[Greenbuilding] geopolymer or alkali activated cements

[Ocean Swells]

DJ,

Thanks for that article.  I had stumbled upon it before but did not
read it.  After your encouragement I read it and am glad I did.  Like
I said, I'm no chemist, but, one difference I see between what
Davidovits (Geopolymer Institute) did, and the roman cement in this
article, is that Davidovits mixed sodium carbonate (washing soda) with
the hydrated lime.  I believe this produces Lye (sodium hydroxide) +
calcium carbonate, which mixed with kaolin clay, or pozzolan produces
water glass (sodium silicate).  I wish someone could confirm this.
(The list has been talking about sodium silicate as a wood preserver.)
 I think sodium silicate is key to geopolymers.

Davidovits also compacted (rammed earth) his concoction.  However, he
originally completely saturated the mix with water and let it dry over
a week until it had zero slump.  Then he compacted it.  I don't know
if there would be difference to that method over the method of just
lightly hydrating a mix.

Anyway!  Let the experimentation begin!  I currently have some
hydrated lime and sodium carbonate.  I'm going to have to get my hands
on some of the volcanic ash.  I also want to try some red dirt
(oxisol) and crushed volcanic cinder.

Jason


On Sun, Apr 17, 2011 at 12:11 PM, David Walker <djudw at hotmail.com> wrote:
> There are several pages discussing various kinds of cement in "Heat: How to
> Stop the Planet from Burning", by George Monbiot.  He mentions geopolymer
> cement, as well as pozzolan cements used by the Romans.  A website reference
> he gives in the notes is the following:
> http://www.romanconcrete.com/Article1Secrets.pdf    I hope it is of interest
> to you.
>
> Regards
> DJ
>