Regeneration and re-aging behavior of SBS- and crumb rubber-modified bitumen under different long-term aging conditions

Asphalt pavements play an important role in modern infrastructure, and their long-term performance is influenced by aging. To improve road performance, longevity, and aspects related to sustainability, styrene-butadiene-styrene modified bitumen (SBSmB) and crumb rubber modified bitumen (CRmB) are two different polymer-modified bitumen (PmB) widely used. PmB still undergoes long-term aging (LTA), so regeneration strategies are applied to counteract aging-induced changes. To characterize the behavior towards LTA and regeneration, the two PmB were aged with standardized Pressure Aging Vessel (PAV) and additional LTA methods called Viennese Binder Aging (VBA) and Lightaging (LA) to include aging factors such as reactive oxygen species (ROS) and sunlight and consequently analyzed with FTIR and DSR. Both types of PmB were regenerated after LTA and compared to PmB that were aged again with the LTA methods for a second time. The results indicated that the SBSmB revealed strong aging susceptibility for VBA and PAV. Regeneration of SBSmB on a chemical basis could not be achieved. For mechanical properties, restoration of complex shear modulus was achieved. For the CRmB, the VBA induced severe aging, and repeated PAV aging caused the highest aging level of this study. Mechanical properties were nearly restored to the initial state. For SBSmB and CRmB, an antioxidant effect is evident, as subsequent aging is reduced after adding regenerator oil. This study provides evidence that PmB is a complex material, as the mechanical and chemical behaviors of the binders are unique, a chemical view is important, and multiple LTAs need to be taken into consideration.