Healing behavior of thermo-oxygen aged asphalt based on molecular dynamics simulations

To understand the change law and causes of the self-healing ability of asphalt during aging, a thin-film oven test was used to simulate different aging degrees of asphalt, and the "damage-healing-damage" test was performed using a dynamic shear rheometer. The influence of structural changes in aged and recycled asphalt on the healing index was analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry. Molecular Studio was used to establish five asphalt healing models. The asphalt healing index decreased with the degree of aging, and the regenerant improved the healing performance. The types of asphalt functional groups were similar, but the sulfoxide group content and the glass transition temperature increased with the aging degree. The asphalt models were verified by the density and glass transition temperature. The two parameters tended to stabilize after 20 ps of healing, and the radial distribution function curves were similar. The mean square displacement and diffusion coefficient of the asphalt model increased with increasing healing temperature and decreased with increasing aging degree. There was a positive correlation between the diffusion coefficient and healing index. Molecular dynamics simulations can help scholars better understand asphalt's healing process and movement law.