Low-temperature reversible aging properties of coal liquefaction residue modified asphalt

Abstract

The primary objective of this paper is to understand reversible aging properties of modified asphalt binders containing different percentages of coal liquefaction residue (CLR), which is a by-product of the coal liquefaction process. To fulfill this objective, regular performance grading test, extended bending beam rheometer test, and dynamic shear rheometer test were conducted to comprehensively evaluate the effect of CLR on base asphalt while reversible aging was also considered. The results showed that adding a certain percentage of CLR significantly increased the high-temperature performance grade of modified asphalt while the regular low-temperature performance grade kept constant. However, when the conditioning time prolonged, all the CLR modified asphalts in this study experienced severe hardening trend and the grade loss higher than 6 °C after 72 h conditioning time. From statistical analysis, it could be concluded that the grade loss had a significant change even just by adding 3% CLR in base asphalt binder. For all the CLR modified asphalt systems containing different percentages of CLR, significant differences in the grade loss between 24 and 72 h conditioning time occurred. However, no significant differences were observed when the conditioning time extended from 72 to 168 h.