Experimental research on bond behavior of reinforced recycled aggregate concrete based on the acoustic emission technique

Abstract

This paper reports the experimental studies of the bond between recycled aggregate concrete (RAC) and ribbed steel bars, using the acoustic emission (AE) technique. Four different recycled aggregate replacement ratios (0%, 50%, 60%, and 70%) were considered in pullout tests. The test results indicate that the strength of the bond between RAC and ribbed bars is highly correlated to the RAC strength; the highest RAC bond strength was measured for the recycled aggregate replacement ratio of 60%. The conducted AE signal analysis included AE hits and energy analysis, positioning of AE events, AE signal average frequency analysis, b-value analysis, and RA-AF association analysis. The analysis results demonstrate that the internal damage of RAC is more severe and more dispersed both in space and in time owing to the initial defect of the recycled aggregate. Using the AE monitoring method, the dependence of the RAC bond failure mechanism on the recycled aggregate replacement ratio is explained.