Creep Recovery Behavior of Fresh, Aged, and Rejuvenated SBS-Modified Asphalt under High Shear Stresses

Abstract

The multiple stress creep recovery (MSCR) test is widely used to evaluate the rutting performance of asphalt binder. However, the results from current MSCR tests with maximum loading stress of 3.2 kPa are difficult to accurately estimate the rutting resistance of asphalt pavement in practice with high stress condition. To comprehensively study the changes in rutting potential of bitumen modified with styrene–butadiene–styrene (SBS-modified bitumen, or SMB) during aging and rejuvenation processes, the effects of different shear stresses and temperatures on the creep recovery behavior of fresh, aged, common, and reactive rejuvenated SMB were investigated. The results indicate that the effects of stress and temperature on the recovery rate and stress sensitivity of different binders vary considerably. The recovery rate and stress sensitivity of SMB are largely unaffected within a temperature range from 34°C to 52°C. However, aging prominently reduces the recovery rate and enhances stress sensitivity of SMB, and these effects would be exacerbated after common rejuvenation. In contrast, reactive rejuvenation mitigates these adverse impacts, particularly under conditions of elevated temperatures and stresses, making it more suitable for higher-level pavement applications. Additionally, the static creep recovery tests reveal that the SBS cross-linked structure supports the retention of creep recovery characteristics under high stress, where excessive stress (≥12.8 kPa) compromises these properties. The recovery rate of aged SBS modified bitumen (ASMB) significantly declines after aging, and deteriorates further with common rejuvenation. Conversely, reactive rejuvenation not only boosts the recovery rate of ASMB, but also improves its delayed recovery ratio and reduces its stress sensitivity due to the reconstituted SBS cross-linked network. These findings provide a critical theoretical foundation for accurately assessing the rutting resistance of various recycled modified asphalt binders under diverse traffic loads and environmental conditions. Asphalt recycling technologies are of great significance for the sustainable development of transportation infrastructure. The performance changes of SBS-modified asphalt during aging and rejuvenation processes have a significant impact on the service characteristics of asphalt pavement. The evolution of creep recovery behavior of SBS-modified asphalt during aging and rejuvenation under high shear stress was comprehensively investigated by MSCR test in this work. The recovery mechanism of creep recovery characteristics of aged SBS-modified asphalt under different rejuvenation methods was revealed, and the service characteristics of rejuvenated SBS-modified asphalt under different environmental temperatures and traffic conditions was also comprehensively grasped. The research results can provide theoretical and methodological support for the design of rejuvenation methods for SBS-modified asphalt pavement, as well as the selection of application scenarios, and contribute to its differentiated and high-quality utilization.