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Re-alkalisation of concrete.

The objective of re-alkalisation is to restore the alkalinity in carbonated concrete and to re-establish a passive environment around the reinforcement with the minimum of disruption to the concrete. The system involves passing an electrical current through the concrete to the reinforcement using an externally applied anode that is attached to the concrete’s surface. An outline of electrochemical re-alkalisation is shown in the Figure.

The system tackles the problem of carbonation without the need to remove contaminated concrete and, taking the cost of alternative ‘repair’ operations into account, can be cost effective. Tests for carbonation should be undertaken before and after re-alkalisation to determine the effectiveness of the treatment.

Re-alkalisation is covered by BS EN 14038, Electrochemical realkalization and chloride extraction treatments for reinforced concrete, Part 1: Realkalization.

Acknowledgement: The Concrete Society

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