Investigation on road and aging performance of rejuvenated SBS modified bitumen mixtures: Towards sustainable modified bitumen pavement

This study aimed to improve the rejuvenation quality of aged styrene-butadiene-styrene (SBS) modified bitumen mixture (PmBM) by employing composite rejuvenation through the synergistic application of various active-flexible rejuvenators (AFRs) featuring distinct molecular structures with aromatic oil (AO). By comparing with the mixture rejuvenated solely by AO, the impact of different AFRs on the pavement performance of aged PmBM as well as its aging resistance after rejuvenation was explored. The results demonstrated that, in comparison to the mixture rejuvenated solely by AO, the incorporation of AFRs considerably enhanced the high-temperature deformation resistance, low-temperature crack resistance, fatigue durability, and water damage resistance of the rejuvenated PmBM. And these properties were restored to levels close to or even surpassing those of fresh mixtures. Compared with sole AO application, AFRs demonstrated superior performance by effectively restoring the cross-linking structures of degraded SBS within the bitumen, while concurrently enhancing interfacial adhesion between the rejuvenated bitumen binders and the granite aggregates. These synergistic effects considerably improved the structural integrity of rejuvenated PmBMs. Moreover, the results of the thermal aging showed that the deterioration degree in pavement performance after aging was considerably lower for the (AFRs+AO) rejuvenated PmBMs compared to those rejuvenated solely with AO. The possible reason is that AFRs enhances the thermal aging resistance of the rejuvenated PmB by reconstructing the cross-linking structure of degraded SBS within the bitumen. The study reveals that during the rejuvenation process of aged PmBMs, it is particularly crucial to prioritize and effectively restore the cross-linking structures of degraded SBS within them. Additionally, when optimizing the molecular structure of AFRs in subsequent study, it is imperative to consider the sensitivity of the molecular structure of AFRs to aging factors, so as to ensure the durability of the rejuvenated PmBMs.