Analysis of behavior and mechanism of repairing agent of microcapsule in asphalt micro crack based on molecular dynamics simulation

Abstract The objective of this study is to analyze the behavior of repairing agent of microcapsule in asphalt micro crack based on molecular dynamics simulation. Based on the molecular dynamics software Material Studio 7.0 (MS), a four-fraction molecular model of asphalt and a molecular model of repairing agent of the microcapsule core material were constructed. Based on this, the micro crack models with and without repairing agents in asphalt were constructed, and the dynamics simulation calculations were carried out. The density and energy of the repairing agent moving in the micro crack after being released from microcapsule were studied, as well as the diffusion coefficient of molecules of the two models. The shear modulus of the models before and after crack repairing were analyzed. Additionally, the effects of temperature and molecular type on crack repairing were also analyzed. The results indicated that crack repairing was a process of mutual diffusion between the repairing agent and asphalt under the main driving force of potential energy. The repairing agent in the cracks accelerated the diffusion of the asphalt molecules to promote crack repairing rate; Crack repairing speed and temperature were positively correlated, that is, the repair rate increases with the increase of temperature. After the crack repair, the shear modulus of the models with and without repairing agent increased by 228.57% and 111.11%, respectively, indicating that the repairing agent also accelerated the mechanical property recovery of the crack model. The light and long chain-like small molecule type repairing agent could more promote the self-repairing process, and be more suitable for use as a core material repairing agent of microcapsules.