Characterization of Linear Viscoelastic Behavior of Asphalt Concrete Using Complex Modulus Model

A new approach for the characterization of linear viscoelastic (LVE) behavior of asphalt concrete is presented in this study. The proposed approach uses the associated function of the original Havriliak-Negami (HN) formulation to model the complex modulus of the material. The model coefficients are determined in two steps. First, the coefficients associated with the complex plane representation of complex modulus are solved in the Cole-Cole domain. Second, the coefficients related to the time-temperature shifting are determined. The results show that the approach can accurately characterize the LVE properties of asphalt concrete contained in the entire data set for the complex modulus. The approach overcomes several shortcomings in the conventional method of constructing a viscoelastic function master curve by fitting a sigmoidal function to test results. Each model coefficient in the proposed approach has a clear physical meaning in interpreting the LVE behavior of asphalt concrete; the same values of model coefficients can be used to construct the master curves of storage modulus, loss modulus, dynamic modulus, and phase angle. Also, the Kronig-Kramers relations are automatically satisfied because the mathematical forms of various viscoelastic functions are theoretically derived from the same complex modulus model, and thus, the results are in compliance with LVE theory. The proposed approach provides a unified and consistent way to characterize the LVE properties of asphalt concrete.