Effect of de-icing salts on the corrosion performance of galvanized steel in sulphate contaminated soil

Failure of mechanically-stabilized earth (MSE) walls attributed to the corrosion of galvanized steel in soil has raised concern on the use of an appropriate type of the de-icing salt for the maintenance of the roads in the winter. This work presents the effect of commonly used de-icing salts such as sodium chloride, magnesium chloride, calcium chloride, and potassium acetate on the corrosion performance of the galvanized steel in sulphate contaminated soil. To achieve this goal, different electrochemical testing methods such as potentiodynamic polarization, Linear Polarization Resistance, and electrical impedance spectroscopy were used to determine the corrosion rate of galvanized steel reinforcement in sodium sulphate containing solution. Results showed that the presence of sulphate in the soil significantly increased the corrosion rates and, thus, it is important to consider the effect of sulphate in determining the type of de-icing salt. In sulphate-free solution, potassium acetate appeared to be the best option; while in the presence of sulphate, MgCl₂ and CaCl₂ had the lowest corrosion rate.