Efflorescence is a term used to describe the depositing of soluble salts (those that dissolve in water) on the surface of finished brickwork. These salts, like magnesium, calcium, potassium, or sodium, might have been present in the clay used for bricks or the sand used for mortar.
Efflorescence in Brickwork:
The most common form of efflorescence is a white deposit that appears on the surface of brickwork. Though it may look unsightly, it doesn’t harm the durability of the bricks. Typically, this white deposit fades away within the first few months of constructing new buildings, especially if the brickwork is exposed during wet weather.
Sources of Soluble Salts:
Common efflorescence mainly comes from soluble salts in clay bricks and mortar sands. Other sources can include impurities in clay, sea sands (avoided for mortars), and even detergents containing harmful salts.
How Efflorescence Forms:
Water dissolves soluble salts in bricks or mortar, holding them in solution. As the water evaporates during the wall drying process, the solution becomes concentrated, leading to the deposition of salts. This can occur within the pores of the brick or on the surface.
The exact occurrence of efflorescence depends on complex conditions such as salt types, brick pore structure, drying rate, and saturation level. We can control saturation to minimize efflorescence.
Minimizing Efflorescence Risk:
While the risk cannot be entirely avoided, it can be minimized by reducing water penetration into brickwork. Designers can use protective details like effective roof verges and eaves. Site practices, such as proper stacking of bricks and protection from saturation, are crucial. Choosing bricks tested for efflorescence extent is also essential.
Dealing with Efflorescence:
The best solution is to periodically brush off salt deposits from dry brickwork until all salts are released. Use a bristle brush, not a wire brush. Avoid washing off efflorescence, as it may re-dissolve salts. Acid treatment is not recommended. Internal efflorescence can be treated with minimal water and careful drying.
Conclusion:
Efflorescence is common but manageable through thoughtful design, construction practices, and regular maintenance. Understanding its sources and formation process helps in proactive steps to minimize its impact, preserving the appearance and durability of brickwork.