Nanoscale insight into the sulfate resistance of calcium silicate hydrate with a silane coating

Silane-based materials are widely used as surface coating materials to improve the corrosion resistance of concrete, but their underlining mechanism is still unclarified. Here, the effects of silane addition on the sulfate resistance of calcium silicate hydrate (CSH) were investigated using a molecular dynamics simulation. The improvement in sulfate resistance can be attributed to the discovery that silane coatings can greatly lessen sulfate adsorption on the CSH surface. The first adsorption layer of sulfate on the CSH surface can be fully removed by adding silane, according to molecular structural investigations. Further addition of silane can completely eliminate the second adsorption layer. Such results are related to the formation of positively charged layers on the CSH surface, which favors the separation of the sulfate adsorption layer from the CSH surface. The details arrangement of water molecules is also discussed by the order parameters. This work possesses a first glance at the sulfate resistance of silane. The mechanism discovered now has the potential to guide the creation of high-performance coatings.