Crack propagation and non-uniform deformation analysis in hydraulic asphalt concrete: Insights from X-ray CT scanning and digital volume correlation

This study investigates the crack propagation and internal non-uniform deformation field of hydraulic asphalt concrete (HAC) under triaxial compression. Utilizing in situ triaxial compression tests at temperatures of 5 °C and 20 °C, the investigation incorporated X-ray computed tomography (CT) scanning to observe internal changes. Through digital volume correlation (DVC), the deformation field within HAC was analyzed in detail. Results indicated that the crack fraction of longitudinal sections at 20 °C was smaller across various deformation stages than that at 5 °C. The displacement and strain fields within the material displayed increased heterogeneity with increasing deformation. It was observed that the probability density distributions of both equivalent and volumetric strains conformed to a normal distribution at different deformation stages. By analyzing the crack propagation and the internal non-uniform deformation field, the progressive failure process of HAC with sub-voxel accuracy at 5 °C and 20 °C was clarified. This research confirmed the presence of both shear deformation failure and volumetric deformation characteristics, which undergo a transition from shear shrinkage to shear expansion at the meso scale.