Research on the self-healing behavior of asphalt mixed with healing agents based on molecular dynamics method

Molecular dynamics is used to simulate the self-healing process of asphalts mixed with a healing agent. Sulfoxide functional groups were introduced into the virgin asphalt to produce a short-term-aged asphalt model. The model is validated by comparing density, diffusion coefficient, solubility parameter, and viscosity with real measurements. Plant oil and Aromatic oil are chosen as typical healing agents. The molecular models of asphalt and healing agent are integrated into a micro-crack model, and the healing process is simulated with molecular dynamics. The results show that Plant oil is a better choice for improving the healing rate of virgin asphalt, while Aromatic oil is better for improving the healing rate of short-term-aged asphalt. The higher the temperature is, the better effect the healing agent will have on the asphalt. Healing is maximized above 15 °C for virgin asphalt and above 45 °C for short-term-aged asphalt. Molecular simulations show that the healing process depends on the diffusion of the healing agent and asphalt into the micro-crack. After the crack is filled, bitumen and oil molecules continue to mix. Aromatic oil produces a better mixing that leads to a more uniform composition and better mechanical properties.