Fracture behaviour analysis of the full-graded concrete based on digital image correlation and acoustic emission technique

Three-point bending tests of the full-graded concrete under different loading rates were carried out. The cracks were quantitatively analyzed by digital image correlation (DIC). The toughening mechanism during the crack development process was observed, and there are obvious crack branching and aggregate interlocking during the crack propagation. At the same load level, the crack opening width increases with the increase of the loading rate. DIC detects a decrease in the tortuosity of the fracture morphology. And at the same time, the damage of the dam concrete was evaluated by the frequency analysis and the damage type analysis from acoustic emission (AE) signals. The signal strength increases at a higher loading rate as well as the tensile type cracks. The results show that the monitoring results of DIC and AE technique are in agreement with each other, which is very effective for determining the fracture behaviour of concrete materials. Highlights The aggregate interlocking and crack branching form the toughening mechanism after peak The interlocking and crack branching decrease with the increase of the loading rate. Signals with different frequency content correspond to different fracture scale. The development type of crack tends to direct tension with the increase of the rate.