Assessment and modification of nationally-calibrated dynamic modulus predictive model for the implementation of Mechanistic-Empirical design

Abstract

This study modifies the viscosity (η) based Witczak dynamic modulus (|E∗|) predictive equation which is used in the recently developed AASHTOWare pavement Mechanistic-Empirical (ME) design software. A total of 21 Superpave (SP) mixtures with different gradations and binder grades were tested for |E∗| at different temperatures and frequencies of loading. Results show that the η-based Witczak model underestimates the |E∗| for New Mexico’s SP mixes. Therefore, revised model is developed using regression analysis. A phase angle (ϕ) predictive model is also developed using the ϕ-values obtained during the |E∗| testing. It was found that the revised η-based Witczak model determines the |E∗| more accurately compared to the original η-based Witczak model.