| With the development of one belt,one road has been developing rapidly.In recent years,the western region has been growing rapidly in terms of new mileage.The climate conditions in the western plateau area of China are extremely bad:the annual average temperature is low,the sunshine time is long,and the ultraviolet radiation is strong.The coupling effect of many factors is easy to lead to the aging of asphalt pavement and seriously affect its service life.In this paper,styrene butadiene rubber latex(SBR),nano montmorillonite powder(MMT)and nano titanium dioxide(TiO2)were used to prepare nano-TiO2/MMT/SBR composite modified asphalt by high-speed shear method.The shear temperature was 150℃,the shear time was 40 min,and the shear rate was 5000 R/min.By studying the relationship between the amount of modifier and the conventional properties and aging resistance of modified asphalt,the amount of modifier in nano-TiO2/MMT/SBR composite modified asphalt is determined:1.5%TiO2,4%MMT and 6%SBR(latex,solid content 60%).By analyzing the rheological properties and anti-aging properties of nano-TiO2/MMT/SBR composite modified asphalt,it is concluded that the composite modified asphalt has better low temperature performance and high temperature performance is also required by composite specifications.Among them,the high temperature performance of composite modified asphalt mainly depends on the interaction between TiO2 and MMT,and the low temperature performance mainly depends on the interaction between MMT and SBR.Through the analysis of mass loss before and after asphalt aging,it can be seen that nano-TiO2 and nano MMT can control the volatilization of light components in the aging process。The anti aging mechanism of nano-TiO2/MMT/SBR composite modified asphalt was studied by scanning electron microscopy,Fourier transform infrared spectrum and gel permeation chromatography.The results are as follows:nano-TiO2 can be used as a physical crosslinking point to promote the combination of MMT and matrix asphalt;nano-MMT and SBR can be intercalated and adsorbed to form a dense and stable network structure in the system with asphalt as the solvent,increasing the contact area with asphalt,effectively isolating oxygen from entering the asphalt;at the same time,nano-MMT can effectively reduce the agglomeration of nano-TiO2 and the formation of SBR rubber chain.Therefore,the micro morphology of Nano-TiO2/MMT/SBR composite modified asphalt is more compact and stable when the three modifiers work together.Based on the analysis of sulfoxide and polysulfone content of MMT modified asphalt,it can be concluded that the composite structure formed by MMT and asphalt can effectively insulate oxygen and slow down the aging process of continuous oxidation of sulfoxide.Because nano-TiO2/MMT/SBR composite modified asphalt can effectively separate oxygen from aging process,delay the oxidation of sulfoxide and control the volatilization of light components,nano-TiO2/MMT/SBR composite modified asphalt has better anti-aging ability. |
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