Fabrication and Properties of Sustainable Superhydrophobic Coating Utilizing Coal Gangue

Conventional superhydrophobic coatings are associated with disadvantages such as costly raw materials and environmental impact. In this study, a sustainable superhydrophobic coating was developed by incorporating solid waste of coal gangue with a cement binder, followed by alkyl functionalization using a nonfluorinated silane. The superhydrophobic coal gangue-cement (SCGC) coating exhibited a water contact angle (CA) of 151.4° and a sliding angle (SA) of 7.7°, accompanied by satisfactory self-cleaning performance and water resistance. Compared to uncoated concrete, the SCGC coating reduced water absorption by 88.9%. Moreover, it demonstrated desirable mechanical robustness against sandpaper abrasion, tape peeling, and water impact. Significantly, the cost of the cement binder used in the SCGC coating was 94.67%–99.89% lower than that of the polymer binder applied in conventional superhydrophobic coatings. The cost-effectiveness and eco-friendliness of SCGC coating contribute to large-scale applications possible in concrete surface treatments.