Effect of hydroquinone and pyrocatechin on the corrosion and electrochemical behavior of steel in a model concrete pore liquid

Abstract

The effect of hydroquinone and pyrocatechin on the corrosion and electrochemical behavior of steel in a model concrete pore liquid has been studied. Corrosion tests have shown that hydroquinone and especially pyrocatechin can be superior in protective properties to sodium nitrite under conditions simulating the corrosion of steel reinforcement in concrete. It has been shown by electrochemical methods that the high efficiency of hydroquinone is observed under conditions of limited oxygen access into the system. It is due to oxygen scavenging and accordingly inhibition of the cathodic reaction. The protective ability of pyrocatechin, which is also capable of scavenging oxygen, is due to the inhibition of not only the cathodic process but also the local depassivation of steel. The mechanism of its inhibition is not quite clear and is possibly associated with inhibitor oxidation at anodic potentials. As a result, steel in fact becomes a non-polarizable electrode, and the potentials of its local depassivation, which are more positive than the potential of pyrocatechin oxidation, are not reached.