Effect of nano-zinc oxide on ultraviolet aging properties of bitumen with 60/80 penetration grade

Abstract

This work evaluates a novel bitumen modification through the use of nano-zinc oxide (nano-ZnO). In order to improve the compatibility between nano-ZnO and bitumen with 60/80 penetration grade, nano-ZnO was surface modified by γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH-560). The modified nano-ZnO was marked as KH-560-nano-ZnO. Ultraviolet (UV) aging mechanism of the binders was revealed by using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The effect of surface modification of nano-ZnO on physical and UV aging properties of bitumen was also investigated. The results show that KH-560 is grafted on the surface of nano-ZnO in the form of chemical bond according to FTIR analysis. The compatibility between bitumen and nano-ZnO is improved by surface modification of nano-ZnO. As a result of UV aging, viscosity aging index of bitumen is decreased with the addition of nano-ZnO and KH-560-nano-ZnO. The carbonyl indices of nano-ZnO and KH-560-nano-ZnO modified bitumens are decreased more remarkably in comparison with that of unmodified bitumen after UV aging. The single phase trend of bitumen is prevented by KH-560-nano-ZnO during UV aging according to AFM analysis, indicating the good UV aging resistance of KH-560-nano-ZnO modified bitumen. Such a result suggests that nano-ZnO can be effectively used as a modifier to improve the UV aging resistance of bitumen.