Performance evaluation of warm-mixed crumb rubber modified asphalt based on rheological characteristics

Abstract

In this study, comparative analysis was carried out to investigate the influence of crumb rubber (CR) powder size and warm mix additives (WMA) on the high-temperature properties of warm-mixed crumb rubber (CR-WMA) modified asphalts by temperature and frequency sweep test as well as repeated creep and recovery test. CR-WMA binders were obtained by mixing modifiers including two different types of rubber powder: an individual mesh and a mixed-mesh, and two different WMA additives: viscosity reducer and surfactant. Anti-rutting performance of asphalt binders was determined through several approaches employing various factors including phase angle δ, complex modulus G∗, rutting factor G∗/sinδ, modified rutting factor G∗/(sinδ)9, high failure temperature, equivalent viscosity η', accumulated strain racc, ratio of permanent deformation to total deformation εp/εL, and the Burgers model to determine creep compliance Jand Generalized Voigt GV. The results showed that the combination of CR and WMA exhibited a positive synergistic effect on asphalt’s rheological properties; and CR-WMA modified binder containing mixed-mesh CR powder and surfactant yielded optimum performance. Moreover, analysis of anti-rutting properties indicated that the effect of mixed powder size was found to be more prominent than that of single particle size, the effect of surfactant was better than that of viscosity reducer, and the modification effect of composite modifiers was greater than that of single modifier alone. Furthermore, the permanent deformation occurred continuously with the increase in the number of loadings and the delayed elastic performance was unstable at the beginning of loading progress.