Those white salt stains can endure all year. To rid your sidewalk of them, mixture together vinegar, a dash of dish soap, and water. Cover the stained area and let it rest for 10-15 minutes, stubborn stains may need more time. Then with a stiff bristled brush, scrub away the markings.
Fill a bucket with warm water and add vinegar and/or 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. Use the Shop vac to remove the excess water.
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.
Efflorescence is the white powdery substance often seen on the surface of concrete or brick. Efflorescence is caused by water vapor migrating through the slab bringing soluble salts to the surface of the concrete. Many people mistake the white powdery substance with mold or mildew.
Efflorescence or "bloom" is a type of white stain that can appear on the surface of concrete, lime and other masonry surfaces. It results when water passes through the concrete, bringing water-soluble salts and other materials in the substrate with it to the surface.
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.
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.
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.
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.
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.
A solution of baking soda (sodium bicarbonate) and water (Approx. 1 lb. Of baking soda per 5-gallons of water) can be used to neutralize the stain. The solution should be applied until it stops fizzing.
The best way to stop the dust is to apply a solvent-based acrylic sealer. We highly recommend this product here. Before you apply an acrylic sealer, you will want to remove as much of the dusting surface as possible without having to grind. We recommend acid etching the surface and make sure to neutralize it properly.
If you need to get rid of rust from concrete, your best bet is to use some WD-40 Multi-Use Product, and some elbow grease. WD-40 is specially formulated to be a penetrant, so when you spray it on a rusted surface, it gets to work right away by getting under the rust.
White vinegar will not damage your concrete. However, leaving this solution for an extended period will damage the cement that binds the concrete together. Hence, you should be careful when using vinegar on your concrete, especially if you will use this solution on polished concrete.
Vinegar or baking soda: These natural cleaners work well to clean cement patios with stubborn charcoal or rust spots. Mix equal parts vinegar and water, scrub the patio with the mixture, then give it a good rinse. If stains don't dissolve, try undiluted vinegar.
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.
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.
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.
An acidic cleaner, such as PROSOCO's Sure Klean Light Duty Concrete Cleaner, and Sure Klean Vana Trol can dissolve efflorescence more effectively.
These products are specifically formulated to dissolve efflorescence and remove dirt from paving stones and concrete surfaces without causing discoloration or damage. To start the maintenance process, you can use a solution of regular dish soap and water along with a stiff plastic scrub brush.
A mild solution of muriatic acid in water is a conventional chemical cleaner used for clearing efflorescence. While this may clear up efflorescence, it can also lead to erosion of masonry if not done properly. People who don't want to use chemical cleaners often resort to applying diluted vinegar to efflorescence.
Will Vinegar Damage Concrete? Cleaning concrete with vinegar will not damage it! However, saturating concrete for an extended period will damage the cement that binds concrete together. Over time, vinegar erodes the concrete itself, so be careful.
The white spots are almost certainly lichen, which can also appear as dark green or black spots. Lichen is not a single organism, but two, and sometimes three (fungi, algae and/or bacteria) living in symbiosis. Lichen thrives on porous surfaces such as stone and concrete, into which it can root itself.
Efflorescence is a transient phenomenon on Ordinary Portland cement. As the cement and weather chemically react together, calcium hydroxide is produced. As the concrete dries, the calcium hydroxide reacts with the carbon dioxide in the atmosphere to produce calcium carbonate, which manifests as a white solid.