Extra-Large Tank Upgrade Project to begin

You def. need to keep in mind the monthly budget when you plan a tank of this size.

Luckily I am covered!!!:D

I haven't had any recent updates, as I have been waiting on a few people to come thru with actual concrete forms (of course to save me some cash).

Looks like I may not be able to do any more construction until I get back from Cabo San Lucas!!!!!

Shoestring! Dream Away!!! Nothing more fun than planning the big upgrade!!!
 
sixxer, just a thought on your reinforcing steel layout for the tank. I'm not sure of your existing concrete slab condition ie thickness compressive strength etc. but I see you've dowled into the slab with the rebar stubs, this will help keep the base of the wall from moving out (shear) so you wont need a keyway as suggested might be needed but it really wont help the bending moment induced at the base of the walls unless the slab is really thick and the bars extend down several inches. I'm assuming the tank will be fully open at the top = no structural top brace so the walls will act as cantilevered retaining walls. You have basic geometery working for you due to the box shape, but I might suggest adding 90 deg bent bars at each of your vertical bars with the other leg of the bend extending into the new floor slab of the tank much like what you've done for the corner horizontal bars. Just a suggestion FWIW
 
I disagree with the description of how basements are constructed. At least in the northeast, "footings" are first poured. The basement walls are then poured on top of the footings and then the actual basement floor is poured. I can not comment on skyscraper construction.

Pouring the floor and walls of the tank at the same time would give the best bonding between them. However, it wolud be very difficult to do this because the concrete wants to seek its own level, i.e. the concrete in the wall forms would want to drain into the floor area.

You would have to construct a "closed" floor form that would stop the concrete on the floor from rising beyond the desired height which woulld prevent the concrete in the wall forms from drianing down into the floor area.


Shoestring:

You can and should build your basement tank. The water pressure against any of the side walls of your foundation is negligible. If you don't believe me remeber that a 1.5 inch piece of acrylic can withstand the pressure. To be extra cautious, I would add some additional enforcement to the front wall.

Also check to see whether your foundation is poured concrete or cement block. Poured is stronger.

Either way you could pour new walls inside the "old" basement walls. If you are concerned regarding heating issues just place some sytrofoam sheets between the new and old walls for insulation.

Sixxer:

Please keep us updated with your progress. This is a great project.

Best,

Brian
 
saltwater: i had envisioned some sort of form that had a 'roof' over the floor area. cool to hear it's a real thing! i'm wondering how you can smooth/compact the floor and level it out when the form would obstruct this. you can't see under the form to even know whether your floor is the desired thickness. any knowledge to share regarding this?

would you fill the walls and let the cement run into the floor form in the bottom?

brett
 
Drax:

I don't know anyone that has used a single pour method but, hey anything is possible.

If I were to use that method, I would pour the floor and then quickly cover it with the "roof" form. I don't think you would need to smooth or level it.

After I poured the floor and while it was still "loose" I would pour the floor walls. If you used a light (watery) mix the concrete from the walls would seek its own level, i.e. push the floor concrete up against the "roof" form.

Although preferable, I do not think the single pour is a necessity. There are many that have blazed this path already who know this answer.

Rbell47, Richard Harker and Mr. 4000 have all built concrete tanks but Rbell is the only one that I have been able to find information on exactly how he constructed his tank. Obviously, he made several pours with sucess. I can't find info on the construction of the other concrete tanks.

Best,

Brian
 
Brian,

I was under the impression that pouring the walls, & floor of the tank at different times would create "cold seals" (I think that is what they are called) that takes away from the stability of the walls, and gives a much higher risk of cracking, and or breaking?

Am I wrong on this?

Thanks
 
Cold joints are a weak point in concrete construction, however reinforcing steel can make up for the lack of bonding between the two surfaces. The main draw back in your case with a cold joint is it's a much larger potential leak line. But if you seal the entire inside of the tank with epoxy paint or another waterproof membrane as mentioned earlier it shouldn't be a problem.
 
sixxer, if you do end up doing multiple pours I would look into adding a moisture/leak stop. This is a small ~1"x1/16" ribbon of plastic that stops moisture from penetrating a cold joint. The bottom half goes in the top of the first pour and the second pour covers the top half. Like thisââ"šÂ¬Ã‚¦

......2nd...........|
outside --------|---------|---- inside tank
.......1st...........|
...................rebar.......stop
 
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Two things, one, I'd like to bump this thread again, and two, Wagerja, I am sorry but I really don't understand that last diagram.
 
Sixxer:

I agree that cold joints are weaker than if you poured the tank all at once but I don't know if the cold joints would be strong enough to stay together/not leak, once filled with water. That why I pointed out the key ways used by Rbell.

JMMAC makes an excellent point. I woud be more concerned that the cold joints would leak than the tank wall would collapse.

I am not familiar with the moisture barrier WAGERJA suggested but it sounds like a good idea to me.

Try contacting Mr. 4000 and ask him this question. He is involved in the construction industry and did a lot of the work on the tank himself. He should know the answer to this question.

Use his method. If his tank didn't collapse/leak then yours won't either.

He recently posted in the large tank forum here on RC.

Best,

Brian
 
dogstar74 said:
Two things, one, I'd like to bump this thread again, and two, Wagerja, I am sorry but I really don't understand that last diagram.
Click to expand...
itââ"šÂ¬Ã¢"žÂ¢s a cross section of he concrete tank wall. Please read below.

Ok, I have not build a concrete tank but I've designed a couple concrete holding vessels for industrial applications. So here is some free advice, take it for what it's worth.

I would do this in two pours, 1st because there is very real possibility that trying to do it in one will not go well (i.e. frantic shoveling of quickly drying concrete out of the basement after a form pops) and 2nd two pours can be done to be just as strong as one.

One possible problem with doing one pour is that getting all the air out of the bottom of the form, and the other is you will have a limited ability to inspect whether or not you have done so.

Two things you can do to counter this are using a submersion concrete vibrator tool(basically shakes the p-ss outta the wet concrete and forces the air out of the concrete) and/or cut multiple 1"dia holes in the "roof form" and have plugs premade and ready to screw down as the pour rises. Neither of these two tactics is foolproof. The vibrator maybe hard to come be and IS going to be a PITA to use with your relatively tall narrow forms, and the holes in the roof may not let all the air out.

Ok, this how I would go about doing two pours.
Your rebar work looks good.. but I would follow jmmaccââ"šÂ¬Ã¢"žÂ¢s suggestion
ââ"šÂ¬Ã…"œbut I might suggest adding 90 deg bent bars at each of your vertical bars with the other leg of the bend extending into the new floor slab of the tank much like what you've done for the corner horizontal bars. Just a suggestion FWIWââ"šÂ¬Ã‚

Next build the out side form to 10in. high. Then build the ââ"šÂ¬Ã…"œroof formââ"šÂ¬Ã‚ with a depth of one 2by4 plus a Ã"šÃ‚½Ã¢â"šÂ¬Ã‚ sheet of plywood = ~4ââ"šÂ¬Ã‚. This would give you a 6ââ"šÂ¬Ã‚ floor depth(a safe over build). Then make your keyway form. You more then likely donââ"šÂ¬Ã¢"žÂ¢t ââ"šÂ¬Ã…"œNeedââ"šÂ¬Ã‚ a keyway with rebar extending between pours but itââ"šÂ¬Ã¢"žÂ¢s so easy to do and canââ"šÂ¬Ã¢"žÂ¢t hurt. Plus I tend to over build the snot outta my stuff unless I have really good calculations done by and engineer I trust. Jmmacc want to run a finite element analyst? ha ha ha, sorry, engineering joke. Anyway get some 1.5ââ"šÂ¬Ã‚ or 2ââ"šÂ¬Ã‚ foam insulation and cut it in this shape \_/ . no more then ~2ââ"šÂ¬Ã‚ wide or 1/3 your wall thickness. Iââ"šÂ¬Ã¢"žÂ¢m not sure where you would source the moisture/leak stop but the wide plastic ribbon used to hold large bundles of wood together at a lumberyard come to mind. Now after you have dry fit every thing its time to pour. Pour about 7ââ"šÂ¬Ã‚ in your form with out the ââ"šÂ¬Ã…"œroof formââ"šÂ¬Ã‚ in place. Then place the ââ"šÂ¬Ã…"œroof formââ"šÂ¬Ã‚ in and twist and settle it in until the top is even with the top of the outside form (after you add more concrete it may start to ââ"šÂ¬Ã…"œfloat upââ"šÂ¬Ã‚ adding some weight may help). Square and even it up. Fill close to the top then add the key by puncturing the foam and sliding it down the rebar until its flush with the top of the forms. Add the last of the concrete to fill any low spots. After it has started to set-up come back and slip the moisture/leak stop sinking half the ribbon width in the drying concrete. This stop is important. The joint area is very susceptible to moisture penetration and paint is likely to crack at this line for various reasons that I wonââ"šÂ¬Ã¢"žÂ¢t get into.(this post is ungodly long as it is). The stop will make the moisture take the long way around there by protecting your rebar. Which would get rusted out in short order once SW got to it and seriously weaken the structure. Thatââ"šÂ¬Ã¢"žÂ¢s why the stop goes between the rebar and where the water will be.

The second pour is petty self-explanatory. After the first pour has set remove the foam keyway form, place higher forms inside and out. Then fill.

Jay
:eek2: woh this post is long, I need to get a life or a job or something!!
 
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why? Wouldn't the relative stability of the temperature of the ground actually help? More effectively in the summer months obviously... Kind of like passive geothermal temperature control?
 
But in the winter, if he has a sandbed, won't he risk the low ground temps wiping out his sandbed population?

I don't know, maybe this isn't a problem, just wondering.
 
Shoestring Reefer -

Put some undergravel heating cables in. That would keep the bed warm and keep the rest of the tank hot too. Might also help with longevity of the bed, particularly if it is deep.

chask
 
Got in from Cabo last night! All I can say is WOW!!!! Beautiful area. I'll try and get some pics. from the trip up for everyone to see. It was very cool seeing fish that I have in my aquarium in their natural habitat, and all kinds of fish I have never seen before.

Back to work on the DIY this week!!!!!


CincyCoral, maybe if your good I'll throw in a pic. of the wife on the beach!!

p.s. - thanks for helping make sure all my fish survived while I was gone!:)
 
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