Dynamic modulus and phase angle models for New Mexico’s Superpave mixtures

This study modifies the viscosity (η)-based Witczak dynamic modulus (|E*|) predictive equation which is used in the recently developed AASHTOWare pavement Mechanistic-Empirical design software. A total of 21 Superpave asphalt concrete 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 Superpave mixes. Therefore, the 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.