• 1 Vote(s) - 5 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Preferred Method for Testing RH?

If I accept your statements as correct without verifying, I believe there are flaws in your examples as they relate to concrete moisture testing.

Yes absorptive materials will retain water. This is why additional water is needed in the box with cotton in it. Once the water saturates the cotton to a point above 50% - 70% any excess water will become suspended in the atmosphere. Over time, the air and the cotton will equilibrate, as do the absorptive materials in concrete.

While you may get your box of water down to 20% Rh or less, you will not get concrete that low. Very old and very dry concrete will measure 50% - 75% RH. The absorptive materials in concrete will retain water and absorb moisture from the air if they fall below this level. The concrete will seek equilibrium with the environment.

What we are testing for is free water, and that will show up as RH levels above 80% or so. If we see a reading of 100%, there very well may be condensation as in your kitchen example (I really enjoy your ability to simplify your examples, it makes things quite easy to understand) but we are not concerned how much water is in a liquid state as this must all evaporate and the RH must come down to 75% - 80% before we know the concrete has stopped hydrating and is ready for flooring.

Concrete that is ready for flooring will have many many gallons of water in it, but this water alone will not create the vapor drive which results in flooring failure. Concrete can live quite happily at 75% relative humidity and be considered 'dry'.
JD Grafton
Concrete Answers for Flooring Problems
[email protected]

Messages In This Thread
Preferred Method for Testing RH? - george - 08-12-2009, 09:24 AM
RE: Preferred Method for Testing RH? - jf222 - 08-13-2009, 11:30 AM
RE: Preferred Method for Testing RH? - jf222 - 08-13-2009, 03:15 PM
RE: Preferred Method for Testing RH? - CC Solutions - 12-17-2009, 10:40 AM

Possibly Related Threads...
Thread Author Replies Views Last Post
  ICRI pH testing Concrete Repair Bulletin eaadams 4 3,207 05-20-2014, 12:00 PM
Last Post: Ashok Kakade
  Concrete Hood Method Blake McFee 9 28,229 11-08-2013, 01:41 PM
Last Post: eaadams
  Tandus removes moisture testing requirement eaadams 2 4,558 09-27-2013, 10:26 AM
Last Post: eaadams
  RH Testing Thick Slabs CCR 33 50,458 11-21-2012, 10:19 AM
Last Post: eaadams
  Calcium Carbide testing and Silicates Lepito 51 87,462 11-19-2012, 11:59 AM
  Carbide moisture testing CC Solutions 4 9,129 09-18-2012, 06:11 PM
Last Post: CC Solutions
  Testing Cost eaadams 22 35,263 07-30-2012, 07:01 PM
Last Post: Ernesto
  Mositure Testing Over Concrete Discussion Ernesto 36 70,378 04-19-2011, 04:59 PM
Last Post: CC Solutions
  I offered free RH testing CC Solutions 9 21,200 04-05-2011, 05:33 AM
Last Post: CC Solutions
  RH testing bob huesgen 2 8,846 09-30-2010, 08:27 AM
Last Post: eaadams

Digg   Delicious   Reddit   Facebook   Twitter   StumbleUpon  

Users browsing this thread:
1 Guest(s)