Waterproof Expansion Joints 1

[kalico]

I'm design a linear "bathtub" for a fish pond that will sit above grade. It will retain about 8 feet of water via cantilever action of the concrete walls. My question is with regards to the joint between the Concrete tank bottom and the cantilevered walls. Naturally this will be a cold joint that will required a rubber waterstop, is it common practice to put this waterstop in the center of the wall? This would stop the water but expose my positive reinforcing steel to water seeping through the joint. I guess the other option is to make the concrete thicker so the waterstop is between the reinforcing steel and the H20.

Thoughts anyone?

 

[JedClampett]

For a normal water bearing structure, we add a waterstop at the base. Usually the thickness is at least 12 inches to accomodate the waterstop and two curtains of reinforcing.
It sounds like you're designing a swimming pool. For swimming pools the walls and floors are made of shotcrete with no horizontal joint. Check with a local swimming pool contractor for details.

 

[SlideRuleEra]

I have used bentonite waterstop for many years on industrial applications instead of traditional PVC. Here is a link to one product:

http://www.cetco.com/groups/bmg/Tech Data/Waterstop-RX Product Manual.pdf

The bentonite product is easier to use (is not embedded in fresh concrete, during placement/finishing). Also joints between lenghts of waterstop are easier. Applications have included underground structures, such as coal reclaim pits, where high ground water table is "trying" to leak "in" and above ground water-containing structures, such as electric generating station cooling tower basins where process water is "trying" to leak "out".
Corrosion of the rebar has not been a problem because there is no flow - with out flow, there is no "new" oxygen getting to the rebar to cause corrosion. Please see my comments at thread507-94877 for an example of this same logic for another application (buried ductile iron pipe).