Mesogenetic Evaluation and Design of Coarse Aggregate Contact within Asphalt Mixture

Abstract

To establish a new gene database and asphalt mixture evaluation method, coarse aggregate contact characteristics from the meso perspective serve as a reference for the improvement of fine design and asphalt mixture performance. In this study, a rapid analysis and evaluation software for coarse aggregate contact software was developed. An optimization calculation method for voids in coarse aggregate of asphalt mixture was proposed based on digital image processing techniques. In addition, the meso characteristic gene of coarse aggregate contact for eight different asphalt mixtures was investigated, and the relationship between coarse aggregate contact mesogenetic parameters and the corresponding macrorutting resistance was established. The results indicate that number of contact points is not appropriate as the mesoparameter for evaluating the skeleton of the asphalt mixture; average coordination number, skeleton ratio, and “free” coarse aggregate content can be used to evaluate the mesostructure of the asphalt mixture. Skeleton ratio is the most sensitive mesogenetic parameter affecting rut depth, which can be used as the main control parameter for fine design of asphalt mixture. The limit standards of the skeleton ratio and “free” coarse aggregate content values are 41.32% and 82.89%, respectively, and the range of average coordination numbers is 0.5–1.72. However, the mesodesign parameters cannot reach the standard theoretical value due to the inhomogeneous granular material characteristics of the asphalt mixture. In the asphalt mixture design process, average coordination number is ≥1.50, skeleton ratio is ≥23.48%, and “free” coarse aggregate content is ≤24.94%; these values can be used as the mesoparameter standard for the fine design of skeleton asphalt mixtures.