Nitrite-benzoate inhibitors for protection against corrosion of steel reinforcement in concrete

Corrosion inhibitors are used to prevent or delay corrosion of steel reinforcement in concrete. Available commercial products are of inorganic nature based on sodium nitrite (acknowledged to be the most effective product), or organic mixtures based on amines, alkanolamines, fatty acids and carboxylic substances. During the last 15 years in our laboratories an intense experimental research aimed at identifying new organic substances or mixtures thereof that might have greater inhibiting effectiveness on corrosion by chlorides. This paper present the results of electrochemical tests carried out in alkaline solution, in the presence of chlorides, that were conducted on binary mixtures made with three substances (nitrite, DMEA and benzoate). Electrochemical tests (namely potentiodynamic and potentiostatic polarisation) were carried out. Some of the mixtures exhibited a marked synergistic effect in the potentiodynamic polarisation tests, with a clear-cut increase in the pitting potential. In potentiostatic polarisation the effect on the critical chloride concentration for the initiation of localised corrosion were limited.

Section: Introductionmentioning

confidence: 99%

Corrosion inhibitors for reinforced concrete structures: a study of binary mixtures

Brenna¹,

Bolzoni²,

Pedeferri³

et al. 2017

“…However, these compounds are considerably inferior in protection efficiency to toxic nitrites and mixed inhibitors based on them that are traditionally used in concrete [16][17][18][19][20]. In view of this, searching for new compounds that provide reinforcement protection in the presence of significant amounts of chlorides is an important task.…”

Section: Introductionmentioning

confidence: 99%

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

2019

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.

“…The latter has been developed at the Institute of Physical Chemistry of the Russian Academy of Sciences and is positioned as a versatile (contact and migrating) corrosion inhibitor for concrete reinforcing steel [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Corrosion and electrochemical behavior of steel in hardening concrete

2017

It has been shown using corrosion and electrochemical methods that reinforcing steel is subject to pitting during the initial period of concrete hardening. It is intensified if chlorides are present in the tempering water and/or if corrosion products exist on the metal surface. IFKhAN-80 inhibitor added with tempering water hinders pit formation on steel during concrete hardening, up to complete suppression of this process. Even at high chloride concentrations and in the presence of corrosion products on the metal surface, reinforcing steel in concrete is passivated some time after concrete tempering.