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earthcrete

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posted 15 years ago

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I was wondering about structural integrity of earthcrete with bamboo or wood used instead of rebar for tensil strenght. Does it seem that rebar has a different expansion/contraction rate than that of earth, causing potential cracking or is rebar the structural integrity needed. Any leads would be great.

Leah Sattler

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posted 15 years ago

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all I know is that the rebar is required to hold the concrete together during heaving. I'm no expert but rebar has some properties significantly different than bamboo. one of which is the ability to flex some with out breaking. and obviously its simple strength. I would hesitate to replace the rebar with anything.

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Jeff Mathias

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posted 15 years ago

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I believe China often uses bamboo in place of rebar in concrete with some success. Also I have seen pictures of scaffolding and bridges made entirely of bamboo as well.

Check out this thesis paper for most of the info I think you are looking for:

GUIDELINES FOR BUILDING BAMBOO-REINFORCED MASONRY IN EARTHQUAKE-PRONE AREAS OF INDIA

http://www.usc.edu/dept/architecture/mbs/thesis/thesis_2002/shreemathi%20iyer..pdf

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posted 15 years ago

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Many thanks for the advice. The thesis was good.
Sustainable on....

paul wheaton

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posted 15 years ago

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Earthcrete? Would that be dirt with portland cement mixed in?

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posted 15 years ago

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I think descendingeagle is talking about earth stabilized with cement paul. We have been discussing using this method on our next home. It doesn't take more than about 5 percent cement to make an amazing difference in the integrity of the earth.
I read somewhere that some people building rammed earth houses are doing this without any sort of reinforcing.
I wondered if it would be worth it to do this with tires. Build using them like an earth ship, only instead of ramming the earth into the tire, cut out one sidewall, lay it down like normal, then fill it with the earth cement mixture, compact it with a plate compactor or similar, and let it set. Don't know if it would be necessary or not but it is something we are thinking about. Thought about it for use with earthbags too.

paul wheaton

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posted 15 years ago

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I read a few things in gaviotas along these lines that I thought was interesting.

One was that they would mix one part portland cement with 14 parts soil. Then they would fill burlap sacks with this mix and build dams for ponds.

Another was where they would fill a sort of long balloon with air, lube it up and then cover it with the mix. When it had cured, they would deflate the balloon and pull it out: instant pipe-like thing!

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Joel Hollingsworth

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posted 15 years ago

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Paul: the recipe you gave doesn't specify what it means by "soil", so I trust it about as much as one that has "food" as an ingredient. My grandma's casserole works OK on that method, but that generality may come at a price.

In some cases (my part of the world, for example), I've heard lime is more appropriate.

Lime has only every limited effect on soils with a high organic matter content (content higher than 20%) and on soils short of clay. It is more effective and can be more effective than cement on clay-sand soils and especially on very clayey soils. The effects of lime are thus highly dependent on the nature of the soils involved but a comparison with the effects of cement can, in many cases, be attempted.

The ebook that produced this quote (link below) seems very good from what I've read so far.

http://nzdl.sadl.uleth.ca/cgi-bin/library.cgi?e=d-00000-00---off-0hdl--00-0----0-10-0---0---0direct-10---4-------0-1l--11-en-50---20-help---00-0-1-00-0-0-11-1-0utfZz-8-00&a=d&c=hdl&cl=CL1.16&d=HASH05930481a9804a3ba0dd4a.6

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paul wheaton

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posted 15 years ago

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True!

Of course, in the book, they describe their soil and it sounds pretty lame. "Gravelly dirt" might be a better fit. And, not a good universal ingredient for this sort of thing.

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So I left, I came home, and I ate some pie. And then I read this tiny ad:

Unlock Free Wood Plans! Download free projects and create unique pieces now!

https:/the-art-of-regenerative-wood-working/