Study on the effect of aging on physical properties of asphalt binder from a microscale perspective

The asphalt binder in pavement mixtures frequently exposed to oxygen and undergoes daily temperature cycles. This results in oxidation and dehydrogenation of its chemical composition, leading to the aging of the asphalt binder. The aging process of asphalt binder directly affects the pavement's service life and therefore has been subject to intense research regarding the chemical composition and rheological properties. However, the microscopic reasons for these changes are not yet clear. A molecular dynamics (MD) simulation is employed to investigate the aging process from a microscale perspective. Six molecular models for six asphalt binders at different aging states are created based on the ratio of saturates, aromatics, resin and asphaltene (SARA) as well as carbonyl and sulfoxide indexes to investigate the effect of aging on physical properties of asphalt binder have been investigated. The results explain the mechanism for hardening of asphalt binder during aging process, and find some correlations between micro and macro phenomena.