The viscoelastic and damage dissipation of hot mix and warm mix bituminous mixture under dry and saturated conditions

Complex issues persist in quantifying the fatigue response of warm mix asphalt (WMA). Due to reduced aging, WMA is expected to perform better in fatigue when compared to hot mix asphalt (HMA). However, the fatigue life of WMA can reduce due to the potential for increased moisture damage. To reduce the moisture induced damage, hydrated lime is usually added. While it can improve the moisture resistance and reduce aging, the stiffness of the hydrated lime treated mixture can increase, leading to poor fatigue response. This investigation attempts to develop an understanding of such disparate issues. In the 1st step, four-point bending tests on WMA and HMA samples for various strain levels are carried out. All the samples are tested with and without moisture damage and with and without hydrated lime. In the 2nd step, the total energy dissipated is apportioned into linear viscous dissipation and dissipation due to damage using three approaches. The 1st approach appeals to the concept of dissipated pseudo strain energy. In contrast, the 2nd and 3rd approach directly computes the linear viscous dissipation from the raw data by appealing to linear viscoelastic constitutive models. Different hypotheses related to the influence of WMA, moisture damage, and hydrated lime on the fatigue damage are made and verified using these 3 approaches.