Recommended Calibration Procedure of MEPDG Asphalt Rutting Model Using Repeated Load Permanent Deformation and Confined and Unconfined Dynamic Modulus Data

Abstract

The repeated load permanent deformation (RLPD) test is recognized as the most appropriate laboratory procedure to characterize rutting in asphalt mixtures. It is currently used in support of the calibration of the rutting model of the Mechanistic-Empirical Pavement Design Guide (MEPDG). However, certain aspects of the RLPD test conditions, method of analysis of the test results, and calibration process are not well defined. The primary objective of this study was to provide an overview of the testing and calibration variables and quantify their effects on the asphalt concrete rutting prediction using the AASHTOWare Pavement ME software. Two hot mix asphalt and two warm mix asphalt were characterized in the laboratory by performing confined and unconfined dynamic modulus tests and RLPD tests at a single temperature. RLPD data for two additional temperatures were obtained mathematically using the dynamic modulus shift factors (from both confined and unconfined conditions). Different scenarios were analyzed by considering the effect of (1) using confined and unconfined dynamic modulus test results to calculate resilient strains, (2) shifting RLPD data, (3) using single or multiple RLPD temperatures, and (4) using confined and unconfined |E*| as an input of the AASHTOWare Pavement ME. Depending on the case considered, differences in the results ranged between 0% and 80% when different methods of analyses were used. The impact of the type of asphalt concrete on rutting prediction seems to be nonnegligible as the two warm mix asphalts show a wider variability than the two hot mix asphalts.