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MMS- Are some unreliable with high RH?
11-09-2011, 07:28 PM
Post: #23
RE: MMS- Are some unreliable with high RH?
Pat,
There are some instances where I do no testing before or after. If the slab is on grade and has no vapor retarder and the facility wants to install a moisture sensitive floor there is no reason to test the slab. It has already failed and is not up to the flooring manufacturer's specifications.

I have seen many, many floors fail that have a low MVER. A very hard troweled floor slab has a mechanically sealed surface that will impede vapor release. These floors can measure as low as 2lbs MVER and still fail miserably in a short amount of time. This proves MVER is not a reliable test, and is not an indicator of a slab's readiness for flooring.

Now the ASTM for F1869 has changed in an effort to show a higher MVER. In my mind it's too late, we have a new method of reading floors by using the Wagner Rapid RH. There are far too many variables with MVER that we don't see with RH testing.

Think of it this way. A slab's RH indicates the potential the slab has for failure. If the slab reads 98% it has a very high potential to fail. It is full of percolating hydration and alkalinity. A slab that reads 70% RH has a low potential for failure. It has completed hydration and is stable.

JD Grafton
Concrete Answers for Flooring Problems
[email protected]
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RE: MMS- Are some unreliable with high RH? - CC Solutions - 11-09-2011 07:28 PM