| Efflorescence is a white, powdery substance that | | | | must be rinsed away completely. Tougher deposits |
| appears on the surface of concrete, masonry, and | | | | can be removed with special cleaning products. Acid |
| stucco products. It's a very common occurrence and, | | | | washing with diluted muriatic acid should only be used |
| although it's usually harmless, efflorescence can be a | | | | as a last resort because it will etch away some of the |
| real eyesore. It goes unnoticeable on plain, gray | | | | cementitious material on the surface. Muriatic acid |
| concrete and block but becomes very visible on | | | | should be diluted to1 part acid and 12 parts water. The |
| colored concrete and brick. Normally, the problem | | | | surface then needs to be neutralized with a solution of |
| doesn't show up until weeks or months after installation | | | | baking soda or diluted household ammonia. This will |
| and often becomes a dispute between angry | | | | stop the acid from attacking the material any further. |
| customers and contractors. | | | | Preventing Efflorescence |
| Efflorescence is caused by water moving through | | | | When it comes to concrete, there are a few steps |
| concrete and masonry products. As it travels through | | | | that can be taken to limit or prevent efflorescence. |
| in a process called capillary action, the water dissolves | | | | Proper drainage away from a slab will help reduce |
| salts contained in the material. When the water | | | | moisture moving up from the subgrade. This also |
| reaches the outside, it evaporates and leaves the salts | | | | includes eliminating any unnecessary sources of water |
| on the surface. Overtime the buildup of the salty | | | | such as downspouts that dump water underneath a |
| deposits can become quite significant. Lower | | | | slab. |
| temperatures, humidity, rain, or anything that will keep | | | | Concrete sealers can also prevent efflorescence from |
| the material wet such as sprinklers facilitates this | | | | reoccurring. Although regular film forming sealers will |
| process. | | | | stop water from seeping down into the pores, they still |
| Despite efforts of manufacturers and contractors to | | | | allow moisture from the sub-grade to pass through. |
| limit efflorescence in their products, they are using raw | | | | This can create and trap efflorescence between the |
| earth materials that contain salt and will vary in salt | | | | sealer and the concrete. Penetrating sealers are the |
| content from batch to batch and from one location to | | | | best defense against efflorescence. These |
| another. | | | | silicone-based sealers work by penetrating the surface |
| Removing Efflorescence | | | | and reacting with free lime to form calcium silicate. It's |
| Most efflorescence can be removed by pressure | | | | like filling the capillaries and pores with cement to block |
| washing with water or scrubbing with water and a | | | | the migration of water. If the water can't get to the |
| brush. The water will dissolve most of the salts but | | | | surface, then salts can't be left behind. |