Comprehensive resistance of fair-faced concrete suffering from sulfate attack under marine environments

•Sulfate resistance of air-faced concrete under marine environments is evaluated.•Surface quality of air-faced concrete suffering sulfate is quantitatively characterized.•The relation between surface quality and sulfate resistance is built and analyzed. The fair-faced concrete structures serving in coastal areas may be harassed by sulfate ions carried by salt fog and rainwater. To explore the sulfate resistance performance of fair-faced concrete used in coastal subway station, specimens were subjected to simulated sulfate attack condition and actual marine environments in this study. The sulfate resistance properties of fair-faced concrete and the impact of sulfate on surface quality were investigated through compressive strength test, sulfate concentration distribution test, and the gray values of surface morphology characterization. The results show that the reminding residual strength of all specimens is still very high after exposed to simulated sulfate attack condition, demonstrating the superior sulfate resistance of fair-faced concrete used in coastal subway. Moreover, the sulfate corrosion can lead to the significantly coarsening of surface morphology, and the fair-faced concreted used in marine environments should pay special attention to sulfate corrosion. Besides, the coarse degree decreases with sulfate resistance coefficient, which means that fair-faced concrete with superior sulfate resistance can not only guarantee durability, but detain the degradation of surface morphology.