Evaluation on the rejuvenation and diffusion characteristics of waste cooking oil on aged SBS asphalt based on molecular dynamics method

Waste cooking oil (WCO) could be used as rejuvenator to restore the physical and rheological properties of aged SBS asphalt, and the rejuvenate effect of WCO was greatly affect by WCO diffusion characteristics. In order to explore the interaction between the WCO and the aged SBS asphalt from molecular scale, the diffusion characteristics and rejuvenation mechanism of WCO in aged SBS asphalt were evaluated through molecular dynamics method. The results found that there was a bottleneck in promoting WCO diffusion by temperature, and the smaller the molecular weight, the faster the diffusion rate. The sulfoxide group produced by asphalt aging increased the force between asphaltene molecules, which resulted in the self-aggregation of asphaltenes and the destroy of the colloidal structure, and further caused the performance degradation. Also, the result found that WCO molecules interspersed around the asphaltene, broke the aggregation behavior of asphaltene so that asphaltene molecules were more dispersed. This research also found that WCO did not reverse the process of thermal-oxidative aging of asphalt but dramatically reduced the negative impact of asphalt thermal-oxidative aging from the polarity of asphalt molecules, intermolecular forces, colloidal structure, and other aspects. This result provides a novel method of evaluating the rejuvenation from a microscopic perspective.