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Abe Connally
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Location: Chihuahua Desert
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Gypsum stabilization for adobe or cob.  Sounds very interesting:
http://www.castearth.com/Pages/cedesc.html
http://web.itu.edu.tr/~isikb/Tech1.htm
 
Jami McBride
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Anyone know if this is breathable like cob?
 
Abe Connally
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I would imagine that it would be very breathable, as gypsum is very porous, and when dried, this mixture is more porous than cob or adobe.

It would be a lot faster to make than cob as well.
 
Jami McBride
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Thanks

Seems this guy promotes working CE/Alker similar to the processes used for cement = limited crew, wooden forms and large machinery.  This is because of it's pourable state and that it sets so fast.  So what if machinery wasn't an option..... could this be mixed and poured in repeated applications by a couple of people to build a wall?  Or put another way, what are it's low-tech applications? 

Hum.... I found some information about CE from a different source.  It is not water proof/resistant and this needs to be addresses in the mix depending on it's intended use.  And because the exact mix is patent pending how to slow down the setting up process is secret unless you become licensed.

Very cool stuff!

 
Abe Connally
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Look at this for more info on lower tech methods used in Turkey:
http://web.itu.edu.tr/~isikb/Tech1.htm

Forms are really not high-tech, and make a job a lot easier (don't use wood forms, use metal). Even adobe uses forms, but by pouring straight to the wall, you only move the material once.  You don't have to have a full height form, 1 or 2 feet tall is plenty.

Check out our Tbrick form method:
http://www.velacreations.com/adobe.html

For machinery, get a concrete mixer.  I've mixed a few homes by hand using adobe and concrete, and I would never recommend it to someone who is not in peak physical shape.  A concrete mixer is easy to use and really saves a lot of work.  Plus, it makes things go a bit faster.

I don't know that Alker would appropriate for a cistern (it's not cement, it's more like rammed earth or adobe), but for a wall, yes.

The fact that it sets up so fast is interesting, because you don't have to cure, or wait for things to set up.  I can see it being useful for pouring vaults or domes without the need for cement.

The thing to do is make up a few small test batches and see how it works for you.  Start off making a brick, then go a bit larger, figuring out what works best for you.

I usually size my forms to take a mix from the mixer, so usually about 1.2 cubic feet at once.  But, with something that sets up a lot faster, your forms could be a lot bigger, saving time and energy setting up the forms.

 
Jami McBride
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Do you use lime in your mix?

How would you address the water repelling issue?

Thanks
 
Abe Connally
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Location: Chihuahua Desert
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ok, just to be clear, I have not used the Alker method.

For my adobe, I have used lime and cement for stabilization (5-10%).

For water repelling of adobe, a combination of good roof with a sealant, like lime plaster, or linseed oil.

I would expect that this would be the same for the Alker method, some sort of external sealant would work just fine.

It also depends on where you are.  In some climates, earth walls can go years without worrying about a sealer.
 
Jami McBride
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Oh, thanks for clearing that up    and all the information.

I'm excited to try my own experiments with CE . . .
 
                                
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Jami McBride wrote:
Do you use lime in your mix?

How would you address the water repelling issue?

Thanks


well, if you're also concerned with assuring high thermal mass within the structure, you could install insulation and siding on the outside of the walls to deflect moisture in the traditional way -
 
Jami McBride
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Thanks Joan,

That would work, but I was thinking along the lines of trying it out for landscaping uses first.  Stepping stones, retaining walls and such.  It would be in contact with wet soil for most of the year here in Oregon. 

So I was wondering if I could add something to make the mix water proof and save money over using a waterproofing sealer after it dried.  Sorry I wasn't clear.

 
Abe Connally
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Jamie,

Put it up on a rock foundation off the ground, and that will help with the moisture.

How well does cob do unprotected in your area?  Another thing you can do, especially for small walls, is top them with flat rocks, like a little roof, and that will help them shed water.

It may be that it is not appropriate for your climate.
 
Glenn Bundesen
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First, I apologize for necro'ing a 6 year old thread.


I ran across mention of two additives to an Alker type mix that would extend the working time before it set up.
IIRC it was-
15% calcined gypsum (plaster of paris)
2.5% hydrated lime
1.66% Molasses (yes, apparently it's also used as an additive in portland cement based concretes as well)
0.833%  Calcium Lignosulphonate (to Plaster of Paris dry wt)

Working time before it sets up is around 2 hours 15 minutes. 
Should produce a brick that has about 620 psi on a crush test, or about double adobe.

I'm wondering about pouring walls with it using slip forms.  If I make the height of the forms twice the height of a pour I should be able to leapfrog the form up the wall as the "bottom" pour has set up but while the "top" pour is still workable, thus preventing and "cold" joints.  Or so I'm thinking....


 
What could go wrong in a swell place like "The Evil Eye"? Or with this tiny ad?
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