Preparation And Properties Of Modified Anti-aging Asphalt

Asphalt pavement properties is great,but the thermal oxygen aging will lead to asphalt properties decline,and the thermal oxygen aging is one of the main reasons for asphalt pavement service life shortened.For a long time,the domestic and foreign scholars to improve the aging properties of asphalt research and discussion has never stopped.At present,it is the most common method to add additives to improve the anti-aging properties of asphalt.Therefore,more and more attention has been paid to the anti-aging properties of asphalt by adding anti-aging agent which can inhibit the reaction process of heat and oxygen aging.In this paper,Irganox 1010 and Irgafos 168 were used to modify the asphalt,and the effects of antioxidant on the physical properties and aging properties for 70# asphalt and SBR asphalt.By Fourier Transform Infrared Spectroscopy(FTIR)and Atomic Force Microscope(AFM)for short-term hot oxygen aging(RTFOT)before and after functional group structure of asphalt,asphalt surface microstructure characterization analysis,discusses the anti-aging mechanism of anti-aging modified asphalt and aging modified asphalt.The main conclusions are as follows:1.The effects of antioxidant on three indexes,viscosity and activation energy of viscous flow of asphalt were studied.The results show that: the penetration,ductility and softening points of modified anti-aging asphalt decreased when Irganox 1010 increase.With Irgafos 168 content increase,the penetration of modified anti-aging asphalt increased,softening point decreased and elongation increased.The viscous activation energy of modified anti-aging asphalt was determined based on viscosity.The viscosity of anti-aging modified asphalt decreased after adding,and the activation energy of viscous flow first decreased and then increased with the content of Irganox 1010.The content of Irgafos 168 decreased with Irgafos 168 increase.A large amount of Irganox 1010 is unfavorable to the low temperature performance of asphalt,and a good effect is achieved at 1%.Small amount of Irgafos 168 has limited effect on asphalt,and the improvement effect on low-temperature propertity tends to be better with the Irgafos 168 increase.2.The short-term thermal oxygen aging of asphalt was simulated,and the thermal oxygen aging resistance of modified asphalt was evaluated by residual penetration(PPR),softening point increment(SPI),elongation retention(DDR),viscosity aging index(VAI)and viscous flow activation energy index(EAI).The results show that: Irganox 1010 and Irgafos 168 have a good effect on the anti-aging performance of asphalt,especially for SBR asphalt.In general,the optimal dosage of Irganox 1010 is 1%;The optimal dosage of Irgafos 168 should be greater than 1%.If the anti-aging agent reaches a certain dosage,some indexes after RTFOT aging are expected to be consistent with that before asphalt aging.Theoretically,the influence of short-term aging on viscosity and softening point can be eliminated when the content of Irganox 1010 in SBR asphalt reaches 3.1%,or when the content of Irgafos 168 reaches 5%.3.FTIR was used to study the effect of antioxidant on the functional group structure of asphalt before and after aging.The results show that: Irganox 1010 generated physical adsorption after blending with asphalt,and Irgafos 168 had chemical reaction with asphalt.The ester groups in Irganox 1010 resulted in decreased penetration and ductility of modified asphalt.Quantitative analysis showed that after asphalt aging,carbonyl and sulfoxide index decreased,while anti-aging agent inhibited the decrease of carbonyl and sulfoxide index.The change rate of functional group index before and after aging indicated that Irganox 1010 and Irgafos 168 could eliminate active free radicals,prevent chain reaction and delay oxidative aging.4.AFM was used to analyze the microscopic morphology of the asphalt surface.It was found that there are more ester groups in Irganox 1010,the number of "bee like structures" increases with the increase of Irganox 1010,and "bee like structures" with larger area and higher wave peaks appear.Irgafos 168,which is dispersed in asphalt,acts as a nucleating agent to promote heterogeneous nucleation of asphaltenes.Agglomeration exists in asphalt,resulting in an increase in the size and height of the "bee structure".After RTFOT aging,the change of different asphalt is different,especially the 10%Irgafos 168 in SBR asphalt has the smallest difference before and after aging.