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Analysis of the protective efficiency of galvanizing against corrosion of reinforcements embeddeed in chloride contaminated concrete
Galvanizing concrete embedded steel reinforcements is one of the methods for avoidng their corrosion. However, whether they can guarantee predicted service lives for structures exposed to highly chloride containing media remains controversial. This paper analyses the protective efficiency of galvanized steel embedded in concrete specimensof variable cement/water/sand ratios immersed in sea water. The results are compared with those obtainedfor bare steel under the same conditions. The influence of concrete porosity on the corrosion rate is discussed. Bare and galvanized steels exhibit a critical threshold level for chloride ion, not determined here, above which their corrosion current rises sharply. It is clear that the critical chloride threshold of galvanized steel is higher than that of bare steel, because the galvanized steel delays for a longer time the appearance of high corrosion rates. After transition from passive to active state has taken place, galvanized steel employed here had lower corrosion rates than bare steel under the same exposure conditions. However, the galvanized steel reaches i(corr) values in the active state above 1 myA/cmcm, so usual galvanized coating thickness can be corroded in about only 5 years. The durability required for a given structure can be attained using thick covers with low permeability (high c/s and low w/c ratio) and higher chloride thresholds (galvanized rebars), at least in media with low or moderate chloride concentration.
Analysis of the protective efficiency of galvanizing against corrosion of reinforcements embeddeed in chloride contaminated concrete
Galvanizing concrete embedded steel reinforcements is one of the methods for avoidng their corrosion. However, whether they can guarantee predicted service lives for structures exposed to highly chloride containing media remains controversial. This paper analyses the protective efficiency of galvanized steel embedded in concrete specimensof variable cement/water/sand ratios immersed in sea water. The results are compared with those obtainedfor bare steel under the same conditions. The influence of concrete porosity on the corrosion rate is discussed. Bare and galvanized steels exhibit a critical threshold level for chloride ion, not determined here, above which their corrosion current rises sharply. It is clear that the critical chloride threshold of galvanized steel is higher than that of bare steel, because the galvanized steel delays for a longer time the appearance of high corrosion rates. After transition from passive to active state has taken place, galvanized steel employed here had lower corrosion rates than bare steel under the same exposure conditions. However, the galvanized steel reaches i(corr) values in the active state above 1 myA/cmcm, so usual galvanized coating thickness can be corroded in about only 5 years. The durability required for a given structure can be attained using thick covers with low permeability (high c/s and low w/c ratio) and higher chloride thresholds (galvanized rebars), at least in media with low or moderate chloride concentration.
Analysis of the protective efficiency of galvanizing against corrosion of reinforcements embeddeed in chloride contaminated concrete
Analyse wirksamen Galvankorrosionsschutzes in chloridkontaminerten Betonverstärkungen
Bautista, A. (author) / Gonzalez, J.A. (author)
Cement and Concrete Research ; 26 ; 215-224
1996
10 Seiten, 6 Bilder, 1 Tabelle, 16 Quellen
Article (Journal)
English
armierter Beton , Stahl , galvanische Zelle , Korrosionsschutz , Beton , Pore , Flüssigkeit , Alkalität , Meerwasser , Chlorid , Gehalt (Zusammensetzung) , Korrosion , Dauer , Zement , Wasser-Zement-Wert , Einflussgröße , Galvanisieren
| British Library Online Contents | 1996
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Corrosion in Concrete and Reinforcements
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