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+-- Forum: Concrete (/forumdisplay.php?fid=1)
+--- Forum: Moisture Measurement in Concrete (/forumdisplay.php?fid=2)
+--- Thread: How much is too much? (/showthread.php?tid=21)
How much is too much? - uvpete - 03-18-2009 10:19 AM
Hi all , this is my first post. I work for a concrete coatings manufacturer. We are relatively new to this business (concrete, not coatings). I have been reading about the moisture issue in concrete and of course come accross the discussion about the Calcium test versus the RH probe test. What I have not found so far is an indication of what values of %RH in the concrete are generally considered as acceptable for a non breathable coating. For the calcium test the generally excepted value is < 3 lbs per 1000 ft^2 per 24 hour period.
Many EU coatings manufacturers list a number of 2 to 5 CM% (I haven't yet figured out what CM % is refering to). Your thoughts on this would be greatly appreciated.
PTW
RE: How much is too much? - rthompson - 04-24-2009 09:44 AM
uvpete
I am not sure what the CM% is. I think it is Concrete Moisture percentage by volume. Wet concrete is about 9% by volume. So a 2 - 5% reading would make sense. The problem with this type of measurment is that concrete density and metal in the concrete can give false negatives.
Respectfully
Rayt