Micromechanical Modeling of Asphalt Concrete Uniaxial Creep Using the Discrete Element Method

ABSTRACT This paper describes a methodology for modeling the creep behavior of Asphalt Concretes (ACs) under uniaxial loading. The approach involves capturing the microstructure of asphalt concretes using X-Ray Computed Tomography (CT) and using the Discrete Element Method (DEM) to describe the microstructure. The viscoelastic properties of mastics were characterized by fitting the Burger model to Dynamic Shear Rheometer (DSR) data. An automated digital image processing technique called Volumetric-based Global Minima (VGM) thresholding algorithm was utilized to process the X-Ray CT images of AC cores. The DEM simulations results were compared favorably to experimental uniaxial creep data. It was found that the models underestimated the creep compliance of the mixtures in the primary creep stage and predicted quite accurately in the secondary creep stage. The maximum absolute error observed for the slope and intercept of this region was not higher than 2.6%. Although the models predicted flow time, no meaningful comparison could be made with experimental flow times.

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