Crack propagation in recycled aggregate concrete under uniaxial compressive loading

In this study, systematic experimental research was carried out to investigate the crack propagation of modeled recycled aggregate concrete (MRAC) and recycled aggregate concrete (RAC) under uniaxial compressive loading. A two-dimensional (2-D) nondestructive digital image correlation (DIC) technique was applied to record the initiation and propagation of surface microcracks. The obtained results indicated that the fracture process and crack pattern of MRAC were greatly affected by the relative strength of new mortar and old mortar. It was also found that the failure mode of RAC was related to the water-cement ratio (w/c) of the mixture. The bond cracks first appeared around the weak interfacial transition zones (ITZs) and then propagated into the mortar region by connecting with each other. The failure pattern of MRAC can provide insight into the influences of the mechanical properties of each phase on the failure mechanism of RAC. © 2012, American Concrete Institute. All rights reserved