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GSBN:netting, fibers, geotextiles, etc.



<x-rich>I've been thinking about this one for a few days and I think the best
place to start may be back with Bruce's first post.  The objection to
the coir netting was, if I remember correctly, was that the
spaces/openings were too small and interfered with the volume of straw
in the mix.  Before talking about that, in my opinion and through
comments from Japanese friends, my opinion is that when it comes to
choosing a fiber, the coir will be the longest lasting and superior
when it comes to strength.  So if at all possible I would explore
every avenue possible to use it, unless another version was discovered
that had bigger openings.  How to use it?  One option would be to go
for a mix with less fiber, perhaps a lime/clay along the lines
suggested by Harry.  Another would be to place it between layers of
plaster.  I know the thought of applying one layer of plaster and then
rolling out the netting so that it is embedded in the mix before the
next layer goes on isn't all that attractive, but it is not
impossible.  Samples we've made in the past show them to be remarkably
strong when it comes to shear (homestyle testing).  


One more option, I'm sure the engineers will love this one, is to use
tensioned rope (right strength and type whatever that is) run all over
the place, foundation to the roof plate, around the corners,
everywhere imaginable.  Before you laugh, my thoughts stem from
traditional Japanese buildings that used to do very much the same
thing by embedding rope/twine in the earth plasters.  It was used in
the ways that I am suggesting above and made quite a stout building
out of their wattle/daub post and beam frames.


Thinking on, if you haven't dismissed me by now, I think a super
critical component in making sb and earth plastered buildings resist
lateral loads is that of compressed or pre-compressed walls (depending
on whether or not it is lb).  I'm talking both lb and non lb designs. 
If non lb, I think that making sure the frame and the walls are
tightly integrated is also equally important.  Given, I haven't gone
through an earthquake and can only speculate what it must be like, but
I would suspect that buildings constructed this way would resist a
pretty good shake even if they weren't plastered.  The image still
sticks in my mind of my 11 and 12 year olds who were messing around in
our old International pickup late one afternoon when everyone from a
workshop had gone indoors. I had left it next to a small building that
had just been put up with the keys in it.  They managed to fire it up
and due to short legs (or so they say) lost control of the clutch as
they were releasing it and proceeded straight on into one of the
walls.  Granted they weren't going 60 miles an hour, but we had
difficulty discerning the slightest amount of movement.


And I think that's enough to think about for today.


Bill

 

Marcus and other concerned fiber conscious individuals,


On Thursday, January 9, 2003, at 03:59 PM, Marcus Hardwick wrote:


<excerpt>


Charmaine wrote:

<excerpt>

Marcus said: It seems like woven geotextile fabric products could be
used as plastic mesh "lath" for clay rendered walls in high seismic
areas. While I'd rather seesomething in a natural fiber develop and be
tested - the geotextiles alreadyhave known engineering properties and
are commonly used for rugged applicationslike road base stabilization.


++++++++++


There are natural fiber weaves, made of Coir, a coconut fiber woven
into rope, then into a lattice weave of rolls 90' long, used for
landscaping ground/river bank erosion.


I bought a roll and used it to plaster onto, getting it taut is a
serious problem, so don't try it for that.  I sent some to Kiko Denzer
and Ianto Evans to experiment with 2 years ago, no answer yet.

</excerpt>


++++++



Yeah, I hear you Charmaine. Thing is, it's not just for strengthening
the

plaster it's own self. Straw or horse manure etc. can do that. For a
seismically

engineered building in, say, San Francisco like Bruce was talking
about it's

vitally important to provide a good strong and lasting connection
between the

roof/upper bond beam and the foundation. This would seem to indicate a
strong

material that is easy to get reasonably taut and is able to be firmly
attached

top and bottom. As a step in that direction, I'm thinking along the
lines of a

non-metalic replacement or substitution for the 2x2 inch welded wire
mesh

currently used with stucco which is being attached to a box beam above
and

toe-ups below with a pneumatic stapler (usually and wrapped around the
members).

Since the steel mesh - even if galvanized - doesn't have a very long
life

expectancy in the clay render due to rusting, what are some options? 


There could probably be a workable system developed using Coir or hemp
mesh and

perhaps vertical bamboo pins. Maybe even woven bamboo strips but how
do you get

that through plan check? Needs a lot of testing to develop numbers
(like EBN is

doing for bales and renders) and that takes time and especially
funding. The

geotextiles have an advantage in that much of the testing needed to
produce

reliable numbers has already been done (on somebody else's nickel).
Disadvantage

is they are petro based and somewhat expensive although when compared
to the

price of real estate in, say, San Francisco - a pittance and a bargain
at twice

the price (kinda like bales - but that's another rant). 


One other drawback is the possible danger of establishing a precedent
for using

geotextiles in clay rendered SBC that might tend to preclude
exploration of bio

based and locally produceable materials. My predilection though is to
somehow

encourage the adoption of clay rendered SB buildings as a better
alternative to

stick built/fibreglass insulated/ concrete stuccoed (or vinyl sided)
buildings

that are common construction hereabouts. I would consider it to be
even better

if this could be done with locally grown hemp and bamboo but if
something like

certain geotextiles could substantially enable the widespread use of
clay or

perhaps lime stabilized clay renders- that seems like a step in the
right

direction. Like in that old Pete Seeger song: "Inch by inch, row by
row..."


Marcus

Overcast and drizzle in Sonoma County


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</excerpt><fontfamily><param>Helvetica</param>Athena & Bill Steen

The Canelo Project

HC1 Box 324

Canelo/Elgin, AZ 85611

absteen@...

www.caneloproject.com</fontfamily>


</x-rich>