Imperative role of SBS molecular structure on the performance properties of modified binders and asphalt mixes

Abstract

ABSTRACT The current study evaluates the impact of SBS molecular structure (L-SBS, B-SBS, HV-SBS, and DB-SB) and concentration on asphalt mix performance. Polymers were characterized using GPC, FTIR, melt rheology, and DSC analysis. GPC analysis indicates that BSBS has the highest molecular weight, while DB-SB has the lowest. FT-IR studies show differences in vinyl content among the four polymers. Asphalt mixture study resonated binder study where B-SBS polymer outperformed their counterparts. Results showed that compared to widely used L-SBS polymer, B-SBS copolymer generates ≈ 33 %, 26 % and 18 % more fatigue resistance, rutting resistance and stiffness behaviour, respectively, at a polymer content of 4.5 wt.%. The combined effect of higher molecular weight, triblock structure and the long-chain branching in B-SBS copolymer contributes to the discussed outcome which facilitates its utilization for high-stressed pavement sections at upper and intermediate service temperatures. However, L-SBS and HV-SBS polymers depict almost similar mixture performance due to their alike molecular structure. Moreover, the presence of a di-block structure and lower molecular weight results in inferior performance for mixes prepared with DB-SB polymer. The results clearly signify the dominance of polymer molecular structure in identifying the mixes’ performance properties at respective polymer content.