Shear behavior of reinforced recycled aggregate concrete beams after exposure to temperatures up to 600 °C

This study aims to investigate the shear behavior of reinforced recycled aggregate concrete (RRAC) beams after exposure to elevated temperatures. A total of sixteen 1/3-scale RRAC beams with the shear span-to-depth ratio of 1.2 were tested using the four-point bending facility. The method of equivalent total water was employed to manufacture the RAC. Four recycled coarse aggregate (RCA) replacement ratios (i.e., 0, 30%, 70% and 100%) and three elevated temperatures (i.e., 200 °C, 400 °C and 600 °C) were considered to examine their effects on the shear behavior of RRAC beams. The test results indicate that increasing of the elevated temperatures leads to the change of concrete color from smoky-gray to grayish-reddish and results in reducing the shear performance (i.e., load bearing capacity and initial stiffness) of RRAC beams. The shear damage and mechanism of RRAC beams were similar to those of reinforced natural aggregate concrete (RNAC) beams at the same elevated temperatures. A finite element method developed based on ABAQUS was used to simulate the thermal and shear behavior of RRAC beams. The parametric analysis was then conducted to investigate the effect of transverse reinforcement spacing and shear span-to-depth ratio on the shear behavior of the beam. Six design provisions including GB 50010, ACI 318, Europe 2, BS 8110, AS 3600 and JSCE 15 were employed to evaluate the residual shear capacity of RRAC beams. The evaluation results indicate that the existing provisions derived from RNAC underestimate the residual shear capacity of RRAC beams within the temperature equal to 500 °C.