Submitted by Dennis Keane, Stego Industries, LLC
Written by Joe Nasvik
Originally published on Concrete Construction in December, 2005.
Efflorescence occurs with all concrete and is the most frequent problem that concrete contractors face with colored concrete. Owners don't care about “plain” concrete, but colored concrete is another matter. They complain that their contractor didn't give them the color they ordered, and sometimes they withhold payment.
Efflorescence is caused when soluble salts and other water dispersible materials come to the surface of concrete and mortars. It's induced by low temperatures, moist conditions, condensation, rain, dew, and water added to the surface of fresh concrete to assist troweling. It can occur very soon after exposure to moist or cool conditions or gradually, especially when it comes from within the concrete or from the sub grade.
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