This study presents a simple method to define representative volume elements (RVEs) of asphalt concrete mixtures without damage. Three different asphalt concrete mixtures (two dense-graded Superpave mixtures with different nominal maximum aggregate sizes of 9.5 mm and 12.5 mm and one stone matrix asphalt mixture with nominal maximum aggregate size of 19.0 mm) often used today are selected and evaluated herein. In order to properly address the significant heterogeneity of asphalt concrete mixtures in defining RVEs, several geometrical factors such as area fraction, gradation, orientation, and the distribution of aggregate particles in asphalt concrete mixtures are considered altogether using two-dimensional actual images of asphalt concrete inner structures produced by digital image processing. Geometrically defined RVEs are then supported by finite element simulations to check if effective non-damage material properties such as the linear viscoelastic dynamic modulus obtained from the RVEs are representative properties of the corresponding bulk asphalt concrete mixture. Analysis results indicate that typical dense-graded Superpave asphalt concrete mixtures can be characterized for their effective non-damage properties with an approximate RVE size of 50 mm. However, the properties of stone matrix asphalt mixtures, which contain larger aggregates, should be measured on a larger scale for improved accuracy. Findings from this study are generally consistent with results presented in the other studies performed based on extensive laboratory tests, which infers that the simple geometrical-numerical method herein can be a potentially efficient approach to define the RVE of asphalt mixtures with much less time and efforts.
Abstract