Fatigue Cracking of Flexible Pavements

This chapter examines theoretically the possible mechanisms of fatigue cracking in asphalt pavements using linear elastic fracture mechanics (LEFM). The effects of a non-uniform transverse contact traction between the tyre and pavement on longitudinal surface fatigue cracking are examined theoretically using a finite element (FE) pavement model. Fatigue cracking due to thermal loading is also examined using a simplified linear viscoelastic pavement model. Results indicate that longitudinal surface fatigue cracking is unlikely to occur due to the non-uniform transverse contact traction. However, for short longitudinal cracks in the pavement surface, the combined vehicle and thermal load cycles may produce conditions that are favourable for fast fracture. Fatigue cracking (both longitudinal and transverse) at the base of the asphalt layer is found to be mainly dependent on the pavement geometry and the magnitude of the normal load.