Corrosion Behaviour of a New Low-Nickel Stainless Steel Reinforcement: A Study in Simulated Pore Solutions and in Fly Ash Mortars

Manuel Criado ,S Fajardo,J M Bastidas

doi:10.1155/2012/847323

Manuel Criado , S Fajardo + Show 1 more

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https://doi.org/10.1155/2012/847323

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Abstract

The present paper studies the corrosion behaviour of a new lower-cost type of austenitic stainless steel (SS) with a low nickel content in alkaline-saturated calcium hydroxide solution (a simulated concrete pore (SCP) solution) with sodium chloride (0.0%, 0.4%, 1.0%, 2.0%, 3.0%, and 5.0% NaCl) and embedded in alkali-activated fly ash (AAFA) mortars manufactured using two alkaline solutions, with and without chloride additions (2% and 5%), in an environment of constant 95% relative humidity. Measurements were performed at early age curing up to 180 days of experimentation. The evolution with time of electrochemical impedance spectroscopy was studied.Rctvalues obtained in SCP solution or in fly ash mortars were so high that low-nickel SS preserved its passivity, exhibiting high corrosion resistance

Highlights

Steel reinforcements embedded in concrete are protected from corrosion by a thin oxide film formed on their surfaces and maintained by the highly alkaline environment of the surrounding concrete, usually with a pH of 12-13 [1]
The depressed semicircle was generally due to dispersion of the time constant caused by irregularities on the steel surface, surface roughness, fractal surface, and, in general, certain processes associated with an irregular distribution of the applied potential [22]
Electrochemical impedance spectroscopy (EIS) results obtained for low-nickel stainless steel (SS) in alkaline-saturated calcium hydroxide solution showed that Rct values decreased with the addition of NaCl

Summary

Introduction

Steel reinforcements embedded in concrete are protected from corrosion by a thin oxide film formed on their surfaces and maintained by the highly alkaline environment of the surrounding concrete, usually with a pH of 12-13 [1]. The presence of chlorides can lead to damaging effects on passivity and the appearance of pitting corrosion when chloride ions reach the metal/concrete interface. Chloride ions are commonly found in construction materials and may originate from the external environment, as in the case of marine environments, deicing salts and acid rain [2]. The reaction kinetics depends on the determinant factors such as humidity, oxygen, and alkalinity medium. These factors can speed up the corrosion process [3, 4]

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