Abstract

Recycled Aggregate Concrete (RAC) is produced through the process of crushing, sieving the old concrete and replacement of the natural aggregate. This paper investigates experimentally and numerically the shear behavior of 74 reinforced concrete beams constructed from RAC. Latest researches confirm the reduction of shear strength due to the use of recycled aggregate instead of natural one. Therefore, one of the main targets of this study is to compensate such reduction in shear strength by using steel fibers. In order to do that, twelve concrete beams (150 mm width, 230 mm height and 1247 mm length) with different longitudinal reinforcement ratio have been constructed. Further, different replacement ratios of recycled aggregate with 0%, 50% and 100% have been introduced. Additionally, volume fractions of steel fiber of 0%, 0.5, 1% and 1.5% have been used to improve the shear behavior. Four points load is used for testing the specimens until failure. Volume fraction of steel fibers, compressive strength of RAC, replacement ratios of RA, shear span-depth ratio and longitudinal reinforcement ratio have been the parameters considered. Ultimate load and load-deflection curve have been studied through the experimental program. It has been found out that adding 0.5% steel fiber to Recycled Aggregate Concrete (RAC) specimen results in increasing the shear strength by 5% compared with Natural Aggregate Concrete (NAC) specimen without steel fiber. The modes of failure of RAC beams in shear are similar to the ones of NAC beams. Finite element analysis has been utilized to simulate the tested beams through ABAQUS software program. Further, the verified numerical model has been used to collect more data through a parametric study. Based on the parametric study, the compressive strength of concrete can be described by a square root function to the shear strength of RAC. Through the 74 test results (62 numerical results and 12 experimental results) of a wide range of most effective variables, a proposed design equation to predict the shear strength of fiber reinforced recycled aggregate concrete (FRRAC) beams has been presented.

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