Waterproofing Concrete Admixtures

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Author Message Ronald L. Geren, RA, CSI, CCS, CCCA, MAI Senior Member Username: specman Post Number: 334 Registered: 03-2003 Posted on Tuesday, September 26, 2006 - 07:29 pm:    We have a below-grade parking structure which was originally designed as a cast-in-place concrete wall with a bentonite waterproof membrane. However, the contractor and owner have agreed that the savings generated by using shotcrete is too good to pass up, so the design team (architectural and structural) is redesigning the foundation system to accommodate this new direction. At first I had suggested a blind-side waterproofing membrane, but like most private, developer-driven projects, the contractor has "suggestions." It has been proposed that a crystalline concrete waterproofing admixture be used in the shotcrete, thereby eliminating the need for a separate waterproofing membrane. Two products were thrown on the table: Kryton International's Krystol Internal Membrane (KIM for short), and Xypex's Admix C-500. The former boasts a 460 ft. head pressure water resistance while the latter states a 350 ft. head pressure water resistance (apparently tested by the Army Corps of Engineers). The KIM product has been approved by ICC-ES as an approved chemical admixture for compliance with the 2003 IBC. Does anybody have any experience with these products or similar products? Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 394 Registered: 07-2002 Posted on Tuesday, September 26, 2006 - 07:41 pm:    these products are marketed heavily in the northwest, and I would still use the blind-side waterproofing with them. the problem with the crystalline formulations is that they only work up to a certain crack size -- and if you have a crack that goes through much of the concrete, they simply won't handle that. if you're not in a seismic zone, have a stable location and the like, perhaps its an "okay" solution to the problem I typically use the Procor products by Grace and have had good luck with them in a blind side application. I wouldn't rely only on the crystalline waterproofing unless there simply wasn't that much water to deal with. I've specified both products that you mention, and gotten approval from our structural consultants for it (they even suggested the Krystol) but again... its not the only thing keeping the location dry. Mark Gilligan SE, CSI Senior Member Username: markgilligan Post Number: 99 Registered: 05-2005 Posted on Wednesday, September 27, 2006 - 01:58 am:    We have used Xypex in our own building and it has performed well. In general I find them an intriguing product. For a structure that is less well ventilated than a garage I would want to understand better the potential moisture transmissibility. Cracks can be patched when they are accessible in a garage. Also a healthy level of reinforcing steel will tend to keep crack size small. The real problem would be where there is a moving crack. I would not out of hand reject these products in earthquake country. I am in Northern California. The earthquake code provisions assume that some damage is acceptable in a large earthquake. The building code provisions were developed with the emphasis on life safety and could result in buildings that would have to be torn down in a major earthquake. In this context the degradation of the waterproofing system due to concrete cracks would not necessarily be a major problem. Ronald L. Geren, RA, CSI, CCS, CCCA, MAI Senior Member Username: specman Post Number: 336 Registered: 03-2003 Posted on Wednesday, September 27, 2006 - 12:57 pm:    The location is downtown Phoenix, and the geotech report indicated that no groundwater was encountered. The depth of the parking level is 12 feet, so I feel pretty confident that hydrostatic pressure is a nonissue. There will be a couple of cold joints where shotcrete abuts cast-in-place construction where the vehicle ramp occurs. For those joints, I plan on using a bentonite product, such as Volcaly's Waterstop-RX. The contractor has indicated that they've used the Kryton product successfully in other buildings, but I'll provide proper due dilligence and get out to those locations to see how they've performed after building occupation. Mark, I'll take your word on the Xypex performance (did you use additional waterproofing as Anne recommended?). Most of the building is surrounded by paved surfaces (walkways, parking, and driveways), but there is an unlined stormwater retention area along one elevation (approx. 10 feet away). This may be enough of a concern to warrant the blind-side waterproofing. Thanks for the feedback. I feel a little better now. David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 728 Registered: 03-2002 Posted on Wednesday, September 27, 2006 - 01:18 pm:    There is two types of concrete: 1) Concrete that HAS cracked. 2) Concrete that WILL crack. How will you keep the water out of as cracked concrete wall? Go with blindside waterproofing or start a savings account for future car damage/concrete epoxy injections. (Why do they always value engineer out the roofing and waterproofing?) Ronald L. Geren, RA, CSI, CCS, CCCA, MAI Senior Member Username: specman Post Number: 337 Registered: 03-2003 Posted on Wednesday, September 27, 2006 - 01:27 pm:    Why? Two words: "developer" and "condominiums." And when the two words are combined in a single project they spell "litigation"; Which is why I'm concerned. I haven't made my decision yet (still researching, obviously), but it won't be heavily based on the contractor's schedule or the developer's budget--it'll be based on our risk. If the owner objects to our decision, then we'll address that issue when we cross it. Harold S. Woolard Senior Member Username: harold_woolard Post Number: 32 Registered: 12-2003 Posted on Wednesday, September 27, 2006 - 02:15 pm:    Try a nice blind side waterproofing membrane. With that kind of hydrostatic head pressure be sure and design a "french drainage system". The use of waterproofing products mixed with shotcrete or concrete can not take that kind of head pressure, and as already stated ALL concrete cracks! I've heard if you spec a bentonite type blind side membrane that some manufacturers want from $1000.00 to $1,600.00 a day for inspection. Grace Pre-Prufe is a sheet roll to consider or Liquid Boot has a spray on system that can be considerd also.