Discrete element-based study of asphalt mastic − Aggregate interface properties and damage mechanisms

To determine the effect of moisture damage on the properties of asphalt mastic materials and the asphalt-aggregate interface, in this study, SBS modified asphalt was blended with cement, mineral powder and anti-stripping agent, respectively, and subjected to different levels of water immersion at 25°C for 0 h, 24 h, 72 h and 168 h, and then orthogonal drawing tests were conducted under multifactorial conditions on granite, limestone, basalt and dolerite specimens, respectively, to quantify and analyze the drawing strength and damage pattern of the interface. Moreover, a virtual drawing test model was constructed by PFC-3D software to statistically analyze the fracture network at the microscopic scale. The results show that the type of aggregate and asphalt thickness are the key factors affecting the adhesion ability of the interface; with increasing asphalt film thickness, the interface damage mode changes from adhesion damage to cohesion damage, but the pullout strength decreases. The virtual drawing test can count the fracture mesh and quantify the interface damage when the stress peaks and when the interface is destroyed. The simulation test results are strongly correlated with the macroscopic test results, and the discrete element method can be used to investigate the asphalt aggregate interface properties and damage mechanisms and to research the multiscale combination of interfacial properties, which provides new ideas for preventing and addressing moisture damage to asphalt pavements in the future.