Concrete delamination is the separation of layers within concrete, typically occurring parallel to the surface, often caused by reinforcement corrosion or poor bonding.
Explanation
Delamination usually develops when internal stresses cause a horizontal split between layers of concrete. A common cause is reinforcement corrosion, where expanding rust creates pressure beneath the surface.
Other contributing factors include:
- Inadequate compaction during casting
- Entrapped air or bleed water
- Freeze–thaw cycles
- Poor surface preparation between layers
Delaminated concrete may initially appear intact but can often be identified by a hollow sound during hammer testing. Over time, it can lead to surface failure and spalling.
In UK structures, delamination is commonly found in car parks, balconies, bridge decks, and exposed slabs.
Why It Matters
If left untreated, delamination can:
- Progress to concrete spalling
- Expose reinforcement
- Reduce durability and performance
Repair typically involves removing the affected layer, treating any exposed reinforcement, and reinstating the area with suitable repair materials.
Early detection helps prevent more extensive structural damage.