Intrinsic temperature sensitive self-healing character of asphalt binders based on molecular dynamics simulations

The molecular dynamics (MD) simulation was used in this study to explain the microscopic process of asphalt self-healing and investigate the influence of temperature on the self-healing capability of asphalt binders. Asphalt average molecular structure models of four types of neat asphalt binders were constructed firstly and a three-dimensional (3D) micro-crack model was further introduced to simulate the asphalt healing process. Based on the simulation results, the density analysis, relative concentration analysis, and mean square displacement analysis (MSD) were performed to investigate the temperature sensitive self-healing character of asphalt binders. Differential scanning calorimeter (DSC) test was adopted to get the phase transition (PT) temperature range of asphalt binders. The DSR-based fatigue-healing-fatigue test at different temperatures was also carried out to observe the self-healing capability of asphalt binders from the macroscopic view. According to the numerical and experimental results, it can be found that the molecular diffusion rate and diffusion range were more distinct especially within the PT temperature range, which indicated that the self-healing capability of asphalt was strong in PT temperature. Moreover, the results showed that there existed an optimal temperature range for asphalt healing, considering too high temperature may lead to permanent deformation, the optimal healing temperature range determined in this paper was 40.3–48.7 °C.