Exploring capillary adsorption of corrosive medium in epoxy resin-modified calcium-silicate-hydrate channels

Abstract

In coastal environment development and island construction, cement-based materials are crucial, but they are exposed to high temperatures, humidity, salt, and weathering in marine environments, leading to the deterioration of offshore concrete structures' durability. To mitigate these effects, epoxy resin, a polymer material with excellent adhesion with cement-based materials and chemical corrosion resistance, can slow down harmful ion erosion and improve concrete structure durability. This paper proposes a molecular dynamics simulation model to investigate the transport of pure water and NaCl solution in calcium-silicate-hydrate (C-S-H) gel pore channels with and without epoxy coating. The study demonstrates that epoxy resin can effectively slow down water molecule and ion transport in the C-S-H channels. When the solution passes through the C-S-H gel pore channel, the water molecules occupy the adsorption sites of the epoxy molecules, resulting in partial exfoliation of the epoxy resin. The exfoliated epoxy resin forms an enhanced hydrogen bonding network with the water molecules and forms ion pairs with the ions, which induces the ions and water molecules to gather around the epoxy molecules and form a larger cluster structure, thus slowing down the migration of ions and water molecules in the C-S-H pore channel.