Full-field measurement and fracture and fatigue characterizations of asphalt concrete based on the SCB test and stereo-DIC

Abstract

This study investigated the full-field displacement and strain fields of asphalt concrete under semi-circular bending (SCB) through the stereo-digital image correlation (stereo-DIC) technique. Fracture and fatigue tests were conducted with two high-speed cameras at 500 frames per second (fps) with a pixel resolution of 1520 × 1160 and two medium-speed cameras at 50 fps with a pixel resolution of 2048 × 2048, respectively. The accuracy of the three kinds of speckle patterns was verified. Further, the out-of-plane displacements in both fracture and fatigue tests were measured. The results indicate that the effects of the out-of-plane displacement cannot be ignored in the SCB test, and stereo-DIC must be used instead of 2D-DIC. The fracture and fatigue characteristics of asphalt concrete were investigated quantitatively based on the full-field displacement and strain fields retrieved by stereo-DIC. The fracture test indicates that the size of the plastic zone at the crack tip is much smaller than the crack length; hence, the linear elastic theory can be used to analyze the crack propagation behavior of asphalt concrete. The fracture energy was further calculated to serve the numerical simulation and modeling of the actual pavement. The fatigue test indicates that many small secondary cracks occur along the area near the main crack during cyclic loading. Based on the average strain of the area of damage, the damage–fatigue cycle curve was finally obtained to assess the asphalt concrete damage.