Development of Fatigue Model for Warm Mix Asphalt Based on Testing Frequency and Post-processing Method

Within the context of warm mix asphalt (WMA), there is a necessity to re-look at the distress mechanisms. Since the WMA undergoes reduced aging during mixing and compaction, one expects a reduction in the stiffness of the initial in-place material. Such reduced stiffness can lead to a widely varying mechanical response of the mixture during the performance and it will be interesting to bench-mark the same, especially, the fatigue behavior, when compared to hot mix asphalt (HMA) and this paper explores the same. In the current study, two types of WMA additives were used and they are Evotherm (chemical-based) and Sasobit (wax-based). To determine the fatigue life, four-point beam bending experiments were conducted at two different frequencies and the data was analyzed using two types of post-processing method. Using S-N plots, calibration factors for fatigue distress prediction model were determined for warm mix asphalt. It was found that the material calibration factors were dependent on the post-processing method used.