A laboratory study on the fatigue performance of warm mix asphalt mixtures

Abstract

Reducing fuel consumption and greenhouse gas emissions are two major challenges for society today. Different technologies have been developed in the last few years to reduce the production and application temperatures of bituminous mixtures. Those mixtures are known as Warm Mix Asphalts (WMA). The important benefits of WMAs, among which the reduction of emissions in their production and the reduction of the amount of fuel spent in the burners can be highlighted, have reinforced their growing development. In the application process, WMAs assure suitable workability for the lay-down and compaction operations at a lower temperature, when compared to conventional Hot Mix Asphalts (HMA) mixtures, making it possible to be transported throughout longer distances, extending the paving season, and allowing their application under less favorable conditions (lower air temperatures). However, the sustainability of WMAs during the road life cycle can only be obtained by optimizing the performance of the mixture. Thus, the objective of this work was to assess the fatigue performance of different WMA mixtures (produced with two commercial additives Sasobit® and Cecabase® and different bitumen types) and one HMA mixture, in order to evaluate the effect of those variables in the resistance of the mixtures to fatigue cracking. Therefore, the mix design was kept constant in terms of aggregate gradation and binder content. Since the additives are different in nature (one is a viscosity reducer and the other is a surfactant), different temperature reductions were achieved for each WMA using the same binder, when similar volumetric properties were sought. The results obtained with the present study allow concluding that it is possible to obtain WMA mixtures with a fatigue performance similar to that of HMA mixtures and that the use of softer binders together with the studied additives resulted in WMA mixtures with the best fatigue performance.