Sulphate attack is the deterioration of concrete caused by sulphate salts in soil or groundwater reacting with components of the cement paste.
Explanation
Sulphates can penetrate concrete from surrounding ground conditions, particularly in foundations, retaining walls, and below-ground structures.
When sulphates react with hydrated cement compounds, they form expansive products that cause:
- Cracking
- Expansion
- Softening of the concrete matrix
- Loss of structural integrity
The risk level depends on soil chemistry, groundwater conditions, and concrete mix design.
In the UK, sulphate attack is primarily associated with aggressive ground conditions and inadequate sulphate-resistant cement specification.
Why It Matters
If not properly assessed, sulphate attack can:
- Compromise foundations
- Reduce durability of below-ground elements
- Require extensive structural repair
Prevention includes appropriate mix design and sulphate-resistant cement. Remedial works may involve concrete replacement, protective systems, and improved waterproofing strategies.