Abstract
Crumb rubber modified (CRM) bituminous binders provide considerable rheological and performance benefits for asphalt surfacings. However, more recent research efforts are considering low dosage CRM binders (5–15 wt.%) for their anti-aging effects, to prolong pavement life in local road surface applications. In this study, low-dose CRM binders were prepared using short and long blending durations, and were subjected to accelerated thermo-oxidative ageing through 20 and 50 h cycles in a pressure ageing vessel. Thermogravimetric analysis of virgin and post-blended crumb rubbers was used to determine the amount of tire polymer effectively dissolved into the base binder, with the associated dispersion of polymer compounds analyzed using Fourier transform infrared spectroscopy (FTIR) to compare blending methods. FTIR analysis was similarly used to determine and quantify changes to key chemical functional groups and ageing indicators to assess the relative ageing resistance imparted from the crumb rubber. It was found that, while increasing rubber contents and reduced blending durations significantly improved chemical ageing resistance by reducing oxidative effects, all CRM binder variants showed improvements compared to the unmodified base binder.