3-D virtual design and microstructural modeling of asphalt mixture based on a digital aggregate library

Abstract

Structural indicators of asphalt mixtures, including aggregate gradation, spatial distribution, orientation, shape, angularity, texture, aggregate content, asphalt content and air void content, determine mixture heterogeneity and therefore significantly affect the micromechanical response of mixtures. An approach to the virtual design of mixture microstructure using structural indicators is proposed, based on a digital library of realistic aggregates. The methodology comprises three main steps, as follows: (1) a digital library containing almost 3000 reconstructed grains with quantified morphological properties based on computed tomography (CT) imaging is established; (2) aggregates which are consistent with volumetric and morphological assignments are identified in the library as the aggregate component of the mixture; and (3) the positions and orientations of selected aggregates are determined according to their distributional assignment, and consequently, the asphalt mortar and air void components are identified to obtain the microstructure of the virtual mixture. The proposed approach customizes the morphology and spatial distribution of aggregates and the content of the three phases of specimens to simulate the mixture’s microstructure, which facilitates the study of the correlation between the structural indicators and the mechanical responses of mixtures. Numerical simulations of indirect tensile tests were conducted to show different mechanical properties of obtained specimens.