The Experts below are selected from a list of 2130 Experts worldwide ranked by ideXlab platform
Heejung Youn - One of the best experts on this subject based on the ideXlab platform.
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accelerated calcite precipitation acp method for recycled concrete Aggregate rca
Construction and Building Materials, 2016Co-Authors: B. H. Nam, J. An, Heejung YounAbstract:Abstract Recycled concrete Aggregate (RCA) is often used as a replacement of Virgin Aggregate in embankments, roadbed, asphalt and concrete pavements. The use of RCA in drainage systems as pipe backfill materials has not received a large attention due to clogging potential. Calcite precipitation is one of major causes of permittivity reduction in filter fabrics. The calcite formation is a long-term process; thus, a means to evaluate the potential of calcite precipitation in an accelerated manner is necessary. In this study, an accelerated calcite precipitation (ACP) procedure of RCA was developed, and its performance was evaluated. Two types of ACP methods were devised: short-term and long-term simulations. The long-term ACP procedure can be used to determine maximum lifetime calcite precipitation while the short-term ACP procedure can be used to evaluate the effect of test variables (e.g. Aggregate type, fine content, etc.) on the calcite precipitation.
B. H. Nam - One of the best experts on this subject based on the ideXlab platform.
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accelerated calcite precipitation acp method for recycled concrete Aggregate rca
Construction and Building Materials, 2016Co-Authors: B. H. Nam, J. An, Heejung YounAbstract:Abstract Recycled concrete Aggregate (RCA) is often used as a replacement of Virgin Aggregate in embankments, roadbed, asphalt and concrete pavements. The use of RCA in drainage systems as pipe backfill materials has not received a large attention due to clogging potential. Calcite precipitation is one of major causes of permittivity reduction in filter fabrics. The calcite formation is a long-term process; thus, a means to evaluate the potential of calcite precipitation in an accelerated manner is necessary. In this study, an accelerated calcite precipitation (ACP) procedure of RCA was developed, and its performance was evaluated. Two types of ACP methods were devised: short-term and long-term simulations. The long-term ACP procedure can be used to determine maximum lifetime calcite precipitation while the short-term ACP procedure can be used to evaluate the effect of test variables (e.g. Aggregate type, fine content, etc.) on the calcite precipitation.
Andrew Hobbs - One of the best experts on this subject based on the ideXlab platform.
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laboratory tests and numerical simulations of mixing superheated Virgin Aggregate with reclaimed asphalt pavement materials
Transportation Research Record, 2015Co-Authors: Kun Zhang, Haifang Wen, Andrew HobbsAbstract:The use of reclaimed asphalt pavement (RAP) in asphalt mix contributes to sustainable construction. However, a high percentage of RAP in asphalt mix causes concern about compromising the performance of asphalt pavement, especially cracking. The binder transfer and blending between RAP and Virgin Aggregate during production in an asphalt plant is a critical procedure that affects the performance of the asphalt mix. The heating of RAP by superheated Virgin Aggregate and the transfer of RAP binder can affect the degree to which Virgin binder and RAP binder are blended and thus affect the performance of mixes containing RAP. Several parameters, such as RAP percentage, mixing time, and RAP moisture content, can affect the heating of RAP and the degree of blending between the Virgin binder and RAP binder. To increase the understanding of RAP heating and RAP binder transfer, laboratory tests and numerical simulations that employed the discrete element method (DEM) were conducted for this study to investigate the...
Valeria Corinaldesi - One of the best experts on this subject based on the ideXlab platform.
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behaviour of beam column joints made of recycled Aggregate concrete under cyclic loading
Construction and Building Materials, 2011Co-Authors: Valeria Corinaldesi, Viviana Letelier, G MoriconiAbstract:Abstract In this work, a recycled-Aggregate concrete (RAC) was prepared by replacing 30% Virgin with recycled concrete Aggregate coming from an industrial crushing plant in which concrete from building demolition is suitably treated. A reference concrete was also prepared by using 100% Virgin Aggregate with the same workability and strength class. Concrete specimens were manufactured for evaluating compressive, tensile, flexural and bond strengths with reinforcing steel bars, as well as static elastic modulus to assess RAC suitability for structural use. The behaviour of beam–column joints (scale of 2–3) made of reinforced concrete and subjected to cyclic loading was also studied. The results obtained gave experimental evidence of the suitability of RAC for structural use.
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mechanical and elastic behaviour of concretes made of recycled concrete coarse Aggregates
Construction and Building Materials, 2010Co-Authors: Valeria CorinaldesiAbstract:In this paper an investigation of mechanical behaviour and elastic properties of recycled-Aggregate concretes is presented. These concretes were prepared by alternatively using two different (coarse and finer coarse) recycled-Aggregate fractions both made of recycled concrete coming from a recycling plant in which rubble from demolition is collected and suitably treated. Several concrete mixtures were prepared by using only Virgin Aggregates (as reference), 30% finer coarse recycled Aggregate replacing fine gravel and 30% coarse recycled Aggregate replacing gravel. Five different water to cement ratios were adopted as: 0.40, 0.45, 0.50, 0.55 and 0.60. Concrete workability was in the slump range of 190–200 mm. Compression tests were carried out after 28 days of wet curing. In addition, concrete elastic modulus and drying shrinkage were evaluated. Results obtained showed that structural concrete up to C32/40 strength class can be manufactured by replacing 30% Virgin Aggregate with recycled-concrete Aggregate. Moreover, a correlation between elastic modulus and compressive strength of recycled-Aggregate concrete was found and compared to those reported in the literature. Finally, on the basis of drying shrinkage results, particularly if finer coarse recycled-concrete Aggregate is added to the mixture, lower strains could be detected especially for earlier curing time.
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influence of mineral additions on the performance of 100 recycled Aggregate concrete
Construction and Building Materials, 2009Co-Authors: Valeria Corinaldesi, Giacomo MoriconiAbstract:Abstract A judicious use of resources, by using by-products and waste materials, and a lower environmental impact, by reducing carbon dioxide emission and Virgin Aggregate extraction, allow to approach sustainable building development. Recycled Aggregate concrete (RAC) containing supplementary cementitious materials (SCM), if satisfactory concrete properties are achieved, can be an example of such sustainable construction materials. In this work concrete specimens were manufactured by completely replacing fine and coarse Aggregates with recycled Aggregates from a rubble recycling plant. Also RAC with fly ash (RA + FA) or silica fume (RA + SF) were studied. Concrete properties were evaluated by means of compressive strength and modulus of elasticity in the first experimental part. In the second experimental part, compressive and tensile splitting strength, dynamic modulus of elasticity, drying shrinkage, reinforcing bond strength, carbonation, chloride penetration were studied. Satisfactory concrete properties can be developed with recycled fine and coarse Aggregates with proper selection and proportioning of the concrete materials.
Baron Colbert - One of the best experts on this subject based on the ideXlab platform.
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the determination of mechanical performance of laboratory produced hot mix asphalt mixtures using controlled rap and Virgin Aggregate size fractions
Construction and Building Materials, 2012Co-Authors: Baron ColbertAbstract:Abstract This study investigates the influence of fractionated reclaimed asphalt pavement (RAP) materials on asphalt mixture performance. The RAP mixture percentages used were 15%, 35%, and 50% in the study. The amount of RAP materials recycled within hot mix asphalt (HMA) drum plants are typically no more than 30% RAP. Asphalt pavement analyzer (APA) rutting, modified Lottman, and dynamic modulus testing were conducted on the RAP and Virgin Aggregate blended asphalt mixtures. On average between all RAP mixtures, the addition of RAP decreased rutting by 24%, and increased resilient modulus by 52% due to the addition of RAP asphalt binder and Aggregates; which stiffen the mixture under higher temperature and heavier loading conditions. Dynamic modulus results indicated a statistical significant difference for high percentage RAP mixtures.
