Chloride threshold value to initiate steel corrosion in simulated concrete pore solution, and the effectiveness of DMEA as an amino-alcohol-based corrosion inhibitor

Abstract

The aim of this study is to examine the corrosion initiation and evaluate the effect of N,N′-dimethylaminoethanol (DMEA) as an organic corrosion inhibitor on the chloride threshold value for the corrosion of steel reinforcement in simulated concrete pore solution. The corrosion potential (Ecorr) measured by open-circuit potential (OCP) and the corrosion current (Icorr) obtained by linear polarization resistance (LPR) and by electrochemical impedance spectroscopy (EIS) measurements, were used to detect the onset of active corrosion, in order to determine the chloride threshold value. The results acquired from OCP, LPR and EIS techniques are relatively consistent, and indicate that the chloride threshold value for the corrosion of steel reinforcement in alkaline solution is estimated around an average value of 0.4, expressed by [Cl–]/[OH–] ratio. However, this value increased relatively in the presence of 0.125 mol.L −1 of DMEA; also in this case, a reduction in the corrosion rate, with 60 to 70% inhibition efficiency is observed after the corrosion initiation. This clearly confirms the effectiveness of DMEA used as a corrosion inhibitor to prolong the service-life of reinforced concrete structures exposed to marine environments.