As a test project for working with earthen materials I’m planning to build a small tool/storage shed. For the wall system I’m using cast In-situ Adobe T-brick technique. With traditional adobe, bricks are made in large forms on the ground. Once the bricks have dried they are used to construct the wall. With the T-brick method individual brick forms are used to make the bricks in place. These rectangular forms measure 12-18″ long, 12″ wide and 8″ tall. In additional there’s a another 8″ tall piece of wood attached to bottom of the rectangular form (See image below).
When constructing the wall, several forms are place end to end on the wall and packed sequentially with Adobe mixture. As, a block firms up the form is removed and placed at the end of the row. In the next layer, the block locations are staggered so that gaps in the layer below can be filled in. This also serves to lock the layers together. Take a look at this article regarding building with T-bricks.
Some of the upsides I see in the technique are:
- Limited finishing plastering required. Using the forms the walls should be pretty even.
- Keeping the layers level and uniform would not require much tamping.
- Inserting deadmen (anchorages) and keeping them flush with the wall should be easy.
- The technique lends itself well to building rectilinear structures.
- Not much form work is required
- The technique would lend itself well to someone working either on their own or in a team.
Some areas where I’m dubious or skeptical:
- There’s not much information on technique. Apart from the article above and this one, there’s not much online I can find.
- I’m a little dubious of being able to pull the forms off cleanly after letting the bricks set for five minutes.
- The article mentions not having to use straw but in some of the pictures the blocks clearly have straw in them
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The author’s preferred wall thickness with this method is 12″ as the forms tend to bow if you get much larger. Most sources I found on earthen building suggest a minimum of 18″ walls to get there thermal mass you need.Regardless, it sounds like a good method to at least try out. I’ll keep you posted on what I come up with/
T-Brinks look very good. The T shape seems like a brilliant solution to building the wall. Do they have much lateral strength? Exactly what are they made of? Colin
The longer(16') wall may need some buttressing for lateral strength. Here's what Earthbag Building says about buttressing, "Adobe codes typically require buttressing (lateral support) every 24 feet on center for walls intended as structures."
The blocks will be composed of clay, sand and lime. Straw may be added as well.