Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5437036 | Cement and Concrete Research | 2017 | 13 Pages |
Abstract
The passivation and chloride-induced depassivation of steel rebars immersed in varying alkaline environments (0.80Â M, 1.12Â M and 1.36Â M NaOH solutions), simulating the pore solutions of low-Ca alkali-activated concretes, were investigated using a range of electrochemical techniques. The passive film on the steel rebars was complex in chemical makeup, composed of Fe-hydroxides, oxy-hydroxides and oxides. An increased degree of passivation of the rebars was observed when exposed to solutions with higher hydroxide concentrations. The critical chloride level ([Clâ]/[OHâ] ratio) required to induce depassivation of steel was strongly dependent on the alkalinity of the pore solution, and was found to be 0.90, 1.70 and 2.40 for 0.80Â M, 1.12Â M and 1.36Â M NaOH solutions, respectively. These values all correspond to a constant value of [Clâ]/[OHâ]3Â =Â 1.25, which is a novel relationship to predict the onset of pitting, interlinking chloride concentration and the solubility of the passive film.
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Industrial and Manufacturing Engineering
Authors
Shishir Mundra, Maria Criado, Susan A. Bernal, John L. Provis,