How much is too much?

[uvpete]

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