Influence of Aging on the Rheological Behavior of Warm Mix Asphalt Binders

Abstract

The Warm Mix Asphalt (WMA) technologies allow a significant reduction in mixing and compaction temperatures of asphalt mixtures through lowering the viscosity of binders. In WMA, different types of additives are added to the binder depending on the technology used and such addition of these materials brings down the viscosity drastically thus reducing the temperature to which the aggregates and binders have to be heated during mixing and compaction. During mixing and compaction of WMA mixture, the binders are subjected to reduced aging compared to conventional Hot Mix Asphalt (HMA) mix. This study is conducted to quantify the influence of short-term aging on the rheological properties of WMA binder at pavement working temperatures. Two types of WMA binders were studied, the first one is Evotherm modified binder and the second one is Sasobit modified binder. A viscosity grade binder (VG30) was used as the control material. All the binders were tested at unaged and short-term aged conditions. All the three samples at two aging conditions were subjected to frequency sweep tests at 25, 35, 45, 55, 65 and 75 °C from 50 to 1 Hz frequency at a rate of 0.1 Hz per second using appropriate parallel plate geometry in a dynamic shear rheometer. Master curves were constructed for all the binders tested. Parametric analysis of the master curve was carried out to quantify the difference in binder response.