| Author |
Message |
Brian E. Trimble, CDT
Senior Member
Username: brian_e_trimble_cdt
Post Number: 54
Registered: 08-2005
| | Posted on Thursday, September 15, 2011 - 06:46 pm: |    |
The tests in TEK 19-7 are directly related to the intergral water repellents which E514 doesn't specifically address. The tests in 19-7 test whether enough product has been included or not. That way you don't have to build a full wall or mock-up to determine if the units actually have intergral water repellent (IWR).
The E514 is great for a full wall test and shouldn't be dropped. |
J Peter Jordan (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, September 18, 2011 - 12:38 pm: | |
I have specified these admix products (for CMU and mortar) for more than 10 years. One of the issues that arises on the job site is that the CMU is not marked in any way. I have had contractors mix normal units with water repellant units with unfortunate results.
Suggest any CA guy enforcing specifications dribble a little water on a representative sample of CMU from each "cube" or tell the contractor that he will be liable for tearing the whole wall down if you find one unit in the wall that is noncompliant.
On, and on that "unfortunate" project? The CMU manufacturer did not even offer to replace the block. |
ken hercenberg
Senior Member
Username: khercenberg
Post Number: 98
Registered: 12-2006
| | Posted on Tuesday, November 01, 2011 - 05:36 pm: | |
Richard, we're getting calls from the same folks. This was my reaction and response:
For now NCMA 19-7 will have to do. My preference is still to take a Rilem Tube (http://www.watersealant.com/rilem-technical-bulletin.pdf) and see how much water actually penetrates the block, mortar, joints, etc using a quantifiable method. Unfortunately no one seems interested in codifying this practice at this time. I’ve been using it for years and it works great.
As to CMU and mortar admixtures, the point is interesting but not of the same importance it held years ago. When using CMU as a cavity back-up material we now apply air barriers, water barriers, and sometimes vapor retarders that are much more effective and last longer than the admixtures. For decorative units used as veneer at cavity walls, we have water-managed cavities.
Best practices like covering the tops of CMU walls during construction probably controls efflorescence more than the admixture, though the admixture does play a role. Still, if water darkening of the wall in-place is a concern once it's built, we’ll probably specify a 100% silane as a topically applied water repellent to the wall after it is constructed. The same is true for single-wythe construction where water penetration is the bigger issue. I would never rely solely on admixtures when it comes to single-wythe construction. Of course at least one ground-face block manufacturer automatically applies an acrylic coating (that I find distasteful, but that's my view of aesthetiecs and performance).
It’s probably more important that we make sure that exterior exposed CMU is normal weight, dense, and properly consolidated during manufacturing to minimize porosity. My guess is that we will continue to include the products in our current spec master. If this other product is comparable, I’d have no qualms about adding it to our spec. |
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