Abstract
In order to explore the variation of crumb rubber modified asphalt (CR) before and after aging at the micro- and nanoscales, the molecular dynamics simulation and atomic force microscopy (AFM) asphalt microstructure scanning were carried out on CR before and after aging. The molecular dynamics energy, radial distribution function (RDF), surface microstructure image, roughness, and other test results of the CR before and after aging were compared and analyzed. The results show that the molecular dynamic energy of the CR after aging increases; the asphaltene-asphaltene RDF is decreased after aging; and the AFM surface microstructure images of asphalt before and after aging do not change significantly, but quantitative analysis by roughness theory shows that aging makes the microscopic surface of the CR more uniform and gentle. By analyzing the changes of asphalt properties before and after aging at two scales, it can be found that there is a certain relationship between the properties obtained at different scales. The reasons and mechanisms for the influence of microstructure on aging are obtained by analyzing this relationship.
Highlights
Mathematical Problems in Engineering of asphalt at different aging degrees was obtained by atomic force microscopy (AFM) test and molecular dynamics simulation
It is found that the addition of Styrene-butadiene rubber (SBR) increases the aggregation of asphaltene molecules and reduces the migration of other component molecules. e macroscopic performance is that the addition of SBR improves the glass transition temperature of asphalt
Wang Lan et al carried out molecular dynamics research on the compatibility between SBR molecules and asphalt, found that the best compatibility state was achieved between asphalt molecules and SBR molecules at 160°C, and studied the compatibility between asphalt molecules and SBR molecules before and after aging under the best compatibility state [13, 14]
Summary
E crumb rubber content was 20%, and the aging crumb rubber modified asphalt was prepared by pressure aging test. Ree main indexes were tested on the original crumb rubber modified asphalt (O-CR) and aging crumb rubber modified asphalt (A-CR). As the temperature coefficient A decreased, the penetration index PI increased, the asphalt temperature sensitivity decreased, and the high-temperature performance of the asphalt improved. E softening point and penetration index of A-CR increased, indicating that its temperature sensitivity was reduced and its high-temperature stability was improved to a certain extent. The decrease of ductility and penetration indicated that the main effect of aging was the deterioration of the low-temperature performance of asphalt. Penetration (5°C, 100 g, 5 s; 0.1 mm) Penetration (15°C, 100 g, 5 s; 0.1 mm) Penetration (25°C, 100 g, 5 s; 0.1 mm) Ductility (5°C; cm) Softening (°C)
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