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.
In fact, it's a normal and natural occurrence that can happen in any cement-based product. In many cases, efflorescence will disappear on its own over time (usually after the first year of a paver or retaining wall installation).
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.
First, for very mild cases of efflorescence, try a 50/50 mix of white vinegar and water. Using a scrub brush, spot treat and scrub affected areas with the vinegar mix. The acidity in the vinegar helps remove the efflorescence and calcium deposits by breaking down mineral crystals.
Removing efflorescence can be quick and simple. In fact, efflorescing salts are water-soluble, which means efflorescence may disappear on its own due to normal weathering. Some of the best ways to remove efflorescence include: Pressurized water: Applying pressurized water may dissolve efflorescence quickly.
An acidic cleaner, such as PROSOCO's Sure Klean Light Duty Concrete Cleaner, and Sure Klean Vana Trol can dissolve efflorescence more effectively.
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.
It is common for people to confuse mold with efflorescence. Efflorescence itself isn't dangerous or harmful. It can lead to potential moisture problems that can cause structural damage to building materials.
Once the water source is eliminated, most efflorescence (also called Calcium Carbonate or limestone) can be removed with abrasive techniques. Dry brushing, light water blasting or light sandblasting followed by flushing with clean water. In large areas, rotary scrubbers with scrubbing pads may also be used.
Unless something else is done, the efflorescence will be back soon. In order to prevent it, you'll need to: Eliminate soluble salts for your concrete or masonry, and/or. Prevent water from transporting soluble mineral salts to the surface.
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.
By sealing with a penetrating concrete sealer, concrete is hardened up to 45% and efflorescence is eliminated. Since humidity can affect efflorescence, it has been shown that it can be a seasonal problem with efflorescence being most common during rainy seasons.
Here's the deal with efflorescence and sealing … you do NOT want to seal before your pavers have had the chance to “breathe” and go through their normal efflorescence cycle. By sealing too soon, you'll run the risk of trapping migrating salts beneath the coating of sealer.
Pressure Cleaning
Using a pressure washer to clean your driveway will remove most of the white spot lichen. It will also remove dirt, moss and grime which all contribute towards keeping the surface of your driveway damp and shaded – ideal conditions for lichen to thrive.
But if you wall has a high salt content, the efflorescence could develop again and again. The first thing to do is to take steps to keep water off of the wall as much as possible and see what happens. Consider a penetrating sealant that is specifically made to prevent efflorescence.
No-one can say how long any incidence of efflorescence will last. It might be a few weeks; it might be a couple or three months; it &could be a year or two. There are so many factors affecting its generation and appearance, and its disappearance that an educated guess is the best we can manage.
A few major differences between efflorescence and mold growth: Mold grows, efflorescence doesn't. Mold can grow on just about any surface, whereas efflorescence doesn't spread. Mold is a fungus, whereas efflorescence is moisture that evaporates into salt deposits.
A mild solution of muriatic acid in water is a conventional chemical cleaner used for clearing efflorescence.
To start the maintenance process, use a solution of regular dish soap and water along with a stiff plastic scrub brush. Avoid using a wire brush, as it can dislodge wires and create rust marks on the surface.
Efflorescence of this type can be removed with a dilute acid solution (such as one part hydrochloric acid in 9 to 19 parts water or one part phosphoric acid in 9 parts water). After treatment the area should be washed with clean water to remove all acid.
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.