Multi-scale studies on interfacial system compatibility between asphalt and SBS modifier using molecular dynamics simulations and experimental methods

Abstract

• Interfacial model of asphalt/SBS modifier is established based on molecular dynamics method; • Representative indexes are proposed to evaluate interfacial compatibility between asphalt/SBS; • The compatibility between asphalt/SBS at the preparation temperature of 170 °C is better one; • The interaction and aggregation between aromatics/SBS are conductive to their compatibility; • Asphalt with more aromatics and less asphaltenes is easier to improve compatibility with SBS. To understand the interfacial property and its effect on the compatibility between styrene–butadienestyrene (SBS) modifier and asphalt, as well as to further reveal their compatibility mechanism, the indexes of interfacial energy, relative concentration, and radial distribution function were used to discuss the interfacial property between asphalt and SBS modifier, as well as to evaluate the compatibility based on the established SBS/asphalt interface model using molecular dynamics (MD) method. Moreover, the laser scanning confocal microscope (LSCM) and scanning electron microscope (SEM) tests were also conducted on SBS modified asphalt samples prepared at the temperatures of 160 °C, 170 °C, 180 °C and 190 °C to study the compatibilities between asphalt and SBS modifier. Results indicate that the compatibility between asphalt and SBS modifier is better at the preparation temperature of 170 °C. At this point, the interfacial energy between asphalt and SBS modifier is larger than those at the other three preparation temperatures. Also, the compatibility at the preparation temperature of 170 °C is promoted by the more obvious interaction and aggregation between aromatics and SBS modifier. Additionally, both aromatics and saturates are conductive to the compatibility between asphalt and SBS modifier, while the asphaltenes are inverse. Finally, asphalt with high-content aromatics and low-content asphaltenes is proposed to use for improving the interfacial property and the compatibility between asphalt and SBS modifier, so as to prepare a high-performance SBS modified asphalt.