What is Efflorescence?
Efflorescence is defined as a change on the surface to a powdery substance upon exposure to air, as a crystalline substance through loss of water. More directly, it’s an unwanted white discoloration to concrete and masonry caused when soluble salts and other water dispersible materials come to the surface as a result of low temperatures, moist conditions, condensation, rain, dew, and/or too much water in the mix. It can happen quickly or overtime, but either way efflorescence can transform an otherwise attractive concrete or masonry surface into an unsightly eye sore on a building, home or other structure.
Any material containing portland cement is susceptible to efflorescence. It generally occurs when calcium hydroxide (lime) formed in the hydration reaction of portland cement is transported by water to the surface through capillaries in the concrete. There it combines with carbon dioxide from the air to produce calcium carbonate and water. But efflorescence can also be caused by hydroxides and sulfates of either sodium or potassium, which are much more soluble in water than calcium. And they form efflorescence more rapidly than calcium hydroxide. These salts can come from cement, aggregates, water, or admixtures. The result in either case is a white discoloration that contrasts with the color of the concrete or masonry surface.
How to Remove Efflorescence?
Despite the best efforts to prevent efflorescence, it can still occur. While sandblasting is a traditional option for removing efflorescence, that process can etch damage and weaken concrete masonry surface. Specially-formulated, water-based chemical treatments like QUIKRETE® Efflorescence and Rust Remover offer an easy, safe and effective alternative to sandblasting. A solvent-free, low VOC product, QUIKRETE® Efflorescence and Rust Remover can enhance concrete and masonry surfaces by eliminating efflorescence in just four steps.
(Always wear rubber gloves, eye protection and rubber boots when working with concrete and masonry cleaning products)
QUIKRETE® Efflorescence & Rust Remover should be test applied in an inconspicuous spot in order to optimize the application technique and to evaluate the effect, before treating the entire area.