WHAT IS EFFLORESCENCE? 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.
Causes of the Efflorescence in Concrete
The efflorescence can be happening when moisture starts to react with concrete causing some white stains in the concrete. Some surfaces and mostly stained concrete will be more susceptible to the reaction than others. These surfaces allow water to travel within the surface.
As moisture rises to the surface of the concrete, it carries with it the calcium salts from within the concrete. These react with CO2 at the surface, forming that white powdery dust. It can be worsened by exposure to moisture, such as rain.
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).
In fact, concrete efflorescence typically does not persist past 18 to 24 months after production, depending on the climate. However, if concrete efflorescence has already formed, follow these procedures to remove it.
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.
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.
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.
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.
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 Washing with Detergent
Simply fill your detergent tank, switch the tank to "On," and begin spraying your concrete with soap. Let it soak into the mold and mildew, and you'll be ready to spray it away.
Efflorescence is salt deposited on surface concrete and masonry. It is created when water carries free salts out of concrete or masonry and they react with the atmosphere, producing insoluble salts typically white in appearance. Water is the trigger that makes efflorescence happen.
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.
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.
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.
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.
As efflorescence is brought about by moisture within your masonry, it is safe to assume that its presence is indicative of damp in your walls. It's here that we can say with confidence that whilst your efflorescence isn't going to cause you any major problems – the damp, if left untreated, most certainly will.
Since chloride salts are highly soluble in water, rain will often wash them off. The amount and character of the deposits vary according to the nature of the soluble materials and the atmospheric conditions. Efflorescence is particularly affected by temperature, humidity and wind.
Efflorescence appears as a white deposit of mineral salts on face of concrete walls and/or floors. Efflorescence usually appears in underground car park areas and other subfloor areas. Efflorescence is driven by hydrostatic pressure – the pressure exerted by moisture as it moves through concrete to the lowest point.
The easiest way to determine if it's efflorescence is to spray water on the substance. If it's mold (or a spider web), it won't change much. If it's efflorescence, it will dissolve.
These white deposits happen when water is drawn out of cement material. It is called efflorescence, and it's not actually mold.