I have a unique installation in that I have to install part of my pool over a sidewalk in the back yard that I can not dig up. This means I will have to have my buttress free 2" support channels on top of the sidewalk. I am going to use 2" Dow Chemical Blue Styrofoam for my bottom, but I have to fill and level between the 2" channels.

I planned on using sand but after seeing it run between cracks in the fence I think it would run out the sides and my foam would break. Then I though of dry mixing concrete with the sand and hope that the concrete will set up with the moisture in the air and set the sand so it would not run. I might even lightly mist it after I level it off with the channel/uprights before I put the 2" foam on top of it.

My question is, has any one mixed concrete with sand like this and if so what is the suggested ratio and which type of concrete do you suggest.

My other option is to level the ground (with sand- I mean I already have like 10 yards of the stuff already) and place an additional layer of 2" Styrofoam between the 2" channels and then add my other 2" foam bottom on top of the foam and channels. I think Dennis said this is how they install pools on concrete floors in showrooms and conventions centers/shows.

What do you all suggest the best way would be. (And don't say dig up the sidewalk and do it right) If I use the sand/concrete mixture, what would be the ratio and any other suggestions would be helpful.

Please help, I am ready to do it this weekend. I already have all my blocks leveled (at least the ones not on the sidewalk). Please help. I need it.

Oh, and I am taking lots of pictures of the whole process if anyone is interested in how it turns out.

Thanks,
Aranon