Raising the floor of the swimming pool

[AJBangkok]

I would like to raise the floor of my pool at one end by 20cm to make it more shallow. The area is about 20 square meters. A pool contractor has suggested putting 7cm of sand and 13cm of cement with rebar. 

 

I am worried about the sand as originally I thought the way to go was chipping and roughing the existing surface ( there are no tiles) add a bonding agent after the rebar and finally pour the cement. 

 

Will the sand increase the chances of the new floor cracking or settling ? 

 

Is this something that shouldn't be even attempted?

 

People have suggested a removable platform but I have no interest in that .

 

thanks

 

[grollies]

9 minutes ago, AJBangkok said:

I would like to raise the floor of my pool at one end by 20cm to make it more shallow. The area is about 20 square meters. A pool contractor has suggested putting 7cm of sand and 13cm of cement with rebar. 

Absolutely not.

9 minutes ago, AJBangkok said:

I am worried about the sand as originally I thought the way to go was chipping and roughing the existing surface ( there are no tiles) add a bonding agent after the rebar and finally pour the cement. 

Spot on. But use concrete, not cement.

 

Go with your instinct, not the builders advice.

9 minutes ago, AJBangkok said:

 

Will the sand increase the chances of the new floor cracking or settling ? 

 

Is this something that shouldn't be even attempted?

 

People have suggested a removable platform but I have no interest in that .

 

thanks

 

 

[maxtwo]

I shallowed my pool in the uk about 20 years ago.As it was a diving pool at one end 13 ft deep.I put in crushed lime stone and used a wakerplate on it as I filled it then 9 to 10 inches of concrete with rebar.And it has never moved.

 

[grollies]

2 minutes ago, maxtwo said:

I shallowed my pool in the uk about 20 years ago.As it was a diving pool at one end 13 ft deep.I put in crushed lime stone and used a wakerplate on it as I filled it then 9 to 10 inches of concrete with rebar.And it has never moved.

 

Yeah, but the OP is only talking about 8" in total.

 

4m3 concrete.

[BEVUP]

Be very careful with the contractors 

The only reason for the sand is that they think it will be cheaper but your only talking 200 mm 

Also I would drill holes in the existing floor to tie the slab in

[BEVUP]

PS : Always keep an eye on the contractors, they know nothing about concrete cancer ( re bar with lack of concrete coverage )

The ones i used straightened the reo for the wall with bits of reo so in the end the only thin covering these straighteners was render, then the tilers wanted to chisel the wall away to make it straighter (lucky i put mosaic tiles on as the glue,glass & epoxy is acting as a water tight barrier )

Not one contractor here would know anything about this (Render fixes all )

[AJBangkok]

Thanks for the replies guys 

[sappersrest]

OK

Some things to consider extra weight on your existing pool structure.

You will be removing  4m/3  of water which will be 4 tonnes in weight.

if you go down the all  concrete route you will be replacing  the 4 tonnes of water with 10 tonnes of concrete . (2.5 tonnes per m/3)

Thus giving your existing pool structure an extra weight load of 6 tonnes .

So we need to lighten the load.

This can be done in several ways.

 

 Lightweight concrete, very similar in appearance to cinder blocks.

http://www.lytag.com/applications/structural-concrete

 

Use a high density polystyrene infill then mesh and a strong sand and cement screed with water poof additives

http://www.isolofoam.com/english/roadways-and-fill

 

Use  lightweight building blocks or slabs i.e. QCON as an infill then mesh and a strong sand and cement screed with water poof additives.

https://qcon.co.th/en/

 

http://tha.sika.com/en/solutions_products/02/02a002/02a002sa32.html

 

Both the first two methods I have been involved with on local authority pools projects in the UK.

 

The third method is the one I would use here  for the fact that every thing is readly available .Approx 167 blocks, but they do make bigger slabs.

 

Remember if you are draining your pool do not drain any faster than 750 mm over a 24 hour period .ie 30 mm per hour is the correct rate .

Rapid emptying and filling of a pool can cause structural damage.

[grollies]

He's the man who should know. Good post, good info.