In this study, a nano-silica (5% to 50%) water-based solution and silane/nano-clay (5% to 50%) composite were used as superficial treatments for concrete. The coatings were applied on concretes with different water-to-binder ratios (0.35 to 0.6). The transport properties of treated concrete were evaluated by the rapid chloride penetrability test and absorption and desorption percentages. Moreover, the treated concrete was subjected to severe durability exposures: physical salt attack and salt-frost scaling. Deterioration of the concrete surface was visually assessed and quantified by mass loss; in addition, mineralogical, thermal, and microscopy analyses were performed on concrete specimens to elucidate the mechanisms of enhancement imparted by surface treatments. The results showed that increasing the concentration of nano-silica in the colloid led to improved performance of concrete, with 50% dosage leading to the least penetration depth, absorption and desorption percentages, and mass loss, whereas for the silane/nano-clay composite, a low percentage (5%) of nano-clay was adequate to mitigate the damage of concrete under aggravated conditions.
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