Study on the Effect of Ternary Regenerant on SBS Modified Bitumen and Its Mixture Pavement Performance

Abstract

To enable the valuable utilization of high proportions of waste SBS modified bitumen mixture (RAP) in warm-mix recycling technology while addressing its insufficient low-temperature crack resistance in cold regions, this study developed a ternary composite rejuvenator composed of epoxidized soybean oil (ESO), triallyl isocyanurate (TAIC), and methyl methacrylate (MMA). The rheological restoration efficacy of this rejuvenator on aged SBS-modified bitumen was systematically appraised through comprehensive viscoelastic characterization (dynamic shear rheometry and bending beam rheometry) alongside mixture-level performance evaluation encompassing rutting resistance, moisture susceptibility (immersion Marshall), freeze-thaw durability, and low-temperature flexural behavior. The study revealed the performance variation patterns and long-term durability of warm-mix rejuvenated mixtures under different RAP content ratios (30% and 50%). Results indicate that the composite rejuvenator, through the synergistic effects of ESO's plasticizing action, TAIC's crosslinking network reconstruction, and MMA's interfacial compatibilization, significantly restores the high-temperature rutting resistance, fatigue resistance, and low-temperature crack resistance of aged SBS-modified bitumen. Specifically, the rutting factor and fatigue factor of ETM-ASMB (ternary recycled bitumen binder) recovered to over 97% of fresh bitumen (SMB), while its low-temperature creep rate (m-value) met relevant specification requirements. With respect to the asphalt mixture, the rejuvenator markedly improved moisture resistance and low-temperature fracture tolerance of the high reclaimed asphalt pavement content blend. Furthermore, following extended oxidative aging, the deterioration of critical performance metrics for the R30-RA formulation was substantially attenuated relative to the unmodified control. This study provides a reliable theoretical basis and practical operational guidance for rejuvenating high-proportion RAP under warm-mix conditions.