Mixing Sand and Concrete ????

[Aranon]

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

[matt4x4]

OK, here's my 2 cents:
DON'T build up sand to put your pool on, not a good idea...
Is your sidewalk level or not??
If it's level, you could use it as a starting point, otherwise build up on top of it with a good solid sub base and compact well, but not using sand. Burriing the sidewalk is not really an issue unless it was built improper and has tendencies to heave with frost - then you have to remove it.
Use the sand for your cove.

[Aranon]

yes my sidewalk is level and i have the columns support 2" channels sitting on them and leveled 16 x 16" blocks on the other side. This leaves me with 2" of nothing under the pools and between the column support channels that are under the pool along with the pressure plates which have nothing under them.

I have to add 2" of something to bring everything level with the 2" galvanized metal channel / column supports before I put my 2" of blue Styrofoam on.

I don't want to pour concrete so I was thinking of a sand and concrete dry mixture that would in theory harden somewhat to keep the sand from running out. I will put patio blocks around the rail to keep it level and supported between the channels and on the ovals.

What do yall suggest?

Aranon

[matt4x4]

Well, sand and concrete would definitely harden, but depending on the ratio can also crumble easily.
Have you thought of trying crusher run or screenings as they're called up here in canada - it's essentailly the fine stuff that falls out of the gravel crusher, the bits are jagged, and teh fine dust hardens nicely with moisture, put this around the edge and under the wall taper it down to ground level and do the inside of the pool in sand.

[Aranon]

Anyone know the ration of mixing sand to concrete for bottom???

[JJ in Tx]

1 part Portland Cement with 8 parts sand NO WATER
you don't want to use something like Quikcrete it has the pebbles etc in it you want the Portland Cement it is just fine powder.
Hope that helps
JJ

[Aranon]

Thanks, Have you done this before and did it work pretty well for you. I didn't realize how fine the sand was until I saw where it ran out thru the cracks in the fence. I have little sand dunes on the other side. I could just picture all the sand running out around the edges and my pool sagging.

[JJ in Tx]

No I didn't have to do that on my install. Mine is round, here is what I did:
Leveled and compaceted existing ground, then I build a pressure treated 2x4 frame that was larger diameter than the pool basically 24' pool 28' frame, this frame got anchored to the ground with lengths of rebar spiked thru it and then back filled with masons sand. I would add some sand and compact it, add sand compact ..... then layed out the patio stones for the wall uprights added some more sand and compacted, assembled pool. It may be unorthodox and a lot more work but the pool hasn't had any issues, I haven't lost any sand from underneath it or anything like that. Personally I'm not familliar with how a oval goes together, maybe if you could post a picture or 2 of the problem we can brainstorm up a workable solution to your problem.
JJ

[Aranon]

I was hoping Dennis would have commented on this. I'm sure he has had this problem at least once.

Aranon

[Aranon]

JJ ,
How long before the sand sets up with the Portland Cement added to it. I would imagine that it only sets up enough to keep the sand together and not spreading or running off instead of a strength type bond. Am I thinking along the right lines. I was thinking of either building a 2x4 wall or using metal angle between the channels and pouring about a six inch rail of concrete to go between the rails and fill the middle with sand to level it off even with the upright channel supports and then I would have a firm level base to lay my 2" foam board on. I am thinking this way the sand wouldn't run out. Please advised. Thanks.
Aranon