Organic substances as inhibitors for chloride‐induced corrosion in reinforced concrete

Abstract

Corrosion inhibitors are used to prevent chloride-induced corrosion in reinforced concrete structures. Since performance of commercial organic inhibitors is only partially satisfactory, a 7-year long research has been carried out in order to set-up a new organic inhibitive mixture, able to prevent chlorides-induced corrosion. A first screening, by means of potentiodynamic polarisation test in alkaline synthetic pore solution, was performed on 80 organic compounds, mainly primary and tertiary amines, aminoalcohols, carboxylates compounds and aminoacids, in order to select the best inhibiting substances. The nine best inhibitive organic substances were selected for long-term tests: 2 amines (dimethylethanolamine and triethylentetramine), 4 aminoacids (aspartate, asparagine, glutamate and glutamine) and 3 carboxylates compounds (tartrate, benzoate and EDTA). Potentiostatic polarisation and free corrosion tests in synthetic pore solution were performed, as well as tests in concrete exposed to accelerated chlorides penetration. Five years of tests allow estimating the efficiency of the substances in preventing chlorides-induced corrosion, in term of influence on chlorides penetration and on critical chlorides threshold.

Experiences on corrosion inhibitors for reinforced concrete

“…• from 1999 to 2011 pure organic compounds have been studied, both in solution and in concrete (Series C) [45][46][47][48].…”

“…The dosage in solution was 1 mol/L, the dosage in concrete was 1% by cement weight with exception of sodium tartrate that was added 0.1%, due to the effect on setting [47].…”

“…The performance of corrosion inhibitors for reinforced concrete structures has been studied at PoliLaPP, Laboratory of Corrosion of materials "P. Pedeferri" of the Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano, in the last 15 years on commercial corrosion inhibitors, both mixed in (nitrite based and organic) and migrating [40][41][42][43][44] and on organic compounds, mainly amines, carboxylates and amino acids [45][46][47][48].…”

Cymbopogon citratusand NaNO2Behaviours in 3.5% NaCl-Immersed Steel-Reinforced Concrete: Implications for Eco-Friendly Corrosion Inhibitor Applications for Steel in Concrete

“…Also included among the first set of steel-reinforced concrete samples is another 0.00% blank sample but for immersion in distilled water environment, tagged blank (H 2 O) hereafter, to serve as positive control for the electrochemical experiment. It is worth noting that all steel-reinforced concrete samples in this first set were cured in curing room for 28 days [67,68], as per ASTM C192/192 M-16a [65]. The second set of steelreinforced concrete samples includes three samples that were cast in similar manner to the samples for electrochemical experiment (the first set) but with 0.00% admixture and which were cured in water for 28 days [11,41,69].…”

Monitoring chloride-induced corrosion of carbon steel tendons in concrete using a multi-electrode system

“…In very severe working condition, if a very long service life is required, additional protection techniques may be used, such as corrosion resistant bars, concrete coating, corrosion inhibitors, cathodic protection or prevention [6][7][8]. Prevention of corrosion continues throughout the entire service life of the structure with scheduled inspection, maintenance and above all monitoring [2][3][4][5].…”