Sandstone hopper and grade question

[msickler]

Hey Folks, new to TFP, so bare with me.

I’m diying a 20x40 steelwall inground. When we excavated the hopper we hit some pretty solid sandstone.

The deep end walls are graded ok, slightly over in spots, due to rocks coming free. Any issue with uneven walls before I pool krete the walls? Am I good to just krete over the sandstone or should I use some steel mesh and concrete before adding the pool base?

We had to go back in forth in the shallow -to -deep transition, so there are some big ruts. Will pool krete hold up the clean shape or do I need to put something (concrete?) in the ruts to smooth that out?

 

[kimkats]

I will call in a couple of people who may have some good input. Hold on while they get back with you!

@jimmythegreek @ajw22 and anyone else that may know!

 

[swimcmp]

Been doing pool base since 1981 and you can go right over the sandstone. No need to put mesh down. You might put some gravel down to smooth it but it probably won't stay

 

[msickler]

Thanks @swimcmp! The local concrete guy says all the folks around here use a "grout mix" for the pool base, but I haven't been able to confirm that with anyone - does that sound right to you?

 

[jimmythegreek]

You can put the vermiculite right over the dirt no need for mesh or anything. Usually for ruts some crusher run or dry concrete is used as it's cheaper than vermiculite. You can shape the pool somewhat that way and just mist with a garden hose to help it stay. Depends how much and how easily you have access to vermiculite. The grout mix guys use is often masons mix out of a redimix plant that's lower in Portland than usual. Just saves time mixing if you have the manpower to apply it. The caveat is that it cracks easier. Vermiculite is more flexible and will give and stay together with some light ground shifting whereas grout mix just breaks up.

 

[msickler]

Nobody around here has vermiculite... I'm looking at doing the Portland cement/sand mix and mixing it onsite, sounds like the grout mix would require some quicker workers to get it done. Since this is our first time, I think if we do the mixing onsite we can take our time and get it right.

 

[jimmythegreek]

I forget the ratio but you can mix it by bags and just dry mix it right in the pool on plywood with a hose sprayer. You could also make screeds with lumber and just screed it off if you aren't confident in your troweling ability. Did you try a search for pool supply houses anywhere near you? Somebody has to carry pool kits for the local PB to install that's who is gonna have vermiculite.

 

[swimcmp]

In the 80s when we started we bought 19# bags of vermiculite and 94# bags of Portland. Mixed half a bag of Portland to the bag of vermiculite