Mechanical and bond properties of completely recycled aggregate in concrete exposed to elevated temperatures

Abstract

This paper aims to assess the performance of fire exposed recycled coarse and fine aggregate concrete (RAC) in terms of mechanical behavior and bond properties. Super ductile (SD) bars are comparatively more ductile and suited for fire hazards. Bond tests were conducted following RILEM specification on recycled aggregate concrete in replacement percentages (0–100%). The samples were fire exposed following the IS0-834 temperature–time graph. The bond-slip performance was analyzed to explain the bond mechanism of RAC with SD bars. A correlation between the load and residual slip as well as the bond-temperature relationship and subsequent deterioration is provided based on test findings. The behavior of the bond at the interface of RAC and SD reinforcing steel was comparable to that of the concrete made with natural aggregate (NAC) exposed to fire when replaced within moderate proportions. Regression-based models were used to demonstrate the degradation of bond strength of RAC and slip of SD bars exposed to various temperatures. The proposed models were in agreement with those of normal strength OPC based concretes. The findings can help anticipate the performance of structural elements made of RAC following exposure to fire or elevated temperatures.