Formulization of asphalt concrete stiffness for specific microstructures based on discrete element method

Document Type

Conference Proceeding

Publication Date



This study presents an approach to formulize asphalt concrete stiffness for specific microstructures. An asphalt concrete was designed on the basis of the Superpave mix design method. Its images were obtained from X-ray Computed Tomography (X-ray CT). Through processing those X-ray CT images, two-microstructure-based models, namely the Model-I and the Model-II were rebuilt on the basis of the discrete element (DE) method. In Model-I, no air void was included, while in Model-II, the air void level was 3.1%. The DE simulation of the asphalt concrete was conducted with those two models whose primary inputs were the stiffness values of both coarse aggregate and asphalt sand mastic. The asphalt sand mastic was defined as a sub-mix of fines, fine aggregate (less than 2.36mm), and asphalt binder. Through regression analysis of the DE simulation results, the asphalt concrete stiffness values were formulized into two analytical equations for Model-I and Model-II, respectively. A potential application of those two equations is to predict effective stiffness values of the asphalt concrete at various temperatures and different loading conditions. At the end of this study, an application example is provided. It was found that compared with the measured data, the formulized equation of Model-II could more precisely predict the asphalt concrete dynamic moduli at various temperatures and different frequencies than other models. © 2010 ASCE.

Publication Title

Geotechnical Special Publication