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December 17, 2008
White Patches on Cement?
I have a brick row house, which has an exterior walk down cellar. Last Spring I had the sidewalls redone due to cracks in the cement. The worker chilled the lose cement off the bricks and replaced it with new cement giving it a brownstone effect. These past several months I’ve noticed that a section of the cement has what it appears to look like patchy white stains. I quickly hosed it, yet it reappeared. Would you think that this is mold?
Comments
Salts. Try vinegar.
Posted by: Bessie at December 17, 2008 10:44 AM
What you're probably describing is efflorescence, and almost certainly not mold. Efflorescence refers to white deposits appearing on building materials of concrete and cement based products. It's often produced by such processes as lime bloom, lime weeping and/or crystallization of soluble salts. Here's a product website (neither recommending nor discounting the product) with photos and more info: http://www.aldonchem.com/popup-ab-efflorescence.htm
Posted by: vinca at December 17, 2008 12:30 PM
Efflorescence is the crystallization of salts on the surface of masonry. Subflorescence is the crystallization of salts inside masonry--this is what does the damage. While surface crystallization isn't aesthetically pleasing, it isn't necessarily damaging. If the efflorescence is just a result of salts in the cement mixture coming to the surface, the salts will eventually go away. [It probably is; this is common with new masonry.] You have a larger problem if the salt is coming out of the nearby ground.
Posted by: BrooklynButler at December 17, 2008 4:09 PM
Thank you for your very informative comments.
Posted by: Giovanna at December 17, 2008 5:22 PM
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