Efflorescence is a crystalline deposit of salts that can form when water is present in or on brick, concrete, stone, stucco or other building surfaces. It has a white or greyish tint and consists of salt deposits that remain on the surface after water evaporates.
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.
Fill a bucket with warm water. Add 2 cups of vinegar and/or 2 tablespoons of dish soap/detergent. Dip the broom into the water and use it to scrub the surface of the concrete. Scrub for several minutes until the salt residue and stains start to lift.
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.
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.
Primary Efflorescence
When salt is added to concrete or clay products, it dissolves or is carried by capillary action to the surface. It becomes noticeable when the water evaporates. This form of efflorescence generally lasts around two to three years and fades naturally as the salt supply decreases.
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).
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.
The easiest way to deal with concrete dusting is to cure your concrete properly. If your concrete has already cured and you are experiencing dusting use a concrete coating or concrete densifier to stop concrete floor dusting.
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.
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.
Indications of Moisture
Efflorescence alone does not pose a major problem, but it can be an indication of moisture intrusion, which may compromise the structural material.
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.
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.
Perhaps the most tell-tale sign of shoddy concrete pouring is the presence of cracks. The primary cause of cracks in dried concrete is tensile stress on the structure.
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.
The acidity in the vinegar helps remove the efflorescence and calcium deposits by breaking down mineral crystals. After cleaning the surface, let dry for 48-72 hours (moisture content below 25%).
RadonSeal Efflorescence Cleaner can be safely used on poured concrete, concrete blocks, bricks, stucco, pavers, and artificial stones. The cleaner chemically breaks down and removes efflorescence, lime deposits, metal salt stains, and rust deposits.
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.
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.
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.
Will rain wash away efflorescence? However, it's worth noting that rain alone may not completely eliminate the problem, especially if it is deeply embedded, or if the surface is not exposed to consistent rainfall. In such cases, additional cleaning methods or treatments may be necessary to address the issue.
Simple washing can sometimes remove efflorescence. Scrub with a stiff brush and mild detergent or plain water. Efflorescence is most soluble when it first appears, so sooner is better than later if you want to try this approach.
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.