Dynamic mechanical characterization of asphalt concrete mixes with modified asphalt binders

The primary objective of this work is to characterize and compare the dynamic mechanical behavior of asphalt concrete mixes with styrene butadiene styrene (SBS) polymer and crumb rubber modified asphalt binders with the behavior of mixes with unmodified viscosity grade asphalt binders. Asphalt binders are characterized for their physical and rheological properties. Simple performance tests like dynamic modulus, dynamic and static creep tests are carried out at varying temperatures and time. Dynamic modulus master curves constructed using numerical optimization technique is used to explain the time and temperature dependency of modified and unmodified asphalt binder mixes. Creep parameters estimated through regression analysis explained the permanent deformation characteristics of asphalt concrete mixes. From the dynamic mechanical characterization studies, it is found that asphalt concrete mixes with SBS polymer modified asphalt binder showed significantly higher values of dynamic modulus and reduced rate of deformation at higher temperatures when compared to asphalt concrete mixes with crumb rubber and unmodified asphalt binders. From the concept of energy dissipation, it is found that SBS polymer modification substantially reduces the energy loss at higher temperatures. Multi-factorial analysis of variance carried out using generalized liner model showed that temperature, frequency and asphalt binder type significant influences the mechanical response of asphalt concrete mixes. The mechanical response of SBS polymer modified asphalt binders are significantly correlated with the rutting resistance of asphalt concrete mixes.

► Rheological characterization showed that polymer modification of asphalt binder improves the temperature susceptibility of asphalt binders, whereas crumb rubber modification might risk the low temperature property of asphalt binder by imparting brittleness but still enhances the high temperature properties.
► At lower frequencies (longer loading times) asphalt mixes with polymer and crumb rubber modified asphalt binder showed higher dynamic modulus values when compared to mixes with unmodified asphalt binder.
► From the multi-factorial analysis of variance, it was found that temperature, frequency and asphalt binder type had significant influence on the measured dynamic modulus values.
► Variation in the phase lag with temperature in polymer modified asphalt binder mixes was substantially lower than that of mixes with crumb rubber and unmodified asphalt binders.
► At high temperature of 60 °C, loss of energy in mixes with polymer modified asphalt binder was found to be lower when compared to mixes with crumb rubber modified binder and mixes with unmodified asphalt binders.
► Asphalt mixes with polymer modified asphalt binder showed higher resistance to creep under dynamic and static loading when compared to mixes with crumb rubber and unmodified asphalt binders at high temperature (60 °C).
► Rutting resistance of mixes with polymer modified asphalt binder was found to be significantly higher when compared to mixes with crumb rubber and unmodified asphalt binders at higher temperature (60 °C).