Composition optimization and performance evaluation of crumb rubber/SBS composite modified asphalt assisted by waste cooking oil

To reduce the cost of styrene-butadiene-styrene (SBS)-modified asphalt, rubber powder (crumb rubber, CR) is used as a partial substitute material for SBS, and waste cooking oil (WCO) is used as an additive, which not only meets the performance requirements of modified asphalt but also promotes the resource utilization of waste materials. The composition of CR/SBS composite modified asphalt (CR/SBSMA) was optimized, and the optimal preparation parameters were determined as follows: CR content 15%, SBS content 2%, WCO content 7%, and shearing temperature 185 °C. The conventional performances, rheological performances and anti-aging performance of CR/SBSMA were comprehensively compared with basic asphalt, rubber asphalt, and SBS modified asphalt, and the improvement mechanism was revealed through surface topography analysis and functional groups analysis. The results showed that the softening point and elastic recovery rate of CR/SBSMA were significantly improved, while the penetration degree was reduced. CR/SBSMA showed better rheological properties and anti-aging properties than traditional SBS-modified asphalt (SBSMA). Its viscosity reduction improved workability. Although the storage stability was reduced, it was still within the specification requirements. The stable physical compatibility between CR, WCO, SBS and base asphalt was the main mechanism for improving performance. This study provides technical support for partially replacing SBS with rubber powder and offers an environmentally friendly solution for the waste resource utilization of rubber powder and WCO in road asphalt.