Experimental Study on Concrete Fracture Process Zone Using Digital Image Correlation Technique

Abstract The fracture process zone (FPZ) of concrete under three-point bending was extensively investigated using the digital image correlation technique. Surface displacement, strain components, crack opening displacement, effective crack length, and crack tip position were calculated and analyzed. The development of crack and FPZ were obtained through data processing and applied to the analysis of mechanical response. The development of the FPZ, divided into three stages, was found to have strong consistency with the change of the mechanical behavior of concrete. Two characteristic parameters of FPZ were used to study the size effect of concrete. It is found that with the increase of size, the FPZ will develop deeper at peak load. However, the ratio of the maximum length of the FPZ to the initial ligament length does not vary with size, which is about 0.85 in this study.