Experimental support for new electro active repair method for reinforced concrete

This paper, describes experiments that form the basis of an invention that aims at improving the durability of conventional (mechanical) repairs to concrete structures suffering from chloride induced corrosion of reinforcing steel. The invention comprises application of a short term, low voltage, DC...

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Veröffentlicht in:Materials and corrosion 2016-06, Vol.67 (6), p.600-606
Hauptverfasser: Geiker, M. R., Polder, R. B.
Format: Artikel
Sprache:eng
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Zusammenfassung:This paper, describes experiments that form the basis of an invention that aims at improving the durability of conventional (mechanical) repairs to concrete structures suffering from chloride induced corrosion of reinforcing steel. The invention comprises application of a short term, low voltage, DC current before or after concrete is broken out and before repair material is applied. It is an additional step in conventional concrete repair. The application of current will last typically 24 h at a current density of typically 5 A/m2 of steel surface area. In laboratory experiments corrosion pits are simulated by placing highly concentrated iron(II)chloride solution in contact with a mortar surface, after which current is applied. The results indicate that this treatment is able to remove 90% or more of the chloride from the simulated pit solutions. Furthermore, the pH has increased from about 3 to more than 12. The combined reduction of chloride content and increase of pH strongly reduces the chloride to hydroxyl ratio of the pore solution and thus the aggressive conditions at the reinforcing steel. After applying alkaline chloride free repair material, this will result in a longer life of the repair, thus reducing the life cycle costs of repaired structures. The process is named EAR, electro active repair. Chloride remaining in corrosion pits on reinforcing steel causes poor durability of concrete repairs. An invention is proposed that removes chloride from corrosion pits by applying a short term direct current from a temporary anode, as an additional step in the conventional repair process. Laboratory experiments show that with this method 90% or more of the chloride ions can be removed and that the pH increases to passivating levels.
ISSN:0947-5117
1521-4176
DOI:10.1002/maco.201608942