Mechanism of Fatigue Cracks Propagation in Asphaltic Layers of Flexible Pavements by Considering Effects of Asphalt Binder Healing

Evaluation of crack propagation in asphaltic mixtures under traffic loading is very important. These cracks that are in relation to fracture in asphalt mixture, can be created in various forms in flexible pavements. These damages can be categorized in thermal cracks, fatigue cracks, and reflective cracks in asphalt overlay on the existing cracked pavement. Among these types of cracks, fatigue cracks divided into top-down cracking (longitudinal cracks) and bottom-up cracking (alligator cracks) can remarkably reduce pavement age. In this research, according to previous works and developed models such as Paris law, mechanism of fatigue crack propagation in asphalt mixture has been investigated, and effects of temperature, loading frequency and asphalt mixture properties have been considered on the mechanism of fatigue cracks propagation. Besides, effects of healing property of asphalt binder on the pavement performance against these types of cracks have been evaluated. According to the results, healing in asphalt binder could increase pavement age against fatigue cracking and considering J integral instead of stress intensity factor could be more appropriate criteria for evaluation of pavement age against fatigue cracking because J integral considers viscoelastic properties of asphalt mixture.