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Re: basement sealant (Scott Haan) and further questions

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I disagree with the statement that it cannot delaminate. We have used xypex and permaquik which are similar in that they are a cementitious applied product promoting crystalline growth in very small cracks. We have seen areas that have delaminated. It was due to improper surface preparation. This is very important with this product and don't let anyone tell you it isn't. We have recently done a job with some large underground sewage treatment tanks. The walls were 20" thick and were reinforced as per skin reinforcement for strict crack control. We have had leaking at and around some construction joints. The joints had waterstops in them and the concrete used was the very high slump type that is almost self compacting (don't want to mention any other brand names). Xypex was applied and in some areas it had to be reapplied because it fell off! I realize that the cementitious coating is a means to deliver the chemicals to start the crystalline growth, however it needs to be there long enough, with water present, to accomplish that job.  We are considering other options now.  Xypex can be added directly to the concrete mix but with such thick walls is was determined to be not cost effective.
Has anybody used an additive for concrete that makes the concrete hydrophobic? I have seen it used on bridge decks with new concrete toppings and wonder if it would be reasonable to put it in a base slab where you can't use standard exterior waterproofing membranes. The product mentioned is HPI system (Hydrophobic Pore-blocking Ingredient) by Everdure Caltite System.  We have a job that has a very high water table and one pumping room that I want to be bone dry (unlike a tank filled with sewage that doesn't matter as much).  This may actually be similar to the xypex when added to the concrete mix but I don't have all the info yet. I was hoping someone had experience with it.
Dave Handy, P.Eng.  
----- Original Message -----
Sent: Thursday, November 17, 2005 9:19 PM
Subject: Re: basement sealant (Scott Haan)

Xypex  is not really a coating & thus it can't "delaminate". It doesn't sound like you've ever used it.
Chuck Utzman, P.E.

Hi Scott,
I have been dealing with moisture ingress in below grade areas for over twenty five years both in the states and in Europe.
In my experience it is a relatively simple procedure to stop moisture entering a substrate. However, any system is only as good as the crew carrying out the work and without the correct preparation the job is doomed to failure!
There are several products on the market which work well over the long term. Xypex is a cementisious coating which like a lot of products, without the correct preparation and bonding agent, will delaminate when  subjected to Hydrostatic pressure and ground salts, and like any waterproofing system ground movement is not recommended....