The gradation of an aggregate is one of the most influential aggregate characteristics in determining how it will perform as a pavement material. In hot mixture asphalt (HMA), gradation helps determine almost every important property. The gradation that produces maximum particle interlock, maximum packing density, maximum strength, desirable air voids and voids in mineral aggregate and lowest permeability is highly desirable for bituminous mixture. Coarse aggregate that have good particle packing can bring the particles closer and can decrease the space between them, and this consequently gives the interlock necessary to increase the strength for better resist to distresses. In this project, different sizes of coarse aggregate are studied to identify their corresponding optimal proportion in bituminous mixture for better density through the packing test. According to the maximum density observed, the optimum proportion for the mix is found to be 14.4 for coarse aggregate retain on 20mm, 21.6 for coarse aggregate retain on 14mm, 24 for coarse aggregate retain on 10mm, and 40 for coarse aggregate retain on 5mm. © 2011 IEEE.