Concrete Pool Shell Problems | Weepers, Efflorescence, and Calcium Nodules

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00:00 - Intro

02:54 - Water chemistry did not cause these problems. These are structural issues.

03:54 - Three main problems: weepers, efflorescence, and calcium nodules.

04:09 - Weepers are active leaks in concrete, where water is flowing through concrete. Usually this is from behind the concrete shell due to groundwater pressure. But it can also be on a raised wall where the pool itself pushes through a weakness in concrete.

06:23 - Shotcrete is applied pneumatically, and the density of it is important. Minimum 4000 PSI.

08:07 - Concrete is not waterproof, it's porous.

10:02 - When water takes minerals with it to the other side, that's called efflorescence. Usually it's calcium, and forms calcium carbonate on the outside. It's often confused with scale.

12:57 - Calcium nodules are another form of efflorescence, but through pool plaster. They happen when moisture is trapped in or behind the cement. The disagreement in the industry is about how the moisture got there.

17:24 - In Eric's opinion, calcium nodules are either in the weakest places in plaster, or they're everywhere. It's almost always a waterproofing failure. Water pushes from the back side, in our experience.

21:03 - You can still have calcium nodules in perfectly LSI-balanced water, because nodules are really a form of efflorescence.

24:16 - How do we prevent these problems? Prevention starts with proper shotcrete installation, and we strongly recommend waterproofing the concrete shell. At a minimum, the raised concrete parts.

26:09 - Proper waterproofing is strongly recommended by Orenda. And we know it's not always necessary with good shotcrete application, but why take the risk? Waterproofing is relatively inexpensive.

28:11 - If you have nodules from groundwater, but not active weepers, the best fix is still chipping out the plaster surface, waterproofing the pool shell, bond coating it, and re-plastering it. It's expensive.

28:43 - Recap. Thanks for listening!

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