Gradient aging behaviors of asphalt aged by ultraviolet lights with various intensities

The ultraviolet (UV) aging of asphalt is one of the main factors to reduce the service span of asphalt pavement. However, the increasing behavior of aging depth of asphalt is still not clear. The research work on the aging behaviors of asphalt is good for understanding the aging mechanism of asphalt, and developing anti-aging technologies for asphalt pavement. In this research, three UV lights with different intensities were generated to age the asphalt binder. After the aging, the asphalt was stripped layer by layer with the dissolution stripping method. The rheological properties and chemical structure of asphalt from different depths were tested with Fourier transform infrared spectrometer (FTIR) and dynamic shear rheometer (DSR) respectively. The results show that under a same condition, the aging effect of UV light with higher intensity on asphalt is more significant than that with lower intensity. The UV aging of asphalt is a process of gradual development, which starts from the surface of asphalt and gradually develops to the deeper part of asphalt. Therefore, with time going, the aging depth of asphalt will increase gradually, and a gradient aging degree also exists in asphalt from different depths. Moreover, even at a same depth, the aging status of asphalt is also different if aged by UV lights with different intensities. The growth behavior of aging depth of asphalt can be divided into two stages, which can be characterized by a two-stage model. During 0-24 h, it accords with the power model; after 24 h, it accords with a linear model. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

UV aging is a key factor in reducing the service life of asphalt pavement. Research on aging behaviors is important for developing anti-aging technologies. High intensity UV light has a more significant aging effect on asphalt, leading to an increase in aging depth and gradient aging degree.