Methodology to Predict Alligator Fatigue Cracking Distress Based on Asphalt Concrete Dynamic Modulus

This study focused on integrating the Mechanistic–Empirical Pavement Design Guide (MEPDG) methodology (NCHRP 1-37A and NCHRP 1-40D) with the simple performance test methodology (NCHRP 9-19) to develop a comprehensive bottom-up fatigue cracking distress prediction model based on the dynamic modulus in a methodology that can be implemented in a probabilistic performance-related specification (PRS) methodology for quality assurance (QA) of hot-mix asphalt (HMA) construction (NCHRP 9-22). The main approach for a comprehensive fatigue cracking–damage predictive methodology was to run MEPDG for a large number of simulations using combinations of inputs that were believed significant in classic load-associated bottom-up alligator fatigue cracking and to develop an accurate closed-form solution for the fatigue damage–cracking distress prediction based on the dynamic modulus of HMA. Four major studies have been completed for fatigue cracking prediction methodology: (a) development of a fatigue damage model based on a two-layer pavement system, (b) development of an asphalt concrete (AC) effective dynamic modulus model, (c) development of a predictive methodology to transform a multilayer to a two-layer pavement system, and (d) validation of the prediction process. The developed methodology approximately but accurately predicts the classic AC alligator fatigue cracking distress that is close to that from MEPDG. Thus, implementation of the methodology into the PRS-based QA system in NCHRP 9-22 is recommended.