Development of a Universal Cracking Amount Model for Fatigue and Reflective Cracking of Asphalt Pavements

This paper reviewed mechanistic-empirical (ME) design and analysis frameworks and identified a weak link: a cracking amount model connecting pavement damage (predicted from mechanistic-empirical analyses) and asphalt cracking distresses. The importance of cracking amount models has not received the attention it deserves. After reviewing all the available existing cracking amount models in the technical literature, a universal cracking amount model was proposed for fatigue and reflective cracking. The new model governed by two parameters ($\alpha$ and $\beta$) fits naturally into the general ME design system. Parameter $\alpha$ is related to pavement life and can be directly predicted from ME analysis because it is the time (or number of load applications) when accumulated pavement damage reaches 100%. Parameter $\beta$ is a shape parameter function of traffic, environment, subgrade, pavement structure and material properties, and existing pavement surface condition when considering asphalt overlays. Because parameter $\alpha$ can be determined by the ME design and analysis system, $t$, the key parameter in the new universal model, is to quantify parameter $\beta$. Both fatigue cracking data in the long-term pavement performance database and asphalt overlay reflective cracking data in Texas were used in this paper to demonstrate and calibrate the new model and develop the $\beta$ functions. In this paper, different $\beta$ functions were established for fatigue and reflective cracking. Further model validation and calibration with more field data, varied traffic load spectra, different environmental conditions, and different materials are still required.