Analysis Of Surface Microoscopic Characteristics And Influenceing Factors Of Aged Asphalt Materials Based On The Principle Of AFM

In recent years, asphalt pavement has been used in a large part of the completed senior pavement, beacause of its superior performance and driving comfort. but due to the aging of asphalt materials, the durability of asphalt pavement is red uced, and the service life is also shorten. Meanwhile, the regeneration of asphalt materials is closely related to the aging process. In order to study regeneration technology deeply and improve efficiency, the aging process of asphalt should be studied clearly. Changes of the micro-structure of material have a great impact on its macro performance. Therefore, the study on the change of the micro level of aging asphalt in depth can explain its aging phenomenon from the macro-scale better. Nearly, AFM techno logy is provided with performance advantage in studying micro-properties of material. Therefore, the paper analyzes the aging asphalt surface feature changes and the aging factors from a micro perspective based on the AFM technology.First of all, in order to better simulate asphalt aging conditions, asphalt aging environmental control chamber has been designed independently, which contains lighting and temperature control systems and spray device, Laboratory equipment can be carried out in light, heat, water, and other factors indoor conditions coupled bituminous materials aging test, In this way, the indoor environment can be further close to the aging condition of the asphalt outside. And because of different origin and marking of asphalt, asphalt aging test is designed reasonably.Secondly, analysis on the change of surface micro characteristics of asphalt has been conducted based on AFM. In this paper, the suitable model and calculation method are selected to calculate the micro surface performance of asphalt by using Analysis Nano Scope and MATLAB software. With the aging of asphalt, the nano hardness and elastic modulus of the material on the surface of the material increased gradually. But the surface free energy and the adhesion force tended to decrease. And for different kinds of asphalt, the changes of these indexes were different. The surface micro roughness of 50# asphalt gradually becomed smaller and the total amount of "bee type" structure tended to decrease. The changes of the surface micro roughness of 70# and 90# asphalt were very smal, and they did’t have the "bee" structures.Thirdly, experiments of different factors of asphalt aging tests were carried out. According to the AFM instrument, it is concluded that the changes of roughness and t he adhesion of asphalt after thermal aging were the most in the aging test. However, after the hydrothermal aging, the changes of surface hardness and elastic modulus of asphalt were the biggest. After the outdoor sun aging, the changes of adhesion of the sample surface were very small, but the nano hardness and elastic modulus of the asphalt surface increased. As for the asphalt extracted from the core samples of the expressway, the surface adhesion of the asphalt was decreased, and the nano hardness increased greatly for some degree. Then, the infrared spectrum test was used to analyze the effect of different factors on the aging asphalt.Finally, through the analysis and conclusion, the conclusion was drawn.