Implementation of a Triaxial Dynamic Modulus Master Curve in Finite-Element Modeling of Asphalt Pavements

The newly developed Mechanistic-Empirical Pavement Design Guide (MEPDG) uses the dynamic modulus master curve to account for the temperature and frequency dependent behavior of asphalt concrete. However, the master curve used in the MEPDG is constructed using dynamic moduli measured in uniaxial testing and the effect of confinement on the mechanical properties of asphalt concrete is disregarded. This study implemented a model of triaxial dynamic modulus master curve in finite-element (FE) modeling of asphalt pavements. The dynamic modulus distribution in asphalt layers due to the contribution of confinement was evaluated for various scenarios. The results show that when the effect of confinement is considered the dynamic modulus can be more than two times the uniaxial value at the same temperature and frequency. The effect of confinement on dynamic modulus is more evident at high temperatures and low frequencies. Various pavement responses were computed using the developed FE model and compared to those obtained using the corresponding uniaxial dynamic modulus. For the pavements analyzed in this study, the confinement has the most pronounced effect on the permanent deformation of asphalt layers. The compressive strain in asphalt layers can be reduced to about half of the value obtained using the uniaxial dynamic modulus.