Effect of ultraviolet aging on rheology, chemistry and morphology of ultraviolet absorber modified bitumen

Seeking a new method to solve the ultraviolet (UV) aging of bitumen is of great importance for road applications since the UV aging is considered to be one of the main causes leading to the performance deterioration of bitumen. In this paper, two UV absorbers (octabenzone and bumetrizole) were applied to modify the bitumen by melt blending. Effect of UV aging on rheology, chemistry and morphology of the UV absorber modified bitumens was investigated, by means of dynamic shear rheometer, thin-layer chromatography with flame ionization detection, Fourier transform infrared spectroscopy and atomic force microscopy, to reveal the mechanisms of action for bitumen and UV absorbers. Results show that the two UV absorbers show opposite influences on the UV aging performance of bitumen depending on the type of UV absorbers. The bumetrizole improves the UV aging resistance of bitumen remarkably since the bumetrizole can inhibit reactions of aromatization and oxidation of bitumen molecules to a certain extent during the UV aging, and thus slows down the rate at which the bitumen transforms from sol to gel. The bumetrizole modified bitumen has the potential to be used in pavement for improvement of the UV aging resistance during service life.