Swelling-degradation dynamic evolution behaviors of bio-modified rubberized asphalt under thermal conditions

The incorporation of bio-oil, derived from agricultural waste, as a partial substitute for asphalt, coupled with the modification of asphalt using crumb rubber from waste tires, synergistically enhances both sustainability and performance, resulting in bio-modified rubberized asphalt (BMR). Nevertheless, the properties of BMR are subject to fluctuations due to the interplay of crumb rubber swelling-degradation and asphalt aging, particularly under thermal conditions. This research delineates the temporal evolution of BMR's properties, with an emphasis on its rheological, chemical, and microscopic attributes. Three distinct phases were observed: initially, crumb rubber absorbed bio-oil, thereby swelling and augmenting high-temperature performance via the micro-skeletal effect. Subsequently, during the intermediate phase, rubber degradation manifested as macroscopic softening in the modified asphalt. Lastly, the aging of the asphalt resulted in hardening. The multi-stage properties of BMR are governed by the dynamic equilibrium between rubber swelling, degradation, and asphalt aging. These observations offer valuable insights for the quality control of BMR, thereby advancing waste reduction and recycling in downstream applications.