Influence of asphalt microstructure to its high and low temperature performance based on atomic force microscope (AFM)

In order to study how the microstructure of asphalt affects its macroscopic performance (high and low temperature performance), this study used 6 asphalt samples, including virgin asphalt (70# and 90#) and aging asphalt (aging temperature 163 ℃, aging time 0 h, 35 h, 75 h, respectively). The microstructure of 6 kinds of asphalt samples was tested by atomic force microscope. The asphaltene content, four-component modulus and adhesion force in “bee structure” were analyzed, and then the degree of association of four components in different aging asphalt AFM diagrams was analyzed to study the effect of asphalt microstructure on its high and low temperature performance. On this basis, the dynamic shear rheometer and bending rheometer were used to test the high and low temperature performance of six kinds of asphalt samples, and the correctness of the effect of AFM based asphalt microstructure on their macroscopic performance was demonstrated. The results show that the high molecular weight represented by asphaltenes in asphalt increases with the aging time, the asphalt hardens, and the degree of association of four components in a single group increases, so the high temperature performance becomes better. At the same time, with the increase of aging time, the small molecular weight represented by the aromatic component in the asphalt decreases, the adhesion between the four components decreases, and the asphalt becomes brittle, so the low-temperature performance becomes poor. The research results have certain theoretical and practical value for further clarifying the microstructure characteristics of asphalt for high and low temperature performance.