“Over the past year, I have been approached by designers regarding "waterproofing admixtures" to mitigate floor covering moisture failures. They seem to be silicate based products that "close" the pores in concrete...thus eliminating (or minimizing) moisture emissions. I have seen these even promote 10-20 year warranties. Has anyone had experience with these products?”
This question was asked recently in the ACI discussion group on LinkedIn. The following was my post to the group. I hope you will also find it helpful.
In Jereme’s original question about waterproofing admixtures and flooring failures I assume he refers to impervious floor coverings. In the case of resilient floor products like vinyl and linoleum, the root of the problem is deterioration of the adhesive caused by moisture vapor condensing under the flooring. This problem was made much worse in recent years due to the replacement of traditional solvent borne adhesives with waterborne ones to comply with VOC regs. This is a slightly different process than the loss of adhesion of an epoxy or urethane floor coating, which is a more physical process. In cases where the MVT is not severe, you can have success with a very low viscosity, penetrating epoxy primer that soaks down and grabs a big chunk of the concrete surface and simply holds the top coat on through brute force. Most other products will not work because they lack the high tensile strength of epoxy. Since the concrete pores are generally blocked by epoxy, this strategy can also be effective at bringing MVT levels low enough to allow waterborne adhesives to last under resilient flooring (and even protect wood flooring). Again, this is only in cases where the MVT problem is not severe.
So what if the MVT is severe? This is where a waterproofing admixture can help. In my experience, there are NO waterproofing admixtures that can stop MVT. We invented the original crystalline waterproofing admixture and have proven over decades that we can stop liquid moisture from penetrating concrete even under high hydrostatic pressure. But as Rodney points out, moisture vapor is quite different than liquid water. The best that a waterproofing admixture can do is to reduce MVT by some percentage. Usually this percentage is less than 50%. However, this may be enough to prevent a severe MVT situation. Using a waterproofing admixture in combination with a deep penetrating epoxy might be the solution that will work for you.