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GSBN: Digest for 2/15/05



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-> Rapport de Recherche: Construction en Blocs de Terre Comprimee
     by ArchiLogic@...
-> Re: GSBN:  compressed earth blocks
     by Bruce King ecobruce@...


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Date: 15 Feb 2005 11:48:22 -0600
From: ArchiLogic@...
Subject: Rapport de Recherche: Construction en Blocs de Terre Comprimee

Bruce, King of Sausalito wrote:

> Can anyone refer me to field experience and/or testing information
> (strength and durability, mainly) for compressed earth blocks without
> cement?

and Mike Faine M.FAINE@... wrote:

> There is a very good publication In Australia with the title "The
> Australian earth building handbook"

> I have designed one compressed earth block house that used
> a 5% (by volume) cement content. For our soils (in the Sydney basin)
> that seems to be about the right combination and accepted wisdom.

Dears Your High!ness and Mike;

I never thought I'd write the words "Australian" and "wisdom" in the same
sentence,
but the CMHC report whose title is mentioned in the subject heading seems
to agree
with the "accepted (Australian) wisdom" and expresses a high regard for
Australian
earthen block-building expertise.

In case WatJohn hasn't already given you a copy of the CMHC report,the
author, Ginette Dupuy (and archi-enginoidal sort) writes:

	"L'Australie est le pays qui a le mieux reussi a integrer la construction
	en terre, la technologie de la terre comprimee est une des mieux
maitrisee.
	En effet, vingt pour-cent des habitations neuves sont construites en
terre."

In the testing that Ginette wrote up in her report, the Quebecois mixes
seem to have required 3 - 5% Portland cement depending upon the native
soil composition of a particular area, which appears to agree with the
Australian experience.

Lots of nifty data/tables/graphs in the report including values for
density, (thermal)conductivity and resistance, heat capacity, freeze/thaw
resitance. permeability, ,water absorption, compression resistance etc.
(I'm guessing about 100 pages).

It's available en francais seulment as I've mentioned to this List
previously, but I would imagine that with email, some of our francophone
friends could easily translate those non- numeric portions where
translation may be required.

That being said, I wonder if the Californian testing might include some
samples using psyllium as the stabiliser, in place of Portland , just for
the heck of it ?

        ~~~ * ~~~
      Robert W. Tom
   Kanata, Ontario, Canada
ArchiLogic@...
(winnow the chaff from my edress in your reply)



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Date: 15 Feb 2005 12:31:52 -0600
From: Bruce King ecobruce@...
Subject: Re: GSBN:  compressed earth blocks




Howdy -

Many thanks to all of you who have responded regarding compressed earth
blocks.  Is it just me,
or is there a lot more happening in this area than, say, over the past
ten years?

I have many of the references y'all suggested, and have even read some.
  There is clearly a whole
library of good (and bad) material out there waiting to be absorbed.

Here's another debate starter:  my understanding about compressed earth
blocks so far is:

1)  Adding some cement
        benefits:  faster set (= faster to be useable), higher strength
and wear resistance
                             dearer to Building Officials everywhere
        detriments:  less ability to absorb indoor moisture, odors, and
pollutants, cost of cement,
                               hassle of 90 minute pot life before
compressing the mixture
                               not quite exactly biodegradable

2)  NOT adding any cement
       pretty much the opposite of above

Anyone want to comment on the above?  Also, please notice that I have
copied
this message to Tom Morton, a chartered Architect doing some
outstanding research in Scotland
(see www.arc-architects.co.uk ) with his wife and partner, Becky
Little.  I am grateful to them for banging
into my engineer skull (even more than many of you already have) that
cement is not always such a great
addition to earthen construction.


>> Thanks!
>>
>> Bruce King, PE
>> Director, Ecological Building Network
>> 209 Caledonia St.
>> Sausalito, CA 94965  USA
>> (415) 331-7630
>> fax 332-4072
>> www.ecobuildnetwork.org
>> bruce@ ecobuildnetwork.org


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