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F710 states that the slab should be tested for ph but i don't see a number of tests per sf. how many areas have to be tested and were is it stated.

One ph test per moisture test is the standard. Obviously you can do more than that if you see something thats looks out of place.
Stephen Perrera dba
Top Floor Installation Co.

PH and moisture will go hand in hand also.
JD Grafton
Concrete Answers for Flooring Problems
[email protected]

(09-20-2010, 02:26 PM)CC Solutions Wrote:  PH and moisture will go hand in hand also.

I disagree. I have seen moisture results well below failure, low 80's%, but pH be in the 12 range (newer slabs). I have seen low pH and high moisture (old slabs).

Moisture is what carries the alkalinity to the surface. Over time the slab surface carbonates and the pH drops.

You can grind into a dry slab and find higher alkalinity inside, but the surface will be low pH. The interior of a slab will remain at a pH of 12-13 for many years, and the moisture equilibrates to 50% - 70% RH.

If moisture is moving rapidly out of a slab, the surface will remain highly alkaline.

This alkali environment is very hard on adhesives, even epoxies. A slab with a very high internal RH has enough moisture in it to cause high alkalinity at the surface when the slab equilibrates under a moisture sensitive flooring. Slabs with low internal RH do not.

This excess moisture is what all these flooring tests are looking to identify. The pH test is a poor indicator of excess moisture, as is the CaCl test.

RH testing is the best non-destructive test available.
JD Grafton
Concrete Answers for Flooring Problems
[email protected]

thanks for that update..

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