Basic Research For Asphalt Characteristics On Micro-scale Based On Asphalt Aging

Asphalt pavement has been widely used in modern road with its excellent pavement performance. Experience method is mostly used in the selection of asphalt nowadays. Asphalt research is mostly on macro-scale as well. Research on micro-scale is limited in China especially the application of atomic force microscope. Both molecular structure and structure distribution situation will influence the macro road performance, so this article mainly focuses on the microscopic characteristics changes in the aging process of asphalt.First of all, traditional penetration system is used to measure the needle penetration, softening point, ductility and viscosity of asphalt, and then asphalt hardness, consistency and other macroscopic properties are analyzed. Dynamic shear rheometer(DSR) is applied to have move shear rheological experiment, temperature scan experiment, and multiple stress repeated creep experiment on samples before and after asphalt aging, so as to analyze and evaluate the mechanical properties of the asphalt. Through a series of indicators, it shows that SBS modifier will generate a certain degree of upgrading on asphalt high temperature, middle temperature and temperature-sensitive performance indicators, as during the process of asphalt aging, asphalt stiffness modulus will be increased, while the incorporation of SBS modifier can mitigate the effects brought by asphalt aging in some ways.Using atomic force microscope to analyze changes in microscopic morphology and mechanical properties during the process of asphalt aging, and then through roughness, bee-type structure area ratio and other indicators to study the microscopic changes law during asphalt aging process, to explain the increased roughness in microscopic surface and increased bee-type structure aggregation after aging. Furthermore, three-dimensional fractal theory is adopted to analyze asphalt morphology, and then fractal dimension is used to determine and explain the phenomenon that along with the aging process, the distribution of bee-type structure in asphalt microscopic surface topography gradually gets even.Asphalt microscopic Young modulus is employed for the analysis of microscopic surface Young modulus in different regions of asphalt samples, and then mathematical analysis method is adopted to verify the independence and difference significance of Young modulus bee-shaped structure and its external continuous phase portion, so as to explain that bee-typed structure is composed of different substances; in addition, wax crystallization theory can better analyze the generation and variations of bee-type structure.Use fourier infrared spectroscopy to study changes of each asphalt spectrum absorption peak before and after the aging, and to analyze the generation and decomposition of functional groups; furthermore, carbonyl coefficient and sulfoxide group coefficient are used to perform quantitative evaluation on components variation of asphalt aging process, supplemented by macro indicators correlation to analyze and verify the reliability of IR evaluation index in aging research.