Study on long-term performance and flexural stiffness of recycled aggregate concrete beams

Abstract

The incorporation of recycled concrete aggregate (RCA) will unfavorably affect the performance of concrete. The aim of this paper is to investigate the long-term performance of recycled aggregate concrete beams for a period of 3045 days and the bending behavior of test beams after sustained load is removed. Three different replacement ratios of RCA (0%, 50% and 100%) are the main parameters. The experiment observes the crack spacing of RAC beams is larger than that of natural aggregate concrete (NAC) beams during the long-term loading. Compared with the control specimen, the long-term deformations of RAC beams are greater and have hysteresis, which is attributed to the fact that creep and shrinkage of RAC have more significant time-dependence. The RAC beam shows a larger deflection recovery value after the long-term load is removed, and long-term creep effect and sustained load value of specimens may be responsible for this result. The RAC beams exhibit more significant stiffness degradation characteristics in flexural test. In addition, the modified equation is proposed to evaluate the reload short-term stiffness of the RAC beams after exposure to sustained loading.