Study on self-healing performance of microcracks in SBS/waste rubber powder composite-modified asphalt based on molecular dynamics simulation

Abstract

The internal microcracks in asphalt materials can heal spontaneously under suitable conditions, and understanding the characteristics of the self-healing behavior of asphalt materials is crucial for evaluating the fatigue life of asphalt pavements. In this paper, a molecular model of modified asphalt microcracks was created by introducing modifier molecules into the virgin asphalt model, and the self-healing process of the asphalt microcrack model under different healing conditions was investigated, which revealed the effects of modifier materials and healing temperatures on the healing performance of asphalt. The results show that the effect of healing temperature on asphalt healing performance is more significant than the modifier material, the relative concentration of molecules at the microcrack healing and the healing temperature is positively correlated; asphalt material healing free volume fraction with the increase in healing temperature gradually increases, the incorporation of modifiers can reduce the free volume fraction growth caused by high-temperature healing, improve the healing stability of modified asphalt. The asphalt ductility specimen crack healing test shows that when the healing temperature exceeds 45 ℃, there is a decreased increase in self-healing rate; taking into account the high-temperature healing is easy to make the asphalt material produce permanent deformation, this paper determines the optimal healing temperature in the vicinity of 48 ℃. The research results have certain reference and application values for asphalt pavement damage repair.