Volume 40, Issue 7 (December 2012)
Characterization of Asphalt Mixture Homogeneity Based on X-ray Computed Tomography
The mechanical performance and life span of asphalt pavement depend largely on the homogeneity of the asphalt mixture. Inhomogeneity of asphalt mixtures is due to the non-uniform segregation of air voids and aggregates in mixtures. In order to evaluate the homogeneity of an asphalt mixture during lab compaction, computed tomography (CT) images of the specimen were obtained based on x-ray CT. The image was virtually cut into slices of various sizes, and the vertical air void distributions and aggregate gradations were quantified. Research results reveal that the air void content in the middle part of the specimen was lower than those on both ends. Also, the homogeneity was better under high compaction levels. The results from aggregate gradations were in good agreement with air void distribution calculations. Therefore, it is feasible to characterize an asphalt mixture’s homogeneity based on the air void distributions and aggregate gradations as determined via x-ray CT.