Effect of surfactant modified phosphogypsum whisker on service performance of asphalt based on multi-scale experiments

Abstract

The development of modern chemical technology had inevitably produced massive phosphogypsum (PSP), the accumulation and storage of PSP had caused serious economic losses and environmental pollution. As the secondary refining product of PSP, the application of phosphogypsum whisker (PSW) to asphalt pavement not only effectively mitigated the adverse impact of PSP on the economy and environment, but also promoted the resourceful utilization of solid waste. However, since PSW was an inorganic material, it was difficult to fuse well with asphalt. Therefore, to enhance the compatibility of PSW with asphalt, this study investigated the modification process of PSW by using four surfactants to modify PSW with organic coating. The effect of surfactants on the surface activity of PSW was evaluated by relevant tests, and the surface enhancement modification mechanism and microstructure of surfactants on PSW were investigated, and then the effect of surfactant-modified PSW (MPSW) on the service performance of asphalt was evaluated. The results showed that the surfactant covered the surface of PSW by intermolecular forces and chemical bonding, which enhanced the surface activity of PSW. The compatibility of PSW with asphalt was enhanced by surfactant, and the MPSW 10599was just physically blended with virgin asphalt. Although the brittleness of virgin asphalt was enhanced to a certain degree by MPSW, the thermophysical properties of virgin asphalt at low temperature was significantly improved, and the incorporation of MPSW enhanced the thermal stability and flame retardancy of virgin asphalt. The incorporation of MPSW would slightly increase the viscosity of virgin asphalt, but the viscous activation energy was reduced and the temperature sensitivity was improved. Furthermore, the low temperature performance of virgin asphalt was improved to a certain degree with the incorporation of MPSW, while the improvement effect was not significant once the temperature was close to the glass transition temperature. Finally, combined with the relevant test results, the recommended dosage of MPSW in asphalt was 10% in this study, and the surface modification of PSW by surfactant was a multifunctional method of powder modification.