Investigating different fatigue failure criteria of asphalt binder with the consideration of healing

Fatigue damage is the deterioration of material strength due to repeated traffic loading and healing is the restoration of the material strength, which essentially delays the fatigue cracking in the asphalt pavement. Several criteria have been developed to determine the fatigue life from laboratory fatigue tests, however, none of these criteria consider healing. The primary objective of this study is to explore the effect of healing on fatigue life using different fatigue failure criteria. Healing is introduced in the fatigue tests by incorporating a rest period between loading. Three different performance grade (PG) binders are tested using fatigue (loading without rest period) and healing (loading with rest period) test methods to assess the effect of healing on the fatigue damage. The fatigue life is determined using three different criteria: Stiffness reduction (Nf50), Dissipated Energy Ratio (DER) and Ratio of Dissipated Energy Change (RDEC). Statistical analysis showed that there is no significant difference between these three approaches for both the fatigue and healing tests. In addition, the fatigue curve is constructed for both the fatigue and healing tests. The comparison of these fatigue curves show that fatigue life increases due to the incorporation of healing in the fatigue tests. An empirical equation is proposed to incorporate healing in the fatigue life equation.