Analytical Characterization of the Passive Film Formed on Steel in Solutions Simulating the Concrete Interstitial Electrolyte

Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) were used to study the effect of chloride (Cl−) and fly ash on behavior of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte. Results showed the presence of fly ash and of Cl− led to an increase in the amount of iron oxyhydroxide (FeOOH) in outer layers of the film and to an increase in the thickness and water content of the passive film. Significant differences in composition and thickness were observed between the films formed in paste solutions and in calcium hydroxide (Ca[OH]2) solutions.