Study on chemical repairation mechanism of aged asphalt based on catalytic hydrogenation and end-groups sealing and effect evaluation
Starting from the essence of asphalt aging,triethoxysilane was used to hydrogenate with aged as-phalt,and the carbonyl and sulfoxide groups in the aged asphalt were changed into low polarity substances.Considering that the active end group of aged asphalt can induce the accelerated aging of new asphalt,the active end group of aged asphalt was capped by free radical inhibitor isocyanate.The mechanism of chemical repair of aged asphalt was investigated by testing the chemical structure and polarity changes before and after catalytic hydrogenation and end group sealing.Using matrix asphalt as a reference,the chemical repair effect of catalytic hydrogenation and end-group sealing on aged asphalt was evaluated by analyzing and testing the changes of mac-roscopic properties of aged asphalt before and after catalytic hydrogenation and end-group sealing.Finally,the internal relationship between chemical structure and low temperature performance of aged asphalt was estab-lished through the linkage analysis of infrared spectrum and low temperature bending test results.The results showed that the chemical structure of aged asphalt was changed in essence by catalytic hydrogenation and end-group sealing.The carbonyl groups and sulfoxide groups in aged asphalt were converted into ester by triethox-ysilane,and the hydroxyl groups inaged asphalt were converted into ester by isocyanate,which reduced the ac-tivity and the polarity of the aged asphalt.After catalytic hydrogenation and end-group sealing,the dielectric constant and viscosity of aged asphalt decreased by 27.3%to 3.2,while the adhesion to limestone increased by 15.8%,and the change range of low temperature stiffness modulus and creep rate pair reached more than 14.0%.The polarity of aged asphalt was significantly weakened,and the intermolecular force and viscosity were significantly reduced,so the adhesiveness and low temperature performance were significantly improved.There is a good correspondence between stiffness modulus and creep rate and functional group index of aged asphalt.
catalytic reductionend group sealingaged asphaltpolaritychemical repair
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