Experimental method for determining the fracture toughness of concrete based on the modified two‐parameter model and DIC technique

Abstract

Abstract An experimental method, based on the modified two‐parameter model and digital image correlation technique, was proposed for determining the mixed mode fracture toughness ( K I+II ) of concrete. Three‐point bending tests on notched concrete beam specimens of different sizes, maximum aggregate sizes, and aggregate volume contents were conducted, and the values of K I+II were evaluated considering the crack deflection. The values of K I+II and K I under mode I loading were compared. The results show that K I+II increases with the specimen size and gradually stabilizes. In addition, K I+II decreases with the maximum aggregate size, but the aggregate volume content has little effect on K I+II . Higher values of K I+II are presented after considering the effect of crack deflection. Only a monotonic loading process is required for the proposed method to determine K I+II .