The Experts below are selected from a list of 12201 Experts worldwide ranked by ideXlab platform
Romildo Dias Toledo Filho - One of the best experts on this subject based on the ideXlab platform.
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compressive stress strain behavior of steel fiber reinforced Recycled Aggregate concrete
Cement & Concrete Composites, 2014Co-Authors: Jodilson Amorim Carneiro, Paulo Roberto Lopes Lima, Monica Batista Leite, Romildo Dias Toledo FilhoAbstract:Abstract The use of Recycled Aggregate from construction and demolition waste (CDW) as replacement of fine and coarse natural Aggregate has increased in recent years in order to reduce the high consumption of natural resources by the civil construction sector. In this work, an experimental investigation was carried out to investigate the influence of steel fiber reinforcement on the stress–strain behavior of concrete made with CDW Aggregates. In addition, the flexural strength and splitting tensile strength of the mixtures were also determined. Natural coarse and fine Aggregates were replaced by Recycled coarse Aggregate (RCA) and Recycled fine Aggregate (RFA) at two levels, 0% and 25%, by volume. Hooked end steel fibers with 35 mm of length and aspect ratio of 65 were used as reinforcement in a volume fraction of 0.75%. The research results show that the addition of steel fiber and Recycled Aggregate increased the mechanical strength and modified the fracture process relative to that of the reference concrete. The stress–strain behavior of Recycled Aggregate concrete was affected by the Recycled Aggregate and presented a more brittle behavior than the reference one. With the addition of steel fiber the toughness, measured by the slope of the descending branch of the stress–strain curve, of the Recycled concretes was increased and their behavior under compression becomes similar to that of the fiber-reinforced natural Aggregate concrete.
Ravindra K Dhir - One of the best experts on this subject based on the ideXlab platform.
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Fresh-state performance of Recycled Aggregate concrete: A review
Construction and Building Materials, 2018Co-Authors: R V Silva, J De Brito, Ravindra K DhirAbstract:Abstract This paper presents a literature review concerning the fresh properties of concrete containing Recycled Aggregates from beneficiated construction and demolition wastes. It starts with the identification of the main variables affecting the workability of concrete, such as the quality and moisture state of the Recycled Aggregates. The effectiveness of water-reducing admixtures and of mineral additions on the fresh properties of Recycled Aggregate concrete is also analysed. A brief insight is given on the influence of using Recycled Aggregates on the main characterizing parameters of the material’s rheological behaviour. Other properties of Recycled Aggregate concrete in its fresh state are also discussed, including stability (i.e., bleeding and segregation), temperature of hydration, air content, and fresh density.
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carbonation behaviour of Recycled Aggregate concrete
Cement & Concrete Composites, 2015Co-Authors: R V Silva, R Neves, J De Brito, Ravindra K DhirAbstract:Abstract This paper reviews the effect of incorporating Recycled Aggregates, sourced from construction and demolition waste, on the carbonation behaviour of concrete. It identifies various influencing aspects related to the use of Recycled Aggregates, such as replacement level, size and origin, as well as the influence of curing conditions, use of chemical admixtures and additions, on carbonation over a long period of time. A statistical analysis on the effect of introducing increasing amounts of Recycled Aggregates on the carbonation depth and coefficient of accelerated carbonation is presented. This paper also presents the use of existing methodologies to estimate the required accelerated carbonation resistance of a reinforced Recycled Aggregate concrete exposed to natural carbonation conditions with the use of accelerated carbonation tests. Results show clear increasing carbonation depths with increasing replacement levels when Recycled Aggregate concrete mixes are made with a similar mix design to that of the control natural Aggregate concrete. The relationship between the compressive strength and coefficients of accelerated carbonation is similar between the control concrete and the Recycled Aggregate concrete mixes.
Jodilson Amorim Carneiro - One of the best experts on this subject based on the ideXlab platform.
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compressive stress strain behavior of steel fiber reinforced Recycled Aggregate concrete
Cement & Concrete Composites, 2014Co-Authors: Jodilson Amorim Carneiro, Paulo Roberto Lopes Lima, Monica Batista Leite, Romildo Dias Toledo FilhoAbstract:Abstract The use of Recycled Aggregate from construction and demolition waste (CDW) as replacement of fine and coarse natural Aggregate has increased in recent years in order to reduce the high consumption of natural resources by the civil construction sector. In this work, an experimental investigation was carried out to investigate the influence of steel fiber reinforcement on the stress–strain behavior of concrete made with CDW Aggregates. In addition, the flexural strength and splitting tensile strength of the mixtures were also determined. Natural coarse and fine Aggregates were replaced by Recycled coarse Aggregate (RCA) and Recycled fine Aggregate (RFA) at two levels, 0% and 25%, by volume. Hooked end steel fibers with 35 mm of length and aspect ratio of 65 were used as reinforcement in a volume fraction of 0.75%. The research results show that the addition of steel fiber and Recycled Aggregate increased the mechanical strength and modified the fracture process relative to that of the reference concrete. The stress–strain behavior of Recycled Aggregate concrete was affected by the Recycled Aggregate and presented a more brittle behavior than the reference one. With the addition of steel fiber the toughness, measured by the slope of the descending branch of the stress–strain curve, of the Recycled concretes was increased and their behavior under compression becomes similar to that of the fiber-reinforced natural Aggregate concrete.
Khoa N. Le - One of the best experts on this subject based on the ideXlab platform.
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Recycled Aggregate in concrete production : a new approach
Proceedings of the 21st International Symposium on Advancement of Construction Management and Real Estate, 2017Co-Authors: Anthony Butera, Khoa N. LeAbstract:This paper investigates the use of carbon-conditioned Recycled Aggregate (\(\mathop {\text{RA}}\nolimits^{{\mathop {\text{CO}}\nolimits_{ 2} }}\) ) in concrete production. Experimental work is conducted for \(\mathop {\text{RA}}\nolimits^{{\mathop {\text{CO}}\nolimits_{ 2} }}\) with varying chamber pressure (0, 75 and 150 kPa), chamber duration (0, 30 and 90 min) and \(\mathop {\text{RA}}\nolimits^{{\mathop {\text{CO}}\nolimits_{ 2} }}\) replacement percentages (0, 30 and 100%) for concrete production. Average of three results on compressive, tensile and flexible strength and modulus of elasticity at 28 curing days are compared. The process of carbon-conditioning refers to the pressurised exposure of Recycled Aggregate to carbon dioxide (CO2) for a certain period of time before concrete mixing. The entraining of CO2 assists to facilitate the negative properties of Recycled Aggregate that produces a deprived final Recycled concrete as well as providing a superior calcium carbonate chemical reaction. Carbon-conditioning reduces porosity and water absorbency of Recycled Aggregate. In addition to improve Recycled Aggregate quality, CO2 emissions from the Aggregate also help filling openings in the concrete composition, generating an improved bond matrix. These two traits assist in enhancing the Recycled concrete properties.
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carbon conditioned Recycled Aggregate in concrete production
Journal of Cleaner Production, 2016Co-Authors: Anthony Butera, Khoa N. LeAbstract:Abstract This paper investigates the use of carbon-conditioned Recycled Aggregate (RA CO2 ) in concrete production. Experimental work is conducted for RA CO2 with varying chamber pressure (0 kPa, 75 kPa, 150 kPa), chamber duration (0 min, 30 min, 90 min) and RA CO2 replacement percentages (0%, 30%, 100%) for concrete production. Average of three results on compressive, tensile and flexible strength and modulus of elasticity at 28 curing days are compared. The process of carbon-conditioning refers to the pressurised exposure of Recycled Aggregate to carbon dioxide (CO 2 ) for a certain period of time before concrete mixing. The entraining of CO 2 assists to facilitate the negative properties of Recycled Aggregate that produces a deprived final Recycled concrete as well as providing a superior calcium carbonate chemical reaction. Carbon-conditioning reduces porosity and water absorbency of Recycled Aggregate. In addition to improve Recycled Aggregate quality, CO 2 emissions from the Aggregate also help filling openings in the concrete composition, generating an improved bond matrix from the formation of calcium carbonates (Zhan et al., 2014). These two traits assist in enhancing the Recycled concrete properties. This paper demonstrates a great potential in the use of RA CO2 in improving physical and mechanical properties of Recycled concrete and provides insight for effective use of Recycled Aggregate for concrete production. The effective use of Recycled Aggregate can reduce the amount of landfill that is utilised for construction and demolition waste.
Li Xu-ping - One of the best experts on this subject based on the ideXlab platform.
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Flexural behavior of reinforced Recycled Aggregate concrete beams
2020Co-Authors: Li Xu-pingAbstract:Based on a large number of the related t results from published literature,a review of the flexural behaviour of reinforced Recycled Aggregate concrete beams was presented,including the applicability of the plane section assumption for reinforced Recycled Aggregate concrete beams,the failure mode,the flexural bearing capacity,and the deformation as well as the stiffness of reinforced Recycled Aggregate concrete beams.It was found that the plane section assumption is applicable for reinforced Recycled Aggregate concrete beams.Compared with normal concrete beams,the failure mode and the flexural bearing capacity of reinforced Recycled Aggregate concrete beams are similar,however,the deformation is somewhat larger and the stiffness is smaller.
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Study on Mechanical Properties of Recycled Aggregate Concrete(II)
Journal of Building Materials, 2020Co-Authors: Li Xu-pingAbstract:Based on the study on the behaviour of Recycled Aggregate concrete under uniaxial compression,this paper deals with the following other mechanical properties: the uniaxial tensile strength,the splitting tensile strength and the correlationships between them,the flexural strength,the fracture energy and the bond strength between steel reinforcement and recycle Aggregate concrete as well as the thermal expansion coefficient and the residual compressive strength after high temperature.It was found that the uniaxial tensile strength,the splitting tensile strength,the flexural strength,the fracture energy and the bond strength all increase with the increase of the cube compressive strength of Recycled Aggregate concrete.The formulations for the uniaxial tensile strength and the splitting tensile strength as well as the bond strength of normal concrete are also suitable for Recycled Aggregate concrete.However,the formulations for the flexural strength and fracture energy for normal concrete tend to be unsafe for Recycled Aggregate concrete.The thermal expansion coefficient of Recycled Aggregate concrete is about 1×10~(-5) K~(-1),which is the same as normal concrete.The residual compressive strengths after high temperature for Recycled Aggregate concrete are somewhat similar to that of light Aggregate concrete.
