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Introduction and Reader's Guide
Published in Ervin Poulsen, Leif Mejlbro, Diffusion of Chloride in Concrete, 2014
Thus, corrosion inhibitors are normally divided into five groups, cf. Fontana (1967), namely: Anodic corrosion inhibitors which inhibit corrosion associated with the stabilization of the passivity film which tends to break down when chloride ions are present at the steel surface. Calcium nitrite is e.g. an inhibitor, and it acts to raise the threshold value of chloride in concrete to initiate corrosion. Calcium nitrite is being offered to improve e.g. the efficiency of concrete repairs (patch repairs). However, calcium nitrite is a set accelerator, and measures ought to be taken to prevent 'flash setting', cf. Broomfield (1997).Cathodic corrosion inhibitors which adsorb on the steel surface and thus act as a barrier to the reduction of oxygen which is the primary cathodic reaction for steel in concrete. However, most cathodic inhibitors, such as amines, phosphates, zincates, and phosphonates severely increase set retardation of concrete, cf. Bentur et al. (1997).Organic corrosion inhibitors or adsorption-type corrosion inhibitors, which appear to affect as well the anodic as the cathodic processes and thus being double-active. Typical of these inhibitors are organic amines, e.g. the amino alcohol type.Vapour phase corrosion inhibitors are similar to the adsobtion-type corrosion inhibitor, but they possess a very high vapour pressure. Therefore, vapour phase inhibitors are suitable to inhibit atmosphere corrosion without being in direct contact with the metal surface to be protected.Oxidizing inhibitors. Such substances as chromates are acting as corrosion inhibitors in many systems. They are primarily used to inhibit the corrosion of metals and alloys that demonstrate active-passive transitions, such as iron and its alloys and stainless steel.
Performance of corrosion inhibitors in cracked and uncracked silica fume cement concrete beams
Published in European Journal of Environmental and Civil Engineering, 2020
Khaled A. Alawi Al-Sodani, Mohammed Maslehuddin, Omar S. Baghabra Al-Amoudi, Tawfik A. Saleh, Mohammed Shameem
Based on a local and international market survey and literature review, five corrosion inhibitors (one generic and four proprietary) were selected for evaluation. The details of the selected inhibitors are as follows:Inhibitor-I: Proprietary liquid concrete admixture based on calcium nitrite.Inhibitor-II: Generic corrosion inhibitor based on calcium nitrite.Inhibitor-III: Proprietary liquid concrete admixture based on amine carboxylate.Inhibitor-IV: Proprietary liquid concrete admixture based on modified amino alcohol.Inhibitor-V: Proprietary liquid concrete admixture based on calcium nitrite.