If you are looking for a strong, local, cheap and eco friendly building material then compressed earth blocks (CEBs) should be in your shopping list. A compressed earth block is nothing but moist earth mixed with a stabilizer (cement or lime) and pressed into a brick form. There are a variety of manual and motorized presses available for making the blocks that could be installed on site. 
Compressed earth blocks are generally fine for load bearing construction upto 3 floors high.

Cement is normally used as a stabilizer (5%) but the choice of stabilizer depends on the type of soil. For sandy soil cement is preferred and for clayey soil, lime is the preferred stabilizer. If cement is used, the blocks must be cured for 4 weeks before use. Since there is no firing involved, the amount of CO2 emissions is about 8 times less compared to country fired bricks.

Its always a good idea to have the soil to be used for blocks tested. A good soil for CEB consist of 15% gravel, 50% sand, 15% silt & 20% clay. The ratio of these 4 components will vary based on the location but a simple analysis will help decide the ratio and type of recommended stabilizer.

Another variation of a stabilized compressed earth block is a compressed fly ash brick which consists of: 

  • Fly ash              50-70%
  • Coarse Sand      20-30%
  • Lime                 8-12%
  • Gypsum            3-4%

A simple manual press can produce about 1000 - 1500 blocks per day. For larger scale production and more consistent quality, motorized/hydraulic block machines are preferred. 

 

 

Resources:

http://taramachines.com/

http://www.earth-auroville.com/

http://www.adobemachine.com/

 

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Admin
Comment by Archisage on June 5, 2011 at 6:24pm

Architect
Comment by vandana naik on June 5, 2011 at 11:44am
ZED Habitats link is awesome...thanks for sharing!

Architect
Comment by Vishal Charles on June 4, 2011 at 7:31pm
@ Saket- Thanks for the link. Interesting stuff. I was reading through the features and specs of their projects -pretty cool for a developer. Definitely worth a visit. Have you been there?
Comment by Saket Sarraf on June 4, 2011 at 11:39am

Check http://www.ecobcil.com/

They are developers based out of Banagalore and use only stabilized blocks. Their works have been internationally acclaimed for adopting sustainable principles in a developer environment


Architect
Comment by Vishal Charles on June 3, 2011 at 9:08pm

Architect
Comment by Vishal Charles on June 3, 2011 at 8:59pm

Architect
Comment by Vishal Charles on June 3, 2011 at 9:02am
I know that New Mexico has adopted 'earthen building materials' in their local building code. I don't think any code specifically bars CEBs. That's for the US. In India, Stabilized CEBs shouldn't pose any problem...but in any case, at least a simple drop test should be done with each batch to make sure the blocks are good enough for construction.
@ Naveen - It'll be an interesting project. I'm tempted to try it in Jodhpur but I want to get some data on embodied energy of quarried stone blocks vs CEBs. Even then, if we have an earth sheltered (sunken) house, there'll be plenty of soil available right on site to build the blocks. You can't beat that!
Comment by ny306 on June 3, 2011 at 8:26am

Related book: Building with Earth: Design & Technology of a Sustainable Architecture.

@ Fryer: Good Question! I would think that Code Restrictions would mainly concern themselves with structural stability, Fire Resistance etc. I would think CEB's do comply if the mix is done right. Sometimes mixing straw for bonding can cause trouble if moisture build up occurs in the wall. Like Vishal points out, if the excavated soil is being used to create CEB's then the clay, sand and aggregate content of the soil becomes an important factor to determine strength. 

FYI - CEB's in the form of Adobe construction in regions like India, Iran, Yemen have lasted for centuries.It all boils down to execution. Moreover, it's extremely sustainable as there is no industrial assembly line or furnaces required to manufacture these.

@Vishal: Itching to do at least one project out of these. It would be interesting to see how soil from various regions create color characteristics in the block. That would make it even more contextual :) 

Comment by Robert P Fryer on June 2, 2011 at 11:48pm
Are there any code restictions for use of the CEB's ?

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