Investigation of the effect of rubber on rheological properties of asphalt binders using superpave DSR

The main objective of this study was to investigate the effect of the rubber additive on the rheological properties of asphalt binders including Superpave rutting parameter, fatigue parameter, storage modulus at six rubber percentages: 0.0, 2.5, 5.0, 7.25, 10, and 15%. The Superpave Dynamic Shear Rheometer (DSR) was used to measure the complex shear modules value and the phase angle for the fresh asphalt binder and the rubber-modified asphalt binders using DSR strain-controlled tests. The DSR tests were conducted at one loading frequency of 10 rad/sec (1.59 Hz) and five temperatures: 58, 64, 70, 76, and 82°C. A 12 percent constant strain was applied in these tests according to the Superpave specifications. The rubber additive improved the complex shear modulus value of asphalt binder at all temperatures. Findings of the study showed that the rubber additive resulted in an increase in each of: the complex shear modulus value, the rutting parameter, the fatigue parameter, and the storage modulus (|G*|, |G*|/sin δ, |G*|sin d, and |G*|cos δ, respectively) of the asphalt binder. In conclusion, the rubber additive improved the rutting resistance as well as the fatigue resistance of the asphalt binder by increasing the complex shear modulus value and the storage modulus, and decreasing the phase angle.