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GSBN: Digest for 10/2/02



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-> Re: GSBN:test results
     by Paul Lacinski paul@...
-> Re: GSBN:test results
     by Athena & Bill Steen absteen@...
-> Re: GSBN:test results
     by Bruce King ecobruce@...
-> Re: GSBN:test results
     by Derek Roff derek@...


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Date: 2 Oct 2002 13:38:56 -0500
From: Paul Lacinski paul@...
Subject: Re: GSBN:test results

Bruce,

Well yes, I find this just as perplexing as everyone else, since it 
contradicts my experience just as directly as everyone else's. 
Here's what I did for a test:  I brought a piece of an old chair 
around to the back wall of our house, which is partially covered by a 
lime-stabilized clay plaster, about 1" thick, and partially covered 
by this same plaster with a 3/8" lime/sand finish coat.   (The system 
that we always use.)  I then attempted to gouge these two plasters 
with the corner of the chair, mimicking, as best I could, a portly 
and slightly drunk matri or patriarch jumping up from the table to 
answer the door or phone or whatever.  And what do you know, the 
lime-coated wall is much more resistant to this type of abuse than 
the clay-only wall.

So, having re-examined the field conditions,  I am led to wonder what 
might possibly have been different about the lab conditions.  The 
only idea I have is that 2" is much thicker than I would ever go with 
lime, without a pozzolanic additive.  (We have poured 2-3" thick lime 
concrete with ground bricks or pottery as a pozzolan and come up with 
compressive strengths that, while never tested by the psi, are 
definately much better than could ever be achieved with earth. 
(Children jumping around on windowsills made of this material seem to 
have no effect.)  I know what when you pick up a chunk of dropped 
lime plaster that has been sitting around for a few weeks at the base 
of a wall, the surface (3/8" or so) will be well set, while the 
material below will be quite weak.  I've gouged these limeplops with 
a screwdriver before, just to see.  The surface is about as hard as a 
finshed plaster; the underside is not much better than the gypsum in 
wallboard.

So, maybe we have a situation where the lime didn't cure much, except 
on the surface,  and the cement dried out too quickly to cure 
properly.  If there are any samples left intact, it would be 
interesting to go at them with an awl or screwdriver, to test this 
theory.  Also- is there any chance it was a bad batch of lime?  Was 
the bag of lime left around the lab for awhile before it was used? 
Was it leftover from a site somewhere?  Is there any chance it got 
damp?

Maybe someone could look at a bit of this material under the special 
microscope (whatever it's called) to check on the cement crystal 
growth?

In any case, thanks again for all of this work.  Whether or not I 
like the outcomes, I'm very happy that the sb world is moving beyond 
testing plasters with the back of a chair.

Chhers,

Paul
- -- 
Paul Lacinski
Amy Klippenstein
GreenSpace Collaborative
Sidehill Farm
PO Box 107
463 Main St.
Ashfield, MA 01330 USA
01-413-628-3800


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Date: 2 Oct 2002 17:34:56 -0500
From: Athena & Bill Steen absteen@...
Subject: Re: GSBN:test results

Once again, I would echo these comments.  And I would add something that 
hasn't come up yet as a possibility and that they the method(s) used for 
testing.  In that I don't recall exactly what the procedure was, could 
it be that there were errors in the way the testing was carried out?

Bill

On Monday, September 30, 2002, at 03:30 AM, Paul Lacinski wrote:

> Bruce,
>
> Well yes, I find this just as perplexing as everyone else, since it 
> contradicts my experience just as directly as everyone else's. Here's 
> what I did for a test:  I brought a piece of an old chair around to the 
> back wall of our house, which is partially covered by a lime-stabilized 
> clay plaster, about 1" thick, and partially covered by this same 
> plaster with a 3/8" lime/sand finish coat.   (The system that we always 
> use.)  I then attempted to gouge these two plasters with the corner of 
> the chair, mimicking, as best I could, a portly and slightly drunk 
> matri or patriarch jumping up from the table to answer the door or 
> phone or whatever.  And what do you know, the lime-coated wall is much 
> more resistant to this type of abuse than the clay-only wall.
>
> So, having re-examined the field conditions,  I am led to wonder what 
> might possibly have been different about the lab conditions.  The only 
> idea I have is that 2" is much thicker than I would ever go with lime, 
> without a pozzolanic additive.  (We have poured 2-3" thick lime 
> concrete with ground bricks or pottery as a pozzolan and come up with 
> compressive strengths that, while never tested by the psi, are 
> definately much better than could ever be achieved with earth. 
> (Children jumping around on windowsills made of this material seem to 
> have no effect.)  I know what when you pick up a chunk of dropped lime 
> plaster that has been sitting around for a few weeks at the base of a 
> wall, the surface (3/8" or so) will be well set, while the material 
> below will be quite weak.  I've gouged these limeplops with a 
> screwdriver before, just to see.  The surface is about as hard as a 
> finshed plaster; the underside is not much better than the gypsum in 
> wallboard.
>
> So, maybe we have a situation where the lime didn't cure much, except 
> on the surface,  and the cement dried out too quickly to cure 
> properly.  If there are any samples left intact, it would be 
> interesting to go at them with an awl or screwdriver, to test this 
> theory.  Also- is there any chance it was a bad batch of lime?  Was the 
> bag of lime left around the lab for awhile before it was used? Was it 
> leftover from a site somewhere?  Is there any chance it got damp?
>
> Maybe someone could look at a bit of this material under the special 
> microscope (whatever it's called) to check on the cement crystal growth?
>
> In any case, thanks again for all of this work.  Whether or not I like 
> the outcomes, I'm very happy that the sb world is moving beyond testing 
> plasters with the back of a chair.
>
> Chhers,
>
> Paul
> -- Paul Lacinski
> Amy Klippenstein
> GreenSpace Collaborative
> Sidehill Farm
> PO Box 107
> 463 Main St.
> Ashfield, MA 01330 USA
> 01-413-628-3800
> ----
> For instructions on joining, leaving, or otherwise using the GSBN list, 
> send email to GSBN@...HELP in the SUBJECT 
> line.  ----
>



----------------------------------------------------------------------

Date: 2 Oct 2002 18:09:47 -0500
From: Bruce King ecobruce@...
Subject: Re: GSBN:test results




on 9/30/02 3:30 AM, Paul Lacinski at paul@...:

> Well yes, I find this just as perplexing as everyone else, since it
> contradicts my experience just as directly as everyone else's.

Thanks for the note, Paul . . we're going to keep looking into it.  I just
met with the local rep for a French natural hydraulic lime (St. Astier), and
they might be willing to spring for additional tests, with better control,
that would hopefully give better results.

best,

Bruce



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Date: 2 Oct 2002 18:52:09 -0500
From: Derek Roff derek@...
Subject: Re: GSBN:test results

While I am in favor of more tests, I have doubts about the use of 
hydraulic limes with SB, which perhaps someone who knows more can 
answer.  Hydraulic limes form various compounds as they cure, in 
addition to the simple ones that we expect from lime plasters.  They 
have things in common with pozzolans and portland cement, both 
chemically and in the sense that they set up soon after mixing, even 
under water.

Some of us like lime plasters because they are fairly vapor 
permeable, easy to repair, have a long working time, and can be 
stored wet for years.  I know that the last attribute is not shared 
by hydraulic lime.  I suspect that the others might not be.  Can 
anyone comment?

Derek

- --On Wednesday, October 2, 2002 4:01 PM -0700 Bruce King 
ecobruce@... wrote:

> on 9/30/02 3:30 AM, Paul Lacinski at
> paul@...:
>
>> Well yes, I find this just as perplexing as everyone else, since it
>> contradicts my experience just as directly as everyone else's.
>
> Thanks for the note, Paul . . we're going to keep looking into it.
> I just met with the local rep for a French natural hydraulic lime
> (St. Astier), and they might be willing to spring for additional
> tests, with better control, that would hopefully give better
> results.
>
> best,
>
> Bruce

Derek Roff
Language Learning Center, Ortega Hall Rm 129, University of New Mexico
Albuquerque, NM 87131  505/277-7368 fax 505/277-3885
Internet: derek@...


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