Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Analytical characterization of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte
The interstitial solution in concrete pores is characterized by a very high pH, which prevents corrosion of reinforcing steel through the formation of a passive film. Composition of the passive film formed on iron in very alkaline media has been the object of some discussion. Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) were used to study the effect of chloride ions Cl(-) and fly ash on behavior of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte. The outermost layers of the passive films formed on the steel in cement paste solutions essentially were composed of iron oxyhydroxide, FeOOH. The concentration of that species increased with the presence of fly ash in the paste and with the concentration of Cl(-) in the solution. The presence of fly ash led to a thicker passive film with a larger degree of H2O incorporation. An identical effect occurred when Cl(-) ions were added to the solution, before or after film formation. This meant Cl(-) was capable of changing the film properties, even after the film formed. Passive films formed in Ca(OH)2 solutions revealed differences in composition and thickness when compared to films formed in the paste solutions, which suggested that extrapolation of the properties of films formed in Ca(OH)2 to a real system should be made with reserve.
Analytical characterization of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte
The interstitial solution in concrete pores is characterized by a very high pH, which prevents corrosion of reinforcing steel through the formation of a passive film. Composition of the passive film formed on iron in very alkaline media has been the object of some discussion. Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) were used to study the effect of chloride ions Cl(-) and fly ash on behavior of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte. The outermost layers of the passive films formed on the steel in cement paste solutions essentially were composed of iron oxyhydroxide, FeOOH. The concentration of that species increased with the presence of fly ash in the paste and with the concentration of Cl(-) in the solution. The presence of fly ash led to a thicker passive film with a larger degree of H2O incorporation. An identical effect occurred when Cl(-) ions were added to the solution, before or after film formation. This meant Cl(-) was capable of changing the film properties, even after the film formed. Passive films formed in Ca(OH)2 solutions revealed differences in composition and thickness when compared to films formed in the paste solutions, which suggested that extrapolation of the properties of films formed in Ca(OH)2 to a real system should be made with reserve.
Analytical characterization of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte
Analyse der Zusammensetzung der Passivschicht auf Betonstahl in einem dem des Stahlbetons vergleichbaren Elektrolyten
Montemor, M.F. (Autor:in) / Simoes, A.M.P. (Autor:in) / Ferreira, M.G.S. (Autor:in)
Corrosion, Houston ; 54 ; 347-353
1998
7 Seiten, 8 Bilder, 3 Tabellen, 23 Quellen
Aufsatz (Zeitschrift)
Englisch
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