Recent progress of hydrophobic cement-based materials: Preparation, characterization and properties

• The assessment methods of hydrophobicity of cement-based materials are introduced. • Surface and integral hydrophobic modification methods are comparatively summarized. • The properties of hydrophobic cement-based materials are summarized. • The existing problems and challenges in this field are discussed and anticipated. The migration and transport of water in the hydrophilic porous structure of cement-based materials are the main reason for the durability degradation. Hydrophobic cement-based materials have been developed to prevent water penetration and hence greatly improve the durability. This paper aims to present a comprehensive review on the latest advances of hydrophobic cement-based materials. Firstly, the assessment and test methods of hydrophobic cement-based materials, including surface wettability, water absorption and impermeability are introduced. Secondly, the strategies of surface and integral hydrophobic modifications are introduced, and the effects of different strategies are holistically evaluated. Thirdly, the durability and mechanical properties of cement-based materials affected by surface and integral hydrophobic modifications are summarized. Finally, the key scientific problems and challenges in this field are concluded and future research directions are proposed. It is expected that this review can guide further research on the design, preparation and characterization of hydrophobic cement-based materials.