Thought I'd see what a little adobe can do. Just finished testing this dome today.
...take a look here if you want the whole thing:
I learned a few things and I'll do my best to answer if I've got one
What happens if you build a fire for a while before the water test?
small domes like this are extremely stable, but if you made a 20 ft one, it would fall down.
You could make a 4ft dome out of almost anything (even paper, literally) and it would hold up to impressive weight tests.
Around here, folks use lime and prickly pear juice to seal adobe....
small domes like this are extremely stable, but if you made a 20 ft one, it would fall down....
oh, I'm not saying that it isn't possibly to build a 20 ft diameter earthen dome, I know it is completely possible.
But the style that you built, it wouldn't go past 8 feet diameter, probably.
In addition to Auroville, do read up on Hassan Fathy and Persian dome construction, and also nubian vaults.
Compressed earth saves a ton of time, labor, and water. Plus, it is a lot stronger in compression (think pre-stressed).
Also, if you are really into domes, check out earthbags. They are considerably faster and don't depend so much on clay/sand ratios.
The reason is they are closer to a catenary shape (everything in pure compression). ...Persian domes take advantage of this, and are easier to build with basic adobe bricks.
Attached are images from Gernot Minke's Build with Earth showing Persian and Nubian dome techniques.
The catenary shape is the final shape I'm actually looking for, because, as you mentioned, all of it's members are in compression in such a way that the horizontal thrust is in the middle third of the base of the wall. -I just haven't figured an easy way to do it (easy as using the compass for the hemispheric domes).
Awesome images, by the way, from Gernot Minke's Build with Earth!
The earth bag method I'm slightly prejudiced against because I don't like encouraging the manufacture of plastics and the bags cost money (now, if you know a way a poor person could manufacture bags...maybe I'd weight this against my prejudice).
Does the use of a compressed earth machine really save time and labor? ....
I'm not sure how you could use words to explain how using a CEB press saves time and labor (other than the drying time which CEB has none if I remember correctly). But I'd listen if you're so inclined.
That's not a rhetorical question -I watched OpenSource Farm (now OpenSource Ecology) run a test on their first CEB machine... it took a lot of people to feed the machine and their conclusion, or should I say, Marcin's conclusion, was that it was no faster than building a cord wood wall. Of course, Marcin is geared towards fast machine production. (Now OpenSource Ecology says they have an automated CEB press, fed by a tractor, which meets their high production goal).
Campy in Nashville, Tennessee, USA wrote:
The results are impressive.
What do you propose would be the best way to water proof it?
I have thought these proof of concept designs would be good for animal enclosures.