Investigation of Different Methods for Obtaining Asphalt Mixture Creep Compliance for Use in Pavement Mechanistic–Empirical Design Software

Abstract

Thermal cracking is a major distress type observed in flexible pavements, especially in regions with cold climates (e.g., northern United States and Canada). The Pavement ME Design Guide software developed under NCHRP Project 1-37A is the pavement analysis and design tool most widely used by state highway agencies for pavement designs. For thermal cracking predictions in flexible pavements, the most important material properties are the creep compliance and indirect tensile strength of an asphalt mixture in Level 1 and Level 2 analyses. Level 3 analyses use material properties and mixture volumetrics to predict creep compliance and indirect tensile strength. This study was part of a comprehensive research effort to characterize asphalt mixtures commonly used in the state of Michigan for implementation of the Pavement ME Design software. The main objective of the study presented in this paper was the investigation of methods of obtaining asphalt mixture creep compliance [D(t)] for use in flexible pavement analysis and design using the Pavement ME Design software. In this study, numerical interconversion between dynamic modulus (|E*|) and the creep compliance of asphalt mixtures with the Prony series method was investigated and validated. Then, the creep compliance of numerous asphalt mixtures was computed from the measured |E*| data. With these data, the creep compliance predictive equation used in Pavement ME Design software was evaluated and locally calibrated. In addition, an analytical model as well as an artificial neural network–based model was developed for improved prediction of D(t) from the mixture volumetrics.