Insight into the diffusion behaviors of SBS-compatibilizer-coupled modified asphalt: Molecular dynamics simulation and experimental validation

Compatibilizers play a crucial role in enhancing the compatibility between styrene–butadiene–styrene (SBS) polymer and asphalt, and the coupling of compatibilizers with SBS affects the motion behavior of asphalt molecules, which influences the performance of SBS modified asphalt. In this investigation, molecular dynamics simulation is employed to evaluate the impact of SBS coupling with compatibilizers on alterations in the self-motion behavior of asphalt molecules, changes in relative free volume, and modifications in system energy. The findings reveal that with the introduction of a compatibilizer, the combined effect of the compatibilizer and SBS coupling amplifies the mobility of the constituents within the modified asphalt. This amplification manifests as increased relative free volume within the system, heightened activation of modified asphalt molecules, and a simultaneous reduction in the interaction energy among these molecules. Following that, the high-temperature rheological properties of SBS modified asphalt were verified with the simulation results, coupled with temperature scanning experiments. This study describes the intrinsic mechanism of interaction of compatibilizers in SBS modified asphalt at the molecular scale.

Highlights

• Molecular dynamics simulations and experimental validation were implemented for styrene–butadiene–styrene (SBS)-modified asphalt.
• Compatibilizers can activate the activity of SBS modified asphalt.
• Compatibilizers allow a better release of the properties of the bitumen and SBS.
• Compatibilizers can replace bitumen and act with SBS to improve its modification efficiency.
• The optimum dosage of compatibilizer is 3%.