An investigation into the impact of warm mix asphalt additives on asphalt mixture phases through a nano-mechanical approach

This paper presents the results of a novel investigation to evaluate the effect of Sasobit, Rediset WMX and Rediset LQ on the mechanical properties of asphalt mixture phases, aggregate, interfacial transition zone (ITZ) and mastic using Nanoindentation. All warm additives improved the nano-mechanical properties of the ITZ if the reduction in the production temperature was not more than 10 °C for an asphalt mixture with the 40/60 hard binder and 20 °C with the 100/150 binder. The nano-mechanical properties of mastic for all WMAs manufactured at 20 °C lower than the control using 40/60 mix were less than the control mix. However, as the reduction in the production temperature decreased to 10 °C, the modulus and hardness of the mastic and ITZ for all WMAs significantly increased. While, 20 °C reduction in the production temperatures was achieved using 100/150 with inclusion of warm additives and the values of nano-mechanical properties of ITZ and mastic was same or even higher than the control mix. It can therefore be concluded that, in order to produce a warm asphalt mixture that performs the same or even better than the traditional HMA, the effect of production temperature must be addressed. In summary, Nanoindentation provides new insight about the effect of warm additives on the nano-mechanical properties of asphalt mixture phases and predicts level of bonding between aggregate and binder.