Hydrophobic or superhydrophobic modification of cement-based materials: A systematic review

Superhydrophobic materials are investigated extensively because of their excellent surface properties, such as self-cleaning, oil-water separation, corrosion resistance, anti-icing, and anti-fogging. Recently, there has also been a lot of interest in hydrophobic or superhydrophobic modifications of cement-based materials. It provides an innovative way to improve the resistance of cement-based materials to external environmental erosion during service. This paper reviews the progress of hydrophobic or superhydrophobic modification of cement-based materials. This work analyses the mechanisms of hydrophobic modification of material surfaces and discusses three hydrophobic modification methods for cement-based materials: templating, external coating, and internal mixing. We also point out the problems of hydrophobic coatings on cement-based materials in mechanical stability and acid-alkali resistance. Further, the comprehensive performance of cement-based materials after hydrophobic modification in terms of hydration and hardening process, waterproofing and impermeability, resistance to aggressive media, and freeze-thaw damage are summarized. And the applications such as self-cleaning, anti-icing of pavements, corrosion protection of coastal structures, and waterproofing of buildings are also listed. Finally, we briefly discuss some problems in the current research and development trends in the future on hydrophobic modification of cement-based materials.