Set formwork blocks on the foundation or in concrete

Filled with water from the inside and pressure from the soil from the outside... I rather thought that the walls can’t move anywhere to shift at the lower area.

The pool is also empty sometimes when the water is changed and the pool is cleaned.

Best regards
Sabine

Hello abc

Formwork blocks are actually just a "formwork". The reinforcement and the concrete provide the stability. I consider 17.5 cm to be undersized. Subtract the thickness of the formwork blocks, then there isn't much concrete left. I would also first create a proper foundation. It's something like a ring beam. The foundation rests on a large surface, so nothing can move. Then you level the first row of formwork blocks, drill 16 mm holes into the foundation, insert 16 mm reinforcing bars, let 30 to 40 cm protrude. Each time insert 2 steel bars horizontally and then pour concrete. Extend the vertical bars up to 5 cm before the top end. Then you will be happy with it forever. And reconsider the 17.5 cm.

Steven

Water acts downward with its force differently than on the walls.

My civil engineering studies were about 30 years ago, but I would bet that the floor "fails" if there is no continuous floor slab of sufficient thickness and with appropriate reinforcement.

Just make a sketch and draw the forces (downward, sideways).

The force (self-weight) acts on the wall from above. Soil "presses" from the outside, water "presses" from the inside.

But the full weight of the water acts on the floor (36 tons! at 1m fill height). That is something...

okay, the strip foundation, or in this case also the ring beam, was planned anyway. I just have some doubts about whether it is really necessary or simply oversized. After all, this is about a pool and not a residential building.

I will embed the steel directly into the foundation and not drill it in afterwards, that provides more stability. I might also make complete cages into the foundation and not just individual rods.

According to the manufacturer's load specifications, the 17.5 cm stones are sufficient for use under traffic load.



The ground will be concreted inside. So basically first the outer walls are erected and then inside gravel and a 10 cm floor slab with reinforcement. The floor slab would actually not be necessary since the pool will be lined with foil. A layer of compacted sand would have sufficed but when installing the foil there are impressions on the floor that cannot be smoothed out anymore, hence the 10 cm floor slab. I would have actually only made 5 cm but I am afraid it would break due to the pressure.

Once the floor slab is in, it can no longer come loose from anything.

Generally, it is natural soil and the subsoil is a heavily compacted clay soil and directly below that begins a rock layer.

once again a very cool forum

*Popcorn*

A look into my crystal ball predicts that if the foundation is not continuous (under the wall), a crack will form at the marked spot (regardless of foil, tiles, waterproof coating, or whatever).

But the wall must also be connected to the foundation with enough rebar (this has also been mentioned) so that the forces acting on it do not "push the wall away" and a horizontal crack can develop.

But in your place, I would consult a professional and/or visit a specialist forum for pool construction as already recommended.

Building it the way a "layperson" thinks might work, but it usually doesn't make sense - sorry. You probably wanted to hear something else.