Efflorescence is the white powdery substance on the surfaces of unsealed concrete and the white blush seen with sealed floors. Efflorescence is caused by vapor migrating through the slab bringing soluble salts to the surface of the concrete.
Usually this white or off-white discoloration to concrete and masonry forms when soluble salts and other water dispersible materials come to the surface through capillary voids as a result of temperature changes, moist migration, condensation, rain, dew, and/or too much water in the mix.
Why is my concrete turning white? Efflorescence is a white salty residue caused when too much moisture is moving through the concrete. As the concrete dries and its moisture rises upwards through the slab, it brings salts within the concrete to the surface as well.
In many cases, efflorescence will disappear on its own over time (usually after the first year of a paver or retaining wall installation). Efflorescence can also be removed with special cleaners like the Gator Efflorescence Cleaner. On average, you should wait about 60 days before applying an efflorescence cleaner.
Efflorescence and alkali salts can be removed by dry brushing with a stiff bristled brush followed by wet sponging the surface with a mild 5% solution of white vinegar (acetic acid) in water. The whole area should then be wiped down with a damp cloth and allowed to dry thoroughly.
Efflorescence on pavers will eventually stop on its own after the salts in the pavers have dissipated. On the other hand, recurring efflorescence may indicate an ongoing problem of water intrusion that needs to be addressed before it causes permanent damage to the structure.
While efflorescence on bricks, white spots on concrete, and chalky mineral deposits are unsightly, efflorescence is naturally occurring and should not be feared as it poses no adverse health risk, generally speaking.
Efflorescence itself isn't dangerous or harmful. It can lead to potential moisture problems that can cause structural damage to building materials. So it is important to take action when you notice efflorescence in your basement, on your paving stones, or on other structures.
Efflorescence is the white chalky powder that you might find on the surface of a concrete or brick wall. It can be a cosmetic issue, or it can be an indication of moisture intrusion that could lead to major structural and indoor air quality issues.
In general, most efflorescence can be removed by dry-brushing followed by flushing with clean water. If brushing is not satisfactory, it may be necessary to use a very light (brush) sandblasting to remove the deposits.
Vinegar and water solution—Efflorescence can be removed by using a dilute solution of household white vinegar and water. A vinegar and water solution is relatively inexpensive, non-toxic, and easy to obtain, mix and apply. Dilution ratio is 20–50% vinegar in water by volume.
Simply sealing concrete from water penetration (using a penetrating sealer) will help prevent efflorescence. V-SEAL creates an incredible water barrier for brick, mortar, and all forms of concrete. To help prevent efflorescence, V-SEAL should be sprayed anywhere brick, mortar or cement will be exposed to water.
Although the bulk of the hydration process takes place in the hours and days immediately after the pour, concrete needs 28 days to fully dry. While the slab will harden and lighten in color before 28 days, don't be fooled into thinking it's done hydrating.
The chalking and dusting of the concrete is caused by a breakdown of the top surface area of the concrete. The surface of the concrete will erode easily under general traffic. This can produce a powdery, chalky appearance.
If your wall started out with only a small amount of water-soluble salts within it, the efflorescence might stay away on its own after one cleaning, or only lightly return. But if you wall has a high salt content, the efflorescence could develop again and again.
Judging from the feedback received at the Pavingexpert website, most cases of efflorescence become noticeable 3-6 weeks after laying is completed and then last for 3-6 months before gradually disappearing over a period of 3-6 months.
If you live in an area of frequent rain and sunny days, efflorescence and its passing may occur quickly. The process may take much longer in drier climates. Typically, efflorescence will stop developing in approx- imately 18 to 24 months.
Overall, efflorescence is a common phenomenon that is individual with each and every case. It is not harmful but can look unappealing and unattractive. However, over time, efflorescence will gradually disappear.
Differences Between Efflorescence & Mold
Mold can grow on just about any surface, whereas efflorescence doesn't spread and forms on cement or brick. Mold is a fungus, efflorescence is moisture that evaporates into salt deposits. Efflorescence will turn into a powder when touched, while mold will not.
Allow the surface to fully dry before applying SEALTIGHT or ULTRA MASONRY BLOCK SEALER. Once the surface is completely dry, you can apply SEALTIGHT or ULTRA MASONRY BLOCK SEALER to waterproof the surface and help keep efflorescence from forming again in the future.
RadonSeal Efflorescence Cleaner is extremely effective for the removal of efflorescence, dissolved salts, lime, and alkalis. However, lime (calcium hydroxide) in the efflorescence gradually reacts with carbon dioxide in the air (carbonation), forming calcium carbonate (CaCO3).
Pressure washing can work to remove white efflorescence once the surface has thoroughly dried. The surface must be thoroughly rinsed to ensure that no residue remains. We also use a safe detergent to ensure a thorough clean.
Efflorescence occurs when water soluble salts travel to the concrete surface. The mineral salts might be a result of the cement hydration reaction or can come from many other sources like sulphate rich sand. Porous concretes, masonry and mortars will be more susceptible to the migration of salts to the surface.
To do this, it is recommended that you treat your concrete walls with a breathable, penetrating concrete sealer like the Siloxa-Tek 8500. The Siloxa-Tek 8500 is able to prevent efflorescence from coming to the surface by reducing moisture intrusion and water infiltration.