Development of fracture process zone in full-graded dam concrete under three-point bending by DIC and acoustic emission

In this paper, the fracture process zone (FPZ) of dam concrete under different loading rates is measured, and the formation process of FPZ is studied by applying digital image correlation (DIC) and acoustic emission (AE) technique. The results show that the FPZ development of dam concrete presents the characteristics of stepwise growth. The FPZ has emerged before the peak load, and the rapid growth is basically complete shortly after the peak load. Large aggregate plays an important role in the FPZ development of dam concrete. It can cause the bifurcation and tortuous development path of FPZ, which lead to the enhancement of fracture toughness and fracture energy of dam concrete. The maximum loads of specimens increase accordingly at a higher rate. Meanwhile, the development of FPZ also have the rate effect. Higher loading rate will weaken the effect of aggregate constrained force, resulting in more direct development of FPZ. The damage also seems to be more serious under the same loading stage from AE results.