Molecular design and experiment of ion transport inhibitors towards concrete sustainability

Regulating the transmission of chloride medium in concrete is the primary research work to improve the durability and sustainability of concrete, effectively saving offshore buildings' maintenance costs. Inspired by the molecular design of drug delivery, this study designed an erosive solution-responsive ion transport inhibitors (ITI) to restrain the transport of erosive solution in calcium silicate hydrates (C–S–H) gel pores, which is expected to reduce the water absorption and chloride diffusion coefficient of concrete efficiently. In this investigation, molecular dynamics was applied to reveal the mechanism of ITI with different main-chain structures on the atomic scale, and an evaluation system of such polymers was proposed. When the main chain is the carboxylic group, the ITI is similar to the hinge of the door. Once the corrosion solution invades the gel channel, the hydrophobic group will be perpendicular to the surface of calcium silicate hydrates to prevent the transmission of the solution. However, when the main chain is alcohol amine, the ITI can gather at the front of the erosion solution to form a water plugging medium and complex with the eroded ions to inhibit the diffusion of ions. On this basis, the optimal ITI is evaluated through water adsorption and chloride ion diffusion tests and further applied in offshore engineering. The results show that they can effectively alleviate chloride ion erosion without sacrificing mechanical properties.