Interesting Test Result

[eaadams]

Just had a testing firm do a slab for us.

CaCl went from 3.7-4.7
rH went from 95.3-99.4 (not rapidrh probes, unfortunately)

yikes!

But what was interesting and relevant to a thread is that the testing firm did a QC test site which I take to mean Quality Check. At one test site they did two rH tests (not on the report but in the picture) and they did two CaCl tests. The CaCl tests came out the same. But I am not sure showing two tests next to each other is necessarily a valid gauge of quality.

Does anyone know if this quality check type test is in the ASTM literature?

[Ernesto]

Well why did you let someone else do testing for you? The rh tests are most likely invalid if they have not calibrated their probes, besides that I bet they got a reading from top to bottom of the hole, again, not valid.

Goes to show you how CaCl tests can be consistant. lol

I think everyone should be doing both, before and after the app.

OK JD, your turn.

[eaadams]

This is an ICRI certified tester. They know what they are doing. (Goes by the name of Lee)

[CC Solutions]

So many questions on this one....

When you say the RH readings went from x to y, what do you mean by that? They jumped in a day? in a month? In an hour?

What is the slab composition? On pan, on blotter, on vapor retarder?

And which probe did they use? Did they let the probe acclimate (some require an hour per hole). Were the probes checked for calibration? (You can't 'calibrate' a probe but you can check their calibration to see if they are still in specification).

We can trust that Lee drilled the proper depth, but upon seeing the variation in readings, did Lee further investigate for discrepancies that can explain the readings?

As for MVER, well you know my thoughts there. And no there is no 'quality test' in ASTM F1869-10 for multiple tests. You know you can buy the standard for about $34.... Or I could probably share a copy with you seeing how we are both working on, or at least discussing, a job together. I don't think I'd be breaking any copyright laws would I?

[eaadams]

Quote:So many questions on this one....

When you say the RH readings went from x to y, what do you mean by that? They jumped in a day? in a month? In an hour?

Over the different # of tests, they went from X to Y. So rH test results went from X to Y.

Quote:What is the slab composition? On pan, on blotter, on vapor retarder?

Yea I'd agree it probably should be cored. It is a 10 year old slab, so I

Quote: And which probe did they use? Did they let the probe acclimate (some require an hour per hole).

[/color]

Not RapidRH - I'd have a lot more faith in the tests if RapidRH

Quote:
Were the probes checked for calibration? (You can't 'calibrate' a probe but you can check their calibration to see if they are still in specification).

I am confident they have been calibrated and tests done properly. This is all this firm does.

Quote:
As for MVER, well you know my thoughts there. And no there is no 'quality test' in ASTM F1869-10 for multiple tests. You know you can buy the standard for about $34.... Wink

Yea I should buy the new one but I don't use it anymore so why bother. I have the old ones, just wondering if they added a quality test in 2010

[CC Solutions]

There's nothing in the standard about a Quality Check.
Revision -10 removed the ability to use the test over lightweight concrete, probably because there are so many failures on lightweight and the test can't reveal the trapped moisture.

[Ernesto]

How is this moisture "trapped'? Because of the pans structure? But moisture in slabs only emits/escapes through the top, right? So why is it trapped?

Why is it any different than a slab wrapped in plastic?

[CC Solutions]

Moisture in lightweight slabs is held in the aggregate. Trapped may not be an appropriate term, but the porous aggregate does retain water for a very long time.

Hey, when have you ever seen a slab wrapped in plastic?

[Ernesto]

(05-06-2011 04:41 PM)CC Solutions Wrote:  Hey, when have you ever seen a slab wrapped in plastic?

Well, about a year or so ago when ...believe it or not...somone was pouring a slab for the local city zoo. I was stunned. Plastic barrier in place ready to recieve mix. Then it had six mil plastic on top of the newly poured one as well! Not many of those around. Certainly not in the residential field.

[eaadams]

wet cure = the best cure