Thermal oxidative and ultraviolet ageing behaviour of nano-montmorillonite modified bitumen

This study aims to develop an advanced bitumen binder using nanotechnology to satisfy the requirements of both thermal and UV ageing resistance. Five different bitumen binders were investigated at different thermal and UV ageing stages. Specifically, two kinds of base bitumen (CAR and SBS modified bitumen) were used and modified with two kinds of processed nano-clay materials (PMMT and OMMT) with 5 wt.% respectively. The bitumen samples were then subjected to thermal oxidative ageing through RTFOT (Rolling Thin Film Oven Test), followed by UV-Ageing procedures. Through dynamic mechanical analysis, frequency sweep and MSCR (Multiple Stress Creep Recovery) tests were conducted to determine the mechanical properties of the original and aged samples. In addition, DSC (Differential Scanning Calorimetry) and FTIR (Fourier Transform Infrared Spectroscopy) tests were employed to investigate the change of chemical compositions. Results indicated that the UV ageing mechanism differed significantly from that of thermal oxidative ageing. The addition of processed nano-clay materials improved the ultraviolet ageing resistance of bitumen to some extent. The OMMT modification was more successful than the PMMT with regard to the thermal oxygen ageing resistance. However, the UV-ageing properties of the OMMT modification are less favourable than those of the PMMT modification. The recovery rate, rutting factor and fatigue factor are recommended to evaluate the aging inhibition properties of bitumen binders. In this research SBS-OMMT is found to be the optimal material in regions with elevated ultraviolet radiation.