Durability of concrete in marine environments is one of the major challenges in civil engineering due to the potential penetration of ions and saline water. In the present study, the effect of incorporating nano-silica into concrete using three different methods—mixing, spraying, and a combined approach—was investigated with respect to concrete durability. Cubic concrete specimens containing various percentages of nano-silica were prepared, and water absorption, permeability, and chloride ion penetration tests were conducted in accordance with standard procedures. The results indicate that the method of nano-silica application has a significant influence on concrete durability. The incorporation of nano-silica through mixing exhibited a greater effect compared to spraying alone, while the combined method demonstrated superior performance relative to both individual approaches. The maximum reductions in water absorption, permeability, and chloride ion penetration were observed in specimens prepared with 0.5% nano-silica by mixing and 2% by spraying, which resulted in decreases of 43%, 44%, and 48%, respectively. Therefore, the optimal utilization of nano-silica can be considered an effective strategy for enhancing the durability of concrete in aggressive marine environments.
Rajabian et al. (Wed,) studied this question.