Shell All 1 Pour or 2 Stages??

CarolinaReaper

New member
Sep 22, 2019
4
Charlotte, NC
Hey everyone,

Pool builder swears by pouring the bottom one day then the walls the following day to get rid of Gunite rebound...

Does this make sense? I’ve always thought monolithic pours with concrete, etc was always best

Wouldn’t that be a giant cold joint around the walls/bottom?
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
41,259
Tallahassee, FL
I am in to learn from this one. There are many ways to do things. Some are better than others. I have always heard that way to get rid of rebound is to scoop it up and throw it away so............
 

Rich D

Bronze Supporter
Aug 3, 2018
567
MA
Welcome to TFP.

This for a plaster pool?

@bdavis466 this make any sense?
Could you explain how to insert these links to alert other Members? The last time I tried it it did not work.

I think that MinerJason could also shed some light on this one..

Thanks, Rich..
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,012
San Clemente, CA
There wont be a cold joint if they prepare the unfinished edge correctly. This is common on very large pools and commercial projects since you simply cannot shoot enough gunite in one day.
 

MinerJason

Bronze Supporter
Jan 29, 2018
269
Tucson, AZ
As Brian said, no cold joint if done properly. Not sure how doing it multiple stages would "get rid of rebound", but it shouldn't have any negative impact.

Cold joints in shotcrete (gunite) are in some ways a myth. Laboratory testing has shown that multiple layer shotcrete has no anisotropic weakness (cold joint) when the layers are applied within 7 days of each other. In the real world a plane of weakness often develops between layers, but it's almost always due to improper surface prep. Dust, dirt, and rebound from shooting adjacent areas will accumulate on the first layer during/after the shoot, and if not thoroughly removed prior to applying the next layer a plane of weakness will develop. If the first layer is troweled smooth it can also impede bonding of the second layer. If too much time passes between layers a cold joint is possible, but in that case the reduction in strength is pretty minimal as long as the surface is properly prepped.

So the short answer is that it will be just as strong as a single shoot, but only if the surface of the first shoot is not troweled smooth and is clean and free of all debris when the second shoot happens.
 
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