A new freeze-thaw resistant superhydrophobic surface for cement-based materials with self-cleaning and anti/de-icing performance

Freeze-thaw (F-T) cycles can significantly deteriorate materials through water infiltration, pore water migration, ice-water phase transitions, and changes in pore structure. Traditional approaches primarily focus on modifying the internal pore structure to passively resist the F-T effects. In this study, we propose an active defense strategy based on wetting theory to enhance F-T resistance. We developed a new superhydrophobic surface tailored for the coarse and porous structure of cement mortar by employing polydimethylsiloxane (PDMS) as the primary film-forming substance and binder. Wetting-modified silica (SiO₂) nanoparticles, treated with silane coupling agent KH570, were used to construct a micro-nano multilayer structure. To further enhance hydrophobicity, a reentrant porous micro-skeleton was formed through the phase separation of the PDMS mixture. By optimizing the chemical composition of the PDMS/KH570@SiO₂ suspension, we achieved an exceptional superhydrophobic surface on the porous cement mortar. The performance of this surface was rigorously evaluated, including assessments of mechanical durability, self-cleaning behavior, anti-icing and de-icing properties, and F-T resistance. The results demonstrate that the new superhydrophobic surface delays the water droplet freezing time by approximately 23 times and improves the F-T resistance of cement mortar by at least 25 % compared to control samples. This study provides a novel approach for enhancing the durability of cement-based materials under F-T conditions in cold region engineering.