Waterproofing Pools

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Author Message Ronald J. Ray, RA, CCS, CCCA Senior Member Username: rjray Post Number: 102 Registered: 04-2004 Posted on Monday, July 16, 2012 - 08:14 am:    Folks, I am involved with a project at a zoo that includes an in-ground pool in the exhibit. The consultant for this portion of the project is of little help in advising if or how the cast-in-place concrete pool should be waterproofed. Discussions so far have suggested that in addition to the epoxy coating on the water side of the concrete we should use Xypex as an add mixture. There has been some discussion as to whether or not there is a need to waterproof the earth side of the base and walls of the pool, the concern being moisture and or moisture vapor migration through the concrete and causing a failure of the epoxy coating on the water side of the pool. If anyone has personal experience with similar situations, I would appreciate your comments. Thanks ken hercenberg Senior Member Username: khercenberg Post Number: 302 Registered: 12-2006 Posted on Monday, July 16, 2012 - 09:10 am:    Sounds like you have to be wary of both water and vapor drive. I don't believe that the admixture option really helps with the vapor drive aspect. The other concern is whether it provides any protection after your concrete dries, shrinks, and cracks. Have you considered an injectable waterstop system? Resinous coatings may be fine but keep in mind that they must be rated for potable water and full immersion service and that they may need a maintenance program (recoating required every 10 years or so). I don't know that epoxy is your best option. Is there possible UV exposure? I would personally opt for a waterproofing membrane on the soil side, maybe a KEE pond liner, as well as the coating on the water side. I'm not usually a big fan of trapping moisture with non-vapor permeable surfaces on both sides but I wonder if you have much choice in this case. I think you're right to be concerned that both forces can cause problems. The last thing anyone wants is for the sea critters in your pool to suffer from migration of contaminants through the concrete. Frankly, I'm hesitant to add unnecessary chemicals to a habitat so the choice of admixtures and coatings becomes pretty important. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 487 Registered: 10-2007 Posted on Monday, July 16, 2012 - 01:39 pm:    A key concern is minimizing the size of cracks in the concrete. This is important whether you use xypex or a rigid membrane. Even if you have a flexible membrane you want small cracks. This means that the pool needs to be well reinforced. This is not a place for an "efficient design". I would be concerned about the epoxy coating reflecting the cracks in the concrete. Xypex will self heal and fill the smaller cracks. Suggest a discussion with the zoo people regarding the impact of type of construction on the animals. My understanding is that this can be more important for some aquatic animals as opposed to mamals that use a pool. The normal leaching from concrete can apparently have an effect on some sea creatures. If you place a membrane on the exterior of the pool would expect a failure in the membrane to occur if there are cracks in the concrete that allow water to pass through to the exterior membrane. anon (Unregistered Guest) Unregistered guest Posted on Monday, July 16, 2012 - 03:28 pm:    take at look at Neogard's PoolGard C. I have specified this for pools. Might work for your condition as well. ken hercenberg Senior Member Username: khercenberg Post Number: 304 Registered: 12-2006 Posted on Monday, July 16, 2012 - 05:57 pm:    I'm not sure that PoolGard C is appropriate for aquatic habitat. It may be, but I don't know. My leaning would be to go with something NSF approved. anon (Unregistered Guest) Unregistered guest Posted on Tuesday, July 17, 2012 - 01:19 pm:    Appropriate for aquatic habitat? What? I assume this is not an aquarium. If Pool Gard C is good for human beings, I fail to see why it wouldn't be just fine for critters at the zoo wanting to take a dip... Lynn Javoroski FCSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 1520 Registered: 07-2002 Posted on Tuesday, July 17, 2012 - 01:59 pm:    See here: http://discus.4specs.com/discus/messages/23/6143.html for additional information...thought we'd discussed this before... Phil Kabza Senior Member Username: phil_kabza Post Number: 513 Registered: 12-2002 Posted on Monday, July 23, 2012 - 09:59 pm:    Is there some reason why CIP concrete is being used rather than gunnite? Gunnite is typical for residential grade pools, and is used without added liners, with a plaster troweled finish that should be fairly inert with respect to its chemical impact on the water following initial flushing of plaster residue. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 491 Registered: 10-2007 Posted on Monday, July 23, 2012 - 11:33 pm:    Gunite is chemically indistinguishable from CIP concrete. They use the same basic materials. Will suggest that in general there is better quality control with CIP concrete. Gunite is used because it is cheaper since you do not need to build forms. With gunite there is the potential of voids behind the reinforcing steel. This is of special concern when you have higher levels of reinforcing. Ronald J. Ray, RA, CCS, CCCA Senior Member Username: rjray Post Number: 107 Registered: 04-2004 Posted on Tuesday, July 24, 2012 - 09:12 am:    Phil, The pools are not residential swimming pools, but rather for aquatic animals. There is gunite on the project, but only for use as decorative rocks and landscaping features within the habitat.