Fracture -healing properties of asphalt mixtures and microwave heating thermo-sensitivity analysis of their constituent materials

The self-healing ability of asphalt mixture can be enhanced by increasing the temperature to improve the flow capacity of the asphalt binder. However, more than 90% of the raw materials that constitute asphalt mixtures are aggregates, and the asphalt binder content does not exceed 10%. In this study, microwave heating was used to evaluate the thermo-sensitivity of asphalt mixture components, including aggregates, asphalt mastics, fine aggregate matrices, and mixtures. The semicircular bending fracture-healing-fracture test was used to analyze the healing properties of asphalt mixtures after microwave and oven heating, and the fracture energy ratios of the two fracture processes before and after healing were defined as the healing index (HI). Finally, an asphalt mixture healing model was established according to the capillary flow theory. The results show that when microwave heating was used to heat the asphalt mixture, the temperature increased linearly as a function of heating time. This process relied heavily on the aggregate to absorb the microwaves and raise the temperature. Additionally, as the aggregate size increased, the heating rate increased. There was no significant variation in temperature between 70# and the SBS asphalt mastic at the same heating conditions. The HImax values for microwave and oven heating in this study were approximately 40% and 56%, respectively. The HI increased as the heating time period increased, but the growth rate first increased and then decreased. In evaluations with AC13 and AC-20 mixtures. AC-13 exhibited superior healing properties. The healing model yielded a good fit with the test results (R2 > 0.96).