Influence of calcium nitrite on the passive films of rebar in simulated concrete pore solution

Abstract

Purpose This paper aims to study the influence of the addition of calcium nitrite on the passive films of rebar to reveal what causes calcium nitrite to further prolong the durability service life of the reinforced concrete structures. Design/methodology/approach A comprehensive experimental study of the passive films, such as components, surface morphologies, electric structure and compactness, was carried out in a saturated calcium hydroxide solution which is normally used to simulate concrete pore solution by using X-ray photoelectron spectroscopy, atomic force microscopy, Mott–Schottky and potentiostatic polarization, respectively. Findings The results showed that the passivation behavior of rebar has been changed dramatically by the addition of calcium nitrite. That is, the passive film formed in the solution with the addition of 10 g/L Ca(NO2)2 had less donor density (Nd), more positive plat potential, smoother surface and lower content of Fehydrox than that formed in the solution without Ca(NO2)2. Originality/value The study focuses on the passive films and provides a more clear cognition of the durability service life extension of the reinforced concrete structures caused by the addition of calcium nitrite.

Influence of Li2+ Doping on the Structural and Optical Properties of CaO Synthesized by Sol–Gel Process

“…8,9 CaO is a cheap inorganic material; there have been many reports on the inhibition effect of calcium salts, such as calcium sulfate, 10 calcium tartrate 11 and calcium nitrite. 12 CaO powders can be prepared by several synthetic methods, such as sol-gel method, 13 sonication-assisted reverse emulsion technique 14 and surfactant-template method. 15 The in°uence of Li 2þ doping on the physical properties of CaO nanocrystalline will be studied for the¯rst time in this work; no literature has been previously published about this kind of impurities.…”

Research Progress of Nitrite Corrosion Inhibitor in Concrete

“…It is the one used most widely and in the largest quantities. Nitrite corrosion inhibitor can delay the failure time of the passivation film and slow down the corrosion rate of the steel bar in the concrete [9,10]. After measuring the potential in the reinforced concrete structures, incorporating dozens of steel bar corrosion inhibitors such as phosphate, zinc oxide, gluconate, and nitrite commonly used in engineering, Gonzalez et al [11] considered that the calcium nitrite has the best corrosion resistance.…”

Chemical Composition of Corrosion Products of Rebar Caused by Carbonation and Chloride

“…There are many factors affecting the destruction of passivation film, including the surface conditions of steel bars, alloy composition, iron phase composition, and other material factors as well as the permeability of concrete, the concentration of chloride ion, the PH of solution, temperature and humidity, and other environmental factors [10][11][12]. The properties of the steel passivation film, that is, the thickness, composition, and stability, are influenced by the polarization potential, the polarization time, and the ion concentration in the medium, and the microstructure characteristics of passivation films are related to passivation potential and passivation time.…”