| With the proposing of the long service life asphalt pavement, more and more attention has been paid to the ultraviolet (UV) aging of asphalt, which becomes one of the hot topics in the field of road materials. Light stabilizers (LSs) which can prevent polymer materials from UV aging effectively have been used to improve the UV aging resistance of asphalt by blending. The cost of LSs modified asphalt is high due to the high price of LSs. Furthermore, LSs modified asphalt is only appropriate for hot mixture asphalt to pave new roads, which limits its application to asphalt pavement during service life. However, these problems could be effectively solved by preparing UV protective coatings containing LSs. As a result, not only the cost can be reduced obviously, but also it can be applied to asphalt pavement in service life.In this paper, different kinds of UV protective coatings were prepared using various LSs and carriers. The LSs were consisted of UV absorbers (UV326, UV531 and UV770) and light shield agents (rubber carbon black N220, pigment carbon black W45 and TiO2), and the carriers included organosilicon solution and asphalt emulsion. The effect of UV protective coatings on UV aging resistance of bitumen was investigated by comparing the changes of physical properties and chemical component of the binders before and after UV aging. The effect of UV protective coatings on pavement safety performance was studied by testing the permeability coefficient (PC), friction coefficient (FC) and structure depth (SD) of asphalt pavement. The results obtained are as follows:1. The penetration retention rate of asphalt coated organosilicon coating with three kinds of LSs were increased after UV aging, while the increment of softening point and viscosity was decreased. The increment of asphaltenes and resins, and the decrement of aromatics and saturates were restrained effectively, indicating the enhanced UV aging resistance of asphalt. Among three kinds of LSs, organosilicon coating with UV326 showed the best effect on increasing the UV aging resistance of asphalt.2. Compared with using single UV326, the organosilicon coating with the mixture of UV326 and UV531 or UV326 and UV770 contributed to the better improved UV aging resistance of the asphalt. Moreover, organosilicon coating with the mixture of UV326 and UV770 contributed to the best improved UV aging resistance of asphalt.3. The penetration retention rate of asphalt coated emulsion coating with LSs was higher, while the increment of softening point and viscosity was decreased. Moreover, the increment of asphaltenes and resins and the decrement of aromatics and saturates could be restrained by the UV protective coatings, indicating the remarkably improved UV aging resistance of asphalt. Compared with UV326 and UV770, the effect of UV531/asphalt emulsion was more obvious.4. The influence of the asphalt emulsion with the UV531 combined with UV326 or UV770 on the improved UV aging resistance of the asphalt were more outstanding than the asphalt emulsion using single UV531, and the UV aging resistance of the asphalt emulsion with the mixture of UV531 and UV770 was more remarkable.5. The asphalt emulsion coating with light shielding agents contributed to the increased penetration retention rate and the reduced the increments of softening point and viscosity of the asphalt after UV aging. The UV protective coatings restricted the increment of asphaltenes and resins as well as the decrement of aromatics and saturates during UV aging, which led to the improved UV aging resistance of asphalt. Compared with N220 and TiO2, the UV aging resistance of asphalt emulsion coatings with W45 was more effective.6. The UV aging resistance of the asphalt could be further improved by combining W45 with UV326 or UV531 or UV770. Furthermore, the improvement of UV aging resistance of asphalt emulsion combined with W45 and UV531 was larger.7. The effect of UV protective coatings on pavement safety performance was investigated by testing the PC, FC and SD of asphalt pavement. The PC of asphalt pavement was decreased obviously after coating as well as the improved impermeability of asphalt pavement, while the FC and SD were reduced to some extent within the limit of technical specification, indicating the limited effect of UV protective coating on pavement safety performance.
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