Reinforcement corrosion is the rusting and deterioration of steel reinforcement (rebar) within concrete, typically caused by carbonation or chloride contamination reducing the concrete’s protective alkalinity.
Explanation
Concrete normally protects embedded steel due to its high alkalinity. When processes such as carbonation or chloride ingress occur, this protection breaks down. Moisture and oxygen then react with the steel, forming rust.
Rust occupies a greater volume than steel, creating internal pressure that leads to:
- Cracking
- Delamination
- Concrete spalling
- Progressive structural weakening
In UK structures, reinforcement corrosion is one of the most common causes of concrete deterioration, particularly in car parks, balconies, bridges, and exposed structural elements.
Why It Matters
If left untreated, reinforcement corrosion can:
- Reduce load-bearing capacity
- Increase safety risks
- Accelerate structural failure
- Significantly increase repair costs
Remedial solutions typically involve concrete breakout, corrosion treatment, reinstatement with structural repair mortars, and the application of protective systems such as anti-carbonation coatings or cathodic protection.