Abstract：To improve the high temperature stability of asphalt mixture, the three-axis numerical test method of asphalt mixture was constructed by partical flow code in 3 dimensions (PFC3D), and the reliability was evaluated by indoor triaxial test. The effects of coarse aggregate grading, fine aggregate grading and coarse aggregate ratio on the shear strength of asphalt mixture were investigated by numerical triaxial test and laboratory test. The AC-20 mineral gradation was proposed based on the shear strength, and the road performance was verified according to the effects of 19.000, 4.750, 0.075 mm mesh pass rates on AC-20 performance. The results show that the three-axis numerical test of asphalt mixture has good similarity with the indoor test. When the volume ratio of coarse aggregates of 19.000~26.500，16.000~19.000，13.200 ~16.000，9.500~13.200 and 4.750~9.500 mm is 4 ∶12 ∶4 ∶10 ∶15, and the fine aggregate takes the corresponding gradation for I equaling to 0.75 with the volume ratio of coarse aggregate of 60 ∶40, the asphalt mixture has the highest shear strength. The coarse aggregates are recommended to be 19.000, 4.750 and 0.075 mm with the pass rate ranges of 90.0%~100.0%, 35.0%~45.0% and 4.0%~7.0%, respectively, and the AC-20 optimized gradation is proposed based on shear strength. Compared with the standard gradation, the shear strength and the dynamic stability of the optimized AC-20 gradation are increased by 26% and 29%, respectively.
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2020, Vol. 41 
