A new equation to predict the shear strength of recycled aggregate concrete Z push-off specimens

This article investigates the shear behaviour of Recycled Aggregate Concrete (RAC) Z push-off specimens. Fifteen specimens with different replacement levels of recycled concrete aggregate (RCA = 0 %, 25 %, 50 %, 75 % and 100 %) were tested. It is shown that a 100 % RCA replacement level reduces shear strength by 17.3 %. The shear behaviour of the specimens was further analysed using nonlinear finite element analysis (FEA). The results show that the shear strength results from the FEA and Digital Image Correlation measurements agree well (within 5 %) with the experimental results. This study proposes a new semi-empirical equation to calculate the shear strength of specimens with different RCA replacement levels. The new equation adopts a fracture mechanics approach, and it explicitly considers the shear slip deformation and crack opening. Compared to existing models, the new equation fits better the experimental data in this study, as well as test results from an extensive database obtained from the literature.