基于三轴试验的AC-20级配优化

AC-20 gradation optimization based on triaxial test

为了提高沥青混合料的高温稳定性,利用PFC^3D(partical flow code in 3 dimensions)软件构建沥青混合料三轴数值模拟方法,结合室内三轴试验评价了其可靠性.通过三轴数值模拟和室内三轴试验,研究粗集料级配、细集料级配和粗细集料比例对沥青混合料抗剪强度的影响规律.通过研究19.000,4.750,0.075 mm筛孔通过率对AC-20性能的影响,提出基于抗剪强度的AC-20矿料级配,并验证其路用性能.结果表明:沥青混合料三轴数值模拟结果与室内试验结果吻合度较好;当粒径为19.000~26.500,16.000~19.000,13.200~16.000,9.500~13.200,4.750~9.500 mm的粗集料的体积比为4:12:4:10:15、细集料取I=0.75时所对应的级配、粗细集料体积比为60:40时,沥青混合料抗剪强度最大;建议在19.000,4.750和0.075 mm通过率范围分别为90.0%~100.0%,35.0%~45.0%和4.0%~7.0%时,确定基于抗剪强度的AC-20优化级配范围;与规范级配相比,优化级配AC-20混合料抗剪强度和动稳定度分别提升26%,29%.

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(PFC^3D),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.