Inhibitory effects of chloride ions on concrete sulfate attack in the marine adsorption environment

To study the inhibitory effects of chloride ions on concrete sulfate attack in the marine adsorption environment, a series of cubic concrete specimens was fabricated. These specimens were totally submerged or partially submerged in 10% Na₂SO₄ solutions with 0, 0.5, 2, and 5% NaCl concentration. Three specific aspects, namely, superficial phenomenon, compressive strength degradation, and X-ray fluorescence spectrometry analysis, were studied during 450 days of long-term exposure. Results showed that Na₂SO₄ solution had a strong corrosive effect on concrete in both the adsorption and submersion zones, especially in the adsorption zone. Chloride ions exerted inhibitory effects on concrete sulfate attack in both the submersion and adsorption zones, and higher concentration of chloride ions will produce stronger inhibitory effects. However, given the different inhibitory effects of chloride ions on concrete sulfate attack with different corrosion mechanisms, the inhibitory effect of the same chloride concentration on concrete sulfate attack was a little lower in the adsorption zone than in the submersion zone.