Efflorescence is the appearance of white, powdery deposits on concrete surfaces caused by soluble salts being carried to the surface by moisture.
Explanation
Efflorescence in concrete occurs when water moves through concrete, dissolving salts within the material. As the water evaporates at the surface, it leaves behind visible salt deposits.
Common contributing factors include:
- Excess moisture within the concrete
- Water ingress from external sources
- Poor drainage or waterproofing
- Newly constructed concrete drying out
Efflorescence is often seen on walls, slabs, and masonry, particularly in basements, retaining walls, and external structures exposed to moisture.
In the UK, it is a common issue due to frequent rainfall and damp conditions.
Why It Matters
Efflorescence is usually not structurally harmful, but it can indicate underlying moisture movement.
If ignored, the source of moisture may lead to:
- Reinforcement corrosion
- Freeze–thaw damage
- Surface deterioration
Treatment may involve cleaning the surface and addressing the source of moisture through improved drainage, sealing, or waterproofing.