Investigation of the Use of Phosphate, Molybdate and Nitrite Mineral Compounds as Corrosion Inhibitors for Low Carbon Steel in Concrete Pore Solution Containing Concentrations of 1/8% and 3/5% Sodium Chloride

Corrosion of steel in concrete is the most important reason for the premature destruction of concrete structures. The use of corrosion inhibitors is a suitable way to control the corrosion of reinforcement in concrete. These chemicals are added in small amounts to the corrosive medium to reduce the rate of corrosion by affecting the rate of anodic, cathodic, or both reactions. In this paper, we investigate the corrosion inhibitory effects of disodium hydrogen phosphate, sodium molybdate, and sodium nitrite in simulated concrete pore solution in two concentrations of 1.8% and 3.5% NaCl. Hence according to the tests performed in simulator solution containing 1.8 wt.% NaCl salts, the nitrite, phosphate, and molybdate inhibitors added in 0.2, 0.0002, and 0.15 M, resulted in the efficiencies of 69, 59 and 81 percent, respectively. Also, in scanning electron microscopy micrographs, it was found that the use of these three inhibitors dramatically reduces the number and distance of surface pits compared to the control sample.