the effects of extreme environments on concrete surface layer and durability and using permeability-reducing admixtures to prevent permeability of harmful liquids

Extreme environmental conditions negatively impact the mechanical properties of concrete, leading to reduced durability. among these conditions, freeze-thaw cycles are particularly detrimental, as they cause the expansion of micro-cracks in the concrete, eventually resulting in serious damage. therefore, in such harsh environments, materials that reduce the permeability of water, oil, or other harmful liquids in concrete are necessary. it is important to note that studying surface strength is meaningful because the top layer of concrete is directly exposed to the environment and is most affected by external conditions. in this study, we measured surface strength and concrete permeability using novel twist-off and cylindrical chamber tests. we then evaluated the impact of extreme environmental conditions on these parameters. finally, we enhanced concrete durability against the permeability of harmful substances by using a permeability-reducing admixture. our findings indicate that fibrous microsilica gel can be used as a permeability-reducing admixture to mitigate the negative effects of extreme environments on concrete surfaces. additionally, water permeability in concrete surfaces increases rapidly during the first 50 freeze-thaw cycles but gradually decreases thereafter. the permeability of plain concrete was found to be 13.3 ml, whereas it was 6.6 ml for concrete containing permeability-reducing admixtures. the results show that the permeability of concrete with permeability-reducing admixtures is approximately 50% less than that of plain concrete.