Concrete lifting

[Bengi010]

As you can see in the pictures the concrete has lifted significantly off the pool walls. It’s NY and heavy clay soil so pretty sure it’s due to soil freezing. Is this common? Is it likely to settle back down when it thaws? Or is it ruined?

This isn’t exactly a new build, the pool is maybe 20 years old I don’t have an exact date but when I bought the house 3 years ago I had the concrete deck cut back 18”around the pool and new cantilevered coping poured. I did this because the pool had been drained and left empty for some years and the old coping was no longer usable they couldn’t attach the liner.

 

[Toxophilite]

Heavy clay is highly expansive. House slabs here with such move as much as 3" over the course of dry and wet seasons, and, not uniformly. My other house had an external drain pipe from house to ground on one end that would separate by a large gap in wet season, and then settle back during dry, but it did it year after year after year. The concern here with yours is why are just now seeing this issue - pool settle or slab raise? I can't see that going back to satisfactory state and needs further investigation.

 

[ajw22]

Let's see what @jimmythegreek thinks since he builds in the region.

 

[Bengi010]

Heavy clay is highly expansive. House slabs here with such move as much as 3" over the course of dry and wet seasons, and, not uniformly. My other house had an external drain pipe from house to ground on one end that would separate by a large gap in wet season, and then settle back during dry, but it did it year after year after year. The concern here with yours is why are just now seeing this issue - pool settle or slab raise? I can't see that going back to satisfactory state and needs further investigation.

It could be this is the first time I’ve noticed it because I don’t usually peek under the cover this early in the year. The only other change was redoing the landscaping around the outer edge of the concrete last summer.

 

[Toxophilite]

It could be this is the first time I’ve noticed it because I don’t usually peek under the cover this early in the year. The only other change was redoing the landscaping around the outer edge of the concrete last summer.

At this point, probably monitor and access over the rest of season. I had a drive that during hottest summers at times the clay soil would shrink back and leave a huge gap under the flatwork. Once the rains came back, I never noticed it for the rest of the year. Maybe yours is just that, too. It's either shrinkage or expansion and the cost of doing business in clay soil. My new house slab could have been made movement free with a floating slab, but that would have more than doubled the cost by the engineer's estimates. So, we just based with select fill and went with post-tension.

 

[Bill1974]

Is the joint between you new coping and exiting decking sealed? Ideally water that falls on the coping and decking around the pool should be shed off so the soil under remains at a consistent moisture level. If the soil moisture level stays constant it won't swell or contract. Since you don't see this during the year when the pool is open, are you sure this is not frost heave? Since you have clay soil that does not drain well, there is a good possibility that during the during the day ice and snow melt and get under the concreate, then freeze when the sun goes down and/or temps drop. Since the clay drains slowly the ice keeps building up till the ground thaws and the water has time to soak it or get drained away.

 

[Bengi010]

Is the joint between you new coping and exiting decking sealed? Ideally water that falls on the coping and decking around the pool should be shed off so the soil under remains at a consistent moisture level. If the soil moisture level stays constant it won't swell or contract. Since you don't see this during the year when the pool is open, are you sure this is not frost heave? Since you have clay soil that does not drain well, there is a good possibility that during the during the day ice and snow melt and get under the concreate, then freeze when the sun goes down and/or temps drop. Since the clay drains slowly the ice keeps building up till the ground thaws and the water has time to soak it or get drained away.

It is not sealed. What kind of product would you use for that?

 

[Bill1974]

I'm not an expert, but I would think a product like Sikaflex.

 

[Bperry]

If it’s like mine (mine moved over an inch) it’s not going back to where it was and will only get worse if it’s not sealed. Water splashing into the open joint will make it worse over time.