Interesting Test Result

[CC Solutions]

Some sealers do a pretty good job of soaking into the surface of the concrete and a light grind will not remove them. Look for the newest revision of the ASTM to mandate some pretty aggressive grinding.

Even a heavy finishing machine with steel pans can create a dense layer on the surface that is 1/8" thick which will impede vapor movement. We have discussed this issue on other forums referring to a study conducted on a warehouse floor than remains open but very wet after 2 years of drying.

But we are getting away from your initial comment Mwoody, that the CaCl reads low and the rH reads high and there is "no legitimate reasoning for the high rH values."

I believe we can find several reasons for the high rH and we also touched on several reasons why the CaCl can read so low. My job is to help figure out what rH readings tell us about slabs, being sure to substantiate the readings we have with field evidence (because any reading is suspect until it makes sense), and help my clients determine slab condition.

If you suspect a problem with the readings you are getting, let's dissect this slab and see what we can learn! This is the fun part!