Understanding the temperature and loading frequency effects on physicochemical interaction ability between mineral filler and asphalt binder using molecular dynamic simulation and rheological experiments

Abstract

Asphalt mastic consists of asphalt binder and mineral filler and the physicochemical interaction between two them plays significant role in the service performance of asphalt concrete, which can be directly evaluated by their interfacial adsorbed film thickness. This study investigated the effects of temperature, loading frequency and other factors on the adsorbed film thickness. The results showed that with the increase of temperature and the decrease of loading frequency, the adsorbed film thickness between asphalt binder and mineral filler became thicker. Additionally, the addition of SBS modifier into base asphalt led to the stronger interaction ability with mineral filler at high temperature (i.e., low frequency) region. Compared with inert mineral filler, the adsorbed film thickness between active filler and asphalt binder was thicker, which provided insight into asphalt mastic design. Furthermore, the investigation of physicochemical interaction mechanism between asphalt and filler paves the way to understand the effect of these factors on interaction ability, which was analyzed at the molecular and atomistic scale through molecular dynamic simulation in this study. The asphalt mastic molecular model was also used to simulate temperature how to influence the adsorbed film thickness. The findings showed that compared with non-polar molecules of asphalt binder, the adsorption force between mineral filler particles and polar molecules was stronger. Asphalt non-polar components moved away from the surface of filler particle with the temperature increasing, while more and more polar components were adsorbed by filler particle, which caused thicker adsorbed film thickness and thus stronger interaction ability between mineral filler and asphalt binder.