| Author |
Message |
Margaret G. Chewning FCSI CCS
Senior Member
Username: presbspec
Post Number: 314
Registered: 01-2003
| | Posted on Tuesday, June 18, 2019 - 12:10 pm: |    |
I have ASTM D4263 and ASTM F1869 for testing the humidity in the concrete floor before placing hi-performance coatings; BUT, need a similar test for the concrete substrate walls where we are applying a hi-performance block filler and coating system. This is for an extreme environment situation in a lab, so making sure the coating doesn't peel off the wall is important. Any recommendations? |
Greta Eckhardt
Senior Member
Username: gretaeckhardt
Post Number: 94
Registered: 08-2013
| | Posted on Tuesday, June 18, 2019 - 01:23 pm: | |
I am not aware of a moisture emissions test protocol designed for use on vertical surfaces, but there are other things that can be done to protect the coating from concrete moisture.
Start with identifying whether the coating will be applied to above-grade or below-grade concrete walls. If the concrete wall is below grade, then make sure the appropriate waterproofing or dampproofing will be applied to the exterior surface.
The next task would be to contact the coating manufacturer to see what they recommend. If the application is for below-grade concrete, make sure that the coating is formulated for those conditions. Find out whether the manufacturer has requirements for relative humidity, in which case testing according to ASTM F2170 (using in-situ probes) might be applicable. Testing for alkalinity (pH) may also be required. If any of these tests reveals unsatisfactory conditions, consult the manufacturer for advice. I don't know of any moisture mitigation membranes for vertical surfaces, but with any luck some means of remediation will be available (unless the concrete is below grade without waterproofing).
Preparation of the concrete surface must also follow the manufacturer's written requirements in terms of producing the roughness needed for proper adhesion of the coating. |
Dan Helphrey
Senior Member
Username: dbhelphrey
Post Number: 21
Registered: 12-2018
| | Posted on Tuesday, June 18, 2019 - 01:52 pm: | |
D4263 can be used on walls and ceilings. |
Mark Gilligan SE,
Senior Member
Username: mark_gilligan
Post Number: 896
Registered: 10-2007
| | Posted on Tuesday, June 18, 2019 - 08:34 pm: | |
Does the coating manufacture require such tests? Has the product have a history of satisfactory usage on concrete walls with out such tests?
The popularity of moisture testing of concrete is an outgrowth of concerns about mold and mildew dur to the moisture in the ground migrating to the conditioned spaces above. If there is an effective building membrane around the building these conditions do not exist.
While some coatings may have problems if applied to green concrete many coatings do not have this problem. In any case if you wait long enough to let the concrete cure then this should not be a problem.
If the coating is permeable to moisture vapor I suggest you will have no problem.
Check out this video. http://www.astmd4263.com/
Does the test really tell you something you can use? |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 1092
Registered: 05-2004
| | Posted on Wednesday, June 19, 2019 - 09:16 am: | |
The Division 09 painting and coating sections typically require moisture testing of concrete and masonry substrates.
J. Peter Jordan, FCSI, AIA, CCS, LEED AP, SCIP
|
Mark Gilligan SE,
Senior Member
Username: mark_gilligan
Post Number: 898
Registered: 10-2007
| | Posted on Thursday, June 20, 2019 - 12:41 am: | |
Why do they require moisture testing?
Justify the requirement.
If it is a real issue then make sure the testing addresses the issue. Check out the video. Where is the video wrong? |
J. Peter Jordan
Senior Member
Username: jpjordan
Post Number: 1094
Registered: 05-2004
| | Posted on Thursday, June 20, 2019 - 10:16 am: | |
If the concrete (or any substrate) is too damp, the coating may not properly adhere to the substrate.
J. Peter Jordan, FCSI, AIA, CCS, LEED AP, SCIP
|
Guest (Unregistered Guest)
Unregistered guest
| | Posted on Thursday, June 20, 2019 - 11:10 am: | |
What does the manufacturer of the high performance block filler and coating system recommend for moisture testing for concrete substrates? What is the maximum moisture limit in concrete that they allow? |
Travis Gold/ Tnemec (Unregistered Guest)
Unregistered guest
| | Posted on Monday, June 24, 2019 - 09:27 am: | |
Hi, Coatings manufacturer chiming in.
Kenneth Trimber penned this article http://rci-online.org/wp-content/uploads/2012-04-trimber-brown.pdf
Essentially stating that the current testing and standards for wall moisture are inadequate. That being said, there are many tools available that provide accurate moisture readings in walls.
You will notice that most wall coatings do not list moisture levels on their data sheets or specifications. Why? Typically these coatings systems are either; breathable and applied to the exterior of a building OR non-breathable and applied to the interior dry substrates.
Of course challenges occur when these systems/substrates are deviated from. What if you have an interior wall that has excess levels of moisture, either created by existing building conditions or construction schedule? How about the desire to apply non-breathable coatings like Fluoropolymers to the exterior of a masonry building for the purpose of enhanced color and gloss retention?
Perhaps I am adding confusion to the issue, it is important to get a global understanding of the moisture/coatings relationship. Especially considered the wide variety of exposures and substrates that we all encounter.
The simple answer to your question is, specify whichever test you are confident with. I like the in-situ probe (ASTM F2170). With this spec, understand that any moisture test results only show the moisture present in the substrate at the time of testing. Moisture levels can change rapidly and for a variety of reasons.
Also keep in mind that you may not get a firm go/no go number from your coatings manufacturer. Epoxy resins on floors typically are limited at 80% Relative Humidity as established from an in-situ probe.
Floor coatings are a different story and you can specify a coating or coatings system that includes moisture mitigation from the same supplier.
In almost all exterior coatings situations we specify a highly breathable coating. Doing so will greatly reduce the number of issues you may have.
Basements seem to be home to many clean rooms, labs and other epoxy wall, floor and ceiling systems. Potential for moisture in these areas deserves extra attention.
When specifying block fillers for any potentially wet (from the inside or outside) be sure to use something that includes cementitious fillers. A pure acrylic block filler can be the weak link in a system.
Thanks for letting me chime in. I am happy to continue this conversation. |
Tguntner (Unregistered Guest)
Unregistered guest
| | Posted on Monday, June 24, 2019 - 11:33 am: | |
I would like to note that when planning to coat an exterior concrete wall with a non-breathable coating, such as; two-part epoxy, polyurethane, or fluoropolymer, ie. (low-perm rated coatings) make sure that the wall construction is a cavity wall design. This will allow for any potential moisture in the wall a pathway out, and not through the coating, to avoid hydrostatic pressure failure of the coating system. Water, in this case, is drawn to the warm side of the exterior concrete. The industry tends to consider hydrostatic pressure as only being a problem with slab-on-grade concrete, however, this can also be a problem with exterior concrete walls that are coated with a non-breathable coating film. |
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