Investigation on aging and rejuvenation of asphalt rubber binders considering liquid and particle effect

Abstract

The aging and rejuvenation behaviors of asphalt rubber (AR) binder are of great importance, while most studies investigated the two processes by regarding the AR binder as a whole. Therefore, the AR binder was regarded as a two-phase system in this study to further clarify the aging and rejuvenation mechanisms behind. The liquid phase and particle phase of AR binders were separated using a physical sieving method, and the liquid effect (LE) and particle effect (PE) were then defined. Results showed that compared with the LE, the PE played a dominant role in affecting the unaged AR binders, especially for those prepared with crumb rubber of larger sizes and higher dosages. After aging, the LE of AR binders remarkably increased while the PE slightly decreased. Specially, at this status, the LE even accounted for a significantly larger proportion of the whole modification effect than the PE. The LE of the rejuvenated AR binders significantly decreased due to the softening effect of the rejuvenator. The PE also slightly reduced after rejuvenation because of the further degradation of crumb rubber. On the other hand, the proportion of asphaltenes and resins increased while the proportion of aromatics and saturates decreased during the aging, and the changes in fractions were on the contrary after the rejuvenation. The statistical analysis revealed that the rheological properties of liquid phases were dominantly affected by chemical fractions for all the unaged, aged and rejuvenated AR binders.