Microscopic performance of modified asphalt based on aging

In order to clarify the effect of modified asphalt after thermal aging (aging for short) on asphalt pavement performance, five groups of asphalt samples were selected as research materials: matrix asphalt group, styrene-butadiene-styrene (SBS) group, styrene-butadiene rubber (SBR) group, stabilizer group and furfural extract oil group. The changes of macro-performance and micro-structure for asphalt were compared and analyzed before and after aging. The micro-morphology of asphalt surface was analyzed by scanning electron microscope (SEM). The cross linking and degradation of asphalt molecules was observed by gel permeation chromatography (GPC). The high temperature performance and exothermic properties were analyzed by differential scanning calorimetric (DSC). The results showed that agglomeration increased with aging and occurred in all asphalt samples, but most particles of composite modifier were evenly distributed and with a few folds being on the surface of the modified asphalt after aging. Double peaks appeared in the chromatogram of the SBS modifier before aging, but only single peak appeared after aging. The chromatogram peak of composite modifier shifted to the right after aging, and the peak of composite modifier was not obvious and dispersed widely. There was a weak exothermic peak from 350 °C to 410 °C in the DSC curve of the asphalt sample and a strong endothermic peak from 420 °C to 510 °C before and after aging. The maximum endothermic peak was at 460 °C. Except for the SBR group, the bond-breaking endothermic rate of macromolecules was higher than that of polymerization exotherm of small molecules during long-term aging, so the heat absorption of long-term aging asphalt was greater than that of short-term aging. The analysis of macro results showed that the comprehensive performance of composite modified asphalt was the best, which had a positive significance for improving the pavement performance and application of modified asphalt.