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[SB-r-us] Fermentation as workability enhancement for Earthen Plasters [Fwd: GSBN: Digest for 10/12/07]



Here's another excerpt from a GSBN List digest that I've only just now  
gotten around to
looking at.

Perhaps when Wild Bill-bob gets back from his 10-day colloquium cruise,  
WBb can set up something at the GSBN List whereby messages with technical  
content get copied directly to SB-r-us so that they are archived and  
accessible to any and all.

The non-technical messages, like those re: membership are probably best  
left off of this List.

(And while you're at it WBb, you might check to see  why it is that my  
postings to GSBN aren't getting through.)

			=== * ===

On the subject of fermentation that Beel and Graeme discuss (below), I'm  
thinking that the enhanced workabilty is not unlike the enhanced  
workability of cementitious mixes (ie concrete and Portland cement  
plaster) when air entraining admixtures are used.

When used with Portland cement plaster or concrete mixes, air entraining  
admixtures have the effect of making the "mud" more "creamy", almost like  
shaving cream (but with stones and coarse sand particles in it), a quality  
which, when found in a plaster, as you would imagine, makes it much easier  
to work with on vertical surfaces.

The air entraining admixtures also impart the quality of better moisture  
retention to the mix. ie If you've ever navigated a wheelbarrowful of wet  
concrete over rough terrain, you will likely have noticed a accumulations  
of green "juice" ... water that has separated out of the mix.  Or if  
you've left a wheelbarrowful of wet concrete sitting for awhile, you might  
find the same green juice. When air-entraining admixtures are used, that  
separation of the critical mixing water does not occur.

In addition to the enhanced workability/moisture retention of the  
still-wet cementitious mixes, when fully cured and hardened,   
air-entrained concrete posesses the property of better frost resistance  
because the voids allow moisture some room to expand as a result of  
freezing, thereby relieving expansion stresses and the likelihood of  
spalling.

Lack of frost resistance is one of the weaknesses of clay mixes and is  
probably the biggest reason why they aren't used more extensively in  
locales where severe freezing occurs.

Although I have no direct experience with earthen plasters, I can't help  
but wonder if the addition of newspaper or office paper to the plaster mix  
and and its fermentation
are necessarily Good Things in the long term ?

I suspect that most people know what happens to newspaper and white paper  
over time as a result of the bleaching process that was used during its  
manufacture. In time, the fibre degrades and disintegrates due to the  
residual acid content.

Degraded/disintegrated fibre = no fibre= no long-term tensile  
reinforcement in the plaster

The fermentation process (that yields the bubbling that seems to be the  
equivalent of air entrainment admixtures) also suggests to me that there  
is some degradation of the fibre occurring as well, and I would suspect,  
with the same implications as above.

Like proper water : cement ratios, proper proportions of air entraining  
admixtures are also critical. Too much will result in a severely weakened  
mortar.

Plain, ordinary laundry detergent powder is often used as a air entraining  
admixture in cementitious mixes. A potential problem with soap though is  
that the surfactants do funny things like render Tyvek useless at  
preventing the passage of liquid water.


============== Forwarded Material ==================
Date: 12 Oct 2007 10:27:21 -0500
From: Athena & Bill Steen absteen@...
Subject: Re: GSBN: Earth plasters

Graeme,
Couple of things. First of all (laughing), plastering in NZ I think
is a tad bit different than dehydrated parts of the world such as
where I live. I suspect Andy's part of the world is in the dehydrated
category.

But on to what you said about fermenting plaster. I have found that
the longer any earth plaster ages the better it seems to get.
Especially this applies to those containing some fiber whether it be
straw or paper.  Even for short periods of time we've had large
batches of clay and straw plaster rise like bread dough, quite
amazing.  The only objectionable thing about longer periods is that
there is a definite organic odor that comes with it.  Personally it
doesn't bother me, but others don't get overly excited about it.  To
see if I can help those who are sensitive we've started some
experimental batches with EM, a product known as Essential
Microorganisms to see if it alters the process somewhat.

Anyhow, what I like about the fermented mixes is that the character
of the mix changes entirely.  It is hard to describe, but it becomes
much more pliable, plastic, easy to work and the breakdown of fiber I
suspect makes it less susceptible to mold when drying in wetter
conditions.

The only down side about adding too much paper for an interior
plaster is that you're going to sacrifice thermal mass and since that
is an impt ingredient when it comes to the performance of a SB
building it would seem we don't want to sacrifice that.

Bill
On Oct 10, 2007, at 2:05 PM, Graeme North wrote:

> We have found the addition of pulped paper as a fine fibre very
> very good.
> Its made either from office paper or newspaper  it can be made by
> throwing soaked paper into a concrete mixer with lots of water and just
> letting it roll until completely broken up , then draining off excess  
> water
> before use.
> It gives a very fine fibre which is enormously beneficial in terms of
> increasing strength, and durability of earth plasters. If it
> ferments a bit even better (all ferment seems to help earth plasters   
> using water
> that has had a bit of straw left in it for a week or two to start to  
> fizz is
> good as well)  - there appears to be some enzymic reaction that takes  
> place
> between paper or ferment water and clay that helps workability and  
> durability.
>
> Paper pulp eliminates dusting from earth plasters  helpful
> especially if
> the soil is a bit silty.  It also sticks well  we use it over
> pre-compressed straw without meshing.
> We also use it as a finishing plaster over drywall  a very nice
> finish and
> it sticks like ...glue.
>
> It is also very effective as an additive to earth bricks as well
> increases
> robustness, durability, and also lowers density giving better
> insulation.
>
> The amount of paper pulp that can be added can be quite high  - we
> often use
> up to around 30% or so by volume to plaster , and have made mud
> bricks with
> up to 50% paper pulp  cardboard houses anyone?
> I am currently looking at building with cob and mud brick mixes using
> roughly 2 parts clay-soil, 2 parts wood shavings (long fibered
> rippings) or
> straw, and 1 part paper pulp  very tough, very light, easy to work,
> and
> looking promising.  Very good insulation, and very nice to use as
> gravity
> increases  remember that there is plenty of evidence that gravity
> doubles
> in strength very thirty years.
>
> As to lime over earth  I1ve found it works well so far IF there is
> good
> keying and wetting  if the initial earth is a cob type mix with
> lots of
> (straw) fibre with plenty of fibres left hanging out of a rough
> surface,
> then that is good too for tying the layers together.
>
> I1ve just lost a patch off a bit of a small experimental earth
> plastered and
> whitewashed straw wall where the earth plasters layers were not
> keyed well
> together. Keying is good.
>
> Best
>
>
> Graeme,
> Graeme North Architects,
> 49 Matthew Road,
> RD1, Warkworth,
> New Zealand 0981
> Ph/fax +64 (0)9  4259305
>
> ecodesign@...
> www.ecodesign.co.nz
>
>
>
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>

Athena & Bill Steen
The Canelo Project
HC1 Box 324
Canelo/Elgin, AZ 85611
absteen@...
www.caneloproject.com




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

Date: 12 Oct 2007 18:52:29 -0500
From: MattsMyhrman@...
Subject: Re: GSBN:Re: Lime plaster problems

In a message dated 10/10/2007 1:17:11 PM US Mountain Standard Time,
andy@...:

> Sometimes however lime plaster
> was not used and rather a cow dung earth plaster was used followed by
> regular coats of lime wash...though at the coast where we experience  
> strong
> wind driven rains a lime coating was the norm.

I believe that many of the cob buildings on the southern coast of England
(Devon?) used several (maybe 4-5 initially) coats of lime wash.  It was
considered somewhat sacrificial, and was followed up, after a year or two,
with a
couple more coats.  After that, another coat every couple of years.  Maybe
Barbara
Jones can check in on this  one, and also tell us whether lime wash over  
cob
or earth plaster has traditionally been used anywhere in the British Isles
where they experience driving rains coming in off the sea (up on the  
northwest
coast of Scotland?).


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Date: 12 Oct 2007 19:57:56 -0500
From: MattsMyhrman@...
Subject: Re: Pulped Paper as a Fiber Source

In a message dated 10/10/2007 2:09:04 PM US Mountain Standard Time,
ecodesign@...:

> We have found the addition of pulped paper as a fine fibre very very  
> good.
> Its made either from office paper or newspaper ­ it can be made by
> throwing
> soaked paper into a concrete mixer with lots of water and just letting it
> roll until completely broken up , then draining off excess water before  
> use.
> It gives a very fine fibre which is enormously beneficial in terms of
> increasing strength, and durability of earth plasters.

Here's a different use of newspaper-sourced fiber.

The top part of my strawbale igloo/office first got a well-scratched layer  
of
earth plaster.  The "scratching" was done with a commercial tool that gives
flat-topped ridges and flat-bottomed valleys that have straight, vertical
sides
 from the top of the ridges down to the bottom of the valleys.

I then troweled on an approximately 1/4 inch thick layer of a mixture of
free, recylcled latex paint and cellulose ceiling insulation (essentially
shredded
newspaper).  To test the bonding between this cello-latex and the  
underlying
earth layer, I applied some onto a similarly scratched earth test tile.   
When
I peeled off the cello-latex, the separation occured not where the c-l met  
the
earth, but, rather, slightly within the earth base, leaving the entire  
bottom
of the c-l covered with a thin layer of earth.

The final layer was a thin, rolled on coat of UV-resistant elastomeric roof
paint.

The performance so far has been outstanding, keeping everything inside
absolutely dry.  Totally non-air-permeable, but tighter than a frog's ass,  
and
that's water-tight.

Matts (feeling the fiber) Myhrman




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Date: 12 Oct 2007 20:09:25 -0500
From: Tom Hahn tomhahn@...
Subject: Re: GSBN:Re: Pulped Paper as a Fiber Source

Sheer poetry, Matts... (pun intended)

That made me chuckle pretty hard...

Tom Hahn


> ... keeping everything inside
> absolutely dry.  Totally non-air-permeable, but tighter than a frog's  
> ass,
and
> that's water-tight.
>
> Matts (feeling the fiber) Myhrman


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

Date: 12 Oct 2007 21:10:10 -0500
From: Graeme North ecodesign@...
Subject: Re: GSBN: Earth plasters

> Hi Bill and others - thanks
>
> I agree totally that long mixing and aging is good for plasters.
>
> And sometimes yes we long for a bit of dehydrated climate - esp when the
mould
> starts growing on us!
>
> An earth/straw house actually makes one hell of a difference in comfort  
> in
> this soggy climate - no more condensation on even single glazed windows
(with
> passive solar design to trap some heat into the mass of the house) - no  
> more
> mould on items such as leather shoes - plenty of spiders to share the  
> house
> with -
>
> Be really keen to hear how you find EM - I1ve just discovered it for the
> garden - it seems to be magic - it may take away that good old fermenting
> smell.
>
> As to significant thermal mass in straw houses - I1m a bit of a fan  
> myself
of
> straw for exterior walls, earth for interior walls and floor, and don1t  
> try
> and pursue much out of the earth plasters where it is going to be pretty
> minimal anyway - and of course only the final plaster of only a few mm  
> thick
> needs the paper additive anyway come to that.
>
> And  - I1ve never found swelling of cellulose fibres to be an issue, even
with
> quite high percentages - its really saturated when we use it - esp if its
been
> sitting a while - and anecdotally - a building near here that burned down
had
> the firemen puzzled because the dry wall was in much better shape than  
> the
> firemen expected to see after a fire - the clay/paper plaster had added
> significant extra protection.
>
> Finally - Limewash over clay- yes toughens up the surface no end -  
> -however
I
> have found on experimental and historic walls that IF the wall gets so  
> wet
> that water gets into the underlying earth plaster, differential swelling
takes
> place and the whitewash spalls off in my humble experience.  If the walls
are
> getting this wet probably something wrong with the design anyway.
>
>
> Graeme
>
>
>
> Couple of things. First of all (laughing), plastering in NZ I think
> is a tad bit different than dehydrated parts of the world such as
> where I live. I suspect Andy's part of the world is in the dehydrated
> category.
>
> But on to what you said about fermenting plaster. I have found that
> the longer any earth plaster ages the better it seems to get.
> Especially this applies to those containing some fiber whether it be
> straw or paper.  Even for short periods of time we've had large
> batches of clay and straw plaster rise like bread dough, quite
> amazing.  The only objectionable thing about longer periods is that
> there is a definite organic odor that comes with it.  Personally it
> doesn't bother me, but others don't get overly excited about it.  To
> see if I can help those who are sensitive we've started some
> experimental batches with EM, a product known as Essential
> Microorganisms to see if it alters the process somewhat.
>
> Anyhow, what I like about the fermented mixes is that the character
> of the mix changes entirely.  It is hard to describe, but it becomes
> much more pliable, plastic, easy to work and the breakdown of fiber I
> suspect makes it less susceptible to mold when drying in wetter
> conditions.
>
> The only down side about adding too much paper for an interior
> plaster is that you're going to sacrifice thermal mass and since that
> is an impt ingredient when it comes to the performance of a SB
> building it would seem we don't want to sacrifice that.
>
> Bill






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-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at chaffY a h o o  dot  c a >
manually winnow the chaff from my edress in your reply



 
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