<div dir="ltr"><div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3">I agree with Rub Tum, that 'staggered clums with alternating nodes or collars is definitely the way to go, with chopped straw for T&S'.</font></div>
<div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3">However, we haven't done that. Our first try, we got the directions wrong, drank too much, and ended up with several staggering clum chums with nudes in collars eating chopped suet, flashing T&A, and blabbering about Bale Bondage. "Clum!" ~Chaucer</font></div>
<div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3"><br></font></div><div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3">So we went with Centaflex, which is sized pretty well, and the plastic coating tends promote bonding. Our mesh is used to hold the bales together, like a basket, and cheese cutting isn't an issue, as it might be with cob. </font></div>
<div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3"><br></font></div><div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3">It seems that metal in earth plaster can and does work, but under what conditions would it fail? The bond is important, and thin metal wires cannot be considered sufficient unless they are very dense (notice that the Our Troops recommended split bamboo over clums for better bonding). The Japanese practice of coating metal with an alkaline plaster certainly points the direction. </font></div>
<div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3"><br></font></div><div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3">John </font></div><div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3"><br>
</font></div><div><font color="#000000" face="Times New Roman, Garamond, Georgia, serif" size="3"><br></font></div><div><span style="color:rgb(0,0,0);font-family:'Times New Roman',Garamond,Georgia,serif;font-size:medium"><br>
</span></div><div><span style="color:rgb(0,0,0);font-family:'Times New Roman',Garamond,Georgia,serif;font-size:medium"><br></span></div><br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Aug 27, 2013 at 9:55 AM, RT <span dir="ltr"><<a href="mailto:archilogic@yahoo.ca" target="_blank">archilogic@yahoo.ca</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Sun, 25 Aug 2013 18:52:24 -0400, <<a href="mailto:GSBN-request@sustainablesources.com" target="_blank">GSBN-request@<u></u>sustainablesources.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Date: Sun, 25 Aug 2013 17:30:55 -0400<br>
From: oasis@oasisdesign.netre: Steel mesh in clay plaster + earthquake safe fireshelters<br>
</blockquote>
<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
it only takes a few hundred pounds of wire to reinforce a 100,000 lb cob building.<br>
</blockquote>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
What is properly sized reinforcement?<br>
</blockquote>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Still being worked out, but 1/8" wire mesh on 6" centers is abetter fit to cob than say, 3/8" rebar on 18" centers.<br>
</blockquote>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
(wire mesh) has a high likelhood of a) enabling the thing to get a permit and be built<br>
</blockquote>
<br>
Y'all;<br>
<br>
It would seem that the third sentence (quoted above) negates the validity of the first sentence.<br>
<br>
I know nothing about designing/building with cob simply because its thermal performance makes it unsuitable for use for energy-efficient buildings in my climate (~8700 HDD/yr) so I've not looked at it in depth.<br>
<br>
However, I do know that in the design of reinforced concrete structures, 6" x 6" x 6 gauge welded wire mesh would be utilised only as secondary reinforcement to control temperature and shrinkage cracking.<br>
<br>
I also know that for reinforced concrete, the ratio of the cross sectional areas of reinforcment : concrete matters -- too much reinforcement can result in sudden destructive failure of the concrete -- too little reinforcement is essentially no reinforcement and can result in catastrophic failure of the structure.<br>
<br>
"A few hundred pounds" of wire mesh to reinforce 50 tons of cob whose thickness is presumably a foot or more sounds like a case of the latter -- essentially a case of trying to use T&S reinforcement as primary reinforcement.<br>
<br>
Quite frankly, I suspect that straw or other fibre in the mix is probably more effective at the task of T&S than either 6x6 or chicken wire mesh and that a bamboo grid (whose spacing/placement/detailing has been properly designed) would be more appropriate for the primary reinforcement.<br>
<br>
I also suspect that in most jurisdictions when seeking plans approval, approaching the Chief Building Officer with alternative reinforcement strategies that were developed by the U.S. Army Corps of Engineers would be looked upon more favourably than a scheme with no engineering documentation and mostly anecdotal support.<br>
<br>
=== * ===<br>
Rob Tom AOD257<br>
Kanata, Ontario, Canada<br>
<br>
< A r c h i L o g i c at Y a h o o dot c a ><br>
(manually winnow the chaff from my edress if you hit "reply")<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><font face="'trebuchet ms', sans-serif"><span style="font-size:x-small"><font color="#666666">John Swearingen<br>Skillful Means Design & Construction<br>
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