Diffusion Study of Chloride and Water Through Nanopore of C-S-H Gel (Jennite) Using Molecular Dynamics Simulation

Abstract

Durability is a crucial characteristic that governs the behaviour of cement-based materials throughout time. Harmful substances like chloride, sulphate, carbonate etc. effects the longevity of reinforced cement concrete. The transport of water and ions via the nanopores of calcium-silicate-hydrate (C-S-H) gels, the primary component of cement-based materials, has a substantial impact on the durability of cement. Due to its structural closeness, Jennite, a significant mineral analogue of C-S-H gel, is initially used to examine the transport behaviour at the molecular level. The size of the nanopore is here one of the most important parameters which are dependent on the water-to-cement ratio in concrete, quality and quantity of cement used, structural health monitoring, type of aggregate used, curing methods etc. for the diffusion of water and chloride. Using the molecular dynamics (MD) simulation method, the structural and dynamical properties of the water, chloride ion and Jennite interface are investigated in this article as well as the influence of calcium chloride solution in transferring chloride and water through the nanopore and explained the binding effect of chloride and C-S-H to test concrete's ionic resistance when the calcium ion exists in the solution and enables a comparison between sodium chloride and calcium chloride and matching the result with previous research. Also, the researchers explained the change of diffusivity of aggressive substances like chloride and water for various sizes of nanopore assumed.