Rheological Evaluation of High Reclaimed Asphalt Content Modified with Warm Mix Additive

Abstract

High temperature for producing reclaimed asphalt mixture becomes the main concern in recycling as this will further age the reclaimed asphalt binder. Highly stiff binder causes workability and compatibility problems, hence affects the desirable performance of pavement. Warm mix asphalt additive is able to decrease the production temperature by reducing the binder viscosity. The synergy of warm mix asphalt and reclaimed asphalt mixtures resulted in a more environmental and energy savings benefits. The effects of a warm mix additive on the rheological properties of conventional asphalt binder containing a high proportion of recovered reclaimed asphalt binder were evaluated. Reclaimed asphalt were obtained from two sources and modified with a warm mix additive named RH. The recovered binders were blended with conventional binder at proportion of 0, 30 and 40 % and then tested for viscosity, stiffness and frequency dependency. Fuel usage and greenhouse gas emission were estimated based on the required fuel to heat up the aggregate and binder from ambient temperature up to the mixing temperature. The addition of RH improves the flow of binders by reducing the viscosity, thus decreases the construction temperature. The initial stiffness of reclaimed asphalt binders influences the effects of RH on the complex modulus and phase angle. The complex modulus increases while the phase angle decreases as the frequency increases, which indicates the binders have become stiffer. The differences in the magnitude of complex modulus are more noticeable at lower frequency and it gets close to each other at the higher frequency. This indicates that in the long run, the performance of modified reclaimed asphalt binders will be slightly better than the conventional hot mix asphalt. The warm mix additive and reclaimed asphalt composite in this study has the potential to reduce the fuel usage and green house gas (GHG) emission by 21 %.

Determining the Effects of Rh-Wma on the Engineering Properties of Bitumen

“…Thus, a reduction of 14°C at 135°C was predicted for 3.91 % RH-WMA. These results are similar to those obtained by Gungat et al [24], where the addition of RH-WMA resulted in lower binder viscosity and the mixing temperature was reduced to 20 °C. Gungat et al [25] also conducted a study using RH-WMA and the results of their study showed that viscosity decreased with higher temperature, and the viscosity of the bitumen was significantly altered at lower temperature.…”