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.
Carbonation to concrete leading to reinforcement corrosion and localised spalled concrete to areas of low concrete cover.
2. Delaminated concrete
Due to widespread carbonation or chloride-induced corrosion.
3. Permeable concrete
Permeable concrete due to inadequate curing, shrinkage cracks, poor compaction and a weak surface layer to the concrete.
4. Low concrete cover
Low concrete cover to reinforcement in exposed areas of the structure.