Predicting dynamic modulus of asphalt mixtures with differential method

Dynamic modulus (|E*|) is one of the fundamental engineering properties of asphalt mixtures and has been selected as a basic material property input in the new American Association of State Highway and Transportation Officials (AASHTO) Mechanicstic-Empirical (M-E) Design Guide. The M-E design guide either requires the direct laboratory testing for |E*| values or recommends using the Witczak model to estimate |E*| values. While laboratory testing is costly and time-consuming to conduct, the Witczak model is a purely empirical regression model in nature. Micromechanics approach provides another possible access to obtaining |E*| values. In this paper, the differential method was employed to predict the dynamic modulus and phase angle of asphalt mixtures. The predictive models were formulated from the differential method. The major characteristics of asphalt mixtures (viscoelastic effect, aggregate gradation, and air voids) were taken into account in the predicting procedures. Laboratory experiments were conducted to evaluate the developed predictive models. The results show that the predicted |E*| values from some predictive models were favourably close to the measured data, which confirmed the potential applicability of these models to asphalt mixtures. © 2009 Lavoisier, Paris.