Study On Modification Mechanism Of Composite High Modulus Modifier HRMA And Its Mixture Performance

In order to study the modification effect of the composite high modulus modifier HRMA,this thesis uses 90-A grade petroleum asphalt as the basic asphalt and the composite high modulus modifier HRMA as the modifier.The 16.7%,21.8%,26.8%and31.6%of HRMA modified asphalt were studied respectively,the modification effect and modification mechanism were studied,and the dynamic mechanical properties of HRMA modified asphalt mixture were studied and SBS modified asphalt mixtures were compared.The specific research content and results are as follows:（1）Through asphalt penetration,penetration index PI,equivalent softening point T₈₀₀,equivalent brittle point T_1.2,softening point,ductility,RTFO aging mass loss,residual penetration ratio and other indicators analyzed the matrix asphalt and the performance of HRMA modified asphalt.The research results show that the penetration of HRMA modified asphalt decreases with the increase of HRMA modifier content,and the softening point and equivalent softening point T₈₀₀increase with the increase of modifier content.Improve the high stability and deformation resistance of the base asphalt.However,the ductility of HRMA modified asphalt decreases with the increase of HRMA modifier content,and the equivalent brittle point T_1.2increases,the low temperature performance of HRMA modified asphalt decreases.（2）Research the high and low temperature performance of base asphalt and HRMA modified asphalt through asphalt rheological test.The research results show that the composite high modulus modifier HRMA modified asphalt has better rutting resistance than base asphalt and a smaller amount of shear deformation,but it has an adverse effect on the low-temperature crack resistance of asphalt.Considering the high and low temperature performance and anti-fatigue performance of the asphalt,the optimal content of the composite high modulus modifier HRMA is finally selected as 21.8%of the asphalt.（3）The modification mechanism of the composite high modulus modifier HRMA was studied through fourier infrared spectroscopy.The research results show that the polar functional groups in the HRMA modifier are chemically stable.And the reaction with the base asphalt is physical Fusion,no new functional groups are generated.The addition of HRMA modifier increases the carbon-hydrogen bond of the CH₂group in the matrix asphalt,the C=C bond and C=O bond in the aromatic ring,and the sulfoxide group S=O bond content.Improve the viscosity and high temperature stability of asphalt.（4）Through the rutting test of asphalt mixture,low temperature trabecular bending test,water immersion Marshall test,freeze-thaw splitting strength test and uniaxial compression dynamic modulus test,the high temperature stability and low temperature resistance of HRMA modified asphalt mixture cracking,water stability and dynamic mechanical properties were studied,and compared with the performance of SBS modified asphalt mixture.The results of the study showed that HRMA modifier significantly improved the high temperature stability,water stability and Dynamic mechanical properties,but the HRMA modifier reduces the low temperature crack resistance of the asphalt mixture to a certain extent.The low temperature crack resistance of the HRMA modified asphalt mixture is slightly worse than that of the base asphalt mixture and lower than that of the SBS modified asphalt mixture.