Study of normal and shear material properties for viscoelastic model of asphalt mixture by discrete element method

• Discrete element model could capture the viscoelastic behavior of asphalt mixture.
• Considering both normal and shear material properties improves modeling accuracy.
• Maxwell element in Burger’s model has a more dominant effect on dynamic properties.
• Normal direction model property is more significant under compressive dynamic test.

In this paper, the viscoelastic behavior of asphalt mixture was studied by using discrete element method. The dynamic properties of asphalt mixture were captured by implementing Burger’s contact model. Different ways of taking into account of the normal and shear material properties of asphalt mixtures have been reviewed. Two models, Model I and Model II, with different design parameters were developed and compared. For Model I, Burger’s model parameters in normal and shear direction were calibrated by using laboratory test results from Frequency Sweep Test performed in both normal and shear direction, respectively; while for Model II, the same calibrated parameters in the normal direction were used, but the values for the shear direction were chosen to be equal with the normal direction. The complex modulus of asphalt mixtures were predicted for both optimized models by conducting DE simulation under dynamic strain control loading. A sensitivity study was carried out, where the effects of different design parameters on the dynamic properties of asphalt mixture has been investigated, including the eight parameters of Burger’s model and the friction coefficient.