Ethyl silicate–nanolime treatment for the consolidation of calcareous building materials

Ethyl silicate (tetraethoxysilane, TEOS) is commonly used for consolidating construction materials containing siliceous components such as sandstone, cement mortars and concrete structures. This is especially due to its high compatibility with the substrates´ silicate matrix. Its lack of bonding to calcareous substrates is however considered an important handicap. Here we investigate the consolidation effectiveness and durability of a combined TEOS-nanolime treatment applied on weathered biocalcarenite stone. We report evidence of physical and chemical interactions between the two consolidant materials resulting in limited drying shrinkage and the formation of calcium silicate hydrate (C-S-H) gel, responsible for improving the treated carbonate substrate mechanical properties and treatment durability as compared to both products used separately. The results of this experimental study are promising and could be the foundation for further studies toward obtaining a compatible, effective, and long-lasting consolidation treatment for porous calcareous building materials.