How to add expansion joint?

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TexEdmond

TexEdmond

Gold Supporter
Jun 16, 2021
661
Edmond, OK
Pool Size
25500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
For a number of reasons we decided to pave over the planter bed on the back side of our pool. They finished the concrete last week and we've noticed they didn't install an expansion joint where the new concrete meets the coping stones. It was totally off my radar and I didn't ask them specifically to do it, and now we find ourselves wondering what's the best course of action to make this right? It seems like the worst case scenario is ripping it all out and re-pouring the concrete with proper prep, but I wanted to check TFP and see if anybody with experience on the issue might see something less drastic as a possible fix? This seems like a situation where both parties involved, contractor and client didn't know what they didn't know and now it's time to make some changes before damage is done to coping, tile, bond beam.

  • Kidney shaped pool with natural stone coping
  • approx 35 feet of contact between new deck and coping
  • "Precast Coping" pool edge with bond beam ledge visible before pouring
Having read a number of threads here and from other reasonable sounding websites, it's looking like our only option other than ripping it all out and restarting is: removing the coping, sawing / drilling out any interfering concrete, and reinstalling coping with the correct joint.

Any other thoughts?

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You need to use a concrete saw with a large enough blade to make a plunge cut down to the dirt wne then the best you can follow the curve and cut away the concrete along the coping to form the expansion joint. Then fill the joint with foam rope and mastic.

It will be messy and you will end up with lots of concrete dirt in your pool that will take a while to filter and clean out.

The expansion joint needs to go around the skimmer and you will need to chisel out concrete by hand and not damage the skimmer. You need to make a U shaped expansion joint around the skimmer that ties into the expansion joint in front of the skimmer along the coping.

You can decide if it is easier ripping out the concrete and starting over.

I also don't see any crack control joints in the new concrete like you have in the old deck section..
 
I was also going to suggest a concrete saw to plunge cut through the concrete and create a gap for the joint. At least your coping stones have a straight back side to them which makes that easier.

Secondary option would be to do something similar but cut out 6” (or some other aesthetically pleasing amount) of the concrete at the joint and repoir just that area with the proper joint.
 
Did they put any rebar in that new pour of concrete?
 
ajw22 said:
Did they put any rebar in that new pour of concrete?
Click to expand...
Yes, there is rebar throughout the new pour, and they matched the existing control cuts, but I believe I'm going to ask them to return and cut them deeper, as some of them are quite shallow. Do you know the recommended depth?
 

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TexEdmond said:
Yes, there is rebar throughout the new pour, and they matched the existing control cuts, but I believe I'm going to ask them to return and cut them deeper, as some of them are quite shallow. Do you know the recommended depth?
Click to expand...
Cut joints 25% of the depth of the slab. A 4" thick slab should have joints 1" deep.

Control Joints in Concrete - When To Cut & Spacing - Concrete Network

Tips for cutting control joints in concrete slabs including information about when to make cuts, depth, proper spacing, corners, and more.
www.concretenetwork.com
 
Bperry said:
Secondary option would be to do something similar but cut out 6” (or some other aesthetically pleasing amount) of the concrete at the joint and repoir just that area with the proper joint.
Click to expand...

Ooh. That's a good idea, we may try to visualize that and execute.
ajw22 said:
You need to use a concrete saw with a large enough blade to make a plunge cut down to the dirt wne then the best you can follow the curve and cut away the concrete along the coping to form the expansion joint. Then fill the joint with foam rope and mastic.
Click to expand...
That's what I thought. I was also visualizing taking off the coping, then using some kind of grinder with a dust hood to cut down some on the dust.

Rookie question: is there any way to make a curved cut in concrete? All the concrete saws I've seen have circular blades, meaning a straight cut. Is there a reciprocating concrete saw blade worth trying?
 
ajw22 said:
The expansion joint needs to go around the skimmer and you will need to chisel out concrete by hand and not damage the skimmer. You need to make a U shaped expansion joint around the skimmer that ties into the expansion joint in front of the skimmer along the coping.
Click to expand...

I notice the original build didn't have this either. I suppose that explains the crack.

I noticed when they removed that section of the patio the skimmer itself appears to be inside a solid concrete structure. I'm having trouble visualizing the proper fix you're describing. Would that be a "U" shaped isolation joint combined with a flat patio poured on top that also doesn't contact and stress the side of the skimmer and pool? Sortof a combination "precast" and "cantilevered" style?
 

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The skimmer is rigidly connected to the pool and part of the pool structure. It needs to be able to move with the pool and not be locked into the deck.
 

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ajw22 said:
The skimmer is rigidly connected to the pool and part of the pool structure. It needs to be able to move with the pool and not be locked into the deck.
Click to expand...
Gotcha. So does that mean the patio section that is poured there needs to be treated like a cantilevered coping section, where it doesn't have overpour that stresses the underlying skimmer masonry?
 
Make the expansion joint wider around that concrete.

You can't get that slab cantilevered over it now.

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TexEdmond said:
Ooh. That's a good idea, we may try to visualize that and execute.

That's what I thought. I was also visualizing taking off the coping, then using some kind of grinder with a dust hood to cut down some on the dust.

Rookie question: is there any way to make a curved cut in concrete? All the concrete saws I've seen have circular blades, meaning a straight cut. Is there a reciprocating concrete saw blade worth trying?
Click to expand...
Cutting concrete is no fun. You can use one of those water cooled concrete saws Home Depot rents and plunge right through 4” of concrete. It’s has a water hose inlet to cut down on dust. If you plan out a series of straight cuts behind the coping that are at least ~14” long, you may be able to get many of them done by just plunging with that style saw, and then finish them with a large angle grinder and/or hammer+chisel. No guarantees the chisel cuts as clean as the saw though. Your concrete guy may have a better idea of how feasible that is with your pool shape.
 
Bperry said:
If you plan out a series of straight cuts behind the coping that are at least ~14” long, you may be able to get many of them done by just plunging with that style saw,
Click to expand...
That makes sense, thanks. My first thought was using a hammer drill in conjunction with something like that. I'm also seeing some smaller circular saw blades that are marketed for curved cuts. I'm reaching out to the concrete sub that the PB used for the install and a neighbor who does concrete work to get some other perspective.
 
ajw22 said:
Make the expansion joint wider around that concrete.
Click to expand...

It seems like the most natural looking location for that joint is where the concrete was already cut. We removed that part on account of when they poured the patio the first time the same thing happened: a crack formed.

Would this be an acceptable location for that joint?

IMG_20220805_105123102_HDR~2.jpg
 
TexEdmond said:
Would this be an acceptable location for that joint?

View attachment 445096
Click to expand...

You are in uncharted territory.

I don't know the characteristics of your ground and its movement. And I don't know how much that slab will be coupled to the ground movement.

My concern is the way the slab presses around the skimmer. There is nothing separating the slab from the plastic skimmer. It has the potential to put pressure on the plastic and crack it. That will not show up immediately and may take a few years. Or you may be fine.
 
Ok. Thanks for helping me understand. For the time being the lid fits in the skimmer much better than it ever did since we have been here, so there's way less stress on it than before.
 
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