Pavement performance and modification mechanisms of asphalt binder with nano-Al2O3

Nanomaterials has been widely adopted in asphalt binder modification in pavement engineering. Considering the advantage of nano-Al2O3 in high-temperature resistance and chemical stability, this study investigated the feasibility of the nano-Al2O3 used in asphalt modification in terms of performances and mechanisms. The impact of the nano-Al2O3 content on modified asphalt binder's pavement performance was analyzed via aging resistance, low temperature performance, high temperature performance, and bonding performance using various tests (e.g. DSR test, BBR test, RTFOT test, and BBS test). Results showed that the nano-Al2O3 is capable of improving base asphalt's aging resistance, high temperature performance and bonding performance, while bringing an insignificant adverse impact on performance at low temperatures simultaneously. Moreover, modification mechanisms of the asphalt binder under the modification of nano-Al2O3 were revealed from a view of functional groups and molecular characteristics via Gel permeation chromatography (GPC) tests and Fourier transform infrared spectroscopy (FTIR) tests. According to the result, modification of base asphalt binder by nano-Al2O3 belongs to physical blended and inhibits the growth of sulfoxide groups during the aging process. Meanwhile, the nano-Al2O3 increases the base asphalt binder's molecular weight based on LMS percentage, number-average and weight-average.