Surface Modification of Basalt Aggregate by Coupling Agent to Improve the Interfacial Adhesion with Asphalt Binder

Abstract

The surface performance of basalt aggregate shows a great influence on the interfacial adhesion between basalt aggregate and asphalt binder and further affects the moisture stability of the asphalt mixture. To improve the interfacial adhesion between basalt aggregate and asphalt binder, as well as to increase the moisture stability of asphalt mixture in hot and humid environments, the basalt aggregate surface was hydrophobically modified by silane coupling agents (SCAs). Microscopically, the surface properties of basalt aggregate before and after surface modification by SCAs were characterized by environmental scanning electron microscope and Fourier transform infrared spectrometer, as well as the adhesion work between basalt aggregate and asphalt was calculated. Macroscopically, the moisture stability of the asphalt mixture was verified by boiling test and asphalt mixture tests. Test results indicate that the surface free energy values of basalt aggregates modified by SCAs and the stripping work values are decreased. Additionally, silanols, hydrogen bonds, and fibrous protrusions are introduced to the aggregate surface for improving the compactness of the asphalt-aggregate system. Finally, the loss rates of asphalt film and immersion scattering are decreased, as well as the freeze-thaw splitting tensile strength ratio is increased. The hydrophobic surface modification of basalt aggregate can enhance the moisture stability of the asphalt mixture.