Fatigue Life Analysis of Asphalt Mixtures with Very High RAP Contents Using Classical and Viscoelastic Continuum Damage (VECD) Approaches

This study focuses on the fatigue life of asphalt mixtures with very high RAP contents (>50%). The classical and viscoelastic continuum damage (VECD) approaches were employed for the analysis of four mixture types designed according to Bailey method with 57%, 65%, 73%, and 100% RAP. Within characterization phase of VECD, 2S2P1D model was used to calibrate generalized Maxwell (GM). Wöhler curves based upon classical and VECD prediction approaches were constructed and compared to find the better method for this type of asphalt mixture. The classical approach establishes strong relationship between fatigue life and strain level but a thorough comparison between the mixtures regarding the fatigue life is not possible. It is because of the strain level. However, VECD effectively removes the strain impact and makes the comparison viable. Also, the averaged released pseudo-strain energy throughout entire test history (GR) was found useful to compare fatigue characteristics of very high RAP content mixtures.