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Kiko Denzer on Art

[Cob] straw in cob or concrete?

Damon Howell dhowell at
Thu Aug 14 14:23:37 CDT 2008

	After I posted, I researched on internet and saw where the Egyptian  
government was experimenting and testing rice straw-cement bricks.  
They found they have a very low compressive strength (60psi), but I  
think maybe because they had too much straw. They did say they soaked  
the straw in sodium chloride for 48 hours, then dried it out before  
adding it to the cement mixture. That was to "neutralize" the  
carbohydrates in the straw, which keeps the cement from hardening,  
they said. So, why does it not make much difference in cob I wonder?  
Is it because concrete is a chemical reaction where cob is a physical  
one? My experience with pine straw is the dry stuff is extremely  
brittle and isn't good for building.

Damon in GA

On Aug 14, 2008, at 2:19 PM, Ron Becker wrote:

> They regularly put fiber in concrete. The only issue would be  
> chemical one. But pine needles would be even stronger and possibly  
> more impervious to adverse chemistry. I'm thinking of the long kind  
> here in the southwest.
> Ron
> Living and playing outside the box.
> On Aug 14, 2008, at 12:13 PM, Damon Howell wrote:
>> Good Day everyone,
>> 	This is kind of off the subject of cob but, maybe someone has done
>> it anyway. If straw is to cob as rebar is to concrete, why wouldn't
>> using straw in concrete work? I have a little concrete work to do
>> where I'm going to try that, unless that seems like a bad idea.
>> Damon
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