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

An experimental method, based on the modified two‐parameter model and digital image correlation technique, was proposed for determining the mixed mode fracture toughness (KI+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 KI+II were evaluated considering the crack deflection. The values of KI+II and KI under mode I loading were compared. The results show that KI+II increases with the specimen size and gradually stabilizes. In addition, KI+II decreases with the maximum aggregate size, but the aggregate volume content has little effect on KI+II. Higher values of KI+II are presented after considering the effect of crack deflection. Only a monotonic loading process is required for the proposed method to determine KI+II. [ABSTRACT FROM AUTHOR]