[Purposes]The effect of nano-silica on the performance of polyethylene modified asphalt mix-ture was studied by preparing composite modified asphalt with different nano-silica content.[Methods]The performance of nano-silica composite modified asphalt mixture was analyzed by four-point bending fatigue test,stiffness modulus test and indirect tensile strength test.[Findings]The test results showed that when the content of nano-silica increased from 1%to 4%,the fatigue life,stiffness modulus and in-direct tensile strength of the mixture increased first and then decreased.When the content of nano-silica is 3%,the fatigue performance of the mixture is optimal at 20 ℃ and 30 ℃.When the content of nano-silica is 2%,the stiffness modulus and indirect tensile strength are the best,and the decrease of indirect tensile strength after short-term aging is the smallest.[Conclusions]Based on the comprehensive perfor-mance indicators,the optimum content of nano-silica is 2%～3%,and the fatigue and mechanical proper-ties of the composite modified asphalt mixture can be increased by more than 40%.
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