Thermal oxidative aging mechanism of crumb rubber/SBS composite modified asphalt

Crumb rubber/SBS composite modified asphalt (CR/SBSCMA) technology is proposed to combine the advantages of crumb rubber (CR) and SBS. Then, the production cost of the modified asphalt could be reduced, the waste rubber resources could be made full utilization, and the performance of asphalt could be improved. Rotate thin film oven test was used for stimulating the thermal oxidative aging of matrix asphalt, crumb rubber modified asphalt (CRMA), SBS modified asphalt (SBSMA) and CR/SBSCMA. The influences of matrix asphalt, CR and SBS on the aging properties have been investigated based on the composition and structure analysis of asphalt and modified asphalt pre and post aging process. Then, the thermal oxidative aging mechanism of CR/SBSCMA has been discussed. The test results demonstrated that the carbonyl index and sulfoxide index could reflect the aging degree of asphalt well. Moreover, due to the presence of CR and SBS at the same time, the aging process of CR/SBSCMA was different from CRMA and SBSMA. In the aging process of CR/SBSCMA, the modifiers degradation products and asphalt secondary components reacted severely, which resulted in the decrease of aromatics and resin and the increase of asphaltenes and toluene insoluble. Meanwhile, the distribution and colloid structure of composite modified asphalt were changed by the modifiers degradation products, the asphalt secondary components and their reaction products, so were the macroscopic properties of CR/SBSCMA.