## 1 Introduction  
The anti-aging performance of asphalt and asphalt mixture is an important factor affecting the service quality and service life of asphalt pavement. The aging process and degree of asphalt in different structural layers of asphalt surface course are quite different, among which the aging of upper layer asphalt is the most serious [1,2]. The external temperature and traffic load on the pavement can be shared by each structural layer of asphalt pavement, but solar radiation, as a natural energy source, can only be borne by the surface layer of asphalt pavement alone [3,4]. Although the direct effect of UV radiation is on the asphalt surface, considering the diffusion of asphalt molecules after aging and the existence of asphalt pavement voids, the actual effect of UV radiation on the asphalt surface can reach about \(1\) cm [5]. UV aging results in an increase in low-temperature stiffness of surface asphalt mixture, from which it is very easy to produce temperature shrinkage cracking, thus increasing the depth of UV incidence. Coupled with the influence of rain and snow, the pavement condition can further deteriorate, which seriously affects the durability of the pavement [6]. Therefore, the aging effect of asphalt pavement materials caused by UV radiation cannot be ignored. UV aging is a type of long-term aging in the process of asphalt pavements. At present, the evaluation indexes and methods for the anti-UV aging performance of asphalt are mainly as follows:  
* Evaluation method based on penetration, ductility, mass loss, and other indicators after UV aging [7, 8, 9];
* Evaluation method based on rheological property index [10, 11, 12, 13, 14, 15];
* Evaluation method based on whole section fracture energy index [16,17];
* Evaluation method based on asphalt colloidal structure component index [18,19];
* Evaluation method based on molecular dynamics index [20]. UV aging has a significant effect on the physical and rheological properties of base asphalt and modified asphalt. The changes in asphalt components directly affect the physical properties of asphalt, and there is a good corresponding relationship between the proportion of soft and hard components and rheological indexes. The differences of chemical components in asphalt leads to different degrees of aging reaction. Aromatic components and gum are the main factors affecting the anti-ultraviolet aging ability of asphalt [21]. The impact of UV radiation on an asphalt pavement mainly occurs in the surface layer. Therefore, the anti-UV aging methods for asphalt pavements mainly focus on two aspects: one is to improve the anti-UV aging performance of asphalt materials [22, 23, 24, 25, 26, 27], and the other is to pave, coat, or spray anti-UV aging materials on the upper layer of asphalt pavement, thus improving the anti-UV aging ability of the upper layer [28, 29, 30, 31, 32, 33, 34]. Studies have found that the UV aging mechanism of asphalt can be explained by the aging mechanism of polymer materials. Therefore, the anti-UV aging methods of polymer materials are also used for reference in the improvement of asphalt UV aging [35,36]. High polymer materials usually add a certain amount of anti-aging agent to improve thermal-oxidative aging and UV aging, such as using TiO2 to improve the UV stability of PVC, adding light shield agent in PVC film to improve its UV aging resistance, or adding hindered amine light stabilizer and antioxidant to improve the UV stability of polymer [37, 38, 39, 40, 41]. At present, the research on the improvement measures of UV aging of asphalt is mainly focused on the anti-UV aging modification of asphalt materials. There are great differences in the intensity of UV radiation in different areas. Therefore, it is important to choose the corresponding UV prevention and control measures according to the intensity of UV radiation. However, the UV aging of asphalt has not been included in the material design index in the relevant specifications of China, and the relevant researches are mostly carried out for local areas.