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Macro- and micro-cell corrosion of steel bars in cracked concrete made with various cements
Macro- and micro-cell corrosion of steel bars in pre-cracked prism specimens exposed to marine environment for 15 years is summarized here. The size of the specimens was l00x100x600 mm. W/C were 0.45 and 0.55. The specimens were made with ordinary portland, slag (Types A, B and C), and fly ash (Type B) cements. A round steel bar of diameter 9 mm was embedded at the center in each specimen. Crack widths were varied from 0.1 to 5.0 mm. Chloride concentrations in the concrete, micro- and macrocell corrosion, passivity grade, anodic polarization curve, deposits in the crack, and pit depths over the steel bars were investigated. Dense microstructure of concrete made with a large amount of slag (SCB, SCC) causes accumulation of more chloride in the vicinity of the unhealed cracks (>0.5 mm). However, it does not lead to a remarkable amount of corrosion at the cracked region compared to the other cements after 15 years of exposure. Narrower cracks (<=0.5 mm) as well as the debonded areas in the vicinity of the root of the crack over the steel bars heal irrespective of the cement types. It improves the passivity of the steel bar at the cracked region. Relations between pit depth and crack widths; and macro-cell and micro-cell corrosion are proposed.
Macro- and micro-cell corrosion of steel bars in cracked concrete made with various cements
Macro- and micro-cell corrosion of steel bars in pre-cracked prism specimens exposed to marine environment for 15 years is summarized here. The size of the specimens was l00x100x600 mm. W/C were 0.45 and 0.55. The specimens were made with ordinary portland, slag (Types A, B and C), and fly ash (Type B) cements. A round steel bar of diameter 9 mm was embedded at the center in each specimen. Crack widths were varied from 0.1 to 5.0 mm. Chloride concentrations in the concrete, micro- and macrocell corrosion, passivity grade, anodic polarization curve, deposits in the crack, and pit depths over the steel bars were investigated. Dense microstructure of concrete made with a large amount of slag (SCB, SCC) causes accumulation of more chloride in the vicinity of the unhealed cracks (>0.5 mm). However, it does not lead to a remarkable amount of corrosion at the cracked region compared to the other cements after 15 years of exposure. Narrower cracks (<=0.5 mm) as well as the debonded areas in the vicinity of the root of the crack over the steel bars heal irrespective of the cement types. It improves the passivity of the steel bar at the cracked region. Relations between pit depth and crack widths; and macro-cell and micro-cell corrosion are proposed.
Macro- and micro-cell corrosion of steel bars in cracked concrete made with various cements
Makro- und Mikrozellen-Korrosion von Stahlträgern im Beton aus verschiedenen Zementen mit Rissen
Mohammed, T.U. (author) / Hamada, H. (author) / Yokota, H. (author)
2004
21 Seiten, 13 Bilder, 8 Tabellen, 13 Quellen
Conference paper
English
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