Fundamental interaction of hydrophobic materials in concrete with different moisture contents in saline environment

•Enhancing the impermeability of concrete.•Reducing chloride diffusion through concrete.•Revealing the morphology and interaction mechanism of materials and concrete.•The effect of initial moisture content on treatments. The present paper investigates the performance and efficacy of four protective surface applied materials; sodium acetate, fluoropolymer, silicone resin and silane when applied to marine structures with different moisture contents. Materials were applied to fully dry and fully saturated concrete along with concrete with 2% and 4% moisture contents. The interaction mechanism of the materials with concrete and their microstructural and morphological assessments were conducted by running SEM, EDX and FTIR analyses to evaluate their performance in the presence of moisture. Also, their efficacy in protecting concrete from water ingress and chloride penetration was evaluated by operating the Initial Surface Absorption Test (ISAT) and Unidirectional salt ponding test respectively. Results demonstrated that moisture content imposes a vital effect on the interaction of the materials with concrete and their adhesion inside the pores, and consequently their efficacy in reducing both, water and chloride penetration.