Preserving or restoring passivity

BS EN 1504 Principle 7 is concerned with preserving or restoring the passivity of the concrete by creating chemical conditions in which the surface of the reinforcement is maintained in or is returned to a passive condition. Where the reinforcement is passive, an additional layer of mortar or concrete may be added over carbonated concrete to provide additional protection

Methods of protection based upon the BS EN 1504 Principle 7 is the use of the following:

• 7.1 Increasing concrete cover to reinforcement.
• 7.2 Replacing contaminated or carbonated concrete.
• 7.3 Electrochemical realkalisation of carbonated concrete.
• 7.4 Re-alkalisation of carbonated concrete by diffusion.
• 7.5 Electrochemical chloride extraction