Experimental study on the properties of recycled aggregate concrete with different replacement ratios from earthquake-stricken area

In order to apply recycled aggregate concrete (RAC) more effectively, the physical and mechanical properties of recycled aggregates (RA) from quake-stricken area were tested. The mechanical properties and the strength variation against time of RAC with different RA replacement ratios were studied based on mixing design of different RAC. The results showed that the performance of RAs is different from NAs, such as higher porosity, 3.5 times higher water absorption, 10% lower density and acceptable strength and surface texture. The RAC with different RA replacement ratios indicates lower density, compressive strength and tensile strength than those of natural concrete. The higher the RA replacement ratio is, the more reduction is. The study on the strength variation against time showed that the absorbed water in RA of the RAC would release gradually with hydration reaction, which improves the strength development, and finally even could result in higher strength than that of natural concrete. Meanwhile, the failure modes of RAC and natural concrete were observed and analyzed from the broken surfaces. The experiment results would provide references to further research on structural hollow sections filled with recycled concrete.