Correlation Analysis Of Aging Index Of Asphalt And Asphalt Mixture

In the construction and use of asphalt pavement,it is inevitable to bear the common influence of natural environment,traffic load and other factors,resulting in cracking and aging of asphalt pavement.At present,the research on the aging law of asphalt pavement is mainly carried out along the two directions of asphalt and asphalt mixture.The research on asphalt mainly focuses on the physical properties and internal microstructure of asphalt.However,the internal relationship between asphalt composition and macro performance needs to be deepened.Therefore,it is of great significance to study the performance of asphalt and asphalt mixture before and after aging,and to explore the correlation between asphalt and mixture aging index.In this paper,the evolution law of physical and chemical properties of asphalt and mixture before and after aging and after anti-aging regulation is studied by using Brinell viscosity,Fourier infrared spectrometer and universal testing machine.The relationship between asphalt and mixture performance and aging mechanism are deeply explored.The main conclusions are as follows:(1)Fourier transform infrared spectroscopy and Brinell viscosity test were used to analyze the variation of functional groups and asphalt indexes.The results showed that the carbonyl group had the highest correlation with the macro index of asphalt and the sulfoxide group had the least correlation.After the anti-aging regulation of asphalt,the predicted value of asphalt macro index deviates from the measured value,which may be due to the inhibition of oxidation reaction of asphalt aging process after adding antioxidant,and the change of physical and chemical properties of the original asphalt.(2)The mechanical properties of asphalt mixture during different aging periods at medium and low temperatures were tested by semi-circular bending test.The results show that the phase difference index of modulus at medium and low temperature is larger than that of strength difference index,which indicates that modulus is most sensitive to the performance of asphalt mixture.When the content of antioxidant is 5% at medium and low temperature,the overall performance is improved to varying degrees.(3)Through the correlation fitting between the asphalt macro index and the asphalt mixture index,it is found that the asphalt macro index has a good internal correlation with the asphalt mixture mechanical index before and after aging.The change law of asphalt mixture index after aging can be predicted by the change of asphalt macro index.In addition,it is found that the macro index of low temperature asphalt has a good correlation with the strength and modulus of mixture.Under medium temperature,the antioxidant will be more sensitive to asphalt and asphalt mixture,and the correlation between asphalt macro index and mixture mechanical index is poor.(4)The characteristics of asphalt mixture bearing capacity under different aging depth are discussed by using finite element method.As a result,both layered aging and full aging bearing capacity are higher than unaged bearing capacity.When the aging depth reaches 3.5 cm,the bearing capacity reaches the maximum value,and the modulus of the mixture after aging decreases with the deepening of the aging depth of the surface layer.The increasing trend gradually slows down.