Fracture Characteristics of Hydraulic Asphalt Concrete Panels under Different Loading Rates Based on Digital Image Correlation

Understanding the fracture behavior of hydraulic asphalt concrete face panels under varying loading rates is essential for ensuring their structural integrity but remains insufficiently explored. This study systematically investigates the crack resistance and propagation mechanisms of hydraulic asphalt concrete, focusing on two critical aspects: the effects of loading rate on fracture performance and propagation behavior, and the precise characterization of high-resolution strain fields at the crack tip using advanced digital image correlation (DIC) techniques. Semicircular bending (SCB) tests were conducted on asphalt concrete specimens subjected to loading rates of 0.05, 0.2, 1, 3, 5, and 10 mm/min. The experimental results indicate a significant increase in the stress intensity factor (KIC) and fracture energy (Gf) with increasing loading rates, whereas the crack resistance index (CRI) exhibits a notable decline. Strain field analysis reveals that the principal strain components (Exx and Eyy) at peak load decrease as loading rates rise. Furthermore, crack propagation patterns vary distinctly with loading rates: at lower rates, cracks follow tortuous paths along coarse aggregate boundaries, whereas at higher rates, cracks propagate more linearly through aggregates and preexisting flaws. These findings offer novel insights into the mechanical behavior and fracture mechanisms of hydraulic asphalt concrete face panels, providing valuable guidance for the design and optimization of hydraulic concrete structures under diverse operational loading conditions.