Experimental and damage modeling research on direct shear behavior of recycled concrete with pebble/gravel coarse aggregate

Recycled concrete aggregate (RA) is composed of original aggregate and attached mortar, in which different kinds of original aggregate play an important role in the mechanical properties of recycled aggregate concrete. In this study, the shear mechanical properties of concrete with gravel aggregate and pebble aggregate as recycled coarse aggregate were assessed by taking the replacement rate of recycled aggregate and the size of specimen as parameters. The results show that the shear mechanical properties of recycled gravel aggregate concrete (GAC) are better than those of recycled pebble aggregate concrete (PAC), and recycled cement mortar can effectively narrow the performance gap between PAC and GAC interfacial transition zone. The 3D scanning results show that PAC has a rougher failure shear plane than GAC. When the specimen size increases, the shear strength and peak displacement of GAC and PAC specimens gradually decrease, and the ductility increases. Finally, the shear damage models of PAC and GAC specimens are established, and the test results are in good agreement with the calculated model.