven cm thick for the dolomite concrete.

  1. Alteration of alkali reactive aggregates autoclaved in different alkali solutions and application to alkali-aggregate reaction in concrete (II) expansion and microstructure of concrete microbar

    SciTech Connect

    Lu Duyou . E-mail: duyoulu@njut.edu.cn; Mei Laibao; Xu Zhongzi; Tang Mingshu; Mo Xiangyin; Fournier, Benoit

    2006-06-15

    The effect of the type of alkalis on the expansion behavior of concrete microbars containing typical aggregate with alkali-silica reactivity and alkali-carbonate reactivity was studied. The results verified that: (1) at the same molar concentration, sodium has the strongest contribution to expansion due to both ASR and ACR, followed by potassium and lithium; (2) sufficient LiOH can completely suppress expansion due to ASR whereas it can induce expansion due to ACR. It is possible to use the duplex effect of LiOH on ASR and ACR to clarify the ACR contribution when ASR and ACR may coexist. It has been shown that a small amount of dolomite in the fine-grained siliceous Spratt limestone, which has always been used as a reference aggregate for high alkali-silica reactivity, might dedolomitize in alkaline environment and contribute to the expansion. That is to say, Spratt limestone may exhibit both alkali-silica and alkali-carbonate reactivity, although alkali-silica reactivity is predominant. Microstructural study suggested that the mechanism in which lithium controls ASR expansion is mainly due to the favorable formation of lithium-containing less-expansive product around aggregate particles and the protection of the reactive aggregate from further attack by alkalis by the lithium-containing product layer.

  2. Humidity and aggregate content correction factors for air-coupled ultrasonic evaluation of concrete.

    PubMed

    Berriman, J; Purnell, P; Hutchins, D A; Neild, A

    2005-02-01

    This paper describes the use of non-contact ultrasound for the evaluation of concrete. Micromachined capacitance transducers are used to transmit ultrasonic longitudinal chirp signals through concrete samples using air as the coupling medium, and a pulse compression technique is then employed for measurement of time of flight through the sample. The effect on the ultrasonic wave speed of storing concrete samples, made with the same water/cement ratio, at different humidity levels is investigated. It is shown that there is a correlation between humidity and speed of sound, allowing a correction factor for humidity to be derived. A strong positive linear correlation between aggregate content and speed of sound was then observed; there was no obvious correlation between compressive strength and speed of sound. The results from the non-contact system are compared with that from a contact system, and conclusions drawn concerning coupling of energy into the samples.

  3. Fracture Properties of Polystyrene Aggregate Concrete after Exposure to High Temperatures

    PubMed Central

    Tang, Waiching; Cui, Hongzhi; Tahmasbi, Soheil

    2016-01-01

    This paper mainly reports an experimental investigation on the residual mechanical and fracture properties of polystyrene aggregate concrete (PAC) after exposure to high temperatures up to 800 degrees Celsius. The fracture properties namely, the critical stress intensity factor (KICS), the critical crack tip opening displacement (CTODC) for the Two-Parameter Model, and the fracture energy (GF) for the Fictitious Crack Model were examined using the three-point bending notched beam test, according to the RILEM recommendations. The effects of polystyrene aggregate (PA) content and temperature levels on the fracture and mechanical properties of concrete were investigated. The results showed that the mechanical properties of PAC significantly decreased with increase in temperature level and the extent of which depended on the PA content in the mixture. However, at a very high temperature of 800 °C, all samples showed 80 percent reduction in modulus of elasticity compared to room temperature, regardless of the level of PA content. Fracture properties of control concrete (C) and PAC were influenced by temperature in a similar manner. Increasing temperature from 25 °C to 500 °C caused almost 50% reduction of the fracture energy for all samples while 30% increase in fracture energy was occurred when the temperature increased from 500 °C to 800 °C. It was found that adding more PA content in the mixture lead to a more ductile behaviour of concrete. PMID:28773752

  4. Petro-chemical features and source areas of volcanic aggregates used in ancient Roman maritime concretes

    NASA Astrophysics Data System (ADS)

    Marra, F.; Anzidei, M.; Benini, A.; D'Ambrosio, E.; Gaeta, M.; Ventura, G.; Cavallo, A.

    2016-12-01

    We present and discuss data from petrographic observation at the optical microscope, electron microprobe analyses on selected glass shards, and trace-element analyses on 14 mortar aggregates collected at the ancient harbors and other maritime structures of Latium and Campania, spanning the third century BCE through the second CE, aimed at identify the volcanic products employed in the concretes and their area of exploitation. According to Latin author Vitruvius assertion about the ubiquitous use of Campanian pozzolan in the ancient Roman sea-water concretes, results of this study show a very selective and homogeneous choice in the material employed to produce the concretes for the different investigated maritime structures, evidencing three main pumice compositions, all corresponding to those of the products of the post-Neapolitan Yellow Tuff activity of the Phlegraean Fields, and a systematic use of the local Neapolitan Yellow Tuff to produce the coarse aggregate of these concretes. However, mixing with local products of the Colli Albani volcanic district, located 20 km east of Rome, has been evidenced at two fishponds of Latium, in Punta della Vipera and Torre Astura. Based on these petrographic and geochemical data, we conclude that the selective use of pozzolan from Campania, rather than of unproved different chemical properties, was the consequence of a series of logistic, economic, industrial and historical reasons.

  5. Effects of waste PET bottles aggregate on the properties of concrete

    SciTech Connect

    Choi, Yun-Wang; Moon, Dae-Joong; Chung, Jee-Seung; Cho, Sun-Kyu

    2005-04-01

    This paper investigates the surface microstructure of waste polyethylene terephthalate (PET) bottles lightweight aggregate (WPLA) to examine the effect of granulated blast-furnace slag (GBFS) on WPLA. The WPLA was made from the waste PET bottles and GBFS, and experimental tests were conducted on compressive strength, splitting tensile strength, modulus of elasticity, slump, and density of waste PET bottles lightweight aggregate concrete (WPLAC). The 28-day compressive strength of WPLAC with the replacement ratio of 75% reduces about 33% compared to the control concrete in the water-cement ratio of 45%. The density of WPLAC varies from 1940 to 2260 kg/m{sup 3} by the influence of WPLA. The structural efficiency of WPLAC decreases as the replacement ratio increases. The workability of concrete with 75% WPLA improves about 123% compared to that of the normal concrete in the water-cement ratio of 53%. The adhered GBFS is able to strengthen the surface of WPLA and to narrow the transition zone owing to the reaction with calcium hydroxide.

  6. Effects of Oil Palm Shell Coarse Aggregate Species on High Strength Lightweight Concrete

    PubMed Central

    Yew, Ming Kun; Bin Mahmud, Hilmi; Ang, Bee Chin; Yew, Ming Chian

    2014-01-01

    The objective of this study was to investigate the effects of different species of oil palm shell (OPS) coarse aggregates on the properties of high strength lightweight concrete (HSLWC). Original and crushed OPS coarse aggregates of different species and age categories were investigated in this study. The research focused on two OPS species (dura and tenera), in which the coarse aggregates were taken from oil palm trees of the following age categories (3–5, 6–9, and 10–15 years old). The results showed that the workability and dry density of the oil palm shell concrete (OPSC) increase with an increase in age category of OPS species. The compressive strength of specimen CD3 increases significantly compared to specimen CT3 by 21.8%. The maximum achievable 28-day and 90-day compressive strength is 54 and 56 MPa, respectively, which is within the range for 10–15-year-old crushed dura OPS. The water absorption was determined to be within the range for good concrete for the different species of OPSC. In addition, the ultrasonic pulse velocity (UPV) results showed that the OPS HSLWC attain good condition at the age of 3 days. PMID:24982946

  7. Effects of oil palm shell coarse aggregate species on high strength lightweight concrete.

    PubMed

    Yew, Ming Kun; Bin Mahmud, Hilmi; Ang, Bee Chin; Yew, Ming Chian

    2014-01-01

    The objective of this study was to investigate the effects of different species of oil palm shell (OPS) coarse aggregates on the properties of high strength lightweight concrete (HSLWC). Original and crushed OPS coarse aggregates of different species and age categories were investigated in this study. The research focused on two OPS species (dura and tenera), in which the coarse aggregates were taken from oil palm trees of the following age categories (3-5, 6-9, and 10-15 years old). The results showed that the workability and dry density of the oil palm shell concrete (OPSC) increase with an increase in age category of OPS species. The compressive strength of specimen CD3 increases significantly compared to specimen CT3 by 21.8%. The maximum achievable 28-day and 90-day compressive strength is 54 and 56 MPa, respectively, which is within the range for 10-15-year-old crushed dura OPS. The water absorption was determined to be within the range for good concrete for the different species of OPSC. In addition, the ultrasonic pulse velocity (UPV) results showed that the OPS HSLWC attain good condition at the age of 3 days.

  8. Evaluation of concrete incorporating bottom ash as a natural aggregates replacement.

    PubMed

    Andrade, L B; Rocha, J C; Cheriaf, M

    2007-01-01

    A study on the incorporation of coal bottom ash from thermoelectric power stations as a substitute material for natural sand in the production of concrete is here presented. The normally coarse, fused, glassy texture of bottom ash makes it an ideal substitute for natural aggregates. The use of bottom ash in concrete presents several technical challenges: the physical and mineralogical characteristics of the bottom ash; the effect on water demand and the participation on cements hydratation. In the production of the concrete, substitutions in volume were used. Two different ways to employ bottom ash were used to make up the mix proportions: one considering the natural humidity present in the porous particles and the other not considering it, seeking to maintain the same strength. These considerations are fundamental given that the process of bottom ash extraction is carried out through moisture. Mechanical tests by compressive strength were performed and the elastic modulus was determined. An analysis of the influence of bottom ash in the formation of pores was carried out through tests for the water loss by air drying and water uptake by capillary absorption. The results show that the higher the bottom ash contents in the concrete, the worse the performance regarding moisture transport. However, for one bottom ash concrete type, the mechanical properties were maintained.

  9. Ultrasound frequency analysis for identification of aggregates and cement paste in concrete.

    PubMed

    Cosmes-López, Mario F; Castellanos, Francisco; Cano-Barrita, Prisciliano F de J

    2017-01-01

    The aim of the present study was to identify specific frequencies related to aggregates and cement paste during concrete hydration, by performing a Fourier analysis of the ultrasonic response of concrete specimens to different excitation frequencies. This identification will reduce the high influence of aggregates in the ultrasound signal analysis, enabling a better assessment of changes occurring in the cement paste. Thirty-five cylindrical specimens with a diameter of 100mm and a length of 200mm were cast with a water to cement ratio=0.60. Thirty specimens were destructively tested at 1, 3, 5, 7, 14 and 28days for their compressive strength. The remaining five specimens were non-destructively tested at 1, 3, 5, 7, 14, 28 and 56days using longitudinal and transversal ultrasonic wave transducers with frequencies from 50kHz to 500kHz. Analysis of the evolution in frequency observed in the specimens identified variations related to progressive hydration of the cement paste, in contrast with the invariant behavior of the inert aggregates. Results show that it is possible to distinguish the behavior of cement paste and aggregates in the frequency domain. As a consequence, it should be possible in future research to evaluate more efficiently different phenomena that affect only the cement paste.

  10. Structural concretes with waste-based lightweight aggregates: from landfill to engineered materials.

    PubMed

    De'Gennaro, Roberto; Graziano, Sossio Fabio; Cappelletti, Piergiulio; Colella, Abner; Dondi, Michele; Langella, Alessio; De'Gennaro, Maurizio

    2009-09-15

    This research provides possible opportunities in the reuse of waste and particularly muds, coming from both ornamental stone (granite sludges from sawing and polishing operations) and ceramic production (porcelain stoneware tile polishing sludge), for the manufacture of lightweight aggregates. Lab simulation of the manufacturing cycle was performed by pelletizing and firing the waste mixes in a rotative furnace up to 1300 degrees C, and determining composition and physicomechanical properties of lightweight aggregates. The best formulation was used to produce and test lightweight structural concretes according to standard procedures. Both granite and porcelain stoneware polishing sludges exhibit a suitable firing behavior due to the occurrence of SiC (an abrasive component) which, by decomposing at high temperature with gas release, acts as a bloating promoter, resulting in aggregates with particle density < 1 Mg/m3. However, slight variations of mixture composition produce aggregates with rather different properties, going from values close to those of typical commercial expanded clays (particle density 0.68 Mg/m3; strength of particle 1.2 MPa) to products with high mechanical features (particle density 1.25 Mg/m3; strength of particle 6.9 MPa). The best formulation (50 wt.% porcelain stoneware polishing sludge +50 wt.% granite sawing sludge) was used to successfully manufacture lightweight structural concretes with suitable properties (compressive strength 28 days > 20 MPa, bulk density 1.4-2.0 Mg/m3).

  11. 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

  12. 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.

  13. Use of recycled chunk rubber asphalt concrete (CRAC) on low volume roads and use of recycled crumb rubber modifier in asphalt pavements. Final report, June 1993-June 1995

    SciTech Connect

    Hossain, M.; Funk, L.P.; Sadeq, M.A.; Marucci, G.

    1995-06-01

    The major objective of this project was to formulate a Chunk Rubber Asphalt Concrete (CRAC) mix for use on low volume roads. CRAC is a rubber modified asphalt concrete product produced by the `dry process` where rubber chunks of 1/2 inch size are used as aggregate in a cold mix with a type C fly ash. The second objective of this project was to develop guidelines concerning the use of rubber modified asphalt concrete hot mix to include: (1) Design methods for use of asphalt-rubber mix for new construction and overlay, (2) Mix design method for asphalt-rubber, and (3) Test method for determining the amount of rubber in an asphalt-rubber concrete for quality control purposes.

  14. Concrete drill core characterization finalized to optimal dismantling and aggregates recovery.

    PubMed

    Bonifazi, Giuseppe; Palmieri, Roberta; Serranti, Silvia

    2017-02-01

    An innovative strategy, based on micro X-ray fluorescence and HyperSpectralImaging in the short wave infrared range (1000-2500nm), was developed in order to characterize drill core samples collected from End-of-Life concrete. Micro X-ray fluorescence maps were realized to check the drill cores chemical composition, to develop the best approach for HSI analyses and to verify the correctness of the obtained HSI results. HSI analysis was carried out in order to recognize and classify aggregates and mortar paste in concrete. A morphological and morphometrical analysis of aggregates was also carried out on the prediction maps. Results showed as the proposed approach can be profitably applied to analyze and characterize demolition waste materials before dismantling. Starting from an efficient in-situ characterization of the objects to dismantle, demolition actions can be optimized in order to maximize the EOL concrete derived materials, minimizing the final waste. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. 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)

  16. 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)

  17. Bond slip detection of steel plate and concrete beams using smart aggregates

    NASA Astrophysics Data System (ADS)

    Qin, Feng; Kong, Qingzhao; Li, Mo; Mo, Y. L.; Song, Gangbing; Fan, Feng

    2015-11-01

    The newly emerged steel plate concrete (SC), benefited from a composite effect of steel and concrete materials, has been applied to shield building and internal structures of AP1000 nuclear power plants. The detection of bond-slip between steel plate and concrete is of great importance to provide early warnings of steel plate and concrete debonding and to ensure the safety of SC structures. In this paper, an active sensing approach using smart aggregates (SAs) is developed to detect the initiation and to monitor the development of bond-slip. A SA, designed by sandwiching a fragile piezoceramic patch between protection materials, can be utilized as both actuator and sensor by taking advantage of the piezoelectricity of piezoceramic material. Two SC beams with distinct shear reinforcement ratios ≤ft({ρ }t\\right) were experimentally investigated. Based on the wavelet packet decomposition of the received signals from SAs, the initiation of bond-slip is detected, and the development of bond-slip is quantitatively monitored to better understand the structural performance of SC beams, including the stiffness and capacity. The bond-slip severities of the two SC beams are compared to study the improvement of bond-slip condition rendered by providing more shear reinforcement.

  18. Concrete modelling for expertise of structures affected by alkali aggregate reaction

    SciTech Connect

    Grimal, E.; Sellier, A.; Multon, S.; Le Pape, Y.; Bourdarot, E.

    2010-04-15

    Alkali aggregate reaction (AAR) affects numerous civil engineering structures and causes irreversible expansion and cracking. In order to control the safety level and the maintenance cost of its hydraulic dams, Electricite de France (EDF) must reach better comprehension and better prediction of the expansion phenomena. For this purpose, EDF has developed a numerical model based on the finite element method in order to assess the mechanical behaviour of damaged structures. The model takes the following phenomena into account: concrete creep, the stress induced by the formation of AAR gel and the mechanical damage. A rheological model was developed to assess the coupling between the different phenomena (creep, AAR and anisotropic damage). Experimental results were used to test the model. The results show the capability of the model to predict the experimental behaviour of beams subjected to AAR. In order to obtain such prediction, it is necessary to take all the phenomena occurring in the concrete into consideration.

  19. Observations on dedolomitization of carbonate concrete aggregates, implications for ACR and expansion

    SciTech Connect

    Prinčič, Tina; Štukovnik, Petra; Pejovnik, Stane; De Schutter, Geert; Bokan Bosiljkov, Violeta

    2013-12-15

    Some carbonate aggregates used in concrete are unstable in a high alkaline solution, which is present also in pore solution of cement binder. This paper investigates the process of dedolomitization of carbonate aggregate rocks and mortar bars. Selected aggregates, limestone and dolostone are of high purity without reactive silica involvement confirmed by the XRD and the XRF. For the process of dedolomitization the effect of various temperatures, solutions and time was examined. In this investigation, measurements of expansion, optical and scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction were used. Te results indicate that the process of dedolomitization occurred not only in the NaOH solution but also in the water on the mortar bar with virgin dolostone aggregate. Elevated temperature, 60 °C, increased the rate of reaction. Furthermore, the rate of reaction significantly correlates with time, which has also been confirmed through the Rietveld analysis. -- Highlights: •The dedolomitization caused no expansion. •It occurs in the dolostone aggregate without reactive silica involvement. •It has taken place already with the presence of the cement binder. •A significant alteration occurred: formation of rims, new pores and phases.

  20. Utilization of recycled asphalt concrete with warm mix asphalt and cost-benefit analysis.

    PubMed

    Oner, Julide; Sengoz, Burak

    2015-01-01

    The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures.

  1. Utilization of Recycled Asphalt Concrete with Warm Mix Asphalt and Cost-Benefit Analysis

    PubMed Central

    Oner, Julide; Sengoz, Burak

    2015-01-01

    The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures. PMID:25574851

  2. 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.

  3. Determination of Coefficient of Thermal Expansion (CTE) of 20MPa Mass Concrete Using Granite Aggregate

    NASA Astrophysics Data System (ADS)

    Chee Siang, GO

    2017-07-01

    Experimental test was carried out to determine the coefficient of thermal expansion (CTE) value of 20MPa mass concrete using granite aggregate. The CTE value was established using procedure proposed by Kada et al. 2002 in determining the magnitude of early-ages CTE through laboratory test which is a rather accurate way by eliminating any possible superimposed effect of others early-age thermal deformation shrinkages such as autogenous, carbonation, plastic and drying shrinkage. This was done by submitting granite concrete block samples instrumented with ST4 vibrating wire extensometers to thermal shocks. The response of the concrete samples to this shock results in a nearly instantaneous deformation, which are measured by the sensor. These deformations, as well as the temperature signal, are used to calculate the CTE. By repeating heat cycles, the variation in the early-ages of concrete CTE over time was monitored and assessed for a period of upto 7 days. The developed CTE value facilitating the verification and validation of actual maximum permissible critical temperature differential limit (rather than arbitrarily follow published value) of cracking potential. For thick sections, internal restraint is dominant and this is governed by differentials mainly. Of the required physical properties for thermal modelling, CTE is of paramount importance that with given appropriate internal restraint factor the condition of cracking due to internal restraint is governs by equation, ΔTmax= 3.663ɛctu / αc. Thus, it can be appreciated that an increase in CTE will lower the maximum allowable differential for cracking avoidance in mass concrete while an increase of tensile strain capacity will increase the maximum allowable temperature differential.

  4. Recycle

    SciTech Connect

    1988-10-01

    ;Contents: The Problem; What`s In Our Trash; Where Does Trash Go; Where Does Our Trash Go; The Solution; What Is Recycling; Why Should We Recycle; A National Goal of 25%; What Can We Recycle; What Do We Do With Our Recyclables.

  5. Fundamental Study on the Development of Structural Lightweight Concrete by Using Normal Coarse Aggregate and Foaming Agent.

    PubMed

    Lee, Han-Seung; Ismail, Mohamed A; Woo, Young-Je; Min, Tae-Beom; Choi, Hyun-Kook

    2014-06-13

    Structural lightweight concrete (SLWC) has superior properties that allow the optimization of super tall structure systems for the process of design. Because of the limited supply of lightweight aggregates in Korea, the development of structural lightweight concrete without lightweight aggregates is needed. The physical and mechanical properties of specimens that were cast using normal coarse aggregates and different mixing ratios of foaming agent to evaluate the possibility of creating structural lightweight concrete were investigated. The results show that the density of SLWC decreases as the dosage of foaming agent increases up to a dosage of 0.6%, as observed by SEM. It was also observed that the foaming agent induced well separated pores, and that the size of the pores ranged from 50 to 100 μm. Based on the porosity of concrete specimens with foaming agent, compressive strength values of structural lightweight foam concrete (SLWFC) were obtained. It was also found that the estimated values from proposed equations for compressive strength and modulus of elasticity of SLWFC, and values obtained by actual measurements were in good agreement. Thus, this study confirms that new structural lightweight concrete using normal coarse aggregates and foaming agent can be developed successfully.

  6. Fundamental Study on the Development of Structural Lightweight Concrete by Using Normal Coarse Aggregate and Foaming Agent

    PubMed Central

    Lee, Han-Seung; Ismail, Mohamed A.; Woo, Young-Je; Min, Tae-Beom; Choi, Hyun-Kook

    2014-01-01

    Structural lightweight concrete (SLWC) has superior properties that allow the optimization of super tall structure systems for the process of design. Because of the limited supply of lightweight aggregates in Korea, the development of structural lightweight concrete without lightweight aggregates is needed. The physical and mechanical properties of specimens that were cast using normal coarse aggregates and different mixing ratios of foaming agent to evaluate the possibility of creating structural lightweight concrete were investigated. The results show that the density of SLWC decreases as the dosage of foaming agent increases up to a dosage of 0.6%, as observed by SEM. It was also observed that the foaming agent induced well separated pores, and that the size of the pores ranged from 50 to 100 μm. Based on the porosity of concrete specimens with foaming agent, compressive strength values of structural lightweight foam concrete (SLWFC) were obtained. It was also found that the estimated values from proposed equations for compressive strength and modulus of elasticity of SLWFC, and values obtained by actual measurements were in good agreement. Thus, this study confirms that new structural lightweight concrete using normal coarse aggregates and foaming agent can be developed successfully. PMID:28788691

  7. Feasibility study of using smart aggregates as embedded acoustic emission sensors for health monitoring of concrete structures

    NASA Astrophysics Data System (ADS)

    Li, Weijie; Kong, Qingzhao; Ho, Siu Chun Michael; Lim, Ing; Mo, Y. L.; Song, Gangbing

    2016-11-01

    Acoustic emission (AE) is a nondestructive evaluation technique that is capable of monitoring the damage evolution of concrete structures in real time. Conventionally, AE sensors are surface mounted on the host structures, however, the AE signals attenuate quickly due to the high attenuation properties of concrete structures. This study conducts a feasibility study of using smart aggregates (SAs), which are a type of embedded piezoceramic transducers, as embedded AE sensors for the health monitoring of concrete structures. A plain concrete beam with two surface mounted AE sensors and two embedded SAs was fabricated in laboratory and loaded under a designed three-point-bending test. The performance of embedded SAs were compared with the traditional surface mounted AE sensors in their ability to detect and evaluate the damage to the concrete structure. The results verified the feasibility of using smart aggregates as embedded AE sensors for monitoring structural damage in concrete. Potentially, the low cost smart aggregates could function as embedded AE sensors, providing great sensitivity and high reliability in applications for the structural health monitoring of concrete structures.

  8. 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.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-10-09

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

  11. Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali-silica reaction

    SciTech Connect

    Stastna, A.; Sachlova, S.; Pertold, Z.; Prikryl, R.; Leichmann, J.

    2012-03-15

    Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali-silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali-silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: Black-Right-Pointing-Pointer ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). Black-Right-Pointing-Pointer Cathodoluminescence was combined with various microscopic techniques and image analysis. Black-Right-Pointing-Pointer ASR was attributed to aggregates. Black-Right-Pointing-Pointer Source materials of aggregates were identified based on cathodoluminescence characteristics. Black-Right-Pointing-Pointer Quartz comes from different volcanic, plutonic and metamorphic parent rocks.

  12. Assessment of optimum threshold and particle shape parameter for the image analysis of aggregate size distribution of concrete sections

    NASA Astrophysics Data System (ADS)

    Ozen, Murat; Guler, Murat

    2014-02-01

    Aggregate gradation is one of the key design parameters affecting the workability and strength properties of concrete mixtures. Estimating aggregate gradation from hardened concrete samples can offer valuable insights into the quality of mixtures in terms of the degree of segregation and the amount of deviation from the specified gradation limits. In this study, a methodology is introduced to determine the particle size distribution of aggregates from 2D cross sectional images of concrete samples. The samples used in the study were fabricated from six mix designs by varying the aggregate gradation, aggregate source and maximum aggregate size with five replicates of each design combination. Each sample was cut into three pieces using a diamond saw and then scanned to obtain the cross sectional images using a desktop flatbed scanner. An algorithm is proposed to determine the optimum threshold for the image analysis of the cross sections. A procedure was also suggested to determine a suitable particle shape parameter to be used in the analysis of aggregate size distribution within each cross section. Results of analyses indicated that the optimum threshold hence the pixel distribution functions may be different even for the cross sections of an identical concrete sample. Besides, the maximum ferret diameter is the most suitable shape parameter to estimate the size distribution of aggregates when computed based on the diagonal sieve opening. The outcome of this study can be of practical value for the practitioners to evaluate concrete in terms of the degree of segregation and the bounds of mixture's gradation achieved during manufacturing.

  13. Properties of Concrete partially replaced with Coconut Shell as Coarse aggregate and Steel fibres in addition to its Concrete volume

    NASA Astrophysics Data System (ADS)

    Kalyana Chakravarthy, P. R.; Janani, R.; Ilango, T.; Dharani, K.

    2017-03-01

    Cement is a binder material with various composition of Concrete but instantly it posses low tensile strength. The study deals with mechanical properties of that optimized fiber in comparison with conventional and coconut shell concrete. The accumulation of fibers arbitrarily dispersed in the composition increases the resistance to cracking, deflection and other serviceability conditions substantially. The steel fiber in extra is one of the revision in coconut shell concrete and the outcome of steel fiber in coconut shell concrete was to investigate and compare with the conventional concrete. For the given range of steel fibe from 0.5 to 2.0%, 12 beams and 36 cylindrical specimens were cast and tested to find the mechanical properties like flexural strength, split tensile, impact resistance and the modulus of elasticity of both conventional and coconut shell concrete has been studied and the test consequences are compared with the control concrete and coconut shell concrete for M25 Grade. It is fulfilled that, the steel fibers used in this venture has shown significant development in all the properties of conventional and coconut shell concrete while compared to controlled conventional and coconut shell concrete like, Flexural strength by 6.67 % for 1.0 % of steel fiber in conventional concrete and by 5.87 % for 1.5 % of steel fiber in coconut shell concrete.

  14. 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

  15. 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.

  16. Estimation of air void and aggregate spatial distributions in concrete under uniaxial compression using computer tomography scanning

    SciTech Connect

    Wong, R.C.K. . E-mail: rckwong@ucalgary.ca; Chau, K.T.

    2005-08-01

    Normal- and high-strength concrete cylinders (designed compressive strengths of 30 and 90 MPa at 28 days) were loaded uniaxially. Computer tomography (CT) scanning technique was used to examine the evolution of air voids inside the specimens at various loading states up to 85% of the ultimate compressive strength. The normal-strength concrete yielded a very different behaviour in changes of internal microstructure as compared to the high-strength concrete. There were significant instances of nucleation and growth in air voids in the normal-strength concrete specimen, while the increase in air voids in the high-strength concrete specimen was insignificant. In addition, CT images were used for mapping the aggregate spatial distributions within the specimens. No intrinsic anisotropy was detected from the fabric analysis.

  17. 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.

  18. 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.

  19. Detection and monitoring of flexural cracks in reinforced concrete beams using mounted smart aggregate transducers

    NASA Astrophysics Data System (ADS)

    Taghavipour, S.; Kharkovsky, S.; Kang, W.-H.; Samali, B.; Mirza, O.

    2017-10-01

    Previous studies have successfully demonstrated the capability and reliability of the use of Smart Aggregate (SA) transducers to monitor reinforced concrete (RC) structures. However, they mainly focused on the applications of embedded SAs to new structural members, while no major attention was paid to the monitoring of existing RC members using externally mounted SAs. In this paper, a mounted SA-based approach is proposed for a real-time health monitoring of existing RC beams. The proposed approach is verified through monitoring of RC beams under flexural loading, on each of which SA transducers are mounted as an actuator and sensors. The experimental results show that the proposed SA-based approach effectively evaluates the cracking status of RC beams in terms of the peak of power spectral density and damage indexes obtained at multiple sensor locations. It is also shown that the proposed sensor system can also capture a precautionary signal for major cracking.

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

    PubMed

    Mangialardi, T

    2001-10-12

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

  1. Municipal waste combustor ash as an aggregate in concrete masonry units

    SciTech Connect

    Berg, E.R.

    1993-12-31

    The use of municipal waste combustor ash (MWCA) as aggregate in concrete masonry units (CMU) was investigated using current commercial portland cement concrete technology in an effort to maximize MWCA utilization with a minimum of additional expense. The project used ASTM standards/protocols for portland cement materials to measure the physical and chemical properties including size and size gradation, chemical composition, organic and moisture contents, and density of the sample MWCA obtained from a refuse-derived-fuel operation. Powder X-ray diffraction, atomic absorption spectrophotometry, scanning electron microscope, and electron probe microanalysis were also used to assist in determining the morphology and mineral composition. MWCA fly ash and bottom ash components were evaluated separately. The fly ash component was found to contain high levels of sulfates and chlorides that created significant adverse reactions. The sulfate content of the bottom ash equalled the recommended limit for chlorides. MWCA bottom ash was used in the trial mixes with only a maximum size control to minimize processing costs. Trial mixes were made using a modified ASTM C-109 protocol to simulate CMU production methods. Techniques known to improve the durability, strength, and sulfate resistance of portland cement concrete were used to improve the performance of the MWCA mixes. Variables included cement type and amount, curing method, water content, sand content for size gradation, coal fly ash and microsilica content, a CMU plasticizer and a non-chloride accelerator. Compressive strengths in excess of 20.9 MPa (3000 psi), satisfactory for commercial CMU, were obtained with a 10 per cent cement content. A 28 day mist cure gave uniformly higher strengths than a 24 hour cycle atmospheric steam cure. The angularity and size gradation of the MWCA bottom ash adversely affected the machinability and strength results.

  2. Progressive collapse of a two-story reinforced concrete frame with embedded smart aggregates

    NASA Astrophysics Data System (ADS)

    Laskar, Arghadeep; Gu, Haichang; Mo, Y. L.; Song, Gangbing

    2009-07-01

    This paper reports the experimental and analytical results of a two-story reinforced concrete frame instrumented with innovative piezoceramic-based smart aggregates (SAs) and subjected to a monotonic lateral load up to failure. A finite element model of the frame is developed and analyzed using a computer program called Open system for earthquake engineering simulation (OpenSees). The finite element analysis (FEA) is used to predict the load-deformation curve as well as the development of plastic hinges in the frame. The load-deformation curve predicted from FEA matched well with the experimental results. The sequence of development of plastic hinges in the frame is also studied from the FEA results. The locations of the plastic hinges, as obtained from the analysis, were similar to those observed during the experiment. An SA-based approach is also proposed to evaluate the health status of the concrete frame and identify the development of plastic hinges during the loading procedure. The results of the FEA are used to validate the SA-based approach for detecting the locations and occurrence of the plastic hinges leading to the progressive collapse of the frame. The locations and sequential development of the plastic hinges obtained from the SA-based approach corresponds well with the FEA results. The proposed SA-based approach, thus validated using FEA and experimental results, has a great potential to be applied in the health monitoring of large-scale civil infrastructures.

  3. Damage Evaluation in Shear-Critical Reinforced Concrete Beam using Piezoelectric Transducers as Smart Aggregates

    NASA Astrophysics Data System (ADS)

    Chalioris, Constantin E.; Papadopoulos, Nikos A.; Angeli, Georgia M.; Karayannis, Chris G.; Liolios, Asterios A.; Providakis, Costas P.

    2015-10-01

    Damage detection at early cracking stages in shear-critical reinforced concrete beams, before further deterioration and their inevitable brittle shear failure is crucial for structural safety and integrity. The effectiveness of a structural health monitoring technique using the admittance measurements of piezoelectric transducers mounted on a reinforced concrete beam without shear reinforcement is experimentally investigated. Embedded "smart aggregate" transducers and externally bonded piezoelectric patches have been placed in arrays at both shear spans of the beam. Beam were tested till total shear failure and monitored at three different states; healthy, flexural cracking and diagonal cracking. Test results showed that transducers close to the critical diagonal crack provided sound and graduated discrepancies between the admittance responses at the healthy state and thedamage levels.Damage assessment using statistical indices calculated from the measurements of all transducers was also attempted. Rational changes of the index values were obtained with respect to the increase of the damage. Admittance responses and index values of the transducers located on the shear span where the critical diagonal crack formed provided cogent evidence of damage. On the contrary, negligible indication of damage was yielded by the responses of the transducers located on the other shear span, where no diagonal cracking occurred.

  4. Material and Structural Performance Evaluations of Hwangtoh Admixtures and Recycled PET Fiber-Added Eco-Friendly Concrete for CO2 Emission Reduction

    PubMed Central

    Koo, Bon-Min; Kim, Jang-Ho Jay; Kim, Sung-Bae; Mun, Sungho

    2014-01-01

    In order to reduce carbon dioxide (CO2) emissions and produce an eco-friendly construction material, a type of concrete that uses a minimal amount of cement, yet still retains equivalent properties to ordinary cement concrete, has been developed and studied all over the world. Hwangtoh, a type of red clay broadly deposited around the world, has traditionally been considered an eco-friendly construction material, with bonus advantages of having health and cost benefits. Presently, Hwangtoh is not commonly used as a modern construction material due to properties such as low strength and high rates of shrinkage cracking. Recent studies, however, have shown that Hwangtoh can be used as a mineral admixture to improve the strength of concrete. In addition, polyethylene terephthalate (PET) fibers recycled from PET bottle waste can be used to control shrinkage cracks in Hwangtoh concrete. Therefore, in this study, performance verification is conducted on newly developed Hwangtoh concrete mixed with short recycled PET fibers. The results show that Hwangtoh concrete has compressive strength, elastic modulus, and pH properties that are similar to these features in ordinary cement concrete. The properties of carbonation depth and creep strain of Hwangtoh concrete, however, are larger and smaller, respectively, than in ordinary cement concrete. According to flexural tests, reinforced concrete (RC) specimens cast with Hwangtoh admixtures (with and without PET fibers) possess similar or better capacities than ordinary RC specimens. The addition of PET fibers significantly improves the structural ductility of RC specimens under normal environmental conditions. However, the implementations of the concrete in aggressive environment must be carefully considered, since a previous study result indicates degradation of its durability performance in aggressive environments, such as seawater [1]. The results of this study validate the possibility of using eco-friendly Hwangtoh concrete

  5. Material and Structural Performance Evaluations of Hwangtoh Admixtures and Recycled PET Fiber-Added Eco-Friendly Concrete for CO₂ Emission Reduction.

    PubMed

    Koo, Bon-Min; Kim, Jang-Ho Jay; Kim, Sung-Bae; Mun, Sungho

    2014-08-19

    In order to reduce carbon dioxide (CO₂) emissions and produce an eco-friendly construction material, a type of concrete that uses a minimal amount of cement, yet still retains equivalent properties to ordinary cement concrete, has been developed and studied all over the world. Hwangtoh, a type of red clay broadly deposited around the world, has traditionally been considered an eco-friendly construction material, with bonus advantages of having health and cost benefits. Presently, Hwangtoh is not commonly used as a modern construction material due to properties such as low strength and high rates of shrinkage cracking. Recent studies, however, have shown that Hwangtoh can be used as a mineral admixture to improve the strength of concrete. In addition, polyethylene terephthalate (PET) fibers recycled from PET bottle waste can be used to control shrinkage cracks in Hwangtoh concrete. Therefore, in this study, performance verification is conducted on newly developed Hwangtoh concrete mixed with short recycled PET fibers. The results show that Hwangtoh concrete has compressive strength, elastic modulus, and pH properties that are similar to these features in ordinary cement concrete. The properties of carbonation depth and creep strain of Hwangtoh concrete, however, are larger and smaller, respectively, than in ordinary cement concrete. According to flexural tests, reinforced concrete (RC) specimens cast with Hwangtoh admixtures (with and without PET fibers) possess similar or better capacities than ordinary RC specimens. The addition of PET fibers significantly improves the structural ductility of RC specimens under normal environmental conditions. However, the implementations of the concrete in aggressive environment must be carefully considered, since a previous study result indicates degradation of its durability performance in aggressive environments, such as seawater [1]. The results of this study validate the possibility of using eco-friendly Hwangtoh concrete

  6. 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

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

    PubMed

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

    2016-11-17

    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 (CDW

  8. High performance of treated and washed MSWI bottom ash granulates as natural aggregate replacement within earth-moist concrete.

    PubMed

    Keulen, A; van Zomeren, A; Harpe, P; Aarnink, W; Simons, H A E; Brouwers, H J H

    2016-03-01

    Municipal solid waste incineration bottom ash was treated with specially designed dry and wet treatment processes, obtaining high quality bottom ash granulate fractions (BGF) suitable for up to 100% replacement of natural gravel in concrete. The wet treatment (using only water for separating and washing) significantly lowers the leaching of e.g. chloride and sulfate, heavy metals (antimony, molybdenum and copper) and dissolved organic carbon (DOC). Two potential bottom ash granulate fractions, both in compliance with the standard EN 12620 (aggregates for concrete), were added into earth-moist concrete mixtures. The fresh and hardened concrete physical performances (e.g. workability, strength and freeze-thaw) of high strength concrete mixtures were maintained or improved compared with the reference mixtures, even after replacing up to 100% of the initial natural gravel. Final element leaching of monolithic and crushed granular state BGF containing concretes, showed no differences with the gravel references. Leaching of all mixtures did not exceed the limit values set by the Dutch Soil Quality Degree. In addition, multiple-life-phase emission (pH static test) for the critical elements of input bottom ash, bottom ash granulate (BGF) and crushed BGF containing concrete were assessed. Simulation pH lowering or potential carbonation processes indicated that metal (antimony, barium, chrome and copper) and sulfate element leaching behavior are mainly pH dominated and controlled, although differ in mechanism and related mineral abundance.

  9. Coniston Dam: The rehabiliation of a 50-year-old concrete dam affected by alkali aggregate reaction

    SciTech Connect

    Read, P.H.; Thomas, M.

    1995-12-31

    This paper discusses the rehabilitation of the Coniston main dam in Ontario, with particular emphasis on the alkali-aggregate reaction (AAR) related aspects of the investigation and the influence of these on the design approach adopted, including measures taken to allow for possible future expansion of the original gravity section concrete. The rehabilitation program was primarily undertaken to increase the stability of the gravity sections and log chute which did not meet current dam safety criteria. However, all parts of the structure were found to be affected by AAR and the downstream face of the gravity sections were severely deteriorated due to the combined effects of AAR and freeze-thaw cycles. Field and laboratory investigations were undertaken to determine the extent of deterioration of the dam structures and to assess the potential for continued deterioration. Based on the findings from these studies, a rehabilitation and upgrade strategy was developed which included removal of badly deteriorated concrete, placement of reinforced concrete liners (upstream and downstream), addition of mass concrete buttresses along the length of the gravity sections, replacement of the deck and epoxy injection of the cracked sluiceway piers. Particular attention was paid to the design of the new concrete mixes (to limit the supply of alkalis to the existing concrete) and to the relief of stress between the original concrete core and new concrete liners. The new gravity section liner was debonded from the core concrete to reduce the transfer of stress due to continued expansion of the core; furthermore, the reinforcement of the liner was designed to resist tensile stresses induced by future expansion. Consideration was also given to minimizing the ingress of water to the dam core in order to reduce the degree of saturation and likelihood of further AAR and freeze-thaw action.

  10. Recycling potential of air pollution control residue from sewage sludge thermal treatment as artificial lightweight aggregates.

    PubMed

    Bialowiec, Andrzej; Janczukowicz, Wojciech; Gusiatin, Zygmunt M; Thornton, Arthur; Rodziewicz, Joanna; Zielinska, Magdalena

    2014-03-01

    Thermal treatment of sewage sludge produces fly ash, also known as the air pollution control residue (APCR), which may be recycled as a component of artificial lightweight aggregates (ALWA). Properties of APCR are typical: high content of Ca, Mg, P2O5, as well as potential to induce alkaline reactions. These properties indicate that ALWA prepared with a high content of APCR may remove heavy metals, phosphorus, and ammonium nitrogen from wastewater with high efficiency. The aim of this preliminary study was to determine the optimal composition of ALWA for potential use as a filter media in wastewater treatment systems. Five kinds of ALWA were produced, with different proportions of ash (shown as percentages in subscripts) in mixture with bentonite: ALWA0 (reference), ALWA12.5, ALWA25, ALWA50, and ALWA100. The following parameters of ALWA were determined: density, bulk density, compressive strength, hydraulic conductivity, and removal efficiency of ions Zn(2+), NH4 (+), and PO4 (3-). Tests showed that ALWA had good mechanical and hydraulic properties, and might be used in wastewater filtering systems. Phosphates and zinc ions were removed with high efficiency (80-96%) by ALWA25-100 in static (batch) conditions. The efficiency of ammonium nitrogen removal was low, <18%. Artificial wastewater treatment performance in dynamic conditions (through-flow), showed increasing removal efficiency of Zn(2+), PO4 (3-) with a decrease in flow rate.

  11. 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.

  12. Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

    SciTech Connect

    Erdem, Savas Dawson, Andrew Robert; Thom, Nicholas Howard

    2012-02-15

    The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity - sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing. In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.

  13. Identification of microstructural characteristics in lightweight aggregate concretes by micromechanical modelling including the interfacial transition zone (ITZ)

    SciTech Connect

    Ke, Y.; Ortola, S.; Beaucour, A.L.; Dumontet, H.

    2010-11-15

    An approach which combines both experimental techniques and micromechanical modelling is developed in order to characterise the elastic behaviour of lightweight aggregate concretes (LWAC). More than three hundred LWAC specimens with various lightweight aggregate types (5) of several volume ratios and three different mortar matrices (normal, HP, VHP) are tested. The modelling is based on iterative homogenisation process and includes the ITZ specificities experimentally observed with scanning electron microscopy (SEM). In agreement with experimental measurements, the effects of mix design parameters as well as of the interfacial transition zone (ITZ) on concrete mechanical performances are quantitatively analysed. Confrontations with experimental results allow identifying the elastic moduli of LWA which are difficult to determine experimentally. Whereas the traditional empirical formulas are not sufficiently precise, predictions of LWAC elastic behaviours computed with the micromechanical models appear in good agreement with experimental measurements.

  14. Environmental evaluation of green concretes versus conventional concrete by means of LCA.

    PubMed

    Turk, Janez; Cotič, Zvonko; Mladenovič, Ana; Šajna, Aljoša

    2015-11-01

    A number of green concrete mixes having similar basic properties were evaluated from the environmental point of view by means of the Life Cycle Assessment method, and compared with a corresponding conventional concrete mix. The investigated green concrete mixes were prepared from three different types of industrial by-products, i.e. (1) foundry sand, and (2) steel slag, both of which were used as manufactured aggregates, and (3) fly ash, which was used as a mineral admixture. Some green concrete mixes were also prepared from a recycled aggregate, which was obtained from reinforced concrete waste. In some of the green concrete mixes the recycled aggregate was used in combination with the above-mentioned types of manufactured aggregate and fly ash. All of these materials are able, to some extent, to replace natural aggregate or Portland cement in concrete mixes, thus providing an environmental benefit from the point of view of the saving of natural resources. Taking into account consequential modelling, the credit related to the avoidance of the need to dispose of the waste materials is considered as a benefit. In case of the recycling of waste concrete into aggregate, credit is attributed to the recovery of scrap iron from the steel reinforcement. In the case of the use of steel slag, credit is attributed to the recovery of metals, which are extracted from the slag before being used as an alternative material. The disadvantage of using alternative materials and recycled aggregates can sometimes be their relatively long delivery distance. For this reason, a transport sensitivity analysis was carried out. The results indicate that the use of the discussed alternative and recycled materials is beneficial in the concrete production industry. Preference is given to the fly ash and foundry sand scenarios, and especially to those scenarios which are based on the combined use of recycled aggregate with these two alternative materials. It was found that longer delivery

  15. PLUTONIUM CONTAMINATION VALENCE STATE DETERMINATION USING X-RAY ABSORPTION FINE STRUCTURE PERMITS CONCRETE RECYCLE

    SciTech Connect

    Ervin, P. F.; Conradson, S. D.

    2002-02-25

    This paper describes the determination of the speciation of plutonium contamination present on concrete surfaces at the Rocky Flats Environmental Technology Site (RFETS). At RFETS, the plutonium processing facilities have been contaminated during multiple events over their 50 year operating history. Contamination has resulted from plutonium fire smoke, plutonium fire fighting water, milling and lathe operation aerosols, furnace operations vapors and plutonium ''dust'' diffusion.

  16. Experimental and numerical modeling of chloride diffusivity in hardened cement concrete considering the aggregate shapes and exposure-duration effects

    NASA Astrophysics Data System (ADS)

    Jie, Wu; Dassekpo, Jean-Baptiste Mawulé; Wan, Chengyong; Zha, Xiaoxiong

    This paper presents an experimental and numerical model describing the effects of the aggregate shapes and exposure duration of chloride diffusion into cement-based materials. A simple chloride diffusion test was performed on a concrete specimen composed of a mixture of cement mortar with crushed granites and round gravels. A simulation was done and the numerical model developed was applied to the matrix at the meso-scale level and the chloride diffusivity was investigated at 30, 60, and 90 days. The experimental and simulation results showed that the aggregate shape and the exposure duration of chloride diffusing into concrete are of high significance. It was indicated that the model with crushed granite presents a good resistance against chloride ingress, while the model with rounded gravels shows some sensitivity to the chloride penetration. It was also found out that when the time dependence of the diffusion coefficient is not taken into account, the diffusion rate will be overestimated. The meso-scale model developed in this study also provides a new method applied in the analysis of the chloride and water transport that causes damage to concrete considering the particle inclusion and the diffusion duration.

  17. Radiation attenuation and nuclear properties of high density concrete made with steel aggregates

    NASA Astrophysics Data System (ADS)

    Bashter, I. I.

    The fast neutron and gamma ray spectra measured behind different thickness of steel scrap concrete with density of 4 g/cm3 have been studied. The mix proportions by weight of this type of concrete were 1 cement: 6.89 steel scrap: 2.9 sand and 0.5 Water. Comparison with a standard ordinary concrete of density 2.3 g/cm3 have been carried out. The measurements were made using a collimated beam of both gamma rays and neutrons emitted from one of the horizontal channel of the Egyptian Research Reactor-1. A fast neutron and gamma ray spectrometer with a stilbene crystal was used to measure the spectra of fast neutrons and gamma rays. Pulse shape discrimination using the zero cross over technique was used to separate the photon pulses from the electron pulses. The equation due to Schmidt has been modified and applied for determining the neutron effective removal cross sections (˜R) for steel scrap, ordinary, hematite-serpentine, ilmenite-limonite and ilmenite concretes. This equation gives results which are in good agreement with the measured values. The derived empirical equation in a previous work to calculate the neutron integral flux behind different thicknesses of different types of concretes, gives good results for steel scrap concrete under investigation comparing with the corresponding experimental data. Total neutron macroscopic cross sections, linear attenuation coefficients for gamma rays and the half-value layers for both radiations at different energies have been obtained for steel scrap concrete and comparing with the corresponding values of ordinary concrete. The results show that steel scrap concrete is better than ordinary, hematite-serpentine, ilmenite-limonite and ilmenite concretes from the radiation shielding point of view.

  18. Aggregate-cement paste transition zone properties affecting the salt-frost damage of high-performance concretes

    SciTech Connect

    Cwirzen, Andrzej; Penttala, Vesa

    2005-04-01

    The influence of the cement paste-aggregate interfacial transition zone (ITZ) on the frost durability of high-performance silica fume concrete (HPSFC) has been studied. Investigation was carried out on eight non-air-entrained concretes having water-to-binder (W/B) ratios of 0.3, 0.35 and 0.42 and different additions of condensed silica fume. Studies on the microstructure and composition of the cement paste have been made by means of environmental scanning electron microscope (ESEM)-BSE, ESEM-EDX and mercury intrusion porosimetry (MIP) analysis. The results showed that the transition zone initiates and accelerates damaging mechanisms by enhancing movement of the pore solution within the concrete during freezing and thawing cycles. Cracks filled with ettringite were primarily formed in the ITZ. The test concretes having good frost-deicing salt durability featured a narrow transition zone and a decreased Ca/Si atomic ratio in the transition zone compared to the bulk cement paste. Moderate additions of silica fume seemed to densify the microstructure of the ITZ.

  19. Reclamation chain of waste concrete: A case study of Shanghai.

    PubMed

    Xiao, Jianzhuang; Ma, Zhiming; Ding, Tao

    2016-02-01

    A mass of construction and demolition (C&D) waste are generated in Shanghai every year, and it has become a serious environment problem. Reclaiming the waste concrete to produce recycled aggregate (RA) and recycled aggregate concrete (RAC) is an effective method to reduce the C&D waste. This paper develops a reclamation chain of waste concrete based on the researches and practices in Shanghai. C&D waste management, waste concrete disposition, RA production and RAC preparation are discussed respectively. In addition, technical suggestions are also given according to the findings in practical engineering, which aims to optimize the reclamation chain. The results show that the properties of RA and RAC can well meet the requirement of design and practical application through a series of technical measures. The reclamation chain of waste concrete is necessary and appropriate for Shanghai, which provides more opportunities for the wider application of RA and RAC, and it shows a favorable environmental benefit.

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

    SciTech Connect

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

    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, 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.

  1. 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.

  2. 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.

  3. Investigation of the effect of aggregates' morphology on concrete creep properties by numerical simulations

    SciTech Connect

    Lavergne, F.; Sab, K.; Sanahuja, J.; Bornert, M.; Toulemonde, C.

    2015-05-15

    Prestress losses due to creep of concrete is a matter of interest for long-term operations of nuclear power plants containment buildings. Experimental studies by Granger (1995) have shown that concretes with similar formulations have different creep behaviors. The aim of this paper is to numerically investigate the effect of size distribution and shape of elastic inclusions on the long-term creep of concrete. Several microstructures with prescribed size distribution and spherical or polyhedral shape of inclusions are generated. By using the 3D numerical homogenization procedure for viscoelastic microstructures proposed by Šmilauer and Bažant (2010), it is shown that the size distribution and shape of inclusions have no measurable influence on the overall creep behavior. Moreover, a mean-field estimate provides close predictions. An Interfacial Transition Zone was introduced according to the model of Nadeau (2003). It is shown that this feature of concrete's microstructure can explain differences between creep behaviors.

  4. pH neutralization of the by-product sludge waste water generated from waste concrete recycling process using the carbon mineralization

    NASA Astrophysics Data System (ADS)

    Ji, Sangwoo; Shin, Hee-young; Bang, Jun Hwan; Ahn, Ji-Whan

    2017-04-01

    About 44 Mt/year of waste concrete is generated in South Korea. More than 95% of this waste concrete is recycled. In the process of regenerating and recycling pulmonary concrete, sludge mixed with fine powder generated during repeated pulverization process and water used for washing the surface and water used for impurity separation occurs. In this way, the solid matter contained in the sludge as a by-product is about 40% of the waste concrete that was input. Due to the cement component embedded in the concrete, the sludge supernatant is very strong alkaline (pH about 12). And it is necessary to neutralization for comply with environmental standards. In this study, carbon mineralization method was applied as a method to neutralize the pH of highly alkaline waste water to under pH 8.5, which is the water quality standard of discharged water. CO2 gas (purity 99%, flow rate 10ml/min.) was injected and reacted with the waste water (Ca concentration about 750mg/L) from which solid matter was removed. As a result of the experiment, the pH converged to about 6.5 within 50 minutes of reaction. The precipitate showed high whiteness. XRD and SEM analysis showed that it was high purity CaCO3. For the application to industry, it is needed further study using lower concentration CO2 gas (about 14%) which generated from power plant.

  5. Alteration of alkali reactive aggregates autoclaved in different alkali solutions and application to alkali-aggregate reaction in concrete

    SciTech Connect

    Lu Duyou; Xu Zhongzi; Tang Mingshu; Fournier, Benoit

    2006-06-15

    Surface alteration of typical aggregates with alkali-silica reactivity and alkali-carbonate reactivity, i.e. Spratt limestone (SL) and Pittsburg dolomitic limestone (PL), were studied by XRD and SEM/EDS after autoclaving in KOH, NaOH and LiOH solutions at 150 deg. C for 150 h. The results indicate that: (1) NaOH shows the strongest attack on both ASR and ACR aggregates, the weakest attack is with LiOH. For both aggregates autoclaved in different alkali media, the crystalline degree, morphology and distribution of products are quite different. More crystalline products are formed on rock surfaces in KOH than that in NaOH solution, while almost no amorphous product is formed in LiOH solution; (2) in addition to dedolomitization of PL in KOH, NaOH and LiOH solutions, cryptocrystalline quartz in PL involves in reaction with alkaline solution and forms typical alkali-silica product in NaOH and KOH solutions, but forms lithium silicate (Li{sub 2}SiO{sub 3}) in LiOH solution; (3) in addition to massive alkali-silica product formed in SL autoclaved in different alkaline solutions, a small amount of dolomite existing in SL may simultaneously dedolomitize and possibly contribute to expansion; (4) it is promising to use the duplex effect of LiOH on ASR and ACR to distinguish the alkali-silica reactivity and alkali-carbonate reactivity of aggregate when both ASR and ACR might coexist.

  6. Application of Image Analysis to Identify Quartz Grains in Heavy Aggregates Susceptible to ASR in Radiation Shielding Concrete

    PubMed Central

    Jóźwiak-Niedźwiedzka, Daria; Jaskulski, Roman; Glinicki, Michał A.

    2016-01-01

    Alkali-silica reaction (ASR) is considered as a potential aging-related degradation phenomenon that might impair the durability of concrete in nuclear containments. The objective of this paper is the application of digital analysis of microscopic images to identify the content and size of quartz grains in heavy mineral aggregates. The range of investigation covered magnetite and hematite aggregates, known as good absorbers of gamma radiation. Image acquisition was performed using thin sections observed in transmitted cross-polarized light with λ plate. Image processing, consisting of identification of ferrum oxide and epoxy resin, and the subsequent application of a set of filtering operations resulted in an adequate image reduction allowing the grain size analysis. Quartz grains were classified according to their mean diameter so as to identify the reactive range. Accelerated mortar bar tests were performed to evaluate the ASR potential of the aggregates. The SiO2 content in the heavyweight aggregates determined using the image analysis of thin sections was similar to XRF test result. The content of reactive quartz hematite was 2.7%, suggesting that it would be prone to ASR. The expansion test, according to ASTM C1260, confirmed the prediction obtained using the digital image analysis. PMID:28773362

  7. Application of Image Analysis to Identify Quartz Grains in Heavy Aggregates Susceptible to ASR in Radiation Shielding Concrete.

    PubMed

    Jóźwiak-Niedźwiedzka, Daria; Jaskulski, Roman; Glinicki, Michał A

    2016-03-25

    Alkali-silica reaction (ASR) is considered as a potential aging-related degradation phenomenon that might impair the durability of concrete in nuclear containments. The objective of this paper is the application of digital analysis of microscopic images to identify the content and size of quartz grains in heavy mineral aggregates. The range of investigation covered magnetite and hematite aggregates, known as good absorbers of gamma radiation. Image acquisition was performed using thin sections observed in transmitted cross-polarized light with λ plate. Image processing, consisting of identification of ferrum oxide and epoxy resin, and the subsequent application of a set of filtering operations resulted in an adequate image reduction allowing the grain size analysis. Quartz grains were classified according to their mean diameter so as to identify the reactive range. Accelerated mortar bar tests were performed to evaluate the ASR potential of the aggregates. The SiO₂ content in the heavyweight aggregates determined using the image analysis of thin sections was similar to XRF test result. The content of reactive quartz hematite was 2.7%, suggesting that it would be prone to ASR. The expansion test, according to ASTM C1260, confirmed the prediction obtained using the digital image analysis.

  8. An experimental study on the hazard assessment and mechanical properties of porous concrete utilizing coal bottom ash coarse aggregate in Korea.

    PubMed

    Park, Seung Bum; Jang, Young Il; Lee, Jun; Lee, Byung Jae

    2009-07-15

    This study evaluates quality properties and toxicity of coal bottom ash coarse aggregate and analyzes mechanical properties of porous concrete depending on mixing rates of coal bottom ash. As a result, soundness and resistance to abrasion of coal bottom ash coarse aggregate were satisfied according to the standard of coarse aggregate for concrete. To satisfy the standard pertaining to chloride content, the coarse aggregates have to be washed more than twice. In regards to the result of leaching test for coal bottom ash coarse aggregate and porous concrete produced with these coarse aggregates, it was satisfied with the environment criteria. As the mixing rate of coal bottom ash increased, influence of void ratio and permeability coefficient was very little, but compressive and flexural strength decreased. When coal bottom ash was mixed over 40%, strength decreased sharply (compressive strength: by 11.7-27.1%, flexural strength: by maximum 26.4%). Also, as the mixing rate of coal bottom ash increased, it was confirmed that test specimens were destroyed by aggregate fracture more than binder fracture and interface fracture. To utilize coal bottom ash in large quantities, it is thought that an improvement method in regards to strength has to be discussed such as incorporation of reinforcing materials and improvement of aggregate hardness.

  9. Chapter K: Progress in the Evaluation of Alkali-Aggregate Reaction in Concrete Construction in the Pacific Northwest, United States and Canada

    USGS Publications Warehouse

    Shrimer, Fred H.

    2005-01-01

    The supply of aggregates suitable for use in construction and maintenance of infrastructure in western North America is a continuing concern to the engineering and resources-management community. Steady population growth throughout the region has fueled demand for high-quality aggregates, in the face of rapid depletion of existing aggregate resources and slow and difficult permitting of new sources of traditional aggregate types. In addition to these challenges, the requirement for aggregates to meet various engineering standards continues to increase. In addition to their physical-mechanical properties, other performance characteristics of construction aggregates specifically depend on their mineralogy and texture. These properties can result in deleterious chemical reactions when aggregate is used in concrete mixes. When this chemical reaction-termed 'alkali-aggregate reaction' (AAR)-occurs, it can pose a major problem for concrete structures, reducing their service life and requiring expensive repair or even replacement of the concrete. AAR is thus to be avoided in order to promote the longevity of concrete structures and to ensure that public moneys invested in infrastructure are well spent. Because the AAR phenomenon is directly related to the mineral composition, texture, and petrogenesis of the rock particles that make up aggregates, an understanding of the relation between the geology and the performance of aggregates in concrete is important. In the Pacific Northwest, some aggregates have a moderate to high AAR potential, but many others have no or only a low AAR potential. Overall, AAR is not as widespread or serious a problem in the Pacific Northwest as in other regions of North America. The identification of reactive aggregates in the Pacific Northwest and the accurate prediction of their behavior in concrete continue to present challenges for the assessment and management of geologic resources to the owners and operators of pits and quarries and to the

  10. Hybrid Cross-Linked Lipase Aggregates with Magnetic Nanoparticles: A Robust and Recyclable Biocatalysis for the Epoxidation of Oleic Acid.

    PubMed

    Cui, Jiandong; Cui, Lili; Jia, Shiru; Su, Zhiguo; Zhang, Songping

    2016-09-28

    Highly stable and easily recyclable hybrid magnetic cross-linked lipase aggregates (HM-CSL-CLEAs) were prepared by coaggregation of lipase aggregates with nonfunctionalized magnetic nanoparticles and subsequent chemical cross-linking with glutaraldehyde. Analysis by SEM and CLSM indicated that the CLEAs were embedded in nanoparticle aggregates instead of covalently immobilized. The resulting HM-CSL-CLEAs exhibited higher thermostability, storage stability, and reusability than standard CLEAs. For example, HM-CSL-CLEAs maintained >60% of their initial activity after 40 min of incubation at 60 °C, whereas standard CLEAs lost most of their activities. The HM-CSL-CLEAs can be easily recovered from the reaction mixture by an external magnetic field. Moreover, the H2O2 tolerance of the lipase in HM-CSL-CLEAs was also enhanced, which could relieve the inhibitory effect on lipase activity. A high conversion yield (55%) for the epoxidation of oleic acid using H2O2 as oxidizing agent was achieved by HM-CSL-CLEAs.

  11. Rice-husk ash paste and concrete: Some aspects of hydration and the microstructure of the interfacial zone between the aggregate and paste

    SciTech Connect

    Zhang, M.H.; Lastra, R.; Malhotra, V.M.

    1996-06-01

    This paper presents an experimental study on the effects of the incorporation of rice-husk ash (RHA) in cement paste and concrete on the hydration and the microstructure of the interfacial zone between the aggregate and paste. The influence on the compressive strength of concrete is discussed, and the results are compared with those obtained with the control portland cement concrete and concrete incorporating silica fume. As for ordinary portland cement paste, it was found that calcium hydroxide and calcium silicate hydrates [C-S-H] were the major hydration and reaction products for the HA paste. Because of the pozzolanic reaction, the paste incorporating RHA had lower Ca(OH){sub 2} content than the control portland cement paste. The incorporation of the RHA in concrete reduced its porosity and the Ca(OH){sub 2} amount in the interfacial zone; the width of the interfacial zone between the aggregate and the cement paste was also reduced compared with the control portland cement composite. However, the porosity in the interfacial zone of the rice-husk ash composite was higher than that of the silica fume composite. The incorporation of the RHA in the cement paste did not increase its compressive strength compared with that of the control. The higher compressive strength of the RHA concrete compared with that of the control is due probably to the reduced porosity, reduced Ca(OH){sub 2}, and reduced width of the interfacial zone between the paste and the aggregate.

  12. 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.

  13. 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

  14. A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate

    PubMed Central

    Sekaran, Alan; Palaniswamy, Murthi; Balaraju, Sivagnanaprakash

    2015-01-01

    Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i) Mix A, conventional concrete mix with no material substitution, (ii) Mix B, 30% replacement of cement with fly ash, and (iii) Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C) had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications. PMID:26421315

  15. Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

    SciTech Connect

    Rodrigues, A.; Duchesne, J.; Fournier, B.; Durand, B.; Rivard, P.; Shehata, M.

    2012-10-15

    Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivieres area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damaged concrete include 'rust' mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH{sub 2}O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.

  16. A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate.

    PubMed

    Sekaran, Alan; Palaniswamy, Murthi; Balaraju, Sivagnanaprakash

    2015-01-01

    Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i) Mix A, conventional concrete mix with no material substitution, (ii) Mix B, 30% replacement of cement with fly ash, and (iii) Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C) had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications.

  17. The influence of coarse aggregate size and volume on the fracture behavior and brittleness of self-compacting concrete

    SciTech Connect

    Beygi, Morteza H.A.; Kazemi, Mohammad Taghi; Nikbin, Iman M.; Vaseghi Amiri, Javad; Rabbanifar, Saeed; Rahmani, Ebrahim

    2014-12-15

    This paper presents the results of an experimental investigation on fracture characteristics and brittleness of self-compacting concrete (SCC), involving the tests of 185 three point bending beams with different coarse aggregate size and content. Generally, the parameters were analyzed by the work of fracture method (WFM) and the size effect method (SEM). The results showed that with increase of size and content of coarse aggregate, (a) the fracture energy increases which is due to the change in fractal dimensions, (b) behavior of SCC beams approaches strength criterion, (c) characteristic length, which is deemed as an index of brittleness, increases linearly. It was found with decrease of w/c ratio that fracture energy increases which may be explained by the improvement in structure of aggregate-paste transition zone. Also, the results showed that there is a correlation between the fracture energy measured by WFM (G{sub F}) and the value measured through SEM (G{sub f}) (G{sub F} = 3.11G{sub f})

  18. Recycled rubber, aggregate, and filler in asphalt paving mixtures. Transportation research record

    SciTech Connect

    1996-12-31

    ;Contents(Partial): Evaluation Systems for Crumb Rubber Modified Binders and Mixtures; Hot Mix Asphalt Rubber Applications in Virginia; Evaluation of Pyrolized Carbon Black from Scrap Tires as Additive in Hot Mix Asphalt; Use of Scrap Tire Chips in Asphaltic Membrane; Effects of Mineral Fillers on Properties of Stone Matrix Asphalt Mixtures; and Quantitative Analysis of Aggregate Based on Hough Transform.

  19. Evaluation of steel slag coarse aggregate in hot mix asphalt concrete.

    PubMed

    Ahmedzade, Perviz; Sengoz, Burak

    2009-06-15

    This paper presents the influences of the utilization of steel slag as a coarse aggregate on the properties of hot mix asphalt. Four different asphalt mixtures containing two types of asphalt cement (AC-5; AC-10) and coarse aggregate (limestone; steel slag) were used to prepare Marshall specimens and to determine optimum bitumen content. Mechanical characteristics of all mixtures were evaluated by Marshall stability, indirect tensile stiffness modulus, creep stiffness, and indirect tensile strength tests. The electrical sensitivity of the specimens were also investigated in accordance with ASTM D257-91. It was observed that steel slag used as a coarse aggregate improved the mechanical properties of asphalt mixtures. Moreover, volume resistivity values demonstrated that the electrical conductivity of steel slag mixtures were better than that of limestone mixtures.

  20. Use of crushed concrete products in Minnesota pavement foundations. Final report, 1987-1994

    SciTech Connect

    Synder, M.B.

    1995-03-01

    The report reviews eleven field and laboratory studies that have been performed to address concerns about the use of recycled concrete aggregate in pavement foundations. Performance concerns have centered on the possible impairment of drainage systems by deposits of calcium carbonate precipitate and other fines derived from the recycled concrete base materials. Environmental concerns have focused on the relatively high pH of the effluent produced by drainage systems that remove water from ungreated recycled concrete aggregate foundation layers. The studies considered in the report demonstrate that all recycled concrete aggregates are capable of producing various amounts of precipitate, with the precipitate potential being directly related to the amount of freshly exposed cement mortar surface. It appears that selective grading and blending with virgin aggregates are techniques that should significantly reduce precipitate potential. One study suggests that washing recycled concrete products will reduce accumulations of crusher dust and other fines in and around the pavement drains. Others indicate that the use of filter fabrics with sufficiently high initial permittivity will allow the accumulation of precipitate and other fines without significant impairing drainage function. The report discusses study results related to environmental concerns and provides recommendations for revisions to current specifications.

  1. Pavement recycling catching on

    SciTech Connect

    Dallaire, G.

    1980-11-01

    The soaring costs of asphalt, aggregates, energy, and labor have revived interest in the recycling of old pavements and road bases. Two types of techniqueshot mix recycling and cold mix recycling are described and compared. The experiences of Wisconsin and Texas with pavement recycling are reviewed. Wisconsin uses the hot mix recycling, while Texas refurbishes its roads with the cold mix recycling. One contractor's doubts about surface recycling of pavements are outlined. (13 photos)

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

    PubMed

    Collivignarelli, Carlo; Sorlini, Sabrina

    2002-01-01

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

  3. Electric conductivity and aggregation of anthracite and graphite particles in concretes

    SciTech Connect

    E.A. Fanina; A.N. Lopanov

    2009-02-15

    A statistical model of the electric conductivity of a heterogeneous system based on coal and a binding agent is presented. In this system, a conductive phase appears because of particle aggregation. The model was tested in the systems of anthracite and graphite in cement stone. The consistency between the experimental and calculated electric conductivities with a correlation coefficient higher than 0.9 was found on a linear interpolation of model parameters. It was found that the presence of a surfactant (cetylpyridinium chloride) and a high-molecular-weight compound (polyvinyl acetate) changed the number of particles in anthracite and graphite aggregates to affect the specific conductivity of the heterogeneous system. 9 refs., 5 figs., 1 tab.

  4. 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.

  5. Sustainable approach for recycling waste lamb and chicken bones for fluoride removal from water followed by reusing fluoride-bearing waste in concrete.

    PubMed

    Ismail, Zainab Z; AbdelKareem, Hala N

    2015-11-01

    Sustainable management of waste materials is an attractive approach for modern societies. In this study, recycling of raw waste lamb and chicken bones for defluoridation of water has been estimated. The effects of several experimental parameters including contact time, pH, bone dose, fluoride initial concentration, bone grains size, agitation rate, and the effect of co-existing anions in actual samples of wastewater were studied for fluoride removal from aqueous solutions. Results indicated excellent fluoride removal efficiency up to 99.4% and 99.8% using lamb and chicken bones, respectively at fluoride initial concentration of 10 mg F/L and 120 min contact time. Maximum fluoride uptake was obtained at neutral pH range 6-7. Fluoride removal kinetic was well described by the pseudo-second order kinetic model. Both, Langmuir and Freundlich isotherm models could fit the experimental data well with correlation coefficient values >0.99 suggesting favorable conditions of the process. Furthermore, for complete sustainable management of waste bones, the resulted fluoride-bearing sludge was reused in concrete mixes to partially replace sand. Tests of the mechanical properties of fluoride sludge-modified concrete mixes indicated a potential environmentally friendly approach to dispose fluoride sludge in concrete and simultaneously enhance concrete properties.

  6. Hanford recycling

    SciTech Connect

    Leonard, I.M.

    1996-09-01

    This paper is a study of the past and present recycling efforts on the Hanford site and options for future improvements in the recycling program. Until 1996, recycling goals were voluntarily set by the waste generators: this year, DOE has imposed goals for all its sites to accomplish by 1999. Hanford is presently meeting the voluntary site goals, but may not be able to meet all the new DOE goals without changes to the program. Most of these new DOE goals are recycling goals: * Reduce the generation of radioactive (low-level) waste from routine operations 50 percent through source reduction and recycling. * Reduce the generation of low-level mixed waste from routine operations 50 percent through source reduction and recycling. * Reduce the generation of hazardous waste from routine operations 50 percent through source reduction and recycling. * Recycle 33 percent of the sanitary waste from all operations. * Increase affirmative procurement of EPA-designated recycled items to 100 percent. The Hanford recycling program has made great strides-there has been a 98 percent increase in the amount of paper recycled since its inception in 1990. Hanford recycles paper, chemicals cardboard, tires, oil, batteries, rags, lead weights, fluorescent tubes, aerosol products, concrete, office furniture, computer software, drums, toner cartridges, and scrap metal. Many other items are recycled or reused by individual groups on a one time basis without a formal contract. Several contracts are closed-loop contracts which involve all parts of the recycle loop. Considerable savings are generated from recycling, and much more is possible with increased attention and improvements to this program. General methods for improving the recycling program to ensure that the new goals can be met are: a Contract and financial changes 0 Tracking database and methods improvements 0 Expanded recycling efforts. Specifically, the Hanford recycling program would be improved by: 0 Establishing one overall

  7. Efficient transformation of grease to biodiesel using highly active and easily recyclable magnetic nanobiocatalyst aggregates.

    PubMed

    Ngo, Thao P N; Li, Aitao; Tiew, Kang W; Li, Zhi

    2013-10-01

    Green and efficient production of biodiesel (FAME) from waste grease containing high amount of free fatty acid (FFA) was achieved by using novel magnetic nanobiocatalyst aggregates (MNA). Thermomyces lanuginosus Lipase (TLL) and Candida antarctica Lipase B (CALB) were covalently immobilized on core-shell structured iron oxide magnetic nanoparticle (80 nm), respectively, followed by freeze-dry to give MNA (13-17 μm) with high yield (80-89%) and high enzyme loading (61 mg TLL or 22 mg CALB per gram MNA). MNA TL showed the best performance among immobilized enzymes known thus for the production of FAME from grease (17 wt.% FFA) with methanol, giving 99% yield in 12 h (3.3 wt.% catalyst). MNA TL was easily separated under magnetic field and reused, retaining 88% productivity in 11th cycle. MNA CA converted >97% FFA in grease (17 wt.% FFA) to FAME in 12 h (0.45 wt.% catalyst), being useful in two-step transformation of grease to biodiesel.

  8. The Value Compressive Strength and Split Tensile Strength on Concrete Mixture With Expanded Polystyrene Coated by Surfactant Span 80 as a Partial Substitution of Fine Aggregate

    NASA Astrophysics Data System (ADS)

    Hidayat, Irpan; Siauwantara, Alice

    2014-03-01

    The value of the density normal concrete which ranges between 2200-2400 kg/m3. Therefore the use of Expanded Polystyrene (EPS) as a subitute to fine aggregate can reduce the density of concrete. The purpose this research is to reduce the density of normal concrete but increase compressive strength of EPS concrete, with use surfactant as coating for the EPS. Variables of substitution percentage of EPS and EPS coated by surfactant are 5%,10%,15%,20%,25%. Method of concrete mix design based on SNI 03-2834-2000 "Tata Cara Pembuatan Rencana Campuran Beton Normal (Provisions for Proportioning Normal Concrete Mixture)". The result of testing, every increase percentage of EPS substitution will decrease the compressive strength around 1,74 MPa and decrease density 34,03 kg/m3. Using Surfactant as coating of EPS , compressive strength increase from the EPS's compressive strength. Average of increasing compressive strength 0,19 MPa and increase the density 20,03 kg/m3,average decrease of the tensile split strength EPS coated surfaktan is 0,84 MPa.

  9. PREPACKED CONCRETE.

    DTIC Science & Technology

    Twenty four hardened plain concrete wallettes , each 31 in. high by 25 in. wide by 6 in. thick, were sawed into various rectangular parallelepipeds...The wallettes represented three groups of prepacked concrete: reference aggregate intruded with fresh-water grout, coral aggregate with fresh-water...prismatic test specimens were involved in the program for determining the effectsof: type of mixing water, type of wiremesh cover atop the wallette form

  10. Evaluation of laboratory test method for determining the potential alkali contribution from aggregate and the ASR safety of the Three-Gorges dam concrete

    SciTech Connect

    Lu Duyou . E-mail: duyoulu@njut.edu.cn; Zhou, Xiaoling; Xu Zhongzi; Lan Xianghui; Tang Mingshu; Fournier, Benoit

    2006-06-15

    The releasable alkali from granite, which was used in the Three-Gorges concrete dam project in China, and from gneiss and feldspar was estimated by extraction in distilled water and super-saturated Ca(OH){sub 2} solution. Results show that: i) the finer the particles and the higher the temperature, the greater and faster the release of alkali; ii) compared with extraction by distilled water, super-saturated Ca(OH){sub 2} solution had a stronger activation on feldspar than on granite and gneiss; iii) for the three rocks tested, thermal activation had the largest effect on gneiss and a lower and similar effect on granite and feldspar. For very fine particles, temperature had a similar effect on the release of alkali by all three rocks. Because the aggregate used in the Three-Gorges dam concrete is non-reactive and a low calcium fly ash was used in the concrete, ASR would not be an issue for the dam, despite the release of alkali from the aggregate into the concrete.

  11. 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.

  12. SUSTAINABLE CONCRETE FOR WIND TURBINE FOUNDATIONS.

    SciTech Connect

    BERNDT,M.L.

    2004-06-01

    The use of wind power to generate electricity continues to grow, especially given commitments by various countries throughout the world to ensure that a significant percentage of energy comes from renewable sources. In order to meet such objectives, increasingly larger turbines with higher capacity are being developed. The engineering aspects of larger turbine development tend to focus on design and materials for blades and towers. However, foundations are also a critical component of large wind turbines and represent a significant cost of wind energy projects. Ongoing wind research at BNL is examining two areas: (a) structural response analysis of wind turbine-tower-foundation systems and (b) materials engineering of foundations. This work is investigating the dynamic interactions in wind turbine systems, which in turn assists the wind industry in achieving improved reliability and more cost efficient foundation designs. The results reported herein cover initial studies of concrete mix designs for large wind turbine foundations and how these may be tailored to reduce cost and incorporate sustainability and life cycle concepts. The approach taken was to investigate material substitutions so that the environmental, energy and CO{sub 2}-impact of concrete could be reduced. The use of high volumes of ''waste'' materials in concrete was examined. These materials included fly ash, blast furnace slag and recycled concrete aggregate. In addition, the use of steel fiber reinforcement as a means to improve mechanical properties and potentially reduce the amount of bar reinforcement in concrete foundations was studied. Four basic mixes were considered. These were: (1) conventional mix with no material substitutions, (2) 50% replacement of cement with fly ash, (3) 50% replacement of cement with blast furnace slag and (4) 25% replacement of cement with fly ash and 25% replacement with blast furnace slag. Variations on these mixes included the addition of 1% by volume steel

  13. Use of selected waste materials in concrete mixes.

    PubMed

    Batayneh, Malek; Marie, Iqbal; Asi, Ibrahim

    2007-01-01

    A modern lifestyle, alongside the advancement of technology has led to an increase in the amount and type of waste being generated, leading to a waste disposal crisis. This study tackles the problem of the waste that is generated from construction fields, such as demolished concrete, glass, and plastic. In order to dispose of or at least reduce the accumulation of certain kinds of waste, it has been suggested to reuse some of these waste materials to substitute a percentage of the primary materials used in the ordinary portland cement concrete (OPC). The waste materials considered to be recycled in this study consist of glass, plastics, and demolished concrete. Such recycling not only helps conserve natural resources, but also helps solve a growing waste disposal crisis. Ground plastics and glass were used to replace up to 20% of fine aggregates in concrete mixes, while crushed concrete was used to replace up to 20% of coarse aggregates. To evaluate these replacements on the properties of the OPC mixes, a number of laboratory tests were carried out. These tests included workability, unit weight, compressive strength, flexural strength, and indirect tensile strength (splitting). The main findings of this investigation revealed that the three types of waste materials could be reused successfully as partial substitutes for sand or coarse aggregates in concrete mixtures.

  14. Use of selected waste materials in concrete mixes

    SciTech Connect

    Batayneh, Malek Marie, Iqbal; Asi, Ibrahim

    2007-07-01

    A modern lifestyle, alongside the advancement of technology has led to an increase in the amount and type of waste being generated, leading to a waste disposal crisis. This study tackles the problem of the waste that is generated from construction fields, such as demolished concrete, glass, and plastic. In order to dispose of or at least reduce the accumulation of certain kinds of waste, it has been suggested to reuse some of these waste materials to substitute a percentage of the primary materials used in the ordinary portland cement concrete (OPC). The waste materials considered to be recycled in this study consist of glass, plastics, and demolished concrete. Such recycling not only helps conserve natural resources, but also helps solve a growing waste disposal crisis. Ground plastics and glass were used to replace up to 20% of fine aggregates in concrete mixes, while crushed concrete was used to replace up to 20% of coarse aggregates. To evaluate these replacements on the properties of the OPC mixes, a number of laboratory tests were carried out. These tests included workability, unit weight, compressive strength, flexural strength, and indirect tensile strength (splitting). The main findings of this investigation revealed that the three types of waste materials could be reused successfully as partial substitutes for sand or coarse aggregates in concrete mixtures.

  15. Performance of Lightweight Concrete based on Granulated Foamglass

    NASA Astrophysics Data System (ADS)

    Popov, M.; Zakrevskaya, L.; Vaganov, V.; Hempel, S.; Mechtcherine, V.

    2015-11-01

    The paper presents an investigation of lightweight concretes properties, based on granulated foamglass (GFG-LWC) aggregates. The application of granulated foamglass (GFG) in concrete might significantly reduce the volume of waste glass and enhance the recycling industry in order to improve environmental performance. The conducted experiments showed high strength and thermal properties for GFG-LWC. However, the use of GFG in concrete is associated with the risk of harmful alkali-silica reactions (ASR). Thus, one of the main aims was to study ASR manifestation in GFG-LWC. It was found that the lightweight concrete based on porous aggregates, and ordinary concrete, have different a mechanism of ASR. In GFG-LWC, microstructural changes, partial destruction of granules, and accumulation of silica hydro-gel in pores were observed. According to the existing methods of analysis of ASR manifestation in concrete, sample expansion was measured, however, this method was found to be not appropriate to indicate ASR in concrete with porous aggregates. Microstructural analysis and testing of the concrete strength are needed to evaluate the damage degree due to ASR. Low-alkali cement and various pozzolanic additives as preventive measures against ASR were chosen. The final composition of the GFG-LWC provides very good characteristics with respect to compressive strength, thermal conductivity and durability. On the whole, the potential for GFG-LWC has been identified.

  16. Organic compounds in concrete from demolition works.

    PubMed

    Van Praagh, M; Modin, H; Trygg, J

    2015-11-01

    This study aims to verify the effect of physically removing the outer surface of contaminated concrete on total contents and on potential mobility of pollutants by means of leaching tests. Reclaimed concrete from 3 industrial sites in Sweden were included: A tar impregnated military storage, a military tar track-depot, as well as concrete constructions used for disposing of pesticide production surplus and residues. Solid materials and leachates from batch and column leaching tests were analysed for metals, Cl, F, SO4, DOC and contents of suspected organic compounds (polycyclic aromatic hydrocarbons, PAH, and pesticides/substances for pesticide production such as phenoxy acids, chlorophenols and chlorocresols, respectively). In case of PAH contaminated concrete, results indicate that removing 1 or 5 mm of the surface lead to total concentrations below the Swedish guidelines for recycling of aggregates and soil in groundwork constructions. 3 out of 4 concrete samples contaminated with pesticides fulfilled Swedish guidelines for contaminated soil. Results from batch and column leaching tests indicated, however, that concentrations above environmental quality standards for certain PAH and phenoxy acids, respectively, might occur at site when the crushed concrete is recycled in groundwork constructions. As leaching tests engaged in the study deviated from leaching test standards with a limited number of samples, the potential impact of the leaching tests' equipment on measured PAH and pesticide leachate concentrations has to be evaluated in future work.

  17. System Chemistry to Control Potential Environmental and Safety Hazards of Recycled Concrete Aggregate With Lead-Based Paint

    DTIC Science & Technology

    2010-01-01

    microwave digestion procedure in which nitric acid, hydrogen peroxide, and hydrofluoric acid were used. This modified microwave digestion procedure is...30 minutes and stirred for 5 minutes with a glass-stirring rod. A nitric acid microwave (Milestone, Model Ethos, Monroe, CT) digestion procedure...of heavy metals. However, the degree of mobility varies by specie, e.g., cobalt, zinc, cadmium, nickel are more mobile in an acid environ- ment. Lead

  18. Impulse-response testing to evaluate the degree of alkali-aggregate reaction in concrete drilled-shaft foundations for electricity transmission towers

    NASA Astrophysics Data System (ADS)

    Davis, Allen; Kennedy, James

    1998-03-01

    Alkali-aggregate reaction (AAR) has affected the concrete in drilled shafts (cast in place piles) beneath electricity transmission towers along a 42-mile (67 km) section of transmission line in Southern California. In order to prioritize the maintenance program for these shafts, a nondestructive test methodology was sought to quantify the severity of the AAR with depth in each shaft. Shaft diameters of 19, 30, 36, 42, and 54 inches (475, 760, 910, 1067 and 1660 mm) were present, with shaft lengths between 10 and 30 feet (3 and 6 m). Over the last thirty years, impulse-response (I-R) testing has been successfully used to evaluate the integrity of drilled shafts, and computer simulation programs have also been developed for matching I-R test responses with theoretical shaft shapes and concrete quality. A program to test as many shafts as could be accessed in the difficult, mountainous terrain along this transmission line included mobilization of equipment and testing personnel by helicopter. Two hundred ten shafts were tested along the line in five days. Matching of test response mobility-frequency plots in computer simulation was achieved by varying the simulated concrete modulus and density, as well as the shaft cross section area. Up to three grades of concrete quality were identified in each shaft, representing the decreasing degree of AAR with depth. The tested shafts were then rated for increasing AAR severity, in order to select shafts for repair or replacement.

  19. Creep in Prestressed Concrete Piles: A Comparison of the Direct Solution Method, the Incremental Time Step Method, and the Curve Fitted Equation Method of Calculating Time Dependent Losses in Hawaiian Aggregate Prestressed Concrete Piles.

    DTIC Science & Technology

    1987-05-01

    and cement content. CFsh ,cc CFsh ,s CFsh ,fa CFsh ,c Eq 4.15 where CF sh shrinkage correction sh,cc factor for concrete composition CFsh s = ?hrnkage...correction act or r slump CFsh fa = shrinka e correction ’ factor for percentage of fine aggregate CFsh ,c = shrinkage correction factor for cement...content. [10] The shrinkage correction factor for slump is: CFshs 0.89 + 0.041 s [10] Eq 4.16 For a six inch slump, the shrinkage correction factor is

  20. Geoenvironmental and engineering properties of rock, soil, and aggregate. Transportation research record

    SciTech Connect

    Not Available

    1992-01-01

    Partial Contents: Use of Waste Materials in Highway Construction: State of the Practice and Evaluation of the Selected Waste Products; Physical and Environmental Properties of Asphalt-Amended Bottom Ash; Use of Cement Kiln Dust, Fly Ash, and Recycling Technique in Low-Volume Road Rehabilitation; Use of By-Product Phosphogypsum in Road Construction; Stabilization of Water Treatment Plant Sludge for Possible Use as Embankment Material; Construction and Performance of a Shredded Waste Tire Test Embankment; Corrosion of Steel Piles in Some Waste Fills; Recycled Plastics for Highway Agencies; Effect of Chloride and Sulfate Contamination in Soils on Corrosion of Steel and Concrete; Permeability and Leaching Characteristics of Fly Ash Liner Materials; Evaluation of Recycled Concrete, Open-Graded Aggregate, and Large Top-Size Aggregate Bases; Engineering Properties of Phosphogypsum-Based Slag Aggregate.

  1. 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.

  2. shRNA-Based Screen Identifies Endocytic Recycling Pathway Components That Act as Genetic Modifiers of Alpha-Synuclein Aggregation, Secretion and Toxicity

    PubMed Central

    Macedo, Diana; Raquel, Helena; Simões, Pedro D.; Giorgini, Flaviano; Ramalho, José S.; Barral, Duarte C.; Ferreira Moita, Luís; Outeiro, Tiago Fleming

    2016-01-01

    Alpha-Synuclein (aSyn) misfolding and aggregation is common in several neurodegenerative diseases, including Parkinson’s disease and dementia with Lewy bodies, which are known as synucleinopathies. Accumulating evidence suggests that secretion and cell-to-cell trafficking of pathological forms of aSyn may explain the typical patterns of disease progression. However, the molecular mechanisms controlling aSyn aggregation and spreading of pathology are still elusive. In order to obtain unbiased information about the molecular regulators of aSyn oligomerization, we performed a microscopy-based large-scale RNAi screen in living cells. Interestingly, we identified nine Rab GTPase and kinase genes that modulated aSyn aggregation, toxicity and levels. From those, Rab8b, Rab11a, Rab13 and Slp5 were able to promote the clearance of aSyn inclusions and rescue aSyn induced toxicity. Furthermore, we found that endocytic recycling and secretion of aSyn was enhanced upon Rab11a and Rab13 expression in cells accumulating aSyn inclusions. Overall, our study resulted in the identification of new molecular players involved in the aggregation, toxicity, and secretion of aSyn, opening novel avenues for our understanding of the molecular basis of synucleinopathies. PMID:27123591

  3. Influence of Elevated Temperatures on Pet-Concrete Properties

    NASA Astrophysics Data System (ADS)

    Albano, C.; Camacho, N.; Hernández, M.; Matheus, A.; Gutiérrez, A.

    2008-08-01

    Lightweight aggregate is an important material in reducing the unit weight of concrete complying with special concrete structures of large high-rise buildings. Besides, the use of recycled PET bottles as lightweight aggregate in concrete is an effective contribution for environment preservation. So, the objective of the present work was to study experimentally the flexural strength of the PET -concrete blends and the thermal degradation of the PET in the concrete, when the blends with 10 and 20% in volume of PET were exposed to different temperatures (200, 400, 600 °C). The flexural strength of concrete-PET exposed to a heat source is strongly dependent on the temperature, water/cement ratio, as well as the content and particle size of PET. However, the activation energy is affected by the temperature, location of the PET particles on the slabs and the water/cement ratio. Higher water content originates thermal and hydrolytic degradation on the PET, while on the concrete, a higher vapor pressure which causes an increase in crack formation. The values of the activation energy are higher on the center of the slabs than on the surface, since concrete is a poor heat conductor.

  4. Leaching behaviour of synthetic aggregates.

    PubMed

    van der Sloot, H A; Hoede, D; Cresswell, D J; Barton, J R

    2001-01-01

    In the framework of EU project "Utilising innovative kiln technology to recycle waste into synthetic aggregate" (BRST-CT98-5234), the leaching behaviour of synthetic aggregates has been studied to assess its environmental compatibility in the various stages of its use. Since the conditions are very different for the different uses, the assessment calls for a variety of different leaching conditions. The pH dependence test is used to cover important differences in pH environment to which the materials are exposed to as well as for an assessment of the buffering capacity of the material. Synthetic aggregate features a low buffer capacity, which makes it sensitive to externally imposed pH conditions. Utilisation and storage exposed to acidic conditions needs to be avoided. The results of the pH dependence test and column leaching test are mutually consistent. The CEN TC 154 method appears to provide systematically low values due to the arbitrary selection of test conditions. Synthetic aggregate studied to date will not adversely affect the concrete in its service life. The main issue for aggregate use is the recycling and the "end of life" condition, when the material becomes construction debris. Not metals, but oxyanions, such as Cr VI and Mo are most relevant under these conditions. A concise test has been applied to assess crucial aspects of leaching for different production mixes.

  5. Ash recycling - the coming of age!

    SciTech Connect

    Barnes, J.M.; Roffman, H.K.; Roethel, F.J.

    1997-12-01

    A major concern of the Waste-To-Energy (WTE) industry is ash disposal and the uncertainty of controlled long term ash management. Ash management costs have risen steadily over the last ten years making it the fastest rising cost segment of the WTE industry. The challenge of how to curb the rising cost while maintaining the protection of human health and the environment has been accomplished by responsibly recycling the ash on a commercial basis. American Ash Recycling Corp. (AAR), utilizing the Duos Engineering (USA), Inc. patent pending ash recycling technology, has promoted ash recycling on a commercial basis in the United States. An important product of the processing and recycling of non-hazardous municipal waste combustor (MWC) ash is Treated Ash Aggregate (TAA). Additionally, ferrous and non-ferrous metals are recovered and unburned materials removed and returned to the WTE facility for re-combustion. The TAA is sized and then treated by the WES-PHix{reg_sign} immobilization process in order to reduce the potential solubility and environmental availability of the metal constituents of the MWC ash. The TAA is available for commercial use in such applications as an aggregate substitute in roadway materials, asphalt and concrete applications, as structural fill, and as landfill cover. Commercial and technical considerations that must be addressed before ash can be beneficially recycled are: permitting requirements, physical and chemical characteristics, potential end uses, environmental concerns (product safety), product market development, and economic viability. True recycling only occurs if all of these considerations can be addressed. This paper presents the details of AAR`s most recent experience in the development of an ash recycling facility in the State of Maine and the associated beneficial use of the TAA product. Each of the considerations listed above are discussed with a special focus on the permitting process.

  6. Properties of Sulfur Concrete.

    DTIC Science & Technology

    1979-07-06

    This report summarizes the state of the art of sulfur concrete . Sulfur concrete is created by mixing molten sulfur with aggregate and allowing the...and many organic compounds. It works well as a rapid runway repair material. Sulfur concrete also has unfavorable properties. It has poor durability

  7. Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete.

    PubMed

    Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

    2016-03-07

    Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete.

  8. Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete

    PubMed Central

    Liu, Hanbing; Wang, Xianqiang; Jiao, Yubo; Sha, Tao

    2016-01-01

    Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete. PMID:28773298

  9. Characterization of cold recycled asphalt mixtures

    SciTech Connect

    Tia, M.

    1982-01-01

    In this study, the long-term behavior of the cold-recycled asphalt mixtures was investigated through nine experimental designs. The scope of the study covered two types of pavement material, three levels of oxydized condition of the old binder and one type of virgin aggregate. The added softening agents included a high-float asphalt emulsion AE-150, a foamed asphalt, and the rejuvenating agents, Reclamite, Mobilsol and DUTREX 739. The Water Sensitivity Test was used to evaluate the resistance of the recycled mixes to water. The results of the study indicated that most of the rejuvenating action of the added binder on the old binder took place during the compaction process. The binders of the recycled mixes which underwent the initial softening during the compaction process generally increased in stiffness with increasing curing time. The results indicated that the gyratory stability index and the gyratory elasto-plastic index could be used to determine the optimum binder content of a recycled mix. However, they could not be used to estimate the resilient modulus or the Marshall stability of the mix.A higher compactive effort generally produced a higher resilient modulus and Marshall stability of the recycled mix. When the binder content is too high, a higher compactive effort generally produces a lower Hveem R-value.The structural performance of these recycled mixes was compared to that of an asphalt concrete using a linear elastic multilayer analysis.

  10. Recycled brake linings as partial aggregate substitute in asphalt paving. Construction and final report. Report for July 1992-August 1996

    SciTech Connect

    Miller, P.A.; Sukley, R.

    1996-09-01

    The purpose of this project was to evaluate the performance of asphalt containing various percentages of brake lining as an aggregate, and compare its performance to that of normal asphalt containing natural aggregate. This project is an effort to explore alternate ways to use waste product. Four test section of FB-2 Modified mix containing brake lining materials were placed in July 1992 along with one control section on SR 3022 in Mercer county. To date all sections are performing satisfactory, and Brake linings should be recommended as a viable partial replacement of aggregate in bituminous materials. This study only considered the performance of only off-spec brake linings, therefore, any performance data or enviromental effects of placement of used brake material should be addressed.

  11. 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.

  12. Effect of microstructure on the mechanical and thermal properties of lightweight concrete prepared from clay, cement, and wood aggregates

    SciTech Connect

    Bouguerra, A.; Ledhem, A.; Barquin, F. de; Dheilly, R.M.; Queneudec, M.

    1998-08-01

    Wood concretes of a clayey matrix are considered herein from the standpoint of developing insulation materials through reliance on local resources and reusing industrial mineral wastes. Both the mechanical and thermal properties of these materials depend heavily on their microstructure and, in particular, on their porous structure which the authors have identified initially. An experimental study of the compression resistance as well as of the thermal conductivity in the dry state and at ambient temperature shows the changes in these characteristics as a function of porosity. A comparison with theoretical models previously tested for other types of cellular materials has served to validate its application in the case of wood concretes of a clayey matrix.

  13. Precast Concrete Pavements

    DTIC Science & Technology

    1981-11-01

    quirements. The concrete used low-weight sintered shale aggregate and high early-strength portland cement that obtained a 28-day compressive strength of...in- place concrete. Typical reasons suggested for precasting have included aggregate shortage, future pas.oment settlement or heaving, critical speed...pavements. Various devices such as dowel bars, tie bar, keyways, or aggregate interlock from sawn construction joints transfer a portion of the load

  14. Influence of the micro- and nanoscale local mechanical properties of the interfacial transition zone on impact behavior of concrete made with different aggregates

    SciTech Connect

    Erdem, Savas Dawson, Andrew Robert; Thom, Nicholas Howard

    2012-02-15

    The influence of the microscale local mechanical properties of the interfacial transition zone (ITZ) on macro-level mechanical response and impact behavior is studied for concretes made with copper slag and gravel aggregates. 3D nanotech vertical scanning interferometry, scanning electron microscopy coupled with energy dispersive X-ray micro-analysis, digital image analysis, and 3D X-ray computed tomography were used to characterize the microstructures and the ITZs. It was deduced that a stronger and denser ITZ in the copper slag specimen would reduce its vulnerability to stiffness loss and contribute to its elastic and more ductile response under impact loading. The analysis also indicated that a significant degeneration in the pore structure of the gravel specimen associated with a relatively weaker and non-homogeneous ITZ occurred under impact. Finally, it was also concluded that increased roughness of ITZ may contribute to the load-carrying capacity of concrete under impact by improving contact point interactions and energy dissipation.

  15. 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

  16. Recycling of paint-contaminated grit.

    PubMed

    Taha, R; al-Alawi, D; al-Nabhani, M; Pillay, A E; al-Hamdi, A

    2001-08-01

    The impact on the environment of using paint-contaminated grit (PCG) as a partial or full replacement for sand in Portland cement mortar and asphalt concrete mixtures was investigated. The grit waste material originated from abrasive blasting of offshore steel structures. There is a major environmental concern regarding the safe disposal of the spent blasting abrasives that contain paint chips or paint particles and other debris removed from the surface of the steel structures. This work investigated the potential reuse of PCG in Portland cement concrete (PCC) and hot mix asphalt concrete. Several studies were conducted to establish the integrity of the materials containing the recycled grit. These included the chemical and physical characterization of natural sand and PCG, the assay of leaches associated with the grit material for hazardous metal contaminants, such as Cr, Cd and Pb, and the assessment of the mechanical properties of the PCG-substituted mortars by applying special tests (such as Marshall stability and determination of the flow properties) to the PCG-substituted asphalt concrete mixtures. The overall results demonstrated that the potential reuse of PCG in PCC and asphalt concrete mixtures would not pose any environmental threat and could produce several benefits, such as reduced disposal costs, protection of water sources from improper disposal practices and reduced costs in the production of natural aggregates and asphalt cement.

  17. Promoting the use of crumb rubber concrete in developing countries.

    PubMed

    Batayneh, Malek K; Marie, Iqbal; Asi, Ibrahim

    2008-11-01

    The use of accumulated waste materials in third world countries is still in its early phases. It will take courage for contractors and others in the construction industry to recycle selected types of waste materials in the concrete mixes. This paper addresses the recycling of rubber tires accumulated every year in Jordan to be used in concrete mixes. The main objectives of this research were to provide more scientific evidence to support the use of legislation or incentive-based schemes to promote the reuse of accumulated waste tires. This research focused on using crumb tires as a replacement for a percentage of the local fine aggregates used in the concrete mixes in Jordan. Different concrete specimens were prepared and tested in terms of uniaxial compression and splitting tension. The main variable in the mixture was the volumetric percentage of crumb tires used in the mix. The test results showed that even though the compressive strength is reduced when using the crumb tires, it can meet the strength requirements of light weight concrete. In addition, test results and observations indicated that the addition of crumb rubber to the mix has a limited effect toward reducing the workability of the mixtures. The mechanical test results demonstrated that the tested specimens of the crumb rubber concrete remained relatively intact after failure compared to the conventional concrete specimens. It is also concluded that modified concrete would contribute to the disposal of the non-decaying scrap tires, since the amount being accumulated in third world countries is creating a challenge for proper disposal. Thus, obliging authorities to invest in facilitating the use of waste tires in concrete, a fundamental material to the booming construction industry in theses countries, serves two purposes.

  18. Maintenance and Preservation of Concrete Structures. Report 3. Abrasion-Erosion Resistance of Concrete.

    DTIC Science & Technology

    1980-07-01

    and polymer concrete ); seven aggregate types ( lime -’ stone, chert, trap rock, quartzite, granite, siliceous gravel, and slag); three .principal water...fiber- reinforced concrete , and polymer concrete ); seven aggregate types ( lime - stone, chert, trap rock, quartzite, granite, siliceous gravel, and slag...effect on the abrasion-erosion resistance of concrete that contains them. The abrasion-erosion loss of concrete containing lime - stone aggregate was

  19. Sustainable management and utilisation of concrete slurry waste: A case study in Hong Kong.

    PubMed

    Hossain, Md Uzzal; Xuan, Dongxing; Poon, Chi Sun

    2017-03-01

    With the promotion of environmental protection in the construction industry, the mission to achieve more sustainable use of resources during the production process of concrete is also becoming important. This study was conducted to assess the environmental sustainability of concrete slurry waste (CSW) management by life cycle assessment (LCA) techniques, with the aim of identifying a resource-efficient solution for utilisation of CSW in the production of partition wall blocks. CSW is the dewatered solid residues deposited in the sedimentation tank after washing out over-ordered/rejected fresh concrete and concrete trucks in concrete batching plants. The reuse of CSW as recycled aggregates or a cementitious binder for producing partition wall blocks, and the life cycle environmental impact of the blocks were assessed and compared with the conventional one designed with natural materials. The LCA results showed that the partition wall blocks prepared with fresh CSW and recycled concrete aggregates achieved higher sustainability as it consumed 59% lower energy, emitted 66% lower greenhouse gases, and produced lesser amount of other environmental impacts than that of the conventional one. When the mineral carbonation technology was further adopted for blocks curing using CO2, the global warming potential of the corresponding blocks production process was negligible, and hence the carbonated blocks may be considered as carbon neutral eco-product.

  20. 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.

  1. Recyclable Photo-Thermal Nano-Aggregates of Magnetic Nanoparticle Conjugated Gold Nanorods for Effective Pathogenic Bacteria Lysis.

    PubMed

    Ramasamy, Mohankandhasamy; Kim, Sanghyo; Lee, Su Seong; Yi, Dong Kee

    2016-01-01

    We describe the nucleophilic hybridization technique for fabricating magnetic nanoparticle (MNP) around gold nanorod (AuNR) for desired photo-thermal lysis on pathogenic bacteria. From the electromagnetic energy conversion into heat to the surrounding medium, a significant and quicker temperature rise was noted after light absorption on nanohybrids, at a controlled laser light output and optimum nanoparticle concentration. We observed a similar photo-thermal pattern for more than three times for the same material up on repeated magnetic separation. Regardless of the cell wall nature, superior pathogenic cell lysis has been observed for the bacteria suspensions of individual and mixed samples of Salmonella typhi (S.typhi) and Bacillus subtilis (B.subtilis) by the photo-heated nanoparticles. The synthesis of short gold nanorod, conjugation with magnetic nanoparticle and its subsequent laser exposure provides a rapid and reiterated photo-thermal effect with enhanced magnetic separation for efficient bactericidal application in water samples. Resultant novel properties of the nano-aggregates makes them a candidate to be used for a rapid, effective, and re-iterated photo-thermal agent against a wide variety of pathogens to attain microbe free water.

  2. Recyclable cross-linked laccase aggregates coupled to magnetic silica microbeads for elimination of pharmaceuticals from municipal wastewater.

    PubMed

    Arca-Ramos, A; Kumar, V V; Eibes, G; Moreira, M T; Cabana, H

    2016-05-01

    In the present work, the use of magnetic mesoporous silica microbeads (MMSMB) as supports was proposed to produce magnetically-separable cross-linked enzyme aggregates (MCLEAs). The effects of cross linking time, addition of bovine serum albumin as protein feeder, pH, glutaraldehyde concentration, and laccase:MMSMB mass ratio on the immobilization yield and enzyme load were investigated. The best conditions allowed the rapid preparation of MCLEAs with high enzyme load, i.e., 1.53 U laccase/mg MCLEAs. The stability of MCLEAs was improved with regard to low pH, presence of chemical denaturants, and real wastewater matrix, compared to free laccase. In addition, the novel biocatalyst exhibited good operational stability, maintaining up to 70 % of its initial activity after 10 successive batch reactions. Finally, MCLEAs demonstrated its catalytic potential to transform acetaminophen and various non-phenolic pharmaceutical active compounds as mefenamic acid, fenofibrate, and indomethacin from biologically treated wastewater effluent, with similar or even higher efficiency than free laccase.

  3. 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.

  4. Strengthening lightweight concrete

    NASA Technical Reports Server (NTRS)

    Auskern, A.

    1972-01-01

    Polymer absorption by lightweight concretes to improve bonding between cement and aggregate and to increase strength of cement is discussed. Compressive strength of treated cement is compared with strength of untreated product. Process for producing polymers is described.

  5. Corrosion-resistant sulfur concretes

    NASA Astrophysics Data System (ADS)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  6. Analysis of chromium and sulphate origins in construction recycled materials based on leaching test results.

    PubMed

    Del Rey, I; Ayuso, J; Galvín, A P; Jiménez, J R; López, M; García-Garrido, M L

    2015-12-01

    Twenty samples of recycled aggregates from construction and demolition waste (CDW) with different compositions collected at six recycling plants in the Andalusia region (south of Spain) were characterised according to the Landfill Directive criteria. Chromium and sulphate were identified as the most critical compounds in the leachates. To detect the sources of these two pollutant constituents in recycled aggregate, environmental assessments were performed on eight construction materials (five unused ceramic materials, two old crushed concretes and one new mortar manufactured in the laboratory). The results confirmed that leached sulphate and Cr were mainly released by the ceramic materials (bricks and tiles). To predict the toxicological consequences, the oxidation states of Cr (III) and Cr (VI) were measured in the leachates of recycled aggregates and ceramic materials classified as non-hazardous. The bricks and tiles mainly released total Cr as Cr (III). However, the recycled aggregates classified as non-hazardous according to the Landfill Directive criteria mainly released Cr (VI), which is highly leachable and extremely toxic. The obtained results highlight the need for legislation that distinguishes the oxidative state in which chromium is released into the environment. Leaching level regulations must not be based solely on total Cr, which can lead to inaccurate predictions.

  7. 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.

  8. 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.

  9. Physical and mechanical properties of carbon fiber reinforced smart porous concrete for planting

    NASA Astrophysics Data System (ADS)

    Park, Seung-Bum; Kim, Jung-Hwan; Seo, Dae-Seuk

    2005-05-01

    The reinforcement strength of porous concrete and its applicability as a recycled aggregate was measured. Changes in physical and mechanical properties, subsequent to the mixing of carbon fiber and silica fume, were examined, and the effect of recycled aggregate depending on their mixing rate was evaluated. The applicability of planting to concrete material was also assessed. The results showed that there were not any remarkable change in the porosity and strength characteristics although its proportion of recycled aggregate increased. Also, the mixture of 10% of silica was found to be most effective for strength enforcement. In case of carbon fiber, the highest flexural strength was obtained with its mixing rate being 3%. It was also noticed that PAN-derived carbon fiber was superior to Pitch-derived ones in view of strength. The evaluation of its use for vegetation proved that the growth of plants was directly affected by the existence of covering soil, in case of having the similar size of aggregate and void.

  10. How Concrete Is Concrete?

    ERIC Educational Resources Information Center

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  11. Construction aggregates

    USGS Publications Warehouse

    Nelson, T.I.; Bolen, W.P.

    2007-01-01

    Construction aggregates, primarily stone, sand and gravel, are recovered from widespread naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size and sold loose or combined with portland cement or asphaltic cement to make concrete products to build roads, houses, buildings, and other structures. Much smaller quantities are used in agriculture, cement manufacture, chemical and metallurgical processes, glass production and many other products.

  12. Production of lightweight aggregate from industrial waste and carbon dioxide.

    PubMed

    Gunning, Peter J; Hills, Colin D; Carey, Paula J

    2009-10-01

    The concomitant recycling of waste and carbon dioxide emissions is the subject of developing technology designed to close the industrial process loop and facilitate the bulk-re-use of waste in, for example, construction. The present work discusses a treatment step that employs accelerated carbonation to convert gaseous carbon dioxide into solid calcium carbonate through a reaction with industrial thermal residues. Treatment by accelerated carbonation enabled a synthetic aggregate to be made from thermal residues and waste quarry fines. The aggregates produced had a bulk density below 1000 kg/m(3) and a high water absorption capacity. Aggregate crushing strengths were between 30% and 90% stronger than the proprietary lightweight expanded clay aggregate available in the UK. Cast concrete blocks containing the carbonated aggregate achieve compressive strengths of 24 MPa, making them suitable for use with concrete exposed to non-aggressive service environments. The energy intensive firing and sintering processes traditionally required to produce lightweight aggregates can now be augmented by a cold-bonding, low energy method that contributes to the reduction of green house gases to the atmosphere.

  13. Proceedings of the waste recycling workshop

    SciTech Connect

    Bailey, R.E.; Thomas, A.F.; Ries, M.A.

    1993-12-31

    Recorded are seventeen talks from five sessions at the workshop. FERMCO`s recycling program, state of the art recycling technology, and an integrated demonstration of deactivation, decommissioning and decommissioning are presented in the plenary session. In the concrete session, decontamination and recycling are discussed. In the transite session, regulations are considered along with recycling and decontamination. In the metals session, radioactive scrap metals are emphasized. And in the regulatory considerations and liabilities session, DOE and EPA viewpoints are discussed. (GHH)

  14. Improving degradation resistance of sisal fiber in concrete through fiber surface treatment

    NASA Astrophysics Data System (ADS)

    Wei, Jianqiang; Meyer, Christian

    2014-01-01

    As part of an ongoing effort to improve the sustainability of reinforced concrete, recycled concrete aggregate is being considered together with natural fibers such as sisal fiber as replacement of synthetic reinforcement. Since natural fibers are known to undergo potential deterioration in the alkaline cement matrix especially in outdoor erosive environment, they need to be treated to improve their durability. This paper describes two such methods (thermal and Na2CO3 treatment) and evaluates their effects on the degradation resistance of sisal fiber and durability of sisal fiber-reinforced concrete with recycled concrete aggregate. Concrete specimens were subjected to cycles of wetting and drying to accelerate aging. The microstructure, tensile strength and Young's modulus of sisal fiber as well as the weight loss of the composite were evaluated. Of primary interest were the effects on compressive and splitting tensile strength of sisal fiber-reinforced concrete. Thermal treatment and Na2CO3 surface treatment were shown to improve the durability of the composite as measured by splitting tensile strength by 36.5% and 46.2% and the compressive strength by 31.1% and 45.4%, respectively. The mechanisms of these two treatment methods were also analyzed. The thermal treatment achieved improvement of cellulose's crystallization, which ensured the initial strength and improved durability of sisal fiber. A layer consisting of calcium carbonate sediments, which protects the internals of a fiber from the strong alkali solution formed in the cement hydration process, was formed and filled in pits and cavities on the Na2CO3 treated sisal fiber's surface to improve their corrosion resistance and durability and reduced the detrimental effects of Na+ ions on concrete.

  15. Lightweight polymer concrete composites

    SciTech Connect

    Fontana, J.J.; Steinberg, M.; Reams, W.

    1985-08-01

    Lightweight polymer concrete composites have been developed with excellent insulating properties. The composites consist of lightweight aggregates such as expanded perlites, multicellular glass nodules, or hollow alumina silicate microspheres bound together with unsaturated polyester or epoxy resins. These composites, known as Insulating Polymer Concrete (IPC), have thermal conductivites from 0.09 to 0.19 Btu/h-ft-/sup 0/F. Compressive strengths, dependent upon the aggregates used, range from 1000 to 6000 psi. These materials can be precast or cast-in-place on concrete substrates. Recently, it has been demonstrated that these materials can also be sprayed onto concrete and other substrates. An overlay application of IPC is currently under way as dike insulation at an LNG storage tank facility. The composites have numerous potentials in the construction industry such as insulating building blocks or prefabricated insulating wall panels.

  16. LENGTH CHANGE OF CONCRETE CONTAINING GLEN CANYON DAM AGGREGATE AND VARIOUS CEMENTS, POZZOLANS AND/OR A LIGNIN-TYPE RETARDING AGENT

    DTIC Science & Technology

    elastic properties, and length change, including autogeneous and drying shrinkage and expansion due to prolonged moist curing of Glen Canyon Dam concrete. Reported are the results of this investigation.

  17. Recycling endosomes

    PubMed Central

    Goldenring, James R

    2015-01-01

    The endosomal membrane recycling system represents a dynamic conduit for sorting and re-exporting internalized membrane constituents. The recycling system is composed of multiple tubulovesicular recycling pathways that likely confer distinct trafficking pathways for individual cargoes. In addition, elements of the recycling system are responsible for assembly and maintenance of apical membrane specializations including primary cilia and apical microvilli. The existence of multiple intersecting and diverging recycling tracks likely accounts for specificity in plasma membrane recycling trafficking. PMID:26022676

  18. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as to their capability to prevent or inhibit the attachment of marine fouling organisms to concrete for OTEC plants. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6-1/2 years in seawater.

  19. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as the their capability to prevent or inhibit the attachment of marine fouling organisms to concrete. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6 1/2 years in seawater.

  20. Concrete density estimation by rebound hammer method

    NASA Astrophysics Data System (ADS)

    Ismail, Mohamad Pauzi bin; Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri; Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin

    2016-01-01

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  1. Concrete density estimation by rebound hammer method

    SciTech Connect

    Ismail, Mohamad Pauzi bin Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri; Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin; Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin

    2016-01-22

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  2. MIX DESIGN FOR SMALL-SCALE MODELS OF CONCRETE STRUCTURES

    DTIC Science & Technology

    An easily applied method of mix design was developed for concretes suitable for use in small -scale models of concrete structures. By use of the...properties were collected for model concretes with portland cement and gypsum cement bases. These concretes had maximum aggregate sizes of No. 4...strength, the model concretes using approximately scaled aggregate were found to have about the same splitting-tensile strength and flexural strength, a

  3. Refractory concretes

    DOEpatents

    Holcombe, Jr., Cressie E.

    1979-01-01

    Novel concrete compositions comprise particles of aggregate material embedded in a cement matrix, said cement matrix produced by contacting an oxide selected from the group of Y.sub.2 O.sub.3, La.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Eu.sub.2 O.sub.3 and Gd.sub.2 O.sub.3 with an aqueous solution of a salt selected from the group of NH.sub.4 NO.sub.3, NH.sub.4 Cl, YCl.sub.3 and Mg(NO.sub.3).sub.2 to form a fluid mixture; and allowing the fluid mixture to harden.

  4. ASTM STANDARD GUIDE FOR EVALUATING DISPOSAL OPTIONS FOR REUSE OF CONCRETE FROM NUCLEAR FACILITY DECOMMISSIONING

    SciTech Connect

    Phillips, Ann Marie; Meservey, Richard H.

    2003-02-27

    Within the nuclear industry, many contaminated facilities that require decommissioning contain huge volumes of concrete. This concrete is generally disposed of as low-level waste at a high cost. Much of the concrete is lightly contaminated and could be reused as roadbed, fill material, or aggregate for new concrete, thus saving millions of dollars. However, because of the possibility of volumetric contamination and the lack of a method to evaluate the risks and costs of reusing concrete, reuse is rarely considered. To address this problem, Argonne National Laboratory-East (ANL-E) and the Idaho National Engineering and Environmental Laboratory teamed to write a ''concrete protocol'' to help evaluate the ramifications of reusing concrete within the U.S. Department of Energy (DOE). This document, titled the Protocol for Development of Authorized Release Limits for Concrete at U.S. Department of Energy Site (1) is based on ANL-E's previously developed scrap metal recycle protocols; on the 10-step method outlined in DOE's draft handbook, Controlling Release for Reuse or Recycle of Property Containing Residual Radioactive Material (2); and on DOE Order 4500.5, Radiation Protection of the Public and the Environment (3). The DOE concrete protocol was the basis for the ASTM Standard Guide for Evaluating Disposal Options for Concrete from Nuclear Facility Decommissioning, which was written to make the information available to a wider audience outside DOE. The resulting ASTM Standard Guide is a more concise version that can be used by the nuclear industry worldwide to evaluate the risks and costs of reusing concrete from nuclear facility decommissioning. The bulk of the ASTM Standard Guide focuses on evaluating the dose and cost for each disposal option. The user calculates these from the detailed formulas and tabulated data provided, then compares the dose and cost for each disposal option to select the best option that meets regulatory requirements. With this information

  5. Micromechanics of Concrete.

    DTIC Science & Technology

    1988-01-25

    reflects the dispersion of the coarse aggregates on the mesoscale. Specifically, the experimental measure- ments indicate ( Mindess and Young 1981, Zaitsev...Mecanique des Materiaux Solides, Dunod, Paris. Mindess , S. and J. Young (1981), Concrete, Prentice-Hall Inc., Englewood Cliffs, NJ. Mura, T. (1982

  6. High temperature polymer concrete

    DOEpatents

    Fontana, J.J.; Reams, W.

    1984-05-29

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system.

  7. Performance of "Waterless Concrete"

    NASA Technical Reports Server (NTRS)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  8. Preparation of low water-sorption lightweight aggregates from harbor sediment added with waste glass.

    PubMed

    Wei, Yu-Ling; Lin, Chang-Yuan; Ko, Kuan-Wei; Wang, H Paul

    2011-01-01

    A harbor sediment is successfully recycled at 1150 °C as low water-absorption lightweight aggregate via addition of waste glass powder. Sodium content in the waste glass is responsible for the formation of low-viscosity viscous phases during firing process to encapsulate the gases generated for bloating pellet samples. Water sorption capacity of the lightweight products can be considerably reduced from 5.6% to 1.5% with the addition of waste glass powder. Low water-absorption property of lightweight products is beneficial for preparing lightweight concrete because the water required for curing the cement would not be seized by lightweight aggregate filler, thus preventing the failure of long-term concrete strength.

  9. Resource recycling through artificial lightweight aggregates from sewage sludge and derived ash using boric acid flux to lower co-melting temperature.

    PubMed

    Hu, Shao-Hua; Hu, Shen-Chih; Fu, Yen-Pei

    2012-02-01

    This study focuses on artificial lightweight aggregates (ALWAs) formed from sewage sludge and ash at lowered co-melting temperatures using boric acid as the fluxing agent. The weight percentages of boric acid in the conditioned mixtures of sludge and ash were 13% and 22%, respectively. The ALWA derived from sewage sludge was synthesized under the following conditions: preheating at 400 degrees C 0.5 hr and a sintering temperature of 850 degrees C 1 hr. The analytical results of water adsorption, bulk density, apparent porosity, and compressive strength were 3.88%, 1.05 g/cm3, 3.93%, and 29.7 MPa, respectively. Scanning electron microscope (SEM) images of the ALWA show that the trends in water adsorption and apparent porosity were opposite to those of bulk density. This was due to the inner pores being sealed off by lower-melting-point material at the aggregates'surface. In the case of ash-derived aggregates, water adsorption, bulk density, apparent porosity, and compressive strength were 0.82%, 0.91 g/cm3, 0.82%, and 28.0 MPa, respectively. Both the sludge- and ash-derived aggregates meet the legal standards for ignition loss and soundness in Taiwan for construction or heat insulation materials.

  10. Effect of SiO2-Al2O3-flux ratio change on the bloating characteristics of lightweight aggregate material produced from recycled sewage sludge.

    PubMed

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

    2006-06-30

    This study investigates the characteristics of lightweight aggregates sintered from sewage sludge ash by modifying the proportion of the main components (SiO(2)-Al(2)O(3)-flux). The ash of incinerated sludge from a municipal sewage treatment plant (STP) was used as the tested material and sintering temperature ranged from 1050 to 1100 degrees C within a time span of 10-30min. The sludge ash appeared to have a high proportion of SiO(2) (44.89%), Al(2)O(3) (11.62%) and Fe(2)O(3) (6.81%) resembling the dilatable shale. When the sintering temperature was raised to above 1060 degrees C, the blowing phenomenon appeared. The aggregates become lighter in weight by prolonging the sintering time and raising the temperature. Cullet powder (amorphous SiO(2)), Al(2)O(3), and fly ash were added to sludge ash to analyse the characteristic changes of the aggregates. The results showed that amorphous SiO(2) lowered the melting point and increased foaming; Al(2)O(3) raised the compression resistance; fly ash lowered the sintering temperature required. However, the composition of fly ash can vary dramatically, resulting in a less predictable characteristic of aggregates.

  11. Refractory recycling

    SciTech Connect

    Oxnard, R.T. )

    1994-10-01

    Businesses are run by profit and opportunity. Businesses will not recycle or reduce waste unless it is profitable, mandatory or perceived to be either in the future. Pressure from investors, government, consumers and accountants will increase the importance of recycling of refractories. The history and trends of refractory recycling and a method for auditing waste is discussed in this article.

  12. 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.

  13. Recycled materials in asphalt pavements. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1995-03-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials for road construction. Citations discuss asphalt concrete mixtures and recycling, recycled materials testing and evaluation, and pavement bases. Engineering and environmental aspects of recycled materials are examined. (Contains a minimum of 78 citations and includes a subject term index and title list.)

  14. 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.

  15. Dual Thermoresponsive Aggregation of Schizophrenic PDMAEMA-b-PSBMA Copolymer with an Unrepeatable pH Response and a Recycled CO2/N2 Response.

    PubMed

    Sun, Hui; Chen, Xiaolu; Han, Xia; Liu, Honglai

    2017-03-14

    A dual thermoresponsive block copolymer of poly[2-(dimethylamino)ethyl methacrylate]-block-poly(sulfobetaine methacrylate) (PDMAEMA-b-PSBMA) exhibited reversible schizophrenic aggregation behavior in water because of the upper critical solution temperature (UCST) of the PSBMA block and the lower critical solution temperature (LCST) of the PDMAEMA block. Both the UCST and LCST shifted to lower values with increasing DMAEMA/SBMA block ratios, which was ascribed to the hydrophobic/hydrophilic balance of both blocks. Because of the salt-sensitive PSBMA and pH-responsive PDMAEMA, the UCST and LCST values of PDMAEMA-b-PSBMA were codetermined by varying the salt concentrations and pH. Specifically, increasing the salt concentration resulted in a notable decrease in the UCST and a slight increase in the LCST due to the salt-induced screening of the electrostatic attractions of the PSBMA and salt-enhanced solubility of the PSBMA blocks, respectively. The LCST decreased with increasing pH because of the deprotonation of PDMAEMA, and the UCST first increased and then decreased with increasing pH. Besides, the copolymer with larger PDMAEMA content was more sensitive to pH. For the repetitive adjustment to thermoresponsive aggregation, repeated addition of acids and bases induced salt accumulation and diminished the switchability of pH, whereas repeated switching cycles were achieved by CO2/N2 bubbling without introducing salt enrichment. The difference in HCl/NaOH titration and CO2/N2 bubbling also existed in the switching cycles when PDMAEMA-b-PSBMA served as a stimulus-responsive emulsifier.

  16. Application of granulated lead-zinc slag in concrete as an opportunity to save natural resources

    NASA Astrophysics Data System (ADS)

    Alwaeli, Mohamed

    2013-02-01

    The last decades marked a period of growth and prosperity in construction industry which involves the use of natural resources. This growth is jeopardized by the lack of natural resources that are available. On the other hand there has been rapid increase in the industrial waste production. Most of the waste do not find any effective use and cause a waste disposal crisis, thereby contributing to health and environmental problems. Recycling of industrial waste as aggregate is thus a logical option to manage this problem. The paper reports on some experimental results obtained from the production of concretes containing granulated slag of lead and zinc industry as sand replacement mixed in different proportions. Granulated slag is substituted for raw sand, partly or totally. Ratios of 25%, 50%, 75% and 100% by weight of sand are used. The effects of granulated lead-zinc slag (GLZS) as sand replacement material on the compressive strength and gamma radiation attenuation properties of concrete are investigated and analyzed. Then, these properties are compared with those of ordinary concrete. The results showed that replacement material have some effects on the compressive strength and gamma radiation properties of the concrete. The experimental results indicate that, the concrete mixed with GLZS as a sand replacement have better strength. Concerning the absorption properties for gamma radiation the data show that the addition of GLZS resulted in an increase of the attenuation of gamma radiation. Consequently, these concretes could be used for construction of shields protecting personnel who work in laboratories where radiation is used. Additionally, the thickness of the concrete with GLZS was calculated and compared with ordinary concrete.

  17. 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.

  18. Mechanics of Concrete II

    DTIC Science & Technology

    1990-10-18

    diffusivity of undamaged concrete is a problem in itself since the diffusivity of the thin transition zones (at the aggregate- cement matrix interface...C3A anhydride remains in the cement after the hydration. Assuming that the amount of gypsum added to portland cement3 clinker is 4% of Mcm (Biczok 1972...enables establishment of rational relationships between the chemical composition of the hardened cement paste, morphology of the pore system, and defect

  19. Environmental durability of polymer concrete

    SciTech Connect

    Palmese, G.R.; Chawalwala, A.J.

    1996-12-31

    Over the past two decades, polymer concrete has increasingly been used for a number of applications including piping, machine bases, chemically resistant flooring, and bridge overlays. Currently, the use of polymer concrete as a wear surface for polymeric composite bridge decks is being investigated. Polymer concrete is a particulate composite comprised of mineral aggregate bound by a polymeric matrix. Such materials possess significantly higher mechanical properties than Portland cement concrete. However, the mechanical characteristics and environmental durability of polymer concrete are influenced by a number of factors. Among these are the selection of aggregate and resin, surface treatment, and cure conditions. In this work the influence of matrix selection and cure history on the environmental durability of polymer concrete was investigated. Particular attention was given to the effects of water on composite properties and to the mechanisms by which degradation occurs. The basalt-based polymer concrete systems investigated were susceptible to attack by water. Furthermore, results suggest that property loss associated with water exposure was primarily a result of interfacial weakening.

  20. Beneficiation of natural aggregates by polymer impregnation

    SciTech Connect

    Webster, R.P.; Fontana, J.J.

    1980-09-01

    The use of polymer impregnation as a means of upgrading natural aggregates has been investigated. The effect of polymer impregnation on the physical and mechanical properties was evaluated in a series of tests performed using four aggregates of varying quality. The strength of concrete cast with polymer impregnated coarse aggregate was also tested. Two monomer systems were used in the investigation; a methyl methacrylate-based system and a styrene-based system. In general, significant improvements in the physical and mechanical properties of each of the four aggregates resulted from polymer impregnation. The strength of concrete cast with impregnated aggregates varied, being increased in some cases and decreased in others.

  1. 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

  2. Portland Cement Concrete Recycling: Technology Review.

    DTIC Science & Technology

    1982-01-01

    at the pavement surface. The mesh reinforcing was effectively broken. Conventional drophammers were used in low-clearance areas. Although much slower...meter (2 by 2 feet). A smaller drophammer was used to break the pavement over the drainage structures on the project. A backhoe with a wider than

  3. Evaluation and Repair of Concrete Slabs

    DTIC Science & Technology

    1992-01-01

    is duce a readily flowable concrete that is capable of listed in Table 1. completely filling the formed area. For large surface areas, it may be...Poor compaction, irregular surfaces, expansive soils , and the presence of mud or soft organic material can all result in a yielding subgrade. Again... fill all the spaces around the coarse aggregate. It is easily recognized by voids in the surface where the concrete appears as coarse aggregate

  4. Environmental performance, mechanical and microstructure analysis of concrete containing oil-based drilling cuttings pyrolysis residues of shale gas.

    PubMed

    Wang, Chao-Qiang; Lin, Xiao-Yan; He, Ming; Wang, Dan; Zhang, Si-Lan

    2017-09-15

    The overall objective of this research project is to investigate the feasibility of incorporating oil-based drilling cuttings pyrolysis residues (ODPR) and fly ash serve as replacements for fine aggregates and cementitious materials in concrete. Mechanical and physical properties, detailed environmental performances, and microstructure analysis were carried out. Meanwhile, the early hydration process and hydrated products of ODPR concrete were analyzed with X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results indicated that ODPR could not be categorize into hazardous wastes. ODPR had specific pozzolanic characteristic and the use of ODPR had certain influence on slump and compressive strength of concrete. The best workability and optimal compressive strength were achieved with the help of 35% ODPR. Environmental performance tests came to conclusion that ODPR as recycled aggregates and admixture for the preparation of concrete, from the technique perspective, were the substance of mere environmental contamination. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Recycled Glass and Dredged Materials

    DTIC Science & Technology

    2007-03-01

    soft drink, beer , food, wine, and liquor containers collected at residential curbside, drop boxes, trash barrels, deposit stations, or recycling...cullet (for new bottles and other containers) or non-container glass cullet (all other uses), and non-container processed cullet production is...crystal, porcelain, etc.), metal (from bottle caps), organics (from food, paper labels, etc.), and other inorganics (from soil, concrete, bricks, etc

  6. 8. Photocopied August 1978. BREAKING CONCRETE BARS, JULY 1898. TESTING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. Photocopied August 1978. BREAKING CONCRETE BARS, JULY 1898. TESTING MACHINE USED BY VON SCHON IN EXPERIMENTS ON METHODS OF MIXING CONCRETE AND ON CONCRETE AGGREGATES WHICH USED LOCAL MATERIALS. (4) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  7. Ideas: Recycling.

    ERIC Educational Resources Information Center

    Chessin, Debby A.; And Others

    1994-01-01

    Presents classroom ideas focusing on connections among mathematics, concern for the environment, and conservation of natural resources, including decomposition, water conservation, packaging materials, use of manufactured cans, and recycling. Includes reproducible student worksheets. (MKR)

  8. Durable fiber reinforced self-compacting concrete

    SciTech Connect

    Corinaldesi, V.; Moriconi, G

    2004-02-01

    In order to produce thin precast elements, a self-compacting concrete was prepared. When manufacturing these elements, homogenously dispersed steel fibers instead of ordinary steel-reinforcing mesh were added to the concrete mixture at a dosage of 10% by mass of cement. An adequate concrete strength class was achieved with a water to cement ratio of 0.40. Compression and flexure tests were carried out to assess the safety of these thin concrete elements. Moreover, serviceability aspects were taken into consideration. Firstly, drying shrinkage tests were carried out in order to evaluate the contribution of steel fibers in counteracting the high concrete strains due to a low aggregate-cement ratio. Secondly, the resistance to freezing and thawing cycles was investigated on concrete specimens in some cases superficially treated with a hydrophobic agent. Lastly, both carbonation and chloride penetration tests were carried out to assess durability behavior of this concrete mixture.

  9. Glass recycling

    SciTech Connect

    Dalmijn, W.L.; Houwelingen, J.A. van

    1995-12-31

    Glass recycling in the Netherlands has grown from 10,000 to 300,000 tonnes per annum. The various advantages and problems of the glass cycle with reference to the state of the art in the Netherlands is given. Special attention is given to new technologies for the automated sorting of cullet with detection systems. In Western Europe the recycling of glass has become a success story. Because of this, the percentage of glass cullet used in glass furnaces has increased. To meet the quality demands of the glass industry, automated sorting for the removal of stones, non-ferrous metals and other impurities had to be developed and incorporated in glass recycling plants. In Holland, Germany and other countries, the amount of glass collected has reached a level that color-sorting becomes necessary to avoid market saturation with mixed cullet. Recently, two systems for color-sorting have been developed and tested for the separation of bottles and cullet in the size range of 20--50 mm. With the increased capacity of the new glass recycling plants, 120,000--200,000 tpy, the quality systems have also to be improved and automated. These quality control systems are based on the automated sorting technology developed earlier for the glass recycling plants. The data obtained are automatically processed and printed. The sampling system and its relation to the theory of Gy will be described. Results of both developments in glass recycling plants will be described.

  10. High temperature polymer concrete compositions

    SciTech Connect

    Fontana, J.J.; Reams, W.

    1985-02-19

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers is a liquid system.

  11. Performance Evaluation of Concrete using Marble Mining Waste

    NASA Astrophysics Data System (ADS)

    Kore, Sudarshan Dattatraya; Vyas, A. K.

    2016-12-01

    A huge amount waste (approximately 60%) is generated during mining and processing in marble industries. Such waste can be best utilized in infrastructure development works. Coarse aggregate 75% by weight was replaced by aggregate obtained from marble mining waste. The impact of marble waste as a partial replacement for conventional coarse aggregate on the properties of concrete mixes such as workability, compressive strength, permeability, abrasion, etc. was evaluated. The test results revealed that the compressive strength was comparable to that of control concrete. Other properties such as workability of concrete increased, water absorption reduced by 17%, and resistance to abrasion was marginally increased by 2% as compared to that of control concrete. Ultrasonic pulse velocity and FTIR results show improvement in quality of concrete with crushed marble waste. From the TGA analysis it was confirmed that, aggregate produced from marble waste shows better performance under elevated temperature than that of conventional aggregates.

  12. Interactions of aqueous Cu2+, Zn2+ and Pb2+ ions with crushed concrete fines.

    PubMed

    Coleman, Nichola J; Lee, William E; Slipper, Ian J

    2005-05-20

    The crushing of reclaimed concrete-based demolition waste to produce recycled aggregate gives rise to a large volume of cement-rich fine material for which market development would be beneficial. It was envisaged that this fine fraction may prove to be an effective sorbent for aqueous heavy metal species by virtue of its ion exchangeable phases and high pH. A batch sorption study confirmed that crushed concrete, in the particle size range 1-2 mm, successfully excluded Cu2+ (35 mg g(-1)), Zn2+ (33 mg g(-1)) and Pb2+ (37 mg g(-1)) from aqueous media. Subsequent distilled water leaching of the metal-laden concrete particles indicated that 1.9, 0.9 and 0.2% of the bound metals, Cu2+, Zn2+ and Pb2+, respectively, were readily soluble. Scanning electron microscopy revealed that the removal of Cu2+ and Zn2+ arose from surface precipitation reactions, whereas, the principal mechanism of uptake of Pb2+ was found to be by diffusion into the cement matrix. The metal ion removal efficiency of crushed concrete fines is compared with those of other low cost sorbents and potential applications which may exploit this sorptive property are also discussed.

  13. Technology meets aggregate

    SciTech Connect

    Wilson, C.; Swan, C.

    2007-07-01

    New technology carried out at Tufts University and the University of Massachusetts on synthetic lightweight aggregate has created material from various qualities of fly ash from coal-fired power plants for use in different engineered applications. In pilot scale manufacturing tests an 'SLA' containing 80% fly ash and 20% mixed plastic waste from packaging was produced by 'dry blending' mixed plastic with high carbon fly ash. A trial run was completed to produce concrete masonry unit (CMU) blocks at a full-scale facility. It has been shown that SLA can be used as a partial substitution of a traditional stone aggregate in hot asphalt mix. 1 fig., 2 photos.

  14. Valorization of post-consumer waste plastic in cementitious concrete composites

    SciTech Connect

    Marzouk, O. Yazoghli; Dheilly, R.M.; Queneudec, M. . E-mail: Michele.Tkint@u-picardie.fr

    2007-07-01

    The sheer amount of disposable bottles being produced nowadays makes it imperative to identify alternative procedures for recycling them since they are non-biodegradable. This paper describes an innovative use of consumed plastic bottle waste as sand-substitution aggregate within composite materials for building application. Particularly, bottles made of polyethylene terephthalate (PET) have been used as partial and complete substitutes for sand in concrete composites. Various volume fractions of sand varying from 2% to 100% were substituted by the same volume of granulated plastic, and various sizes of PET aggregates were used. The bulk density and mechanical characteristics of the composites produced were evaluated. To study the relationship between mechanical properties and composite microstructure, scanning electron microscopy technique was employed. The results presented show that substituting sand at a level below 50% by volume with granulated PET, whose upper granular limit equals 5 mm, affects neither the compressive strength nor the flexural strength of composites. This study demonstrates that plastic bottles shredded into small PET particles may be used successfully as sand-substitution aggregates in cementitious concrete composites. These new composites would appear to offer an attractive low-cost material with consistent properties; moreover, they would help in resolving some of the solid waste problems created by plastics production and in saving energy.

  15. Valorization of post-consumer waste plastic in cementitious concrete composites.

    PubMed

    Marzouk, O Yazoghli; Dheilly, R M; Queneudec, M

    2007-01-01

    The sheer amount of disposable bottles being produced nowadays makes it imperative to identify alternative procedures for recycling them since they are non-biodegradable. This paper describes an innovative use of consumed plastic bottle waste as sand-substitution aggregate within composite materials for building application. Particularly, bottles made of polyethylene terephthalate (PET) have been used as partial and complete substitutes for sand in concrete composites. Various volume fractions of sand varying from 2% to 100% were substituted by the same volume of granulated plastic, and various sizes of PET aggregates were used. The bulk density and mechanical characteristics of the composites produced were evaluated. To study the relationship between mechanical properties and composite microstructure, scanning electron microscopy technique was employed. The results presented show that substituting sand at a level below 50% by volume with granulated PET, whose upper granular limit equals 5mm, affects neither the compressive strength nor the flexural strength of composites. This study demonstrates that plastic bottles shredded into small PET particles may be used successfully as sand-substitution aggregates in cementitious concrete composites. These new composites would appear to offer an attractive low-cost material with consistent properties; moreover, they would help in resolving some of the solid waste problems created by plastics production and in saving energy.

  16. Microstructural investigations on aerated concrete

    SciTech Connect

    Narayanan, N.; Ramamurthy, K.

    2000-03-01

    Aerated concrete is characterized by the presence of large voids deliberately included in its matrix to reduce the density. This study reports the investigations conducted on the structure of cement-based autoclaved aerated concrete (AAC) and non-AAC with sand or fly ash as the filler. The reasons for changes in compressive strength and drying shrinkage are explained with reference to the changes in the microstructure. Compositional analysis was carried out using XRD. It was observed that fly ash responds poorly to autoclaving. The process of pore refinement in fly ash mixes is discussed with reference to the formation of Hadley grains as well as fly ash hydration. The paste-void interface in aerated concrete investigated in relation to the paste-aggregate interface in normal concrete revealed the existence of an interfacial transition zone.

  17. Cohesive fracture model for functionally graded fiber reinforced concrete

    SciTech Connect

    Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

    2010-06-15

    A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

  18. Analysis of Physical Properties and Mineralogical of Pyrolysis Tires Rubber Ash Compared Natural Sand in Concrete material

    NASA Astrophysics Data System (ADS)

    Syamir Senin, Mohamad; Shahidan, Shahiron; Syazani Leman, Alif; Izzati Raihan Ramzi Hannan, Nurul

    2016-11-01

    Waste tires pose significant health and environmental concerns if not recycled or discarded properly. At the same time, natural sand is becoming scarcer and costlier due to its non-availability. Waste tires as fine aggregate can be an economical and sustainable alternative to the natural sand. Recent years, the interest on recycling waste tires into civil engineering applications by the researchers has increased. In this research, the chemical and physical properties of the tires rubber ash and the natural sand have been analysed. The densities of the rubber ash are lower than the natural sand. Rubber ash had finer particle size compared to the natural sand. Almost all chemical in the natural sand had in rubber ash with the additional sulphur trioxide and zinc oxide in the rubber ash, made the rubber ash better than natural sand. Rubber ash seems to be a suitable material to use in concrete as sand replacement.

  19. Micro Environmental Concrete

    NASA Astrophysics Data System (ADS)

    Lanez, M.; Oudjit, M. N.; Zenati, A.; Arroudj, K.; Bali, A.

    Reactive powder concretes (RPC) are characterized by a particle diameter not exceeding 600 μm and having very high compressive and tensile strengths. This paper describes a new generation of micro concrete, which has an initial as well as a final high physicomechanical performance. To achieve this, 15% by weight of the Portland cement have been substituted by materials rich in Silica (Slag and Dune Sand). The results obtained from the tests carried out on the RPC show that compressive and tensile strengths increase when incorporating the addition, thus improving the compactness of mixtures through filler and pozzolanic effects. With a reduction in the aggregate phase in the RPC and the abundance of the dune sand (southern of Algeria) and slag (industrial by-product of the blast furnace), the use of the RPC will allow Algeria to fulfil economical as well as ecological requirements.

  20. Proposal of Environmental Impact Assessment Method for Concrete in South Korea: An Application in LCA (Life Cycle Assessment).

    PubMed

    Kim, Tae Hyoung; Tae, Sung Ho

    2016-11-02

    This study aims to develop a system for assessing the impact of the substances discharged from concrete production process on six environmental impact categories, i.e., global warming (GWP), acidification (AP), eutrophication (EP), abiotic depletion (ADP), ozone depletion (ODP), and photochemical oxidant creation (POCP), using the life a cycle assessment (LCA) method. To achieve this, this study proposed an LCA method specifically applicable to the Korean concrete industry by adapting the ISO standards to suit the Korean situations. The proposed LCA method involves a system that performs environmental impact assessment on the basis of input information on concrete mix design, transport distance, and energy consumption in a batch plant. The Concrete Lifecycle Assessment System (CLAS) thus developed provides user-friendly support for environmental impact assessment with specialized database for concrete mix materials and energy sources. In the case analysis using the CLAS, among the substances discharged from the production of 24 MPa concrete, those contributing to GWP, AP, EP, ADP, ODP, and POCP were assessed to amount to 309 kg-CO₂ eq/m³, 28.7 kg-SO₂ eq/m³, 5.21 kg-PO₄(3-) eq/m³, 0.000049 kg-CFC11 eq/m³, 34 kg/m³, and 21 kg-Ethylene eq/m³, respectively. Of these six environmental impact categories selected for the LCA in this study, ordinary Portland cement (OPC) was found to contribute most intensely to GWP and POCP, and aggregates, to AP, EP, ODP, and ADP. It was also found that the mix design with increased prop proportion of recycled aggregate was found to contribute to reducing the impact in all other categories.

  1. Proposal of Environmental Impact Assessment Method for Concrete in South Korea: An Application in LCA (Life Cycle Assessment)

    PubMed Central

    Kim, Tae Hyoung; Tae, Sung Ho

    2016-01-01

    This study aims to develop a system for assessing the impact of the substances discharged from concrete production process on six environmental impact categories, i.e., global warming (GWP), acidification (AP), eutrophication (EP), abiotic depletion (ADP), ozone depletion (ODP), and photochemical oxidant creation (POCP), using the life a cycle assessment (LCA) method. To achieve this, this study proposed an LCA method specifically applicable to the Korean concrete industry by adapting the ISO standards to suit the Korean situations. The proposed LCA method involves a system that performs environmental impact assessment on the basis of input information on concrete mix design, transport distance, and energy consumption in a batch plant. The Concrete Lifecycle Assessment System (CLAS) thus developed provides user-friendly support for environmental impact assessment with specialized database for concrete mix materials and energy sources. In the case analysis using the CLAS, among the substances discharged from the production of 24 MPa concrete, those contributing to GWP, AP, EP, ADP, ODP, and POCP were assessed to amount to 309 kg-CO2 eq/m3, 28.7 kg-SO2 eq/m3, 5.21 kg-PO43− eq/m3, 0.000049 kg-CFC11 eq/m3, 34 kg/m3, and 21 kg-Ethylene eq/m3, respectively. Of these six environmental impact categories selected for the LCA in this study, ordinary Portland cement (OPC) was found to contribute most intensely to GWP and POCP, and aggregates, to AP, EP, ODP, and ADP. It was also found that the mix design with increased prop proportion of recycled aggregate was found to contribute to reducing the impact in all other categories. PMID:27827843

  2. Alkali-silica reactions of mortars produced by using waste glass as fine aggregate and admixtures such as fly ash and Li2CO3.

    PubMed

    Topçu, Ilker Bekir; Boğa, Ahmet Raif; Bilir, Turhan

    2008-01-01

    Use of waste glass or glass cullet (GC) as concrete aggregate is becoming more widespread each day because of the increase in resource efficiency. Recycling of wastes is very important for sustainable development. When glass is used as aggregate in concrete or mortar, expansions and internal stresses occur due to an alkali-silica reaction (ASR). Furthermore, rapid loss in durability is generally observed due to extreme crack formation and an increase in permeability. It is necessary to use some kind of chemical or mineral admixture to reduce crack formation. In this study, mortar bars are produced by using three different colors of glass in four different quantities as fine aggregate by weight, and the effects of these glass aggregates on ASR are investigated, corresponding to ASTM C 1260. Additionally, in order to reduce the expansions of mortars, 10% and 20% fly ash (FA) as mineral admixture and 1% and 2% Li(2)CO(3) as chemical admixture are incorporated by weight in the cement and their effects on expansion are examined. It is observed that among white (WG), green (GG) and brown glass (BG) aggregates, WG aggregate causes the greatest expansion. In addition, expansion increases with an increase in amount of glass. According to the test results, it is seen that over 20% FA and 2% Li(2)CO(3) replacements are required to produce mortars which have expansion values below the 0.2% critical value when exposed to ASR. However, usages of these admixtures reduce expansions occurring because of ASR.

  3. Semi lightweight concretes produced by volcanic slags

    SciTech Connect

    Topcu, I.B.

    1997-01-01

    The properties of the semi-lightweight concretes produced by using volcanic slags as coarse aggregate were investigated. The volcanic slags were brought from the quarry crushed and then classified according to their aggregate sizes of 0--8, 0--16, 0--31.5, 4--8, and 8--16 mm. The concrete series of five different volcanic slag sizes were produced by addition of a specific cement paste in volume fractions of 0.15, 0.30, 0.45 and 0.60. The cubic, cylindrical and prismatic specimens were made from each of the concrete series. The physical and mechanical properties of the concrete series were determined by conducting unit weight, slump, ultrasound velocity, Schmidt hardness, cylindrical and cubic compressive, bending and splitting tensile strength tests. The results indicated that the volcanic slags can be safely used in the production of semi lightweight concrete.

  4. Fracture properties of lightweight concrete

    SciTech Connect

    Chang, T.P.; Shieh, M.M.

    1996-02-01

    This study presents the experimental results of fracture properties of concrete incorporating two kinds of domestic lightweight aggregate (LWA) manufactured through either a cold-bonding or a sintering process. The cold-bonded aggregates were mainly made of pulverized fly-ash through a cold-pelletization process at ambient temperature, while the sintered aggregates were made of clay and shale expanded by heat at a temperature near 1,200 C. Experimental results show that the 28-day compressive strengths of {phi} 100 x 200 mm cylindrical concrete specimen made of those LWAs range from 30.1 (sintered) to 33.9 MPa (cold-bonded). By means of size effect law, it is found that the fracture energies, G{sub f}, were 34.42 N/m (sintered) and 37.2 N/m (cold-bonded), respectively.

  5. Textile recycling

    SciTech Connect

    Jablonowski, E. ); Carlton, J.

    1995-01-01

    The most common household textiles include clothing, linens, draperies, carpets, shoes, handbags, and rugs. Old clothing, of course, is the most readily reused and/or recycled residentially generated textile category. State and/or local mandates to recycle a percentage of the waste stream are providing the impetus to add new materials to existing collection programs. Concurrently, the textile industry is aggressively trying to increase its throughput by seeking new sources of material to meet increased world demand for product. As experienced with drop-off programs for traditional materials, a majority of residents will not recycle materials unless the collection programs are convenient, i.e., curbside collection. The tonnage of marketable textiles currently being landfilled provide evidence of this. It is the authors' contention that if textile recycling is made convenient and accessible to every household in a municipality or region, then the waste stream disposed may be reduced in a similar fashion as when traditional recyclables are included in curbside programs.

  6. 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.

  7. Evaluation of the Influence of Specific Surface Treatments of RBA on a Set of Properties of Concrete.

    PubMed

    Ondova, Marcela; Sicakova, Alena

    2016-03-03

    High water absorption of recycled brick aggregate (RBA) is one of the most discussed parameters in terms of its application in the production of concrete-its influence on the amount of mixing water and, hence, the quality of the concrete, is usually considered negative. In this paper, different methods of decreasing the absorption of RBA and, consequently, the impact on the properties of concrete, are described. The RBA has been treated to decrease the water absorption capacity by impregnation approach using specific impregnators. Afterwards, the RBA samples have been dried at two different temperatures in the laboratory oven-20 and 90 °C. Concretes using 4/8 fraction of the treated RBA instead of natural aggregate (NA) have been mixed and tested. The effectiveness of the RBA treatments have been evaluated on the basis of their influence on the properties of the hardened concrete; by means of the following tests: flexural strength, compressive strength, capillarity, total water absorption capacity, depth of water penetration under pressure, and frost resistance. The method of ranking by ordinal scale has been used as it is suitable for the comparison of a large set of results, while results have been analyzed in terms of the most important technological parameter that influences the quality of the concrete-effective water content. Out of all the tested surface-treatments of RBA, treatment by sodium water glass has the best potential for reduction of the water/cement (w/c) ratio. When the effective w/c ratio is kept within standard limits, concretes containing treated RBA are possible to be specified for various exposure classes and manufacturing in practice. The experiment confirms that at a constant amount of mixing water, with decreasing water absorption of RBA, the effective amount of water in the concrete increases and, hence, the final properties of the concrete decrease (get worse). As the water absorption of the RBA declines, there is a potential for the

  8. Sludge ash as lightweight concrete material

    SciTech Connect

    Tay, J.H.; Yip, W.K.

    1989-02-01

    Sludge is an inevitable by-product of wastewater treatment. Its abundance poses disposal problems that can be drastically reduced if sludge can be converted for economical uses in construction as substitute materials. Digested and dewatered sludge, after incineration at a high temperature, yields a hard, cellular, porous mass with low unit weight. This hardened mass of sludge ash can be crushed to smaller-sized aggregates, which, when graded in suitable proportions, manifest the basic attributes required of lightweight aggregates. When used as aggregates in the production of lightweight concrete, experimental results show that the resulting concrete satisfies the physical requirements of a lightweight concrete in terms of unit weight, strength, heat-insulating properties, and fire resistance, thus indicating that sludge ash could be a potential source of suitable lightweight aggregates.

  9. Recycling Philology.

    ERIC Educational Resources Information Center

    Knapp, Peggy A.

    1993-01-01

    Proposes that English teachers recycle philology as a field of study. Redefines the shape of philology in view of postmodern theories of signification. Considers concepts of hermeneutics in retheorizing the aims of philology. Shows how such philological investigation might be used in the classroom to study literary texts. (HB)

  10. Assessment of the potential suitability of southwest Brooklyn incinerator residue in asphaltic-concrete mixes. Final report

    SciTech Connect

    Chesner, W.H.; Collins, R.J.; Fung, T.

    1988-02-01

    The results of a one-year incinerator residue sampling program at the Southwest Brooklyn Incinerator in New York City are reported. The program was designed to characterize the physical properties of incinerator residue. Asphalt mixes were prepared using blends of sampled incinerator residue with conventional aggregate, to determine the suitability of using incinerator residue in asphaltic concrete for road paving applications. The results of the investigation are compared with those of previous studies. Engineering and processing requirements are presented for converting residue into a usable aggregate material. Capital costs, operating costs, potential revenues and net annual costs are provided for a full-scale residue processing facility at the Southwest Brooklyn Incinerator. Environmental issues associated with residue recycling are identified and discussed. Recommendations are provided for additional laboratory work and field applications needed to demonstrate the use of residue in asphalt mixes.

  11. Study on the characteristics of high-strength lightweight concrete for icy waters

    SciTech Connect

    Asai, Y.; Itoh, Y.; Kanie, S.; Sakai, M.; Saeki, H.

    1994-12-31

    The authors have developed a new lightweight coarse aggregate whose surface is covered by a high molecular paraffin to prevent water absorption into the aggregate under high pumping pressure. The coated aggregate makes it possible to produce lightweight concrete with high durability against freeze/thaw cycles, abrasion and fire. In order to verify the efficiency of the coated aggregate and the durability of the concrete using the aggregate, various tests on the coated aggregate and concrete have been carried out. This paper reports on the main results obtained from various tests.

  12. Modeling the thermal characteristics of masonry mortar containing recycled materials

    NASA Astrophysics Data System (ADS)

    Laney, Morgan Gretchen

    As the building industry in the United States rapidly expands, the reuse of recycled demolition waste aggregates is becoming increasingly more important. Currently, the building industry is the largest consumer of natural resources. The constant use of raw virgin aggregate is resulting in depleting resources, lack of space for landfills, increasing costs, and heightened levels of pollution. The use of these recycled aggregates in building envelopes and the study of thermal properties are becoming a popular area of research in order to improve building energy usage. The construction of Zero Energy Buildings (ZEB) is encouraged by the United States government as a result of the unresolved finite resources and environmental pollution. The focus of this research is on the impact of using recycled demolition waste aggregates on thermal properties, including specific heat capacity and thermal conductivity, in masonry mortar applications. The new forms of aggregate were analyzed for efficiency and practical utilization in construction in seven locations across the United States by embedding the new material into the building envelope of a strip mall mercantile build model from the National Renewable Energy Laboratory (NREL) in the EnergyPlus Building Energy Simulation Program (BESP). It was determined that the recycled aggregate mortar mixtures performed as well as or better than the traditional mortar mix. Opportunities for future research in recycled aggregate mortar mixtures exist in a regional analysis, a regional recycled aggregate cost analysis, and a life cycled cost analysis (LCCA).

  13. Marginal Aggregates in Flexible Pavements: Background Survey and Experimental Plan

    DTIC Science & Technology

    1994-08-01

    of asphalt concrete mixtures. A review of this research has been conducted and summarized into general categories that best relate to marginal... concrete mixtures. A review of this research has been conducted and summarized into general categories that best relate to marginal aggregates as defined by...Aggregate on Properties of Bituminous Concrete ," Pennsylvania Department of Transportation, Research Project Report 70-28. 23. Ahlrich, R. C. 1991. "The

  14. Concrete waterproofing in nuclear industry.

    PubMed

    Scherbyna, Alexander N; Urusov, Sergei V

    2005-01-01

    One of the main points of aggregate safety during the transportation and storage of radioactive materials is to supply waterproofing for all constructions having direct contact with radiating substances and providing strength, seismic shielding etc. This is the problem with all waterside structures in nuclear industry and concrete installations in the treatment and storage of radioactive materials. In this connection, the problem of developing efficient techniques both for the repair of operating constructions and the waterproofing of new objects of the specified assignment is genuine. Various techniques of concrete waterproofing are widely applied in the world today. However, in conditions of radiation many of these techniques can bring not a profit but irreparable damage of durability and reliability of a concrete construction; for instance, when waterproofing materials contain organic constituents, polymers etc. Application of new technology or materials in basic construction elements requires in-depth analysis and thorough testing. The price of an error might be very large. A comparative analysis shows that one of the most promising types of waterproofing materials for radiation loaded concrete constructions is "integral capillary systems" (ICS). The tests on radiation, thermal and strength stability of ICS and ICS-treated concrete samples were initiated and fulfilled in RFNC-VNIITF. The main result is--ICS applying is increasing of waterproofing and strength properties of concrete in conditions of readiation The paper is devoted to describing the research strategy, the tests and their results and also to planning of new tests.

  15. Evaluation of the Influence of Specific Surface Treatments of RBA on a Set of Properties of Concrete

    PubMed Central

    Ondova, Marcela; Sicakova, Alena

    2016-01-01

    High water absorption of recycled brick aggregate (RBA) is one of the most discussed parameters in terms of its application in the production of concrete—its influence on the amount of mixing water and, hence, the quality of the concrete, is usually considered negative. In this paper, different methods of decreasing the absorption of RBA and, consequently, the impact on the properties of concrete, are described. The RBA has been treated to decrease the water absorption capacity by impregnation approach using specific impregnators. Afterwards, the RBA samples have been dried at two different temperatures in the laboratory oven—20 and 90 °C. Concretes using 4/8 fraction of the treated RBA instead of natural aggregate (NA) have been mixed and tested. The effectiveness of the RBA treatments have been evaluated on the basis of their influence on the properties of the hardened concrete; by means of the following tests: flexural strength, compressive strength, capillarity, total water absorption capacity, depth of water penetration under pressure, and frost resistance. The method of ranking by ordinal scale has been used as it is suitable for the comparison of a large set of results, while results have been analyzed in terms of the most important technological parameter that influences the quality of the concrete-effective water content. Out of all the tested surface-treatments of RBA, treatment by sodium water glass has the best potential for reduction of the water/cement (w/c) ratio. When the effective w/c ratio is kept within standard limits, concretes containing treated RBA are possible to be specified for various exposure classes and manufacturing in practice. The experiment confirms that at a constant amount of mixing water, with decreasing water absorption of RBA, the effective amount of water in the concrete increases and, hence, the final properties of the concrete decrease (get worse). As the water absorption of the RBA declines, there is a potential for

  16. 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

  17. Precipitation Recycling

    NASA Technical Reports Server (NTRS)

    Eltahir, Elfatih A. B.; Bras, Rafael L.

    1996-01-01

    The water cycle regulates and reflects natural variability in climate at the regional and global scales. Large-scale human activities that involve changes in land cover, such as tropical deforestation, are likely to modify climate through changes in the water cycle. In order to understand, and hopefully be able to predict, the extent of these potential global and regional changes, we need first to understand how the water cycle works. In the past, most of the research in hydrology focused on the land branch of the water cycle, with little attention given to the atmospheric branch. The study of precipitation recycling which is defined as the contribution of local evaporation to local precipitation, aims at understanding hydrologic processes in the atmospheric branch of the water cycle. Simply stated, any study on precipitation recycling is about how the atmospheric branch of the water cycle works, namely, what happens to water vapor molecules after they evaporate from the surface, and where will they precipitate?

  18. Precipitation Recycling

    NASA Technical Reports Server (NTRS)

    Eltahir, Elfatih A. B.; Bras, Rafael L.

    1996-01-01

    The water cycle regulates and reflects natural variability in climate at the regional and global scales. Large-scale human activities that involve changes in land cover, such as tropical deforestation, are likely to modify climate through changes in the water cycle. In order to understand, and hopefully be able to predict, the extent of these potential global and regional changes, we need first to understand how the water cycle works. In the past, most of the research in hydrology focused on the land branch of the water cycle, with little attention given to the atmospheric branch. The study of precipitation recycling which is defined as the contribution of local evaporation to local precipitation, aims at understanding hydrologic processes in the atmospheric branch of the water cycle. Simply stated, any study on precipitation recycling is about how the atmospheric branch of the water cycle works, namely, what happens to water vapor molecules after they evaporate from the surface, and where will they precipitate?

  19. Latex improvement of recycled asphalt pavement

    NASA Astrophysics Data System (ADS)

    Drennon, C.

    1982-08-01

    The performance of a single unmodified milled recycled asphalt concrete was compared to milled asphalt concrete modified by addition of three types of rubber latex. Latex was added at 2, 3, 5, and 8 percent latex by weight of asphalt in the asphalt concrete. Lattices used were a styrene butadiene (SBR), a natural rubber (NR), an acrylonitrile butadiene (NBR), and four varieties of out of specification SBR lattices. Marshall tests, while indecisive, showed a modest improvement in properties of SBR and NR added material at 3 and 5 percent latex. Addition of NBR latex caused deterioration in Marshall stability and flow over that of control. Repeated load tests were run using the indirect tensile test, analyzed by the VESYS program, which computes life of pavements. Repeated load tests showed improvement in asphalt concrete life when 3 and 5 percent SBR was added. Improvement was also shown by the out of specification SBR.

  20. Automatic detection and classification of EOL-concrete and resulting recovered products by hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Palmieri, Roberta; Bonifazi, Giuseppe; Serranti, Silvia

    2014-05-01

    The recovery of materials from Demolition Waste (DW) represents one of the main target of the recycling industry and the its characterization is important in order to set up efficient sorting and/or quality control systems. End-Of-Life (EOL) concrete materials identification is necessary to maximize DW conversion into useful secondary raw materials, so it is fundamental to develop strategies for the implementation of an automatic recognition system of the recovered products. In this paper, HyperSpectral Imaging (HSI) technique was applied in order to detect DW composition. Hyperspectral images were acquired by a laboratory device equipped with a HSI sensing device working in the near infrared range (1000-1700 nm): NIR Spectral Camera™, embedding an ImSpector™ N17E (SPECIM Ltd, Finland). Acquired spectral data were analyzed adopting the PLS_Toolbox (Version 7.5, Eigenvector Research, Inc.) under Matlab® environment (Version 7.11.1, The Mathworks, Inc.), applying different chemometric methods: Principal Component Analysis (PCA) for exploratory data approach and Partial Least Square- Discriminant Analysis (PLS-DA) to build classification models. Results showed that it is possible to recognize DW materials, distinguishing recycled aggregates from contaminants (e.g. bricks, gypsum, plastics, wood, foam, etc.). The developed procedure is cheap, fast and non-destructive: it could be used to make some steps of the recycling process more efficient and less expensive.

  1. 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…

  2. Recycled materials in asphalt pavements. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (Contains a minimum of 160 citations and includes a subject term index and title list.)

  3. Ultrasonic testing of reactive powder concrete.

    PubMed

    Washer, Glenn; Fuchs, Paul; Graybeal, Benjamin A; Hartmann, Joseph Lawrence

    2004-02-01

    Concrete is a critical material for the construction of infrastructure facilities throughout the world. Traditional concretes consist of cement paste and aggregates ranging in size from 6 to 25 mm that form a heterogeneous material with substantial compressive strength and a very low tensile strength. Steel reinforcement is used to provide tensile strength for reinforced concrete structures and as a composite the material is useful for structural applications. A new material known as reactive powder concrete (RPC) is becoming available. It differs significantly from traditional concrete; RPC has no large aggregates, and contains small steel fibers that provide additional strength and, in some cases, can replace traditional steel reinforcement. Due to its high density and lack of aggregates, ultrasonic inspections at frequencies 10 to 20 times that of traditional concrete inspections are possible. This paper reports on the initial findings of research conducted to determine the applicability of ultrasonic testing techniques for the condition assessment of RPC. Pulse velocities for shear and longitudinal waves and ultrasonic measurement of the modulus of elasticity for RPC are reported. Ultrasonic crack detection for RPC also is investigated.

  4. Mechanical properties of concrete containing a high volume of tire-rubber particles.

    PubMed

    Khaloo, Ali R; Dehestani, M; Rahmatabadi, P

    2008-12-01

    Due to the increasingly serious environmental problems presented by waste tires, the feasibility of using elastic and flexible tire-rubber particles as aggregate in concrete is investigated in this study. Tire-rubber particles composed of tire chips, crumb rubber, and a combination of tire chips and crumb rubber, were used to replace mineral aggregates in concrete. These particles were used to replace 12.5%, 25%, 37.5%, and 50% of the total mineral aggregate's volume in concrete. Cylindrical shape concrete specimens 15 cm in diameter and 30 cm in height were fabricated and cured. The fresh rubberized concrete exhibited lower unit weight and acceptable workability compared to plain concrete. The results of a uniaxial compressive strain control test conducted on hardened concrete specimens indicate large reductions in the strength and tangential modulus of elasticity. A significant decrease in the brittle behavior of concrete with increasing rubber content is also demonstrated using nonlinearity indices. The maximum toughness index, indicating the post failure strength of concrete, occurs in concretes with 25% rubber content. Unlike plain concrete, the failure state in rubberized concrete occurs gently and uniformly, and does not cause any separation in the specimen. Crack width and its propagation velocity in rubberized concrete are lower than those of plain concrete. Ultrasonic analysis reveals large reductions in the ultrasonic modulus and high sound absorption for tire-rubber concrete.

  5. The Apparent Thermal Conductivity of Pozzolana Concrete

    NASA Astrophysics Data System (ADS)

    Bessenouci, M. Z.; Triki, N. E. Bibi; Khelladi, S.; Draoui, B.; Abene, A.

    The recent development of some lightweight construction materials, such as light concrete, can play an important role as an insulator, while maintaining sufficient levels of mechanical performance. The quality of insulation to provide depends on the climate, the exposure of the walls and also the materials used in the construction. The choice of a material to be used as an insulator, obviously, depends on its availability and its cost. This is a study of natural pozzolanas as basic components in building materials. It is intended to highlight their thermal advantage. It is economically advantageous to use pozzolana in substitution for a portion of the clinker as hydraulically active additions, as well as in compositions of lightweight concretes in the form of pozzolanic aggregate mixtures, which provide mechanical strengths that comply with current standards. A theoretical study is conducted on the apparent thermal conductivity of building materials, namely concrete containing pozzolana. Thermal modeling, apparent to that commonly used for porous materials, has been applied to pozzolana concrete. Experimental results on measurements of the apparent thermal conductivity of pozzolana concrete are reported in this study, using an approach that considers that concrete is composed of two solid ingredients, a binding matrix (hydrated cement paste) and all aggregates. A second comparative theoretical approach is used for the case where concrete consists of a solid phase and a fluid phase (air).

  6. Nanogranular origin of concrete creep.

    PubMed

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-06-30

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate ( approximately 1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years.

  7. Nanogranular origin of concrete creep

    PubMed Central

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-01-01

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium–silicate–hydrates (C–S–H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C–S–H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C–S–H forms: low density, high density, ultra-high density. We demonstrate that the creep rate (≈1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years. PMID:19541652

  8. Thin, applied surfacing for improving skid resistance of concrete pavements

    NASA Astrophysics Data System (ADS)

    Scholer, C. F.

    1980-12-01

    The use of select aggregate in a thin wearing surface of portland cement mortar to prolone or restore a concrete pavement's ability to develop high friction was accomplished. Two fine aggregates, blast furnace slag and lightweight expanded shale were found to exhibit skid resistance greater than the other aggregates evaluated. The British polishing wheel was used in the laboratory evaluation of aggregate to simulate wear. The need for a method of restoring friction to a worn, but otherwise sound concrete pavement led to a field evaluation of several different techniques for placing a very thin overlay. The successful method was a broomed, very thin layer of mortar, 3 mm thick.

  9. Physical and microstructural aspects of iron sulfide degradation in concrete

    SciTech Connect

    Schmidt, Thomas; Gallucci, Emanuel; Scrivener, Karen

    2011-03-15

    The microstructural aspects of iron sulfide degradation in dam concrete were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) in both dam concrete samples and laboratory concrete. The results show that iron sulfide inclusions with a diameter of a few micrometers in the aggregates are reactive and appear to generate expansion first in the aggregates and consequently in the cement paste. The expansion from the iron sulfides is a consequence of the increase in volume of the reaction products formed. The types of iron sulfide present in the aggregate, mainly pyrrhotite (FeS) and pyrite (FeS{sub 2}), show similar reaction behavior in the aggregates. The released sulfate can lead to a secondary ettringite formation in the concrete matrix, but the degradation associated with this appears to be minor. The reaction of the iron sulfides was found to be very slow even when laboratory samples were exposed to elevated temperatures.

  10. 45. EXPOSEDAGGREGATE CONCRETE AT NICHE, NORTH BOUNDARY, SEVERAL TEXTURES POURED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    45. EXPOSED-AGGREGATE CONCRETE AT NICHE, NORTH BOUNDARY, SEVERAL TEXTURES POURED AT ONE TIME, October 1987 - Meridian Hill Park, Bounded by Fifteenth, Sixteenth, Euclid & W Streets, Northwest, Washington, District of Columbia, DC

  11. 12. VIEW OF RIGHT ABUTMENT TIE AT LEFT, CONCRETE PLACEMENT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW OF RIGHT ABUTMENT TIE AT LEFT, CONCRETE PLACEMENT LINES AT CENTER, POWER PLANT NEARING COMPLETION, AND AGGREGATE OPERATION AT CENTER RIGHT December 16, 1926 - Horse Mesa Dam, Salt River, 65 miles East of Phoenix, Phoenix, Maricopa County, AZ

  12. SA-based concrete seismic stress monitoring: a case study for normal strength concrete

    NASA Astrophysics Data System (ADS)

    Hou, S.; Zhang, H. B.; Ou, J. P.

    2016-09-01

    The stress history of concrete structures that have survived an earthquake can serve as a critical index to evaluate the health of the structure. There are currently few reliable monitoring methods to assess concrete stress after a seismic event. Piezoelectric-based smart aggregate (SA) provides an innovative experimental approach to monitor stress on concrete. The principle of SA-based concrete seismic stress monitoring is based on the assumption that concrete stress can be reliably predicted by the average output voltages of limited SAs with an acceptable margin of error. In this study, the meso-scale randomness of concrete was evaluated throughout the overall stress range of concrete and the influence of different load paths was considered. Four cylindrical specimens of normal strength concrete were embedded with a total of 24 SAs. The SA output sensitivity curve in the paths of loading-unloading with different amplitudes and monotonic loading up to failure was obtained. Monitoring errors were analyzed during pre- and post-peak stages from the experimental results. This research suggests that SA-based concrete seismic stress monitoring for normal strength concrete is reliable.

  13. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.; Horn, W.H.

    1981-11-04

    Quick setting polymer concrete compositions which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

  14. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, T.; Kukacka, L.E.; Horn, W.H.

    1983-05-13

    Quick setting polymer concrete compositions are described which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

  15. Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

    DOEpatents

    Sugama, Toshifumi; Kukacka, Lawrence E.; Horn, William H.

    1985-01-01

    Quick setting polymer concrete compositions with excellent structural properties are disclosed; these polymer concrete compositions are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate, which may be wet, and with a source of bivalent metallic ions.

  16. Innovative hyperspectral imaging (HSI) based techniques applied to end-of-life concrete drill core characterization for optimal dismantling and materials recovery

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Picone, Nicoletta; Serranti, Silvia

    2015-02-01

    The reduction of EOL concrete disposal in landfills, together with a lower exploitation of primary raw materials, generates a strong interest to develop, set-up and apply innovative technologies to maximize Construction and Demolition Waste (C&DW) conversion into useful secondary raw materials. Such a goal can be reached starting from a punctual in-situ efficient characterization of the objects to dismantle in order to develop demolition actions aimed to set up innovative mechanical-physical processes to recover the different materials and products to recycle. In this paper an innovative recycling-oriented characterization strategy based on HyperSpectral Imaging (HSI) is described in order to identify aggregates and mortar in drill core samples from end-of-life concrete. To reach this goal, concrete drill cores from a demolition site were systematically investigated by HSI in the short wave infrared field (1000-2500 nm). Results obtained by the adoption of the HSI approach showed as this technology can be successfully applied to analyze quality and characteristics of C&DW before dismantling and as final product to reutilise after demolition-milling-classification actions. The proposed technique and the related recognition logics, through the spectral signature detection of finite physical domains (i.e. concrete slice and/or particle) of different nature and composition, allows; i) to develop characterization procedures able to quantitatively assess end-of-life concrete compositional/textural characteristics and ii) to set up innovative sorting strategies to qualify the different materials constituting drill core samples.

  17. Criteria for Asphalt-Rubber Concrete in Civil Airport Pavements. Volume 2. Evaluation of Asphalt-Rubber Concrete.

    DTIC Science & Technology

    1987-03-01

    194 ix LIST OF TABLES Table Page 1 1977 FAA Aggregate Grading Band for Bituminous Surface Course with 1/2" (12.5m) Maximum Particle Size* ...... 6 2...Asphalt Concrete and Asphalt-Rubber Concrete. . . . . . . . . . . . . . . . . . . . . . . . . 106 xi LIST OF FthJiJRf1 Figure Page 1 1977 FAA...were blended to meet the 1977 FAA aggregate grading specification for pavements with a bituminous surface course and designed to accommodate aircraft

  18. Nanomechanics and Multiscale Modeling of Sustainable Concretes

    NASA Astrophysics Data System (ADS)

    Zanjani Zadeh, Vahid

    The work presented in this dissertation is aimed to implement and further develop the recent advances in material characterization for porous and heterogeneous materials and apply these advances to sustainable concretes. The studied sustainable concretes were concrete containing fly ash and slag, Kenaf fiber reinforced concrete, and lightweight aggregate concrete. All these cement-based materials can be categorized as sustainable concrete, by achieving concrete with high strength while reducing cement consumption. The nanoindentation technique was used to infer the nanomechanical properties of the active hydration phases in bulk cement paste. Moreover, the interfacial transition zone (ITZ) of lightweight aggregate, normal aggregate, and Kenaf fibers were investigated using nanoindentation and imagine techniques, despite difficulties regarding characterizing this region. Samples were also tested after exposure to high temperature to evaluate the damage mechanics of sustainable concretes. It has been shown that there is a direct correlation between the nature of the nanoscale structure of a cement-based material with its macroscopic properties. This was addressed in two steps in this dissertation: (i) Nanoscale characterization of sustainable cementitious materials to understand the different role of fly ash, slag, lightweight aggregate, and Kenaf fibers on nanoscale (ii) Link the nanoscale mechanical properties to macroscale ones with multiscale modeling. The grid indentation technique originally developed for normal concrete was extended to sustainable concretes with more complex microstructure. The relation between morphology of cement paste materials and submicron mechanical properties, indentation modulus, hardness, and dissipated energy is explained in detail. Extensive experimental and analytical approaches were focused on description of the materials' heterogeneous microstructure as function of their composition and physical phenomenon. Quantitative

  19. Lightweight Concrete Produced Using a Two-Stage Casting Process

    PubMed Central

    Yoon, Jin Young; Kim, Jae Hong; Hwang, Yoon Yi; Shin, Dong Kyu

    2015-01-01

    The type of lightweight aggregate and its volume fraction in a mix determine the density of lightweight concrete. Minimizing the density obviously requires a higher volume fraction, but this usually causes aggregates segregation in a conventional mixing process. This paper proposes a two-stage casting process to produce a lightweight concrete. This process involves placing lightweight aggregates in a frame and then filling in the remaining interstitial voids with cementitious grout. The casting process results in the lowest density of lightweight concrete, which consequently has low compressive strength. The irregularly shaped aggregates compensate for the weak point in terms of strength while the round-shape aggregates provide a strength of 20 MPa. Therefore, the proposed casting process can be applied for manufacturing non-structural elements and structural composites requiring a very low density and a strength of at most 20 MPa. PMID:28788007

  20. Lightweight Concrete Produced Using a Two-Stage Casting Process.

    PubMed

    Yoon, Jin Young; Kim, Jae Hong; Hwang, Yoon Yi; Shin, Dong Kyu

    2015-03-25

    The type of lightweight aggregate and its volume fraction in a mix determine the density of lightweight concrete. Minimizing the density obviously requires a higher volume fraction, but this usually causes aggregates segregation in a conventional mixing process. This paper proposes a two-stage casting process to produce a lightweight concrete. This process involves placing lightweight aggregates in a frame and then filling in the remaining interstitial voids with cementitious grout. The casting process results in the lowest density of lightweight concrete, which consequently has low compressive