Fabrication and numerical verification of two-dimensional random aggregate virtual specimens for asphalt mixture

Abstract This paper proposes a two-dimensional (2D) virtual specimen fabricating method to create 2D virtual specimens that can accurately characterize the microstructure of asphalt mixtures. In this method, the gradation of the 2D aggregate area and the proportion of 2D voids area are calculated by the phase separation method. Random aggregates are generated by using the geometric characteristics database of random aggregates, which is established by the Aggregate Image Measurement System (AIMS). The random aggregate placement angle is determined according to the aggregate angle distribution law. Random aggregates are placed using a method that accurately identifies the scope of the conflicting judgment, and the random voids are generated with image binarization. Four AC-13 2D random aggregate virtual specimens with the same gradation were generated in this research to verify the practicability and effectiveness of the virtual specimen fabricating method. Virtual complex modulus parallel tests were performed on these four virtual specimens in COMSOL finite element software. By comparing the calculated results with the lab test results, it was found that the 2D random aggregate virtual specimens generated by the method proposed in this paper adequately predict the complex modulus of asphalt mixtures. The virtual test is repeatable and provides new ideas and references to creating virtual specimens for asphalt mixtures.