Recursive pseudo fatigue cracking damage model for asphalt pavements

Mechanistic-empirical (M-E) fatigue models for asphalt concrete (AC) pavements often ignore damage induced-changes in the AC, although laboratory testing and field studies show that AC modulus deteriorates as the extent and severity of cracking accumulates. This study developed a pseudo fatigue cracking damage model that incorporated damage-induced changes in AC modulus and AC fatigue endurance limit (FEL) for a more realistic fatigue analysis. The model, based on layered elastic theory, implements incremental-recursive damage accumulation, and its goal is to further minimise empiricism in M-E fatigue modelling. Bending beam fatigue (BBF) test data from 20 AC mixtures constructed at the National Center for Asphalt Technology Pavement Test Track during several research cycles were used to formulate the model. The functional form of the model was identified through iteration and showed high potential in simulating BBF damage curve. The model inputs are AC modulus, FEL and applied strain level. In applying the model, a trial pavement cross-section is simulated in WESLEA, a layered elastic analysis programme, to generate a fatigue damage curve, where AC modulus degrades versus load applications. Suggestions for implementing the model in pavement design procedures are discussed. Field validation is recommended before the model is used for pavement design.