EFFLORESCENCE THE FROST ON YOUR CURBING OR CONCRETE PRODUCTS

Create-A-Curb

Some of you have made a concern call about the white frost look on top of your concrete curbing, This time of year is when that happens to concrete, when the temperatures lower and it is more of a rainy season or more moisture on the ground and in the air. Usually from December through April or May and sometimes in July and August. This is called Efflorescence or Frost. Efflorescence comes from within the concrete itself. All concrete products contain cement, and cement inherently contains lime. To make a concrete product, in addition to cement, a manufacturer adds specific amounts of other raw materials including sand, rock, water, chemical add mixtures and pigments. These material are mixed together then poured or molded into specific shapes. After all this happens the materials sits or cures for a period of time. Although the concrete products is solid and useable after curing it contains millions of microscopic pores of capillaries that go from the surface of the product down into the interior. As soon as the product starts to harden, which it will do for quite a while, the process of efflorescence may start. How does efflorescence occur? Water is necessary to make the concrete, rain, moisture from dew or even water from your sprinklers system, reacts with the free lime in the cement forming hydroxide. As the concrete product dries out, the water migrates to the surface through the pores in the concrete product carrying with it the calcuim hydroxide. When the calcuim hydroxide comes in contact with the carbon dioxide in the air a hard white substance forms which sticks to the surface of the concrete after the moisture evaporates. This is the "Frost" or Efflorescence that you see. It will continue to form so long as the concrete is curing and calcuim hydroxide is free to move to the surface. The Efflorescence phenomenon will stop when no more calcuim hydroxide forms. Just be patient. Efflorescence will go away. The hard white frost eventurally will dissolve in the presence of rainwater and carbon will wash away, but it takes time. Consequently, if you live in a area of frequent rain followed by sunny days, the entire process of efflorescence from formation to elimination will happen quickly. On the other hand, if you live in a drier more arid climate, the entire process will obviously take longer. What if I can't wait? If the frost is so obvious and detracts from the beauty of your concrete product, a very diluted acid solution can remove efflorscence. You must know, however that the acid can change the surface of your product, and that will alter its appearance. This change becomes expecially noticeable on products that are colored with iron oxide pigments. If you feel you must do something about efflorescence, you can follow these steps,

1st- Put on protective goggles and gloves for mixing and application, A long sleeve shirt should also be worn.

2nd- Wash the surface thoroughly with water.

3rd- Mix water with hydrochloric (muriatic) acid. To dilute the acid, add 1 part acid to 10-20 parts of water, making certain to add the acid to the water carefully.

4th- Use a stiff brush to apply the diluted acid.

5th- Allow the solution to stay on the surface only about 15 seconds.

6th- Wash if off thoroughly with water.

Note: Make certain to follow (1) the concrete product manufactures recommendations and use appropriate safety precautions, and (2) all applicable enviromental regulations managing wastewater resulting from this procedure.