Effect of hydrophobic nanoparticle size on corrosion resistance of superhydrophobic mortar

The deterioration of cement-based materials is frequently associated with water infiltration. This work introduces hydrophobic nanoparticles (NPs) synthesized from silicon dioxide with varying particle sizes, which significantly enhance the water repellency when incorporated into mortar. The results indicate a clear negative correlation between the water contact angle (WCA) of the mortar and the size of the hydrophobic NPs; when 20 nm hydrophobic NPs are incorporated, the WCA can reach 153.16 °, exhibiting three-dimensional superhydrophobicity. Furthermore, the water absorption rate of the superhydrophobic mortar after 120 hours immersion is only 42.16 % of that of ordinary mortar. In electrochemical corrosion experiments, the corrosion current density of the superhydrophobic mortar is two orders of magnitude lower than that of ordinary mortar, effectively preventing corrosive liquids from penetrating the steel reinforcement within the concrete. This work provides a solid scientific and theoretical foundation for the widespread application of superhydrophobic cement-based materials in harsh, high-humidity, and corrosive environments.