Effect of uneven porosity distribution in cement paste and mortar on reinforcing steel corrosion
β Scribed by Ping Gu; Yan Fu; Ping Xie; J.J. Beaudoin
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 871 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0008-8846
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β¦ Synopsis
The influence of heterogeneity of cementitious matrices, e.g. uneven porosity distribution in repair cement paste or mortar, on surface corrosion of the reinforcing steel was investigated using a low frequency impedance technique. Rebar embedded in lower porosity matrices had lower surface impedance and phase angle values in the frequency range 1Hz to 10mHz. The corrosion reactions appeared to preferentially occur on the surface of rebar embedded in denser matrices. This observation was valid in cases with and without admixed chloride ions. A possible explanation of the surface corrosion mechanism of reinforcing steel is given. The phenomenon is explained by the depletion of oxygen concentration at the steelcement paste interface resulting in the formation of an "anodic area". The chloride ions accelerate the corrosion reaction by destroying the iron oxide film and reducing the pH values at the steel-cement paste surface.
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