In considering the control of anodic areas to prevent corrosion with Principle 11 (Control of anodic areas), it is important to understand that particularly in heavily chloride contaminated structures, spalling due to reinforcement corrosion happens first in areas of low concrete cover.
Additionally, it is also important to protect repaired areas from the future ingress of aggressive agents (carbonation, chlorides). A protective cement slurry can be applied directly on the reinforcement after appropriate cleaning, to prevent further steel dissolution at the anodic areas.
In order to protect against the formation of incipient anodes in the areas surrounding the patch repairs, a corrosion inhibitor can be applied to migrate through the concrete and reach the reinforcement, where it forms a barrier, also protecting the anodic zones.
Note: Dual function inhibitors such as Sika®FerroGard® 903+ also protect the cathodic areas simultaneously.