Effects of thermal oxidative ageing on dynamic viscosity, TG/DTG, DTA and FTIR of SBS- and SBS/sulfur-modified asphalts

Thermal oxidative ageing as an inevitable process in the practical application of road asphalt has a great effect on the properties of polymer-modified asphalts (PMAs). In this article, the influences of short-term and long-term thermal oxidative ageing on the dynamic viscosity, thermal stabilities, and infrared spectra of styrene–butadiene–styrene (SBS)- and storage-stable SBS/sulfur-modified asphalts were studied respectively. Although the addition of sulfur improved the dynamic viscosity and the thermal stability of SBS-modified asphalt significantly due to the formation of a chemically crosslinked polymer network structure, the improved properties declined evidently after ageing and the losses of properties became very severe with the ageing aggravated and the binder with sulfur showed a visible viscous behaviour compare with the corresponding binder without sulfur after ageing due to the severe degradation of vulcanized SBS, therefore SBS/sulfur-modified asphalt was more susceptible to ageing. Besides, the SBS structure also had a great effect on the properties of binders before and after ageing. In infrared spectra analysis, the structural evolutions of binder under different ageing modes were characterized by using right ageing index and the conclusions of thermal analysis and dynamic viscosity tests were confirmed further by the changes of butadiene and carbonyl indexes.