The high cost of Hot Mix Asphalt (HMA) maintenance related to field fatigue cracking requires the need for a better understanding of pavement fatigue phenomena, especially under typical Canadian conditions. The fatigue resistance of HMA pavement depends on many factors such pavement thickness, age, traffic loading and the quality of materials used in the asphalt mix. The mechanism of fatigue crack initiation and propagation involving the microstructure damage under repetitive load is not well-defined. This paper describes and validates a microstructure Finite Element Model (FEM) based on a twodimensional (2D) digital image to predict the fatigue life considering the asphalt concrete mixtures’ heterogeneity effect on beam response. The numerical results were validated with the experimental outcomes of four Superpave? asphalt mixes based on a four-point bending test. The mixes include Recycled Asphalt Shingles (RAS) and Reclaimed Asphalt Pavement (RAP). Viscoelastic material properties of the asphalt cement are included in the model based on available dynamic modulus data. The result of a microstructure model showed a better understanding of stress and strain distribution in fatigue beam compared to the macrostructure. A good correlation has also been observed between the measured and FEM predicted values for the mixes used in the study.
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