Preparation, characterization, and properties of asphalt modified by surface-treated anhydrous calcium sulfate whiskers

In this study, anhydrous calcium sulfate whiskers (ACSW) were surface-treated with sodium carbonate and stearic acid to prepare inorganic–organic surface-co-treated ACSW modified asphalt. To investigate the mechanism, the co-treated ACSW were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), water contact angle (WCA), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). Additionally, the rough surface of the calcium stearate was examined. The effects of the co-treated ACSW on asphalt binder properties were examined using conventional tests (penetration, ductility, softening point, and storage stability) and rheological tests, such as dynamic shear rheometer (DSR) and multiple stress creep recovery (MSCR) tests. The results indicated that 2–3% of the co-treated ACSW enhanced the high-temperature stability and deformation resistance properties of asphalt but weaken the low-temperature performance to a lesser extent. Microstructural analysis showed that the co-treated ACSW were physically modified with asphalt and uniformly distributed in the modified asphalt binder. This study provides a new concept for the ACSW surface treatment for practical applications in asphalt road pavement engineering in high-temperature regions.