Molecular simulation and experimental analysis on co-aging behaviors of SBS modifier and asphalt in SBS-modified asphalt

Styrene-butadiene-styrene block copolymer (SBS) is the most commonly used asphalt modifier. Studying the aging process of SBS-modified asphalt and clarifying the role of SBS and asphalt in the aging process can provide a basis for the targeted regeneration of SBS-modified asphalt. In this research, the physical and chemical changes of SBS and asphalt in the aging process were studied by FTIR (Fourier Transform Infrared Spectroscopy) analysis and SARA (Saturate, Aromatic, Resin, and Asphaltene) analysis. The effects of the thermal oxidation of asphalt and SBS on the viscosity and tensile properties of the SBS-modified asphalt were investigated by Brookfield Rotational Viscosity Test, force ductility test, and molecular dynamics simulation. Furthermore, the influence of asphalt and SBS aging on the adhesion property of the asphalt-aggregate interface was analyzed. The results show that the impact of SBS aging on the increase of viscosity and tensile yield stress was far less than that of asphalt aging. The adhesion energy of the modified asphalt-silica interface increases with both aging of SBS and asphalt. SBS and asphalt jointly influence the performance of modified asphalt in the aging process, but asphalt aging is the dominant factor.