Self-healing properties and mechanisms of montmorillonite and bagasse fiber modified asphalt

Abstract

To elucidate the self-healing evolution laws and mechanisms of montmorillonite and bagasse fiber modified asphalt (MBMA), this study employed a Dynamic Shear Rheometer to conduct Fatigue-Healing-Fatigue tests. The effects of modifier content, rest period, and temperature on the self-healing performance of MBMA were systematically evaluated. Furthermore, a molecular dynamics (MD) simulation was used to construct a self-healing model for cracked asphalt, unraveling the driving mechanisms of MMT and BF on asphalt self-healing behavior at the micro-scale. The results indicate that the modified asphalt exhibits the optimal synergistic self-healing effect when doped with 1 % MMT and 2 % BF. Prolonging the rest period, increasing the temperature, or reducing the damage degree can effectively enhance self-healing performance. Grey Relational Analysis confirmed that temperature and rest period are the most significant controlling factors. MD simulations further revealed that elevated temperatures significantly increase the diffusion coefficient and fractional free volume (FFV) of asphalt. Compared with virgin asphalt (VA), MBMA requires less time to reach density equilibrium in the microscopic model, and the molecular diffusion behavior at the crack interface is more intense. Mechanistically, the incorporation of MMT and BF effectively increases the FFV of the system and expands the spatial channels for molecular diffusion, thereby enhancing diffusion capacity and self-healing efficiency. The microscopic simulation results align well with the macroscopic experimental conclusions, achieving cross-scale verification from molecular mechanism to macroscopic performance.