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ICE Handbook of Concrete Durability, 2nd Edition

Third edition now published

Introduction
The purpose of chloride extraction is to rehabilitate a reinforced concrete part from corrosion activity non-destructively and to provide long term corrosion protection of steel reinforcement in concrete which has been affected by chloride. The duration of the treatment is from several weeks up to as much as several months, depending on the amount and ingress depth of accumulated chloride, the permeability of the concrete, the layout of the reinforcement and other factors.

There are other electrochemical procedures that can be used to provide corrosion protection to steel in concrete structures. These include cathodic protection and re-alkalization. There are European standards for cathodic protection of steel in concrete (EN ISO 12696) and for the re-alkalization of carbonated concrete (EN 14038-1).
It has been assumed in the drafting of this document that design and execution of a chloride extraction application will be entrusted to appropriately qualified, competent and experienced people, for whose use it has been prepared.

ABSTRACT
This review discusses the origins and development of the criteria for the control of corrosion by cathodic protection of steel embedded in atmospherically exposed concrete. It considers the underlying theory of cathodic protection and the laboratory and field data that support the criteria. The conclusions and recommendations discuss gaps in our present knowledge and how they might be addressed.

This paper reviews the history of the development of impressed current cathodic protection of atmospherically exposed reinforced concrete from the first trials in 1959 on bridges to recently installed systems on a wide range of structures around the world. The paper covers the research efforts, anode developments, control systems and monitoring sensors which are reviewed and their evolution explained. The research into the potential and actual side effects of cathodic protection currents in concrete are summarised. The development of standards and guidance on impressed current cathodic protection is also reviewed.