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Re: GSBN:Interesting test results


for lime one layer should not exceed more than 10 mm due to moisture
protection, so building up thickness traditionally is done in layers
(normally 3). Does this team is confirming this tradition?


----- Original Message -----
From: "Chris Magwood" TLSEditor@...
To: "GSBN" GSBN@...
Sent: Thursday, December 09, 2004 1:35 AM
Subject: GSBN:Interesting test results

> Hello all,
> I was just giving a talk for the Engineering Department at Queen's
> University in Kingston, Ontario last week. There is a prof/student
> team there doing some testing work on bale walls, and I was able to
> check out the results of what they've been doing. Very interesting...
> They set out to try to determine if they could establish a minimum
> strength for a plaster for a load-bearing bale wall. They made a
> series of mixes of a 75% lime/25% portland mix, from intentionally
> weak to as strong as they could brew it. They then plastered single
> bales with these mixes, at three different thicknesses per mix.
> Their results indicate that the actual strength of the plaster had
> much less effect on the working strength of the plastered bale than
> did the thickness of the plaster. So making a really strong plaster
> is not as important as putting it on the wall thickly.
> They are now busy writing up the results, and will present them in
> TLS later this winter, but I thought I'd share this with you for your
> cogitation.
> Along the same plaster strength lines, this summer I had to send some
> test cubes of earthen plaster to a lab for testing before the
> engineering firm would let us use earth plaster for a load-bearing
> building. Our samples (taken directly from the wheelbarrows of goop
> that were going on the wall at the time) came back in the range of
> 2.1 to 2.4 MPa. This didn't mean much to me until I saw the test
> results from the lime/portland mix (taken at 28 days) at Queen's,
> where their strongest mix was a 1.7 MPa. I know that a lime-rich
> plaster likely takes more than 28 days to reach full strength, but I
> was encouraged by the comparison, and the Queen's guys were well
> astounded at the earth plaster figures. Especially since the earth
> plaster goes onto the wall more thickly than the lime/portland.
> Thanks to both of you who've already tackled a Myth/Reality article
> for the next issue of TLS. Anybody else?
> Cheers,
> Chris
> --
> ***************************
> Chris Magwood / Camel's Back Straw Bale Construction
> <a  target="_blank" href="http://www.strawhomes.ca";>http://www.strawhomes.ca</a>
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> The Last Straw Journal?
> You should!
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