Role of the concrete cover to suppress corrosion of steel in carbonated concrete
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2020-09
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Other Conference Item
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Abstract
Carbonation of cementitious materials raises concerns with respect to corrosion of embedded rebars in reinforced concrete, especially when it comes to binders with high clinker replacement. It is has been shown that the rate of carbonation induced corrosion depends mostly on the water content around the rebars. Corrosion rates of practical concern are reached when the steel gets in contact with the water front resulting from wetting events. The cover depth and the concrete microstructure play an important role in controlling the water transport from the exposed surface to the steel.
Here, we present results from an experimental study. Adsorption isotherms of carbonated and non-carbonated mortars were measured, showing clear differences in the water adsorption behavior. Carbonated mortar samples, with embedded steel bars at different depths, were exposed to varying wetting and drying cycles, during which corrosion potential, corrosion rate and electrical resistance were monitored. Preliminary results show that high corrosion rates are only reached after a prolonged exposure to water. For cover depths higher than 2 cm it takes more than 24 hours even for porous concrete. The results of this study contribute to a better understanding of the processes leading to damage in carbonated concrete, and illustrate that a conceptual change may be needed, namely considering the concrete cover as a protection barrier against water ingress rather than against carbonation. This may improve the acceptance of high clinker replacement levels.
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published
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Book of Abstracts of the 74th RILEM Annual Week & the 40th Cement and Concrete Science Conference
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Pages / Article No.
53 - 53
Publisher
RILEM Publications
Event
74th RILEM Week and 40th Cement and Concrete Science Conference (virtual)
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09593 - Angst, Ueli / Angst, Ueli
Notes
Conference lecture held on September 4, 2020. Due to the Coronavirus (COVID-19) the conference was conducted virtually.