Effect of physical hardening on low temperature performance of DCLR modified asphalt

Abstract

This study aims to investigate the effect of physical hardening on the low temperature performance of direct coal liquefaction residue (DCLR) modified asphalt. The extended bending beam rheometer (EBBR) method was used to evaluate the low temperature performance of DCLR modified asphalt with benzaldehyde, silane coupling agent and xylene compatibilizer. Meanwhile, the microstructure and morphology of DCLR modified asphalt before and after physical hardening were quantitatively characterized by atomic force microscope (AFM) and image processing software. In this study, the physical hardening was performed by placing the DCLR modified asphalt at low temperature conditions for a certain time. The test results show that as the conditioning temperature decreased and the conditioning period increased, both low temperature grade loss and hardening rate of asphalt increased, indicating that the low temperature performance deteriorated. Compared to the room-temperature conditions, the total number of “bee-structures” of DCLR modified asphalt under low temperature conditions were less, but the shape of a single “bee-structure” became larger and longer. The compatibilizers hindered the growth of “bee-structure”, which demonstrated that the compatibilizers could improve the low temperature performance of asphalt. The three compatibilizers had different effects on low temperature performance of DCLR modified asphalt. Among them, the silane coupling agent was the most effective, followed by benzaldehyde and xylene.