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The Corrosion of Steel Reinforcement in Carbonated Concrete Under Different Humidity Regimes

Published online by Cambridge University Press:  21 February 2011

Anastasia G. Constantinou  and
Karen L. Scrivener
Anastasia G. Constantinou
Affiliation:
Department of Materials, Imperial College of Science, Technology and Medicine, London, SW7 2BP, England
Karen L. Scrivener
Affiliation:
Department of Materials, Imperial College of Science, Technology and Medicine, London, SW7 2BP, England
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Abstract

In this investigation, four concretes (two mix designs and two curing regimes), containing reinforcing bars at covers 11 mm and 20 mm were carbonated fully in 100% CO2 and 65% relative humidity (RH). They were then placed in two different humidity environments (65% RH and 90% RH). The progress of the corrosion of the samples was followed electrochemically (using the linear polarisation technique) and microscopically (using a scanning electron microscope).

Electrochemical monitoring of the corrosion rate showed that corrosion started very soon after placement in the humidity regimes and generally increased with time. The water/cement ratio, the concrete cover of the reinforcement and the curing of the concrete had a significant effect the length of time taken to carbonate the specimens. However, the effect of these variables on the corrosion rate was negligible. In addition, the corrosion rate showed no dependance on the humidity regimes.

Microstructural examination of the samples revealed the existence of corrosion products at the steel/concrete interface after 6 months in the humidity regimes. There was more corrosion product in the samples at 90% RH. The samples with the low w/c showed more extensive cracking in the interfacial region.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 370: Symposia Va/Vb – Microstructure of Cement-Based Systems/Bonding and Interfaces in Cement... , 1994 , 471
Copyright
Copyright © Materials Research Society 1995

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References

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