Study on UV aging characteristics of low-grade asphalt in the desert climate

Abstract

Abstract The Taklamakan Desert in China’s Xinjiang region faces severe heat conditions that cause rutting in asphalt pavements. In order to combat this issue, local construction management has been advocating for the utilization of low-grade asphalt with penetration levels between 20 and 50, to enhance the pavement’s resistance to rutting. However, there is limited research on the durability of low-grade asphalt under intense UV irradiation in the region. To this end, a multiscale investigation was conducted, examining three different types of asphalt (30#, 50#, and 70#), under various conditions such as virgin, UV aging, and Pressure Aging Vessel aging. Analytical techniques such as Atomic Force Microscope, Gel Permeation Chromatography, Fourier Transform Infrared Spectroscopy, Dynamic Shear Rheology, and Bending Beam Rheometer were employed. The results revealed that the surface roughness of the three types of asphalt increased by 15.50% (30#), 5.99% (50#), and 2.70% (70#) after UV aging, compared to the virgin samples. Furthermore, the adhesion properties of lower-grade asphalt were less affected by UV aging. Weight-average molecular weight of the three types of asphalt increased significantly after UV aging, with a 26.96% increase in 30#, 51.92% increase in 50#, and 43.76% increase in 70# compared to the samples prior to UV aging. The 30# asphalt with higher large molecule content exhibited slower UV aging. The 30# asphalt also exhibited the smallest increase of C=O and S=O after UV aging among the three types of asphalt. The study also found that UV aging had a lesser effect on the high- and low-temperature performance of asphalt, compared to PAV aging. Overall, the effects of UV irradiation on various properties of 30# asphalt were less pronounced than those of 50# and 70# asphalt. These findings offer valuable insights into aging resistance in the Taklamakan Desert, benefiting road contractors and the academic community.