What is that Flaky, White Powder on my Concrete?
If the powdery white substance is building up on your concrete surfaces only, then most likely not mold. Instead, this powder is a mineral salt that's commonly referred to as efflorescence. This builds up on concrete surfaces in crawlspaces and basements often, occurring as part of the process of moisture coming from the earth, passing through the concrete, and advancing into your basement.
Concrete is porous, and it absorbs groundwater like a sponge. When concrete is being used as part of a basement or crawl space, it soaks up moisture from the earth around it continuously. As it does, the water can pass through to the inside surface of the concrete walls (known as the "negative side"), where it's added to the air inside the building.
As moisture evaporates into the air, it leaves any mineral deposits carried with it behind, which forms a saltlike coating on the walls and floor. The ugly white powdery buildup is the efflorescence you see on your foundation walls.
How to Clean Concrete Efflorescence
Eliminating efflorescence is best done with a power washer -- you can find one at a local hardware store. Your local store will also have a variety of chemicals that you can use in combination with the washer that will quickly and effectively clean your concrete.
For a simpler method, however, simply combine one part bleach with ten parts water. Use a sturdy push broom, and scrub those walls thoroughly.
Phosphoric acid has also been known to be effective against efflorescence. However, this should be used with extreme care, and it should never be combined with ammonia products, as these two create a poisonous gas when mixed. Phosphoric acid will have the added benefit of being able to eliminate other stains as well, such as those from rust or oil. Be sure to consult with a professional firsthand before using this substance.
Preventing Concrete Efflorescence
The best way to stop efflorescence is to halt the advancement of water vapor through the walls and into your home. One excellent way to do so is by sealing the concrete on the inside, thereby preventing it from making its way through into your home. This has the added benefit of creating a moisture barrier that will seal away water vapor that would otherwise contribute to the indoor humidity levels of your basement or crawl space.
When choosing a concrete sealant, be sure not to use concrete paint. These types of products are notorious for flaking off the walls over time by both the pressure of the moisture and by buildup of efflorescence behind the coating. Instead of these, it's very important to find a product that will seal the concrete by bonding deep within its pores, creating a solid barrier that prevents water from passing through without the long-term blistering, peeling, and flaking associated with waterproofing paint and other products.
When you're looking for a concrete sealant, we recommend Concrete Treat: Concrete Sealer and Blanket. When applied, this product creates a glasslike silicate bond deep within the pores of the concrete. The bond seals away humidity and prevents efflorescence buildup on cleaned concrete surfaces. It's usable on both cured and newly placed concrete, and it is also appropriate for outdoor concrete use
Article Source: http://www.articlesbase.com/home-improvement-articles/removing-preventing-white-flaky-powder-on-concrete-basement-walls-and-floors-4048629.html
About the AuthorFor more information, or to order Concrete Treat, call us at (203) 376-9810 during normal business hours, EST.