This concrete admixture can eliminate the problems associated with moisture migration in concrete and it’s adverse affects on flooring.
The cost is 70 - 80 cents per SF up front. While this is a substantial amount of money, it is significantly less than the $3.50 to $5.50 per SF Owner’s have had to pay for topical solutions before flooring can be installed over noncompliant concrete.
What are your real life, time-tested experiences with this product?
Yeah, I got a meeting with them guys to. There telling me that there stuff is better than they’re cometitor’s stuff, and I am not to sure I believe that. If I can get better information, I might put there stuff in my spec, but until then I am just going with what I got in their now.
Just had a lunch presentation from INSTALL Internation Standards & Training Alliance. They made a strong case that these “Magic Bullet” products are not the cure all, end all.
I too was approached by the guys selling Barrier 1 products. I found their information and test results sketchy at best. Because of the lack of good solid technical information and test results, among other things, I will not specify their products or other comparable systems.
One of the main deficiencies to these types of products is quality control. How does one to ensure that the admixture was actually added in the proper quantity at the batch plant? Another problem is what to do when the concrete slab will inevitably crack. Since these admixture products are not crack bridging, there will be a gap in the system that will allow water vapor to transmit.
It is best to stick with an underslab vapor barrier.
If you are woried about whether the admixture was added in the proper quantity then you should be equally worried about the other concrete admixtures. One strategy to deal with this concern is to have the inspector verify the concrete batch tickets that the driver is given at the batching plant. Another one is to have an inspector at the batch plant to verify no problems with the batching as DSA and OSHPD require in California.
You might try xypex which should acomplish the same thing and which has some ability to heal cracks. My bias would be to use these systems as backup if you have free water under the slab.
Tests have shown that well consolidated concrete will not allow any significant amount of moisture to flow through the slab. Thus the moisture that supposidly causes problems with flooring failures dosen’t come from the soil under the slab, except in maybe rare circumstances. Rather the moisture comes from the air in the room or the moinsture in the concrete voids due to mix water and curing water.
Mark, you are lumping bulk water and moisture in the form of vapor into the same category. Moisture in the soil under slabs on grade ABSOLUTELY contribute to floor covering failures in every region of the US. This is a basic law of physics - look up vapor pressure as it relates to buildings.
Crystalline waterproofing (Xypex and others) is not effective in controlling moisture migration through the slab in the form of vapor. It is a good water proofing solution for water in liquid form. Check the manuf literature.
Xypex also will “heal” only hairline cracks. their literature gives the dimension, but they admit that the product is not useful if there is real slab movement. I would agree that the crystalline methods are secondary methods, at best.
Anonymous I appreciate that moisture travels through concrete and I know the difference between vapor and liquid water. I will admit that there are some circumstances where the moisture flow from the soil to the building is significant.
The point that I was trying to make is that most of the floor failure problems that occur early in the life of the building are not due to moisture in the subgrade. They are due to problems with the PH of the concrete surface, normal moisture in the surface of the concrete, or potentially due to the humidity in the room. The reality is that the moisture flows reported by the standard moisture done tests cannot be supplied by vapor flowing through well consolidated concrete. Check out Professional Page.
I did check out the xypex web site and while they touted the product for use in resisting hydrostatic water pressure I did not see any disclaimer that it would not help limit moisture transfer. The reality is that for most concrete the interior voids are filled with water thus preventing vapor from flowing through without a phase change. Thus I do not see how by filling the voids we are not limiting the flow of moisture. In any case I have asked Xypex for clarification.
Anonymous I appreciate that moisture travels through concrete and I know the difference between vapor and liquid water. I will admit that there are some circumstances where the moisture flow from the soil to the building is significant.
The point that I was trying to make is that most of the floor failure problems that occur early in the life of the building are not due to moisture in the subgrade. They are due to problems with the PH of the concrete surface, normal moisture in the surface of the concrete, or potentially due to the humidity in the room. The reality is that the moisture flows reported by the standard moisture done tests cannot be supplied by vapor flowing through well consolidated concrete. Check out Professional Page.
I did check out the xypex web site and while they touted the product for use in resisting hydrostatic water pressure I did not see any disclaimer that it would not help limit moisture transfer. The reality is that for most concrete the interior voids are filled with water thus preventing vapor from flowing through without a phase change. Thus I do not see how by filling the voids we are not limiting the flow of moisture. In any case I have asked Xypex for clarification.
Mark:
I would appreciate your thoughts on my earlier post on Dec 7th post:
Also, please clarify for me my understanding of the use of vapor barriers under slabs-on-grade. I have always had the understanding that the plastic sheet “vapor barrier” was intended primarily for keeping moisture in the concrete until after the curing process has been completed. Investigations of old installations have shown that the previously used 6-mil poly has deteriorated and is either non-existant or deteriorated beyond it’s useful purpose; hence the recent use of “high performance” products such as 10-mil, internally reinforced, puncture and tear resistance polyethylene laminates. The use of a stone subcourse provides the capillary break for any upward moisture migration. Is there anything I am missing?
Reasons floor coverings fail over slabs on grade are due to moisture migration, in the form of vapor, through the slab, sometimes* from moisture in the slab. The moisture that exists in the concrete after the pour and prior to the installtion of the floor covering has to be at a level acceptable to the floor covering manufacturer before the floor covering is installed, and *most manufacturers and specs have requriements for various tests that measure the moisture level. We don’t allow contractors to install floor coverings over slabs on grade until moisture levels are where they are required to be, or the contractor applies a surface vapor retarder product - hope you guys are doing the same on your projects.
Are you with me Disco Stu? OK, then. The vapor retarder is there to prevent moisture migration from the soil/subbase through the slab, causing failure of the floor covering. There are several articles that you NEED to read to edify yourselves about this important phenomenon, a few are as follows:
The use of a vapor retarder has nothing to do with keeping moisture in the slab until after curing. Not sure where the heck that came from. A blotter layer (sand layer) used to be used for this purpose but it is NOT advisable to do so any longer - see article above on that.
The CSI Phoenix Chapter developed a Green Sheet on “Moisture Vapor Emmission & Concrete Slabs” about 3 years ago. Copies are still available. If anyone is interested, please go to the Phoenix Chapter website at this link.
I got a response back from Xypex regards the ability of xypex to reduce vapor transmission. They state that it will completely stop the flow of liquid water but will only reduce the amount of vapor by 50 percent.
What this tells me is that while xypex will stop the flow of liquids it will not stop the flow of all moisture since the small amounts of moisture that get through can evaporate into the interior space and thus are not normally perceived. Rember few materials have a permiability of o.o.
First a disclaimer. I share the statement in one of the ACI publications that good quality concretetypically dosen’t need densifiers. Thus I do not specify these products unless the Architect feels the need for them.
Checking some manufacturers literature densifiers fill the surface voids in the concrete.
Xypex used as an admixture will help fill the voids for the full thickness of the concrete. Also xypex has some healing properties. To benefit from this I recomment a fair amount of reinforcing to keep the cracks small.
Vapor barriers under slab are not needed to cure concrete. the old practice of placing sand between the membrane and the slab was partially intended to allow moisture to leave the slab from the bottom thus balancing that lost from the top thus minimizing curling.
ACI 302 now recommends placing the membrane immediately below the slab to reduce moisture problems. To control curling you need to be more careful about curing of the top of slabs in dry windy weather. Some may add reinforcing to deal with this but good curing should control the problem.
The membrane of today needs to be able to deal with the PH of concrete and the chemicals in the soil. In addition it needs to be tough to resist the construction process.
The only thing that I would suggest is that you become familiar with the recommendations of ACI 302 regards membranes under slabs on grade.
It would be appreciated if you would identify yourself.
When I post on this forum I risk making a mistake and making a fool of myself. I appreciate it when the other parties on the forumn are taking the same risk. i also like to understand something about the other posters to help understand where they are comming from and what their biases may be. I am sure you know many of mine.
Please also note that when communicating without hearing or seeing the other person it is easy to leave the wrong impression. I think there is a line between forcefully disagreeing with someone and being condecending. I hope that I do not cross the line.
It is also a good idea to not use cute phrasings such “Are you with me Disco Stu?” since they might be taken the wrong way. Maybe I am just lucky that I don’t know what you are trying to communicate.
For the record none of the reference recently posted contain any fundamental information that I was not at least aware of, even if not knowing all the details.
Anon’s postings bother me as well, but so much because they’re anonymous, but because she or he takes a condescending and snarky approach to posting. The readers of this forum are highly knowledgeable in many areas, and don’t need admonitions to read more on a topic that we’ve all read plenty about (slab moisture vapor transmission). The citations anon gives are interesting, but nothing new, and not particularly well-sourced.
Anon’s contributions would be fine anonymously if they proceeded like an adult discussion, rather than like a lecture given to a teenager who stayed out too late. This particular person is using their anonymity to hide behind so they can be obnoxious, which other anon’s in this forum have not done.
