Newbie Questions: Lightweight Concrete Fountain
#1
08-17-09, 02:38 PM
Newbie Questions: Lightweight Concrete Fountain
Thanks to anyone with the patience to respond, Im trying to cover all my questions, and am a total neophyte so am providing quite a bit of detail. If there is a resource where most/all of this is answered then Id appreciate a reference.
Ive read a lot of DIY concrete info (sometimes conflicting), and want to limit the chances of screwing up!
Here is the project: Basically a concrete slab, approx 28 w x 40 h x ? thick, poured with 1/2 PVC pipe embedded to deliver water pumped from a bowl to the top of the slab. The PVC will protrude from the slab slightly at the outlets, with tile fitted around the PVC outlets, and the slab will be ceramic tiled and framed with a molded concrete border tile. The bottom of the slab will be formed with a large gap (~ 9 inches high) to accomodate inserting a bowl to catch the water and the PVC input. The remaining area on the bottom will have "feet" out of the front only so it will stand with attachment. (it will be positioned against a wall so need for support to the back). Id like to pour the entire slab in one piece, not attach the feet later if possible. The entire project will sit on a rectangular concrete base.
Here are my questions: How thick does the slab need to be for sufficient strength but limit the weight? (I assume the recipe will include fiber reinforcement.) The couplings for the embedded PVC are probably a little more than an inch in outside diameter. Recipe suggestions for the slab and the block (if different) ? As light as possible that will accomplish the job. Its Southern California so freeze/thaw is not a concern, and the temperature during pouring in the 70s, relatively low humidity.
Depending on the thickness, the slab will be 2-3 cubic feet, the base around 9 cubic feet. They will be poured at different times (and maybe different recipes if recommended above). Will hand mixing in a large bucket work (in batches for the base), or do I need to rent wheelbarrow/mixer? I do have a paint mixer attachment to a hand drill if that would do the trick.
For the "feet" at the bottom of the slab, is rebar needed? L shaped? Rebar in the veritcal rise of the slab? Does there need to be some time for the bottom of the pour to harden before placing the PVC so the weight of the top of the pour doesnt push the PVC all the way to the bottom. Similar question on the rebar ( if rebar is needed).
Since this will be a wet environment any recommendations on cure/waterproofing sealer (that will allow for adhesion of thin-set for the tile)? Recommendations for the thin-set for the tiling? Grout? (must be white).
I assume wood is fine for the walls of the form but what about the 28 x 40 bottom? Will a wood bottom release after sufficient curing time or do I need to expect that to be permanent (and therefore need to use a higher quality wood/material) since it will bear all of the weight of the concrete during curing.
Recommendations for the release to be used? How do I know when the form should be removed? How critical is the timing for removal of the form? (Ie will watiing too long after it is sufficiently hardened result in difficult/impossible release?)
From what Ive read, waterproofing sealer/cures are best applied right after any bleed water is absorbed. After that I assume the project should be "bagged" for curing? I would add posts to the form to support the bag so it doesnt fall onto the slab, but how "tight" should the clearance be to recirculate the moisture for a good cure? And most importantly: what should I have asked and didnt!
Thanks again for reading if you made it this far!
Ive read a lot of DIY concrete info (sometimes conflicting), and want to limit the chances of screwing up!
Here is the project: Basically a concrete slab, approx 28 w x 40 h x ? thick, poured with 1/2 PVC pipe embedded to deliver water pumped from a bowl to the top of the slab. The PVC will protrude from the slab slightly at the outlets, with tile fitted around the PVC outlets, and the slab will be ceramic tiled and framed with a molded concrete border tile. The bottom of the slab will be formed with a large gap (~ 9 inches high) to accomodate inserting a bowl to catch the water and the PVC input. The remaining area on the bottom will have "feet" out of the front only so it will stand with attachment. (it will be positioned against a wall so need for support to the back). Id like to pour the entire slab in one piece, not attach the feet later if possible. The entire project will sit on a rectangular concrete base.
Here are my questions: How thick does the slab need to be for sufficient strength but limit the weight? (I assume the recipe will include fiber reinforcement.) The couplings for the embedded PVC are probably a little more than an inch in outside diameter. Recipe suggestions for the slab and the block (if different) ? As light as possible that will accomplish the job. Its Southern California so freeze/thaw is not a concern, and the temperature during pouring in the 70s, relatively low humidity.
Depending on the thickness, the slab will be 2-3 cubic feet, the base around 9 cubic feet. They will be poured at different times (and maybe different recipes if recommended above). Will hand mixing in a large bucket work (in batches for the base), or do I need to rent wheelbarrow/mixer? I do have a paint mixer attachment to a hand drill if that would do the trick.
For the "feet" at the bottom of the slab, is rebar needed? L shaped? Rebar in the veritcal rise of the slab? Does there need to be some time for the bottom of the pour to harden before placing the PVC so the weight of the top of the pour doesnt push the PVC all the way to the bottom. Similar question on the rebar ( if rebar is needed).
Since this will be a wet environment any recommendations on cure/waterproofing sealer (that will allow for adhesion of thin-set for the tile)? Recommendations for the thin-set for the tiling? Grout? (must be white).
I assume wood is fine for the walls of the form but what about the 28 x 40 bottom? Will a wood bottom release after sufficient curing time or do I need to expect that to be permanent (and therefore need to use a higher quality wood/material) since it will bear all of the weight of the concrete during curing.
Recommendations for the release to be used? How do I know when the form should be removed? How critical is the timing for removal of the form? (Ie will watiing too long after it is sufficiently hardened result in difficult/impossible release?)
From what Ive read, waterproofing sealer/cures are best applied right after any bleed water is absorbed. After that I assume the project should be "bagged" for curing? I would add posts to the form to support the bag so it doesnt fall onto the slab, but how "tight" should the clearance be to recirculate the moisture for a good cure? And most importantly: what should I have asked and didnt!
Thanks again for reading if you made it this far!
#2
08-17-09, 07:32 PM
Wow! Appparently you've been doing some reading somewhere. I'll try to answer some of your questions, but some of them are incomprehensible.
First off, lightweight concrete is not really lightweight. it weighs about 2/3 as much as regular concrete, so it's still very heavy, about 12 lbs per square foot at 1.5 inches thick. Concrete is typically poured at 4 inches thick.
You do not want to pour over the top of (imbed) the pvc pipe, or you will get a crack directly over where the pipe is. You want the pipe completely under the fill stone or sand that you're pouring on, with 4 inches of concrete over that. You could bring the pipe up vertically and pour around that with no real problems though.
Concrete is not really "poured", but placed. If you can pour it like a liquid, it's too wet and will have no strength. That said, your paint mixer will be of no use whatsoever. You'll either need a drum mixer, or mix it with a rake/hoe in a wheelbarrow. Just buy ready mix concrete (sakrete) and follow the mixing instructions on the bag as to how much water to add. It will seem stiff if the directions are followed, but this is correct.
The wood forms need to be removed after a couple of days so they don't just rot away. waiting longer than a few days will not hurt anything. For release, you can use motor oil, diesel fuel, or better yet, Murphy's Oil Soap. You can actually use none at all and the forms will not stick. When the concrete dries, the forms will release easily on their own.
Any rebar should be placed halfway into the slab. In other words, in a 4 inch thick slab it should be about 2 inches deep.
You can pour the bowl the day after the base if you desire, but it may be better to wait a day or two longer to give the concrete time to cure a bit.
As to curing, just lay plastic sheeting directly on the slab and it will hold moisture in, thus helping the slab to cure. Concrete needs moisture to cure thoroughly, and plastic will not let it evaporate.
I have no idea if I've answered your multitude of questions, but you may find some help in here somewhere. Good luck.
First off, lightweight concrete is not really lightweight. it weighs about 2/3 as much as regular concrete, so it's still very heavy, about 12 lbs per square foot at 1.5 inches thick. Concrete is typically poured at 4 inches thick.
You do not want to pour over the top of (imbed) the pvc pipe, or you will get a crack directly over where the pipe is. You want the pipe completely under the fill stone or sand that you're pouring on, with 4 inches of concrete over that. You could bring the pipe up vertically and pour around that with no real problems though.
Concrete is not really "poured", but placed. If you can pour it like a liquid, it's too wet and will have no strength. That said, your paint mixer will be of no use whatsoever. You'll either need a drum mixer, or mix it with a rake/hoe in a wheelbarrow. Just buy ready mix concrete (sakrete) and follow the mixing instructions on the bag as to how much water to add. It will seem stiff if the directions are followed, but this is correct.
The wood forms need to be removed after a couple of days so they don't just rot away. waiting longer than a few days will not hurt anything. For release, you can use motor oil, diesel fuel, or better yet, Murphy's Oil Soap. You can actually use none at all and the forms will not stick. When the concrete dries, the forms will release easily on their own.
Any rebar should be placed halfway into the slab. In other words, in a 4 inch thick slab it should be about 2 inches deep.
You can pour the bowl the day after the base if you desire, but it may be better to wait a day or two longer to give the concrete time to cure a bit.
As to curing, just lay plastic sheeting directly on the slab and it will hold moisture in, thus helping the slab to cure. Concrete needs moisture to cure thoroughly, and plastic will not let it evaporate.
I have no idea if I've answered your multitude of questions, but you may find some help in here somewhere. Good luck.
#3
08-17-09, 10:46 PM
Thanks pecos
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Hopefully the image works!
Ok, I obviously misunderstand the form itself to start with. You say that the pipe should be completely in the fill stone/sand Im pouring on. I was thinking that the bottom of the form would be wood/melamine/etc not stone or sand.
What keeps at least a thin layer of the stone/sand from adhering to the concrete and partially embedding the PVC? While I have no problem with the vertical and horizontal feeders being exposed in the back, at least the outlet pipes have to be embedded in the concrete as the (hopefully) diagram shows. Will that cause cracks in the concrete? How else would I feed the water from the horizontal feeder through the slab and out the front?
also you mention what to do with the rebar, but where is it needed? in the feet? vertically or horizontally in the main slab?
[/IMG]Hopefully the image works!
Ok, I obviously misunderstand the form itself to start with. You say that the pipe should be completely in the fill stone/sand Im pouring on. I was thinking that the bottom of the form would be wood/melamine/etc not stone or sand.
What keeps at least a thin layer of the stone/sand from adhering to the concrete and partially embedding the PVC? While I have no problem with the vertical and horizontal feeders being exposed in the back, at least the outlet pipes have to be embedded in the concrete as the (hopefully) diagram shows. Will that cause cracks in the concrete? How else would I feed the water from the horizontal feeder through the slab and out the front?
also you mention what to do with the rebar, but where is it needed? in the feet? vertically or horizontally in the main slab?
#4
08-18-09, 04:20 AM
I wasn't getting the picture of what you're trying to accomplish when I mentioned pouring on stone/sand. It's more clear to me now, but not completely.
I gather that you're pouring one vertical element with pipes imbedded in it. This element stands in or above a separate horizontal element (bowl?) that holds water that you want to recirculate. Is this correct?
I gather that you're pouring one vertical element with pipes imbedded in it. This element stands in or above a separate horizontal element (bowl?) that holds water that you want to recirculate. Is this correct?
#5
08-18-09, 10:08 AM
Yes, thats the goal.
If embedding the pipes is still a problem I was thinking it may be easier to build it from wood , run the pipes in that, leaving the back open for access, and then mud (? clad? not sure of the right term) the front and sides in concrete/stucco and then tile over that?
Will the concrete/stucco hold in that kind of application? I assume tiling over is no problem as long as there are no coatings over it (other than a penetrating sealer?)
Thanks again for your time
If embedding the pipes is still a problem I was thinking it may be easier to build it from wood , run the pipes in that, leaving the back open for access, and then mud (? clad? not sure of the right term) the front and sides in concrete/stucco and then tile over that?
Will the concrete/stucco hold in that kind of application? I assume tiling over is no problem as long as there are no coatings over it (other than a penetrating sealer?)
Thanks again for your time
