Concrete block wall art

[meow2222]

I wrote this for another thread, but I think it deserves its own...

Finally you can make your own concrete blocks if you want, need a simple wood frame on a flat sheet, line it with polythene, and pour in load after load. A 4x8 mould is 2 m^2 or so of blocks, so with 9" blocks you can work out what you'd save.

The best thing about diy blocks is you can make them any design you want. You can let the kids arrange brick rubble in them first for decoration (flat side of brick pieces down), you can sprinkle the mould with coloured stone chippings, or use coloured glass if you want it to sparkle. Put a thin layer if white cement in if you want white but to never need to paint it. Or if you want to make it even more unusual you can make those blocks any interlocking shape you can think of. You can also cast blocks for the wall top and ends with moulded in decoration, eg straight framing, egg and dart, whatever you can make or find. Also you can cast cubby holes in a few blocks for trailing strawberries, etc etc etc

If you take a look at the famous concrete castle, you'll see what a remarkably artistic material concrete blockwork can be. Check out the

2nd and 3rd pics here for a start: much more intersting stuff on that castle, just ran out of google time.

For rectangular blocks, a single 4'x8' mould will make 30 blocks of

8.25" x 14" in one pour, of whatever thickness you want. This uses 2" thick perimeter wood and 3/4" thick dividers. And of course block dimensions can be whatever you want, as long as theyre no bigger than 4'x8' apiece!

NT

[Chris Bacon]

meow2222 wrote

Why make blocks when you can cast whole walls in stages?

[Ian Stirling]

Why cast walls in stages, when you can cast walls in one? Cast the slab for the floor. Level it, get it nice and flat, then cast the other walls on it, and tip them up into place.

[Guy King]

The message from Ian Stirling contains these words:

Easy to do the damp-proofing, too. While the house is on its side, paint one "wall" with rubbery masticy stuff then flip it over.

[Rob Morley]

Because you need a lot less shuttering if you do it in stages.

[Mike Halmarack]

Ah! To block or not to block? That is the question. I wondered where I'd seen the name before. :)

[Ian Stirling]

Not much less. You cast it on the floor slab, so you only need 30cm or whatever of shuttering round the edge, then tip it up vertical.

[Chris Bacon]

How do you "tip it up vertical"? How do you join corners? What about internal walls?

[meow2222]

Appearance of course. I did just explain that in a fair bit of detail in the post above. Poured walls are not pretty.

NT

[Mike Halmarack]

ISTM the essential point about the OP's posting was the potential for modeling and decorative effect. Achieving this level of design on a monolithic slab would be quite an undertaking.

[Weatherlawyer]

That's the easy bit, is it?

All this has been done for millenia. Or do you think prefabs are something new?

What I'd like to design is a scoop that takes buckets full of molten lava and work it into some sort of mass production instant maonry. It would save a fortune in greenhouse emission and help prevent resources being swallowed up in the flow from the suitable volcanoes.

Not exactly a steady stream of work but an extremely interestin on if sporadic. Believe it or not we do have the technology. But moving it to place at the time in time would be difficult.

[Chris Bacon]

Block walls are at least as bad! Both these things are better rendered.

[Mike Halmarack]

That's a silly thing to say in the context of the subject. You really do resent difference of opinion don't you? It gets right under your rind and causes your statements to become rasher and rasher. :-)

[Chris Bacon]

It wasn't in the context of the subject, though, was it. However, if you want it to be, I should say that casting walls would make it easier to get an artistic effect (e.g. by using moulds) than it would be to get an effect using blockwork.

No. I resent lots of things, but difference of opinion (where one opinion does not fly in the face of fact) is not one. Perhaps I should add that this reply is not in the context of the subject of this post, or necessarily your statement.

Oh dear oh dear.

[Mike Halmarack]

Just thought it might be one you'd never heard before. :)

[Ian Stirling]

The design is the fun bit. Obviously, in order to tip it up, you need a largish crane, or a really strong back (or a really small building).

As an example, let's say we've got a 3*3m slab, and want 2.5m high walls 30cm thick.

First pour the slab. Now, cast one 2.2m*2.5m slab on one corner, 30cm from the edge. Tip it up, and you've got the door-side wall. Now, cast a 2.7m*2.5m(with a 10cm fall on the top) slab on the adjacent side,

30cm from the edge again, tip up and bolt to the other wall. Do the same with a 2.7*2.4m slab, and bolt it to side wall. Repeat with a 2.4*2.5m(again, with a 9cm fall on the top) slab, and you've got most of it up. All you now need to do is to cast a 30cm*30cm pillar to finish off the side adjacent to the door, and add a roof.

Putting windows in before now is probably a good plan too.

You can get horribly fancy with this sort of technique, if you don't use the bare slab to cast on, but make large earth moulds to pour into, including curved walls, ...

And if you want, you can get as fancy as you like on the inside. For example, spraying on blobs of different colours of concrete, then immediately pouring the main slab, or text, or mosaic, ... The outside can be smooth, polished just before it sets, have harling (throw gravel on), ...

It is a fairly rapid, and versatile technique. There are probably ways to make the wall erection simpler, one that springs to mind is simple hinges, cast into the walls, so you don't have to worrry about securing the bottom while lifting.

The weight is of course a problem - for this small shed, the longest side weighs 2 tons, which is fine with relatively trivial equipment - a couple of 6*6's in an a-frame, some rope, and a block and tackle. For larger walls, it gets problematical.

[Guy King]

The message from Chris Bacon contains these words:

These are left as exercises for the reader.

[Guy King]

The message from Chris Bacon contains these words:

The t'ween house walls in our terrace are poured - I'm facing one now. Once semi-skimmed[1] and properly papered with crosslining it's fine. Probably the flattest wall I've seen in years.

[1] Most of the concrete is just bare sized concrete, but where it's a bit low it's been skimmed. Perhaps 20% of the area is actually covered in plaster.

[Guy King]

The message from Ian Stirling contains these words:

I've always wanted a dome-house (domus?) made by spraying concrete onto inflatable domes with re-bar woven over 'em. Use aerated concrete and they'd be insulating, strong and beautiful. Blank off a segment and when it's down you could do several intersecting domes to give extra side rooms.

[Mike Halmarack]

I designed one of these in 1975. It was intended to be built by a movable shutter on the end of a pivoting trammel beam. The intersecting domes would be more easily built using the inflateable method. Is it the woven re-bar that prevents the inflatable formers from distorting under the weight of concrete? I wonder what the multi-storey potential would be?