Chloride Attack
Corrosion of reinforcement driven by chloride ions penetrating the concrete, typically from sea air, sea spray or brackish groundwater. Chlorides break down the protective layer on the steel even where the concrete is still alkaline.
On an actual building
This is the dominant deterioration mechanism on Mumbai's sea-facing buildings and the reason coastal structures age faster than inland ones. Chlorides accumulate — they do not evaporate out — so repairs must remove contaminated concrete rather than cover it.
What we most often have to correct
That painting a coastal facade stops it. Chloride already in the cover concrete keeps working regardless of what is applied on top.
Where this comes up in our work
Terms that come up alongside this one
- Carbonation
The slow reaction of atmospheric carbon dioxide with the alkaline compounds in concrete, which lowers its pH.
- Spalling
Concrete breaking away from a structural member, pushed off from behind by corrosion products forming on the reinforcement.
- Incipient Anode Effect
New corrosion that begins immediately around a concrete repair patch.
More deterioration terms
Chloride Attack — questions we get asked
What does chloride attack mean in waterproofing?
Corrosion of reinforcement driven by chloride ions penetrating the concrete, typically from sea air, sea spray or brackish groundwater. Chlorides break down the protective layer on the steel even where the concrete is still alkaline.
Why does chloride attack matter on a real project?
This is the dominant deterioration mechanism on Mumbai's sea-facing buildings and the reason coastal structures age faster than inland ones. Chlorides accumulate — they do not evaporate out — so repairs must remove contaminated concrete rather than cover it.
What do people commonly get wrong about chloride attack?
That painting a coastal facade stops it. Chloride already in the cover concrete keeps working regardless of what is applied on top.
Have a building showing this?
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