Relation between meso-skeleton characteristics and macro performances of OGFC asphalt mixture

ObjectiveIn response to the current limitations in understanding the skeleton structure and the skeleton composition of open-graded friction course (OGFC) asphalt mixture, this study utilizes an analysis on the skeleton by using IPAS-2 image analysis software.MethodFirst, the threshold segmentation was applied to categorize images into two target regions, i.e., skeletons (target object) and voids. Second, the coarse aggregates with particle size over 2.36 mm and contact points with contact distance less than 0.54 mm were identified through pixels; so as to identify and make statistics on the meso-skeleton structure and parameters of OGFC asphalt mixture, e.g., contact points quantity, average contact line length, average coordination number, contact direction angle and internal structure index. Finally, the statistical result was subjected to Pearson correlation analysis and linear regression analysis with the experimentally measured macro-mechanical properties of asphalt mixture, including Marshall stability, split tensile strength, and rutting dynamic stability.ResultPearson correlation coefficients between Marshall stability, representing the deformation resistance of asphalt mixtures, and the number of contact points and average coordination number are 0.87 and 0.85, respectively. For the indirect tensile strength represented by split tensile strength, the Pearson correlation coefficients with the number of contact points and average coordination number are 0.94 each. Additionally, the linear regression coefficient between internal structure index and rutting dynamic stability is 0.934 4.ConclusionThe proposed meso-skeleton indicators exhibit the strong correlation with measured macro-mechanical properties. These indicators can be effectively used to characterize the macro-mechanical performance of OGFC asphalt mixture.