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Reactive sol creates durable superhydrophobic concrete coating
Researchers have developed an advanced ormosil-based sol that penetrates concrete pores and chemically bonds with the cement matrix, producing a long-lasting superhydrophobic coating. On-site validation on a concrete memorial in Lithuania confirmed sustained performance after 21 months.
Water is the principal carrier of decay agents in concrete due to the material’s permeable and hydrophilic nature. While numerous superhydrophobic treatments combining hydrophobicity and water repellence have been developed in recent years, their main limitation remains poor durability, particularly under outdoor conditions. To address this gap, researchers have developed an advanced material that delivers long-lasting superhydrophobic performance through chemical bonding with the cement matrix.
The system is based on an organically modified silica (ormosil) sol formulated to penetrate the pores and cracks of concrete and spontaneously react with portlandite to produce calcium silicate hydrate (C-S-H) gel, the main component of cementitious materials. A comprehensive investigation of the interaction processes confirmed that the sol forms chemical bonds with the substrate through two complementary mechanisms: direct reaction of the silica precursors and pozzolanic reaction of the resulting silica xerogel.
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Superhydrophobic performance through nanoroughness and low surface energy
Laboratory testing on cement mortars confirmed that the treatment achieves superhydrophobic properties, including a static contact angle of 160° and a sliding angle below 5°. These properties result from the combined effect of reduced surface energy provided by the organic components and the regular nanoroughness produced by silica nanoparticles incorporated into the sol. The treatment maintained its performance after a heavy rain test, with durability directly linked to its capacity to bond chemically with the cement matrix.
Successful on-site validation in Lithuania
Beyond laboratory results, the coating was applied and validated in a real-world setting on a concrete-based memorial in Lithuania. The performance was maintained after 21 months of outdoor exposure, demonstrating the long-term effectiveness of the system under genuine environmental conditions. These findings highlight the potential of reactive ormosil-based sols as a sustainable strategy for the long-term preservation of concrete structures.
Source: Luna, M. et al., Long-term superhydrophobic coatings for concrete by producing bonds with cement matrix. Progress in Organic Coatings, 110128 (2026).
