Investigation of corrosion inhibitors for carbon steel used as reinforcement of concrete in artificial pore solution

Abstract

The aim of this study was to evaluate the potential application of some chemical compounds as corrosion inhibitors for a carbon steel (CA-50) used as reinforcement of concrete in artificial pore solution. The tested compounds were sodium nitrite (1.5% in mass), hexamethylenetetramine (1.5% in mass) and benzotriazole (10-2 M). The techniques used in this investigation were electrochemical impedance spectroscopy (EIS), potentiodynamic polarization tests and open circuit potential measurements as a function of time. Each compound tested was added to a solution whose composition simulates that of the liquid inside the pores of concretes. To this solution was also added sodium chloride (3.5% in mass) to simulate the corrosive effects of marine atmospheres. The corrosion resistance of the carbon steel (CA-50) was evaluated in the solutions with and without the additives. A beneficial effect (corrosion resistance increase) was found for all types of inhibitors tested, but sodium nitrite and benzotriazole showed a significant inhibiting effect.