[Strawbale] Geopolymeric Cements

[Chris Green]

Hicks, Shawn wrote:
> Hello
>
> George Monbiot in his book Heat talks about geopolymeric cements being
> made from readily available materials (including wastes) and being
> produced at a much lower temperature than other cements.  My local
> concrete folks have never heard of them.  Does anyone have any
> experience with these?
>
> Thank you  
>
>   
Until recently I have a history of being highly skeptical of the claims 
made by the people who are promoting this stuff. However,  Prasad 
Boudreaux, a member of the Organic_Architecture Yahoo Group who lives 
and works in Oregon, has been experimenting with geopolymer cements, so 
my skepticism is being tempered a bit.

Prasad was kind enough to send along a recipe he worked out for 
geopolymer cement to the O_A list last month. I haven't tried this yet, 
but here is an edited copy of his recipe post for those who want to try 
making some.

Safety First: When using lye, be sure to wear eye protection and gloves.

Prasad and Shahoma McAlister make glasscrete countertops and work with 
earthen plasters, which can be seen at their web site here:

www.mixingitup.us


Cheers,

Chris Green.
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> > To: organic_architecture at yahoogroups.com
> > From: shahoma prasad
<snip>
> > Date: Sun, 25 Mar 2007 09:58:34 -0700 (PDT)
> > Subject: Re: [organic_architecture] Re: geopolymer
> > cements, recipe
> > 
>   
>> > > For anyone who might be interested, here is a
>>     
> > starting point for a simple geopolymer recipe. In
> > Joy,
> > Prasad 
>  
>   
>> > >  Geopolymer Cement notes.
>>     
>  
> > The making of alkaline solution,
> > 
> > *12 hr before mixing, slowly! disolve 320gm sodium
> > hydroxide (pure lye, as in a drain cleaner) into a
> > liter of water. This should be stirred in  slowly,
> > with care, wearing gloves and goggles as it is very
> > caustic. This mix will generate some heat while
> > dissolving.
> > 
> > *After the lye solution is fully dissolved (12hr) mix
> > one part lye solution with 2 1/2 parts sodium
> > silicate. (availible at pottery supplies)
> > 
> > * Basic recipe #8
> > 4 1/2 parts metakaolin
> > 1/2 part lime (type s)
> > 8 parts aggregate (sand mix)
> > alkaline solution as needed (about 1/3 the amount of
> > metakaolin and ash, by weight)
> > 
> > *Mix all the dry ingredients together then stir in
> > just enough alkaline solution to make a stiff mix.
> > Keep the liquid content as low as possible.
> > Cure like concrete, warm and moist.
> > 
> > *Class C Fly ash can replace the metakaolin and
> > lime,
> > if its type F fly ash replace only the metakaolin. 
>   
<snip>
> > Geopolymer concrete negates the need for Portland
> > cement as a binder. Instead, materials such as fly
> > ash
> > are activated by alkaline liquids (most often at
> > temperatures below 150 degrees Celsius) to create
> > the
> > cement. Hence concrete can be produced without the
> > need for large quantities of fuel, making it far
> > more
> > energy efficient, and avoids much of the
> > environmental
> > pollutants associated with traditional Portland
> > cement production.
> > 
> > It takes only a moment to realize the peace that is
> > already alive within you.
>   
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