Corrosion Behavior of F30S30 Concrete under Wet-Dry Cycles in Simulated Seawater with Magnesium Salt and Sulfate

In this paper, we present the corrosion behavior of F30S30 concrete used for a bridge cap which was investigated in simulated seawater with 2.0% NaCl, 0.35% MgCl 2 , and 0.25% Na 2 SO 4 under wetdry cycles. This behavior was compared with those in 3.5% NaCl, 5.0% Na 2 SO 4 , and 3.5% NaCl + 5% Na 2 SO 4 solutions. Results show that the change in pore structure obtained through X-ray computed tomography could reflect the amount of corrosion products and the degree of destruction. The variety and quantity of corrosion products varied with the corrosive environment. The damage mechanisms of concrete also changed according to the corrosive environment. The effects of Mg 2+ and SO 4 2- were superimposed on each other for the simulated seawater environment, thereby posing a serious threat to the structure, primarily through damage and coarsening of the pore structure caused by Mg 2+ .