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/diy/ - Do It Yourself

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2440536 No.2440536 [Reply] [Original]

anyone with experience in concrete or woodworking, ideally both, and maybe even built a concrete wall with woodforms around?
i have a crazy project where i want to build a giant 9ft tall concrete wall, 1ft thick, lets just say, a very long distance.

it really just boils down to a few questions about the forms:
would it be possible to butt joint two 15ft 2x4 boards together to make a massive 30ft long concrete form, 9ft tall?
would the seam in the middle of the form show up in the concrete? any way to prevent this if so? silicone perhaps?
and finally, would these forms even be able to hold the weight of all this concrete? something like pic related

>> No.2440612

You're going to need a massive foundation. Are you going to build a dungeon to keep a sex slave in?
Unless you want a retaining wall you are a retard. You also need rebar and will probably want to have a cement pump put it in the form. I think you will have a seam in middle but I don't think the Palestinians will complain about it.

>> No.2440615

That is a lot of concrete

>> No.2440616

>>2440612
>I don't think the Palestinians will complain about it
kek, nice

>> No.2440706
File: 590 KB, 2364x1765, concrete forms.jpg [View same] [iqdb] [saucenao] [google]
2440706

>>2440536
>make a massive 30ft long concrete form, 9ft tall?
yes, it's very possible to make a form that large out of 2x4 and plywood or HDO board, but you will start to run into quite a few issues at that size.
The way that the concrete flows becomes and issue and special formulations and care becomes necessary to insure that you don't have voids or stratification happening.
You can lap or buttjoint the 2x4, it doesn't matter and there won't be a meaningful seam.
Observe the pic related

>> No.2440716

>>2440706
There are commercial applications where they can pump a wall of concrete 40' deep in one continuous pour, but they are going around a large perimeter where they put in a lift of a few feet of concrete and then by the time they return to pump more into that part of the wall, it's already had awhile to set up and gain some self supporting qualities.

Run a quick calculation about concrete hydrostatic pressure and you will find that putting in a 9' lift with anything resembling conventional formwork is pretty crazy.

OP, don't reinvent the fucking wheel--- this topic has been explored in depth by many many other people around the world.

>> No.2440839

>>2440716
So should OP just do a concrete tiltup?

>> No.2440873
File: 84 KB, 880x650, Project-1-EM50541-880x650.jpg [View same] [iqdb] [saucenao] [google]
2440873

Why not install a pre cast wall?

>> No.2440899

Paint the butt joints for the inside or something, to not have them show
They dont really show anyways, and you can scrape ridges while the concrete is fresh

You need tons of bracing the whole way along to hold forms up/straight

There has to be places to rent forms somewhere, or just do it section by section

Remember to vibrate while pouring

And you def need to go down like 10 feet to keep it stable

>> No.2440932

>>2440716
so wait, are you saying these forms just wont work like we think? my buddy was saying bolting together basement concrete forms should work fine. they wont?

>> No.2440954

>>2440932
Yes they will work, but don't fill all 9 ft in a single lift. Pour it like half way full (being careful not to pour onto the sidewalls or rebar too much so that you hopefully don't separate the concrete) use plenty of vibration to help consolidate it, and then let it set up a bit before you fill the other half.
Also, make sure that your form is sensibly designed so you won't have a blowout. This is doable with 2x4 and plywood, but copy a proven design if you don't know how to run the numbers or do it yourself.

>> No.2440999

>>2440954
thanks a ton bro. so let it set for maybe a few hours or so first before the second half? also, could i just use basement forms for this, bolting a ton together or would that not work?

>> No.2441112
File: 90 KB, 1000x1000, cinder-blocks-100002886-64_1000.jpg [View same] [iqdb] [saucenao] [google]
2441112

>>2440536

>> No.2441935

>>2440536

Just go the ICF route - it goes together like Lego - Fill with concrete - and then coating of some sort - I'd go Plywood around for strength if it's hit . . . then maybe spray it with concrete colored rhino liner or another truck bed liner.

I've helped build 3 houses out of the stuff, and an inground pool.

>> No.2441936
File: 64 KB, 800x420, ICF Walls.jpg [View same] [iqdb] [saucenao] [google]
2441936

>>2441935
forgot a PIC incase you don't know what ICF is.

>> No.2441940

>>2441935
I mean - I guess I should ask what you want it for - if it's a large thermal mass to soak up the suns heat and radiate it at night - then the ICF wouldn't be a good solution.

>> No.2441969
File: 1.83 MB, 2612x1959, 20141230_150424.jpg [View same] [iqdb] [saucenao] [google]
2441969

>>2440536
yes but your going to need some 2x6 and 2x4 nails tie backs and some other crap
unless your planning to build with the wood its after the concrete its cheaper just to rent the premade forms. its all a game of supporting said concrete small leaks wont hurt much

>> No.2441972
File: 2.15 MB, 2448x3264, 20140723_120405.jpg [View same] [iqdb] [saucenao] [google]
2441972

>>2440873
they are not as uniform as you would think so if you wanted a straight wall more than 1-2 courses you will have to shim to keep things plumb

>>2440954
dont listen to this tard brace it right and pour it in one go
>>2440716
concrete pumps can pump hundreds of feet into the air I have been on a job building a smoke stack it was a 120ft continuous pour. we would jack the forms up slowly as they pumped in concrete for 35 hours

pic related stairs I built forms for