Organic substances for inhibition of carbon steel corrosion in chloride containing alkaline solution

摘要

Corrosion inhibitors are a simple and cost effective technique to prevent and stop chloride induced corrosion in concrete structures. Nowadays, there is a number of admixtures available on the market: inorganic compounds based on nitrites and sodium monofluorophosphate, or organic compounds based on mixtures of alkanolamines and amines. This paper deals with a systematic study on the inhibiting effectiveness of organic compounds, never tested in concrete as corrosion inhibitors, focusing on the effectiveness on corrosion initiation period, i.e. influence on pitting potential and on critical chlorides threshold. Analysed substances belong to different categories: amines, alkanolamines, aminoacids and carboxylic acids. The organic compounds were added to a synthetic alkaline pore solution (pH 12.6), varying chlorides concentration from 0.05 mol/L to 1 mol/L, in order to simulate corrosion condition of rebars embedded in chloride contaminated concrete. Both potentiodynamic and potentiostatic polarisation tests have been performed as well as free corrosion potential and corrosion rate measurements. Results are discussed taking into account pitting potential and critical chlorides threshold variation. Some substances show good results, in both solution tests. The next step will be the study of the inhibiting action of these compounds in chloride contaminated concrete.