• Title/Summary/Keyword: steel reinforced recycled aggregate concrete

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A Study on the Structural Characteristic of Recycled Aggregate Concrete Reinforced Steel Fiber (강섬유 혼입 순환골재 콘크리트의 구조적 특성에 관한 연구)

  • Kim, Jeong-Sup;Shin, Yong-Seok;Park, Young-Bai;Kim, Jeong-Hoon;Cho, Chang-Ho
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.5
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    • pp.35-42
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    • 2008
  • In this study, a sample was fabricated according to the recycled aggregate replacement level(0%, 30%, 60%), and the steel fiber mixing status in order to use recycled aggregate as a concrete alternative coarse aggregate, and then the materials and structural characteristics of recycled aggregate and steel fiber which impacted the reinforced concrete were analyzed. A conclusion was derived as follows. After considering the results of various material experiments and mock-up test, when a flexural strength and a ductility factor is increased and the replacement level is increased through mixing the steel fiber with the recycled aggregate concrete, the ductility and flexural strength reduction seems to be inhibited by adding the steel fiber. Also, it is indicated that the recycled aggregate has almost-similar compressive strength, tensile strength flexural strength and ductility capacity to the concrete which using the general gone even though the steel fiber is used and the replacement level is increased to 30%. Accordingly, the reinforced concrete frame using the steel fiber mixture and recycled aggregate seems to apply to the actual structure.

Bond behaviors of shape steel embedded in recycled aggregate concrete and recycled aggregate concrete filled in steel tubes

  • Chen, Zongping;Xu, Jinjun;Liang, Ying;Su, Yisheng
    • Steel and Composite Structures
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    • v.17 no.6
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    • pp.929-949
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    • 2014
  • Thirty one push-out tests were carried out in order to investigate the bond behavior between shape steel, steel tube (named steels) and recycled aggregate concrete (RAC), including 11 steel reinforced recycled aggregate concrete (SRRAC) columns, 10 recycled aggregate concrete-filled circular steel tube (RACFCST) columns and 10 recycled aggregate concrete-filled square steel tube (RACFSST) columns. Eleven recycled coarse aggregate (RCA) replacement ratios (i.e., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) were considered for SRRAC specimens, while five RCA replacement ratios (i.e., 0%, 25%, 50%, 75% and 100%), concrete type and length-diameter ratio for recycled aggregate concrete-filled steel tube (RACFST) specimens were designed in this paper. Based on the test results, the influences of all variable parameters on the bond strength between steels and RAC were investigated. It was found that the load-slip curves at the loading end appeared the initial slip earlier than the curves at the free end. In addition, eight practical bond strength models were applied to make checking computations for all the specimens. The theoretical analytical model for interfacial bond shear transmission length in each type of steel-RAC composite columns was established through the mechanical derivation, which can be used to design and evaluate the performance of anchorage zones in steel-RAC composite structures.

An Experimental Study on the Behavior of Reinforced Concrete Beams using Recycled Coarse Aggregate (재생 굵은골재를 사용한 철근 콘크리트 보의 거동에 관한 실험연구)

  • Lee, Myeong-Gyu;Kim, Gwang-Seo;Lee, Geun-Ho;Yun, Geon-Ho;Jeong, Sang-Hwa
    • Journal of the Korea Institute of Building Construction
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    • v.4 no.3
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    • pp.133-141
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    • 2004
  • The object of this study is to investigate experimentally the shear behavior of reinforced concrete beams using recycled coarse aggregate. At first, the specimens are manufactured for the compressive strength of 210kgf/$\textrm{cm}^2$ with recycled coarse aggregate ratio of 0%, 20%, 40%, 60%, 80%, 100%, respectively. From the results, Reinforced concrete beams using recycled coarse aggregate were made with recycled coarse aggregate ratio of 0%, 20%, 40%, 60%, 80%, with stirrups and recycled coarse aggregate ratio of 0%, 20%, 40% without stirrups. The results of crack pattern and failure mode, load-displacement curve(center point and load point) and load-steel curve(compressive, tensile, stirrup) were analysed. It is concluded from the test that the shear behavior of recycled concrete beams is determined to have similar behavior of normal concrete beams. Therefore, from this study the application of recycled concrete to concrete structures may be possible. But, for using the recycled concrete widely, it is expected that the more studies on quality control, substitution ratio and mix design related with recycled concrete are necessary.

Properities of Freshly Mixed Concrete Using Recycled Coarse Aggregates and Steel Fiber (강섬유를 혼입한 굳지 않은 재생 콘크리트의 특성에 관한 연구)

  • 구봉근;김창운;김태봉;박재성
    • Journal of the Korea Concrete Institute
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    • v.12 no.5
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    • pp.93-99
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    • 2000
  • The physical properties of freshly mixed steel fiber reinforced recycled concrete(SFRRC) were_investigated. Physical state and quality of fresh concrete were monitored batch by batch. the properties of freshly mixed SFRRC were determined in terms of slump, air content, superplasticizer, and bleeding ratio. Concrete mixtures were produced for three kinds of aggregate proportions. So, the experimental variables are various aggregate proportions, steel fiber contents(0, 0.5, 1.0, 1.5%) and steel length(30, 50, 60mm). From experimental results, optimum s/a by various experimental variables, variations of the slump by the air contents, and optimum superplasticizer to decrease unit water were presented.

Axial compression behavior of circular recycled concrete-filled steel tubular short columns reinforced by silica fume and steel fiber

  • Chen, Juan;Liu, Xuan;Liu, Hongwei;Zeng, Lei
    • Steel and Composite Structures
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    • v.27 no.2
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    • pp.193-200
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    • 2018
  • This paper presents an experimental work for short circular steel tube columns filled with normal concrete (NAC), recycled aggregate concrete (RAC), and RAC with silica fume and steel fiber. Ten specimens were tested under axial compression to research the effect of silica fume and steel fiber volume percentage on the behavior of recycled aggregate concrete-filled steel tube columns (RACFST). The failure modes, ultimate loads and axial load- strain relationships are presented. The test results indicate that silica fume and steel fiber would not change the failure mode of the RACFST column, but can increase the mechanical performances of the RACFST column because of the filling effect and pozzolanic action of silica fume and the confinement effect of steel fiber. The ultimate load, ductility and energy dissipation capacity of RACFST columns can exceed that of corresponding natural aggregate concrete-filled steel tube (NACFST) column. Design formulas EC4 for the load capacity NACFST and RACFST columns are proposed, and the predictions agree well with the experimental results from this study.

A Study on the Flexural Toughness of Steel Fiber Reinforced Recycled Concrete (강섬유 보강 재생 콘크리트의 휨인성에 관한 연구)

  • Koo, Bong-Kuen;Kim, Tae-Bong;Kim, Chang-Woon;Park, Jae-Seong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.4 no.4
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    • pp.161-169
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    • 2000
  • Recycled aggregates were generated when concrete structures were dismembered. However, in concrete structures, because of durability, strength and toughness, recycled aggregates don't use generally. This study was done to use recycled aggregate in concrete structures. Problems of durability, strength, and toughness were caused troubles, when recycled aggregates were used, were solved as steel fibers and additives were added. Of course, steel fiber length, steel fiber contents, additive substitution, and recycled aggregate substitution were variables of this study. After flexural specimens($15{\times}15{\times}70cm$) with notch(45mm) were fabricated, basic strength tests were done and toughness was estimated using fracture mechanics parameters. The results suggest that JIC is a promising fracture criterion for all of these, while KIC(or GIC) almost certainly are not.

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Axial compression mechanical properties of steel reinforced recycled concrete column exposure to temperatures up to 800℃

  • Chen, Zongping;Liang, Yuhan;Mo, Linlin;Ban, Maogen
    • Steel and Composite Structures
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    • v.41 no.5
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    • pp.731-746
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    • 2021
  • The purpose of this paper is to investigate the axial bearing capacity and residual properties of steel reinforced recycled aggregate concrete (SRC) column after elevated temperature. A total of 48 SRC columns were designed for the static loading test after elevated temperature. The variables include replacement ratios, designed temperature, target duration, thicknesses of cover concrete, steel ratios and stirrup spacing. From this test, the mass loss ratio and stress load-deformation curve were obtained, and the influence of various parameters on residual bearing capacity were analyzed. ABAQUS was used to calculate the temperature field of specimens, and then got temperature damage distribution on the cross-section concrete. It was shown that increasing of the elevated temperatures leaded to the change of concrete color from smoky-gray to grayish brown and results in reducing the bearing capacity of SRC columns. The axial damage and mechanism of SRC columns were similar to those of reinforced natural aggregate concrete columns at the same temperatures. Finally, the calculation method of axial compressive residual bearing capacity of SRC columns recycled concrete columns after high temperature was reported based on the test results and finite element analysis.

Experimental Study of Flexural Behavior of Reinforced Concrete Beam Using WFS and Recycled Aggregate (순환골재와 폐주물사를 활용한 철근콘크리트보의 휨거동에 관한 실험연구)

  • Kim, Seong-Soo;Lee, Dae-Kyu
    • KIEAE Journal
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    • v.8 no.5
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    • pp.61-68
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    • 2008
  • For the recycling of the resources and the preservation of the environment, this study's purpose is to measure flexural behavior of the reinforced concrete beams with the major variables like concrete strength, replacement ratio of the recycled aggregate and the waste foundry sand and the tension reinforcement ratio and to present the data of the recycled aggregate used for the structure design. The experiment on the flexural behavior resulted in the followings. The ultimate strength of recycled R/C beam was manipulated proportionate to the tension reinforcement ratio, however the strength instantly decreased after passing the ultimate load due to the destroyed concrete of the compression side. The deflection at the maximum load varied from the tension reinforcement ratio by 5.5 times. The test specimen with the tension reinforcement ratio less than $0.5{\rho}b$ showed constant curve without change in the load from the yield to the ultimate load in contrast to the distinctive plastic region where the displacement was rising. Although the strain of main tension steel with the reinforcement ratio indicate different, the design of recycled concrete member can be applied for current design code for reinforced concrete structure as the ratio of tension reinforcement district the under the reinforcement ration in a balanced strain condition.

Performance Evaluation of Recycled Aggregate Concrete Block Reinforced with GFRP (GFRP로 보강된 순환골재콘크리트 블록의 성능평가)

  • Kim, Yongjae;Lee, Hyeongi;Park, Cheolwoo;Sim, Jongsung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.12
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    • pp.6565-6574
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    • 2013
  • Precast concrete blocks are used mainly for score protection, slope protection and riverbed structure protection, etc. Because these concrete blocks are exposed to water or wetting environments, the steel rebar used as reinforcements in concrete blocks can corrode easily. Corrosion of the steel rebar tends to reduce the performance and service life of the concrete blocks. In this study, Glass Fiber Reinforced Polymer(GFRP) rebar, which does not corrode, was applied instead of a steel rebar to prevent performance degradation of the blocks. Recycled concrete aggregate and high early strength cement(HESC) were used in the concrete mix for field applicability. The experiment results showed that the workability and form removal strength of the recycled aggregate concrete using HESC showed comparable results to normal concrete and the compressive strength at 28 days increased by about 18% compared to normal concrete. The load resistance capacity of the recycled aggregate concrete blocks reinforced with a GFRP rebar increased by approximately 10~30% compared to common concrete block.

Reinforced fibrous recycled aggregate concrete element subjected to uniaxial tensile loading

  • Hameed, R.;Hasnain, K.;Riaz, M. Rizwan;Khan, Qasim S.;Siddiqi, Zahid A.
    • Advances in concrete construction
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    • v.9 no.2
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    • pp.195-205
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    • 2020
  • In this study, effect of recycled aggregates and polypropylene fibers on the response of conventionally reinforced concrete element subjected to tensile loading in terms of tension stiffening and strain development was experimentally investigated. For this purpose, concrete prisms of 100 × 100 mm cross section and 500 mm length having one central deformed steel re-bar were cast using fibrous and non-fibrous Recycled Aggregate Concrete (RAC) with varying percentages of recycled aggregates (0%, 25%, 50%, 75% and 100%) and tested under uniaxial tensile load. For all fibrous RAC mixes, polypropylene fibers were used at constant dosage of 3.15 kg/㎥. Effect of recycled aggregates and fibers on the compressive strength of concrete was also explored in this study. Through studying tensile load versus global axial deformation of composite and strain development in concrete and steel, it was found that replacement of natural aggregates with recycled aggregates in concrete negatively affected the cracking load, tension stiffening and strain development, and this negative effect was observed to be increased with increasing contents of recycled aggregates in concrete. The results of this study showed that it was possible to minimize the negative effect of recycled aggregates in concrete by the addition of polypropylene fibers. Reinforced concrete element constructed using concrete containing 50% recycled aggregates and polypropylene fibers exhibited cracking behavior, tension stiffening and strain development response almost similar to that of concrete element constructed using natural aggregate concrete without fiber.