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How much is too much?
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03-18-2009, 10:19 AM #1
uvpete Newbie *
Status: Offline Posts:1 Threads:1 Joined:Mar 2009
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.

04-24-2009, 09:44 AM #2
rthompson Industry Expert *****
Status: Offline Posts:72 Threads:0 Joined:Sep 2008
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.

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