Concrete spalling is the cracking, flaking, or breaking away of concrete from a surface, often caused by reinforcement corrosion, freeze–thaw cycles, or prolonged moisture exposure.
Explanation
Spalling commonly occurs when steel reinforcement within concrete begins to corrode. As steel rusts, it expands, creating internal pressure that forces the surrounding concrete to crack and detach.
Typical signs include:
- Surface cracking or delamination
- Exposed reinforcement bars
- Rust staining
- Loose or falling concrete fragments
In UK structures, spalling is frequently linked to carbonation, chloride contamination (such as de-icing salts), and insufficient concrete cover over reinforcement.
Why It Matters
Concrete spalling is not just cosmetic. If left untreated, it can:
- Compromise structural integrity
- Accelerate reinforcement corrosion
- Create safety hazards
- Increase long-term repair costs
Professional repair usually involves removing damaged concrete, treating reinforcement, reinstating with structural repair mortars, and applying protective coatings to prevent recurrence.