Diffusion and reinforcement mechanism study of the effect of styrene/butadiene ratio on the high-temperature property of asphalt using molecular dynamics simulation

Abstract

ABSTRACT The performance of styrene–butadiene-styrene (SBS)-modified asphalt depends on the diffusion and enhancement mechanism between SBS modifier and asphalt, and particularly the styrene/butadiene (S/B) ratio is a crucial factor affecting the enhancement properties of the modified asphalt. In this study, the effects of S/B ratios (20/80, 30/70 and 40/60) on the interaction mechanism between SBS modifier and asphalt was studied using viscoelasticity characterisation and molecular simulations. The diffusion coefficient and binding energy were adopted to reveal the mechanism of dynamic shear rheometer (DSR) variation. The results showed that the binding energy of asphaltenes with light components (saturates and aromatics) was gradually raised with the styrene ratio, increasing from 11.5% to 22.1%, while the binding energy between SBS polymer and light components gradually decreases from 8.9% to 112.7%. In addition, as the S/B ratio gradually decreases from 40/60 to 20/80, the diffusion coefficients of asphalt molecular gradually increase from 1% to 20%. The DSR test result was consistent with the molecular simulation results as the deformation resistance of the modified asphalt is weakened as the S/B ratio increases. This study provided the reference for the high-performance block copolymer-modified asphalt design and application in the highway and building industry.