Development of Complex Modulus-Based Rutting Index Parameter for Asphalt Mixtures

Abstract

Rutting distress within a pavement structure has a direct correlation with mixtures’ structural responses to loading. For this reason, the complex modulus (|E*| and phase angle) master curves may be used to estimate the mixtures’ rutting performance. This research introduces and investigates five different complex modulus-based rutting index parameters (CMRI) to evaluate the rutting performance of asphalt mixtures. These parameters are developed based on three selected points on the |E*| and phase-angle master curves. The first point is related to the reduced frequency on the master curve at which the peak phase angle happens (Point A), and the second point is related to the reduced frequency on the master curve that reflects the Hamburg wheel tracking test (HWTT) testing conditions (Point B). The third point (Point C) corresponds to the average of the phase angle and dynamic modulus values of points A and B on the master curves. The results from investigating 22 asphalt mixtures indicate that a strong correlation (R2=0.89) exists between the rutting and the rate of drop in |E*| with respect to changes in the frequency between the two selected master curve points.