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glorfon

Bricks v. concrete

So, I think we're in agreement we'll build underground.  Up until now we've been working under the assumption that we'll use concrete.  However, has any one considered bricks?  I think bricks might work better.   Mostly because if we use brinks we don't need to make forms to pour the concrete into.
Zeerahks

AFAIK, mortar doesn't hold up very well to the damp...
UnMeilleurReve

We need to get in contact with the masons and convince them to share the secrets of making underground tunnels, lol.
vov35

i am pretty sure concrete would work better... wood for molds if pretty cheap
glorfon

On advantage of bricks is that we could add on with out having to dig up the surface.  If we used concrete we would have to remove the surface pour the concrete and than bury it.
Zeerahks

Why do you say that?  Couldn't we pour the concrete in the tunnels themselves, as long as we have a fairly good airflow, and then put it up?  There's no reason to dig to the surface!
glorfon

Well firstthere's the issue of getting the concrete down there.  That aside concrete has to be poured into molds.  There would be no way of getting the out side of the mold into place to pour the concrete.
vov35

but, the mold is going to go in though the tunnel entrance...
that entrance should be the same size as the tunnel...
glorfon

What do you mean?
Zeerahks

Can't we assemble the mold inside the tunnel?  Who says we have to construct it outside?
vov35

that too  Laughing  Razz
glorfon

There would have to be an out side of the mold to hold it in place. Plus we would have to get on top of the mold to pour the concrete into it.
vov35

a tunnel that goes down is hard to be underneath of :p
Zeerahks

Quote:
a tunnel that goes down is hard to be underneath of :p


WTF???

Quote:
There would have to be an out side of the mold to hold it in place. Plus we would have to get on top of the mold to pour the concrete into it.


I'm not quite understanding you.  I get that we can't make the whole wall and put it up, but couldn't we make a wall in say, four sections?

In fact, we'll want to make a sectioned wall, because of temperature fluctuations and water freezing.  If we use four sections, held together with a light mortar (maybe even sloped ever so slightly outward?), we can avoid most water damage and make the walls inside the underground rooms.
glorfon

So you mean some what of a composite of the two.  Giant slabs of concrete held together with mortar (basically big bricks).
Zeerahks

No mortar, just the weight of the slabs themselves (these are thick!!).  Also, not having mortar will allow them to shift around a bit more.
vov35

and then moisture gets in and we rot!
glorfon

If these are going to be so big how will we move them into place.
Zeerahks

No, moisture won't get in, especially if we use the insulation ideas presented in other areas of the forum.

As for putting them up: sheer willpower, and a lot of people.  I'm thinking 4'x4'x1' segments.  We can make our ceilings 8 feet high (which is actually fairly short), and our walls as long as we want.
glorfon

And the ceiling?
UnMeilleurReve

Once you've constructed the mold, the real trick is filling it evenly throughout. If the top is too thin, you have a problem. Also, you need to fill it in with rebar in place, which makes it twice as complicated.
vov35

if they're one foot thick thats excessive, i'd say 6-9 inches, but with steel bars inside the concrete
its called reinfoced concrete lol.

on that note...
2300 kg/m3 is the average density of concrete
16 ft3 = 0.45307m3
and a mass of:
1042.061 kg = 2297.351254lbs
have fun lifting that...
now if it were 2*2*1
it would weigh around 575 lbs, which three or four men could lift
glorfon

What about cinder blocks? We could pour conrete floors, Build cinderblock walls, and  build wooden ceilings covered in plaster.
vov35

rebar goes through the holes in cinderblocks, and sand is poured in around it, and then you've got solid material. cinderblocks can be broken kind of easy, but its a good idea, that i support
Zeerahks

....Domed concrete, with a central flared column for support (possibly not needed?)
vov35

nice as that would be, how do you plan to build that?
Zeerahks

Carefully, on piece at a time, with a lot of planning beforehand.  Lots and lots of planning and design.
vov35

ummm...do you plan to dig out alot of earth to do this?
that is gonna require a lot of work.

i am not sayying its impossible, but it is difficult...
Zeerahks

Dig out a rough torus, centered on the center column, with the walls the final height you want them to be, plus a bit (for the ceiling to attach to/rest on).  Then, build up the center column, slowly raising the ceiling as you go.  Finally, when most of the center column is concreted, bricked, etc, finish off the roof by building small but wide curved strips of concrete that can be layered all around the torus to decrease the water leakage.

By using this design, you use the earth itself as a support column, rather than building a roof and then building a support column.

Of course, I have no idea if this will work, especially with many feet of soil on top.  Currently it's all in the "intellectual thought experiment" stage.  But I think it would.
vov35

try making a mini model to see how it works   Razz
UnMeilleurReve

Cinder block is porous. In the desert, we have the problem that groundwater in raised yards sinks through and then molds. Usually it's black toxic mold. Cinder block is definitely out.

The dome would be much harder and less efficient with space usage, btw. It would also be difficult to expand.
Zeerahks

Granted it would be harder, but it would also last much longer.  Also, we're underground.  We have plenty of lateral space, so we don't really need to worry about vertical space as long as we go deep enough.
vov35

digging that deep is difficult
glorfon

Are you sure cinder blocks are so prone to mold.  I've seen alot of cinder block basements.
vov35

they're concrete (nonporous) blocks.
*checks walls for evil black mold*
glorfon

vov35 wrote:
digging that deep is difficult

Not to mention the risk of hitting the ground water.
vov35

but at the same time, we need groundwater.
Zeerahks

If you can, find out how far down the water table is on the land we have currently.  If we want to go below that, we'll (obviously) have to have a very good pump system.
UnMeilleurReve

Okay, I've given this some thought, and here's what I've come to.

Once you get to a certain depth, I think we'll have to worry very little about root systems damaging our walls. If we have any problems with mildew, we can bleach it. However, if we go below the water table, not only will we need pumps to begin construction, but we need a totally non-porous material to work with that can keep water out indefinitely. We also want to consider how important it will be to be able to repair things.

With concrete, we'd have to pour, mould, etc. to repair, and getting the damned stuff to set will be difficult. With bricks, most of the construction is done for us and the issue of transporting the materials is solved much better. If we make a gigantic hollow box and use steel lattice or triangle frames to support the walls, we don't need massive beams and we can make multiple layers. Expansion is also easier with bricks because we can remove some and not risk our structural integrity and then make another hollow box and fill it in with layers. I think the material used for the bricks should be our concern. Cement just causes too many problems with the actual construction.

The issue that we find, then, becomes how we get the mortar to set. So I now stand behind bricks. We could possibly find a type of brick and a way to set them that allows us to prevent seepage.
vov35

nonetheless, dams are built from cement not brick. perhaps cement stops water better?
I honestly don't know, so i am not trying to be a smart ass

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