Characterization of Phase Structure and Performance Degradation of Aged SBS-Modified Asphalt

Abstract

Although previous studies have broadly explored the aging process of styrene-butadiene-styrene (SBS)-modified asphalt, there still is a lack of understanding of the precise evolution patterns of its phase structure during aging, and whether aged SBS-modified asphalt retains its modified properties or reverts to conventional asphalt. To fill these gaps, this paper focused on key performance characteristics that differentiate SBS-modified asphalt from conventional asphalt, including viscosity, elasticity, and toughness properties; evaluated how aging influences mechanical properties; and examined morphological changes at different aging stages. The effective method for phase structure characterization was established. Based on the results, it was found that mechanical property variations, especially in the toughness curve, effectively indicate the phase structure. The fracture strength σB and fracture elongation εB of SBS-modified asphalt after rolling thin-film oven (RTFO) aging for 8 h closely matched those of 70# base asphalt after RTFO aging for 8 h, with values of 1,364.32 and 0.005, compared with 1,421.07 and 0.007, respectively. This curve helps determine whether aged SBS-modified asphalt remains modified or reverts to conventional asphalt. Aging primarily affected instantaneous elastic deformation, and had a minimal impact on delayed elastic deformation. Morphological analysis supported these findings, and showed that SBS polymer degradation precedes significant network disruption, and increased toughness results mainly from SBS polymer presence.