A Multistage Analysis of Asphalt Binder Nanocrack Generation and Self-Healing Behavior Based on Molecular Dynamics

In order to study the characteristics and laws of nanocrack generation and self-healing behavior of asphalt materials under tensile action, the molecular dynamics (MD) method was used to simulate the continuous "tensile failure-self-healing" process, and this study remedies the shortcomings of existing experimental and observational methods. It is found that the MD-reproduced formation process of asphalt binder nanocrack contains four stages: "tensile extension", "nanocrack generation", "crack adding, expanding and penetrating" and "cracking failure". The influence of tensile conditions on the tensile cracking simulation of an asphalt binder model was analyzed, and it was found that low temperature and high loading rate would increase the tensile strength of the asphalt binder model. In addition, the MD-reproduced healing process of asphalt binder nanocracks can be divided into four stages: "surface approach", "surface rearrangement", "surface wetting" and "diffusion", which is similar to the healing process of polymers. Finally, from the perspective of energy change, the change rule of dominant van der Waals energy in the self-healing process was studied. Based on the existing research, the influence of damage degree on the healing performance of asphalt binder and its mechanism were further analyzed. The research results further enrich the theoretical research on microlevel cracking and healing of asphalt materials, and have certain theoretical value for the further development of self-healing asphalt materials.