Mechanical performance of asphalt rubber mixtures with warm mix asphalt additives

The growing concern regarding global warming has led to the recent development of warm mix asphalt (WMA) technology in the field of pavement materials. Production and compaction temperatures can be reduced by lowering the binder viscosity and in turn reduce greenhouse gas emissions (GHG) and energy consumption without significantly changing the mechanical characteristics of the mixtures. There are different additives and technologies which reduce production temperatures, but not all of them have been studied, especially regarding asphalt rubber (AR) mixtures with a high content of rubber (20% over the weight of bitumen). These mixtures, with a high viscosity binder, must be produced at higher temperatures compared to a conventional mixture. This study contrasted and assessed AR mixtures with waxes as WMA additives in order to test: water sensitivity, resistance to permanent deformation and fatigue as well as stiffness. The study demonstrated that the waxes used enhance resistance to permanent deformation without compromising fatigue resistance. Water resistance is slightly inferior and the stiffness modulus depends on production temperature.