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07-22-2013, 08:47 AM #5
CC Solutions Concrete Moisture Evangelist *******
Status: Offline Posts:1,067 Threads:69 Joined:Dec 2009
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

Messages In This Thread
PH TESTING - MINUS - 09-02-2010, 10:04 AM
RE: PH TESTING - Ernesto - 09-03-2010, 08:11 AM
RE: PH TESTING - CC Solutions - 09-20-2010, 02:26 PM
RE: PH TESTING - hausenheimer - 07-22-2013, 07:07 AM
RE: PH TESTING - CC Solutions - 07-22-2013, 08:47 AM
RE: PH TESTING - hersitervery - 04-02-2014, 04:10 AM

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