Evolution Of The Structure And Properties Of Crumb Rubber Modified Asphalt In Aging Process

Crumb rubber modified asphalt (CRMA) as a new environment-friendly pavement materials, which has the better pavement performance than that of traditional asphalt, especially the aging properties improved. Currently, the aging of CRMA is mainly focused on the study of macro performance, while the aging mechanism is not clear. In this paper, the macro performance and microstructure of two types of CRMA under different aging conditions were analyzed, and the aging mechanism of CRMA was explored.Firstly, rolling thin film oven was used for simulating the short term aging (thermal oxidative aging) of CRMA. The evolution of structure and performance of CRMA was evaluated in aging process. Results showed that both the composition, dissolution and crosslink density of crumb rubber (CR) as well as asphalt changed simultaneously in aging process. Besides, the resistance to aging of asphalt was enhanced because of the dissolution of CR increased, while the CR had the anti-aging effects for asphalt is not obvious. The aging degree of modified asphalt increases with the aging time extended.Secondly, CR was decomposed deeply to the analog asphalt substances to prepare the highly degraded rubber modified asphalt(CRMA-TB), and the changes of structure and properties of TB in UV light ageing process were studied.Research indicated that both the composition and dissolution of CR as well as asphalt changed simultaneously. The ability to resist UV aging of modified asphalt, which relates to the changes of rubber in aging process, and the resistance to aging of asphalt is improved by the rubber dissolved and carbon black released.Finally, CRMA, CRMA-TB, Styrene-butadiene-styrene (SBS) modified asphalt (MA) and base asphalt (BA) were exposed outdoor for aging, and effect the weather aging on the chemical composition and rheological properties of polymer modified asphalt were analyzed. Results showed that the aging performance of different polymer modified asphalt is different. Meanwhile, the changes of SBS modified asphalt is largest, while the CRMA-TB is better.