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frequency to read RH
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05-02-2013, 10:14 AM #1
eaadams Concrete Moisture Expert *****
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Have a 12" slab reading 99%. Subcontractor wants to know how often to check the RH? every 24hrs. every 72hrs. I told him probably once a week.

BTW: Jason - thanks for scaring the pants off my foreman. Now it looks like he will be going to WOC next year for ICRI certification.

05-03-2013, 07:12 AM #2
CCR Concrete Moisture Coach ***
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When was the slab poured? How is it finished? Vapor retarder?

I had a job I wrote about in a post last Fall about a 18" slab that was 1.5 years old and it was in the upper 90s with Stego Wrap. Had a very dense power troweled finish. I told them it will never dry completely. Even wrote to Jason who confirmed my opinion.

JK Nixon
Concrete Restoration Services, LLC
Pittsburgh, PA
http://www.rhtester.com

05-03-2013, 08:42 AM #3
eaadams Concrete Moisture Expert *****
Status: Offline Posts:591 Threads:85 Joined:Jul 2010
It is about a year old, direct on membrane. Don't know about finish. Don't need it to dry completely just get to <98%.

05-06-2013, 07:32 PM #4
Rubensgt40 Concrete Moisture Coach ***
Status: Online Posts:172 Threads:13 Joined:Oct 2011
Possibly an O/T question, and possibly discussed elsewhere, but... remind me again how does one get probes down 180mm, and then retrieve the Easy Reader??

The problem with socialism is that you soon run out of other people's money.
- Margaret Thatcher


05-07-2013, 06:33 PM #5
jim decker Concrete Moisture Enthusiast *
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Concrete dries completely???

05-07-2013, 06:36 PM #6
eaadams Concrete Moisture Expert *****
Status: Offline Posts:591 Threads:85 Joined:Jul 2010
What I mean by that is 75% - 80% what most people worry about hitting for most flooring. Sorry, assumed that was our pov

05-07-2013, 06:50 PM #7
jim decker Concrete Moisture Enthusiast *
Status: Offline Posts:40 Threads:3 Joined:Nov 2011
What I was referring to was that the Tramex moisture meter measures moisture content 1% to 6% couldn't have come up with RH readings of 75% but yes it is unlikely in El Paso Rh readings I have done for IFTI ranged from 40% to 70% tops. I have done testing for IFTI and they ask many questions if it doesn't make sense.

05-07-2013, 07:19 PM #8
eaadams Concrete Moisture Expert *****
Status: Offline Posts:591 Threads:85 Joined:Jul 2010
Two different posts. Thus, you are confusing two different projects. Tramex was used on another project / post. And I'm not talking about IFTI in either case.

05-09-2013, 04:25 AM #9
CCR Concrete Moisture Coach ***
Status: Offline Posts:236 Threads:14 Joined:Dec 2011
(05-06-2013, 07:32 PM)Rubensgt40 Wrote:  Possibly an O/T question, and possibly discussed elsewhere, but... remind me again how does one get probes down 180mm, and then retrieve the Easy Reader??

I wouldn't attempt placing a sensor lower than 1/2" of total the length of the reader. That would be maybe 12" slab or so. I have only encountered a couple of those.

JK Nixon
Concrete Restoration Services, LLC
Pittsburgh, PA
http://www.rhtester.com

05-10-2013, 10:06 AM #10
CC Solutions Concrete Moisture Evangelist *******
Status: Offline Posts:1,065 Threads:69 Joined:Dec 2009
Jason or Ed can correct me if I'm wrong, but with the RH that high, I'd install a new probe in a couple of weeks and see what it says.

High RH means high alkalinity and that can damage probes. You will also have hysteresis to contend with. And don't forget the probe can be off by several percentage points at the high RH levels you have.

So if you absolutely have to guarantee the RH is below 98%, I'd wait until the probes read 95% and use a new probe for each reading.

JD Grafton
Concrete Answers for Flooring Problems
JGrafton@ccsolves.com








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