Influence of Bio-Oil on the Performance and Microstructure of Rejuvenated Asphalt Binder

Bio-oil is a type of green and renewable resource that is widely used in the regeneration of road asphalt. Addressing the issues of diverse sources and inconsistent properties of bio-oil, this study utilized three types of bio-oil as base oil, which incorporated plasticizers, penetrants, and wetting agents to prepare bio-oil-based asphalt rejuvenators. By exploring the rejuvenation mechanism and performance of the rejuvenated asphalt binder, this study investigated the molecular weight distribution, composition, temperature sensitivity, adhesion, and rheological properties of the rejuvenated asphalt binder. The rejuvenator and aged asphalt are physically miscible without significant chemical changes. All three rejuvenators effectively improved the molecular weight distribution of the aged asphalt. Among them, the castor oil–based rejuvenator and gutter oil–based rejuvenator exhibited superior effects compared to soybean oil–based rejuvenator. The adhesion of castor oil–based and gutter oil–based rejuvenated asphalt to aggregates was better than that of soybean oil–based rejuvenated asphalt, while the temperature sensitivity showed the opposite trend. The rejuvenators significantly improved the rheological properties of aged asphalt, with castor oil–based showing the best effect. The rejuvenators had a negative impact on the compatibility of aged asphalt, with soybean oil–based rejuvenated asphalt exhibiting lower compatibility and low-temperature cracking resistance compared to castor oil–based rejuvenated asphalt and gutter oil–based rejuvenated asphalt. Overall, the rejuvenation effects of castor oil–based rejuvenator and gutter oil–based rejuvenator are superior to those of soybean oil–based rejuvenator.