In this paper a series of digital image processing methods were adopted for getting separated coarse aggregates from asphalt mixture specimen using high-resolution X-ray Computed Tomography ( CT) images． The existing three dimensional ( 3D) particles matching methods based on two dimensional ( 2D) continuous cross sections were analyzed and a new ‘overlap area method’ was presented． After the 3D particles were extracted one by one successfully， the basic parameters of each aggregate: perimeter， area， surface area， and volume were calculated by chain code method． Finally， the 3D mass center coordinates and the sphericity index were introduced．

       Key words: asphalt mixture; X-ray CT; three dimensional matching; chain code; sphericity