[Cob] Fwd: Fwd: cob shake test info

[Henry Raduazo]

	Does anyone know how the bamboo was used in the Australian test? I wonder specifically if the bamboo was used as whole round tubes or if it was split. The Hida Tool Company  http://www.hidatool.com/shop/shop.html sells a tool to convert rigid bamboo tubes into flexible strips that will follow the curvature of the wall and I believe the strips will form a stronger bond to the mud because of their shape.
	I have been using the bamboo strips in wattle and daub structures for many years. The 5-8 way splitters are the most useful for 1-3 inch diameter bamboo.

Ed

On May 21, 2012, at 2:55 PM, dhowell at pickensprogressonline.com wrote:

> 
> 
> Begin forwarded message:
> 
>> From: Shawn King <sbkingster at gmail.com>
>> Date: May 21, 2012 2:35:53 PM EDT
>> To: "dhowell at pickensprogressonline.com" <dhowell at pickensprogressonline.com>
>> Subject: Re: [Cob] Fwd: cob shake test info
>> 
>> Actually, I think this only went to D. Howell, could you post to the cob list for me, good sir?  Traveling, limited email functionality, thanks!
>> 
>> On Mon, May 21, 2012 at 11:34 AM, Shawn King <sbkingster at gmail.com> wrote:
>> Hello folks, I found an article where bamboo as reinforcement in cob was tested on a shake table very successfully, at a university in Australia.  The article is copied in entirety below.  Bamboo apparently works very well.  Hope this is helpful.
>> 
>> __________________________________________________________________
>> 
>> ANCIENT BUILDING METHOD THE KEY TO SUSTAINABLE EARTHQUAKE RESISTANT
>> HOUSING
>> December 2008, UTS Engineering newsletter, UTS Sydney, Australia
>> 
>> Specialist earth builder and guest researcher in the Faculty of Engineering and Information
>> Technology, Peter Hickson, has combined one the world's most ancient building techniques, "cob"
>> construction, with modern engineering methods to develop a model house as part of an effort to
>> create low cost earthquake resistant housing for millions of people around the world.
>> On Wednesday 17 December at noon it was zero hour for the half-size model made of earth and
>> bamboo when it was put to the test on the state-of-the-art UTS shake table, the only earthquake
>> simulator of its kind in Australia. The four tests were based on the El Salvador 2001 earthquake
>> which measured at 7.8 on the Richter scale. The first test was set at 100% intensity, the second at
>> 125% intensity. The third and fourth tests represented the aftershocks that occur after the main
>> earthquake hits and these were set at 100% intensity. Impressively, the model suffered minor cracks
>> but remained standing.
>> 
>> Hickson has collaborated with Professor Bijan Samali, UTS senior lecturer and expert in Structural
>> engineering and final-year engineering students Luke Punzet and Jean-Michel Albert-Thernet in building and testing the model.
>> "If this were an actual building then it could have been safely reoccupied without any repair. It is an outstanding success because
>> not collapsing and killing or injuring people is enough to claim success," said Professor Samali. Hickson has been given the go
>> ahead to safely use his construction system anywhere seismic activity is common and a hazard to life.
>> "Cob is a building material made from subsoil, straw and water," Hickson said. "Clay is the binder, sand, silt and gravel the fillers
>> and straw the reinforcing. Lumps of earth and straw mixture (cobs) are melded into a monolithic structure. It has been used
>> worldwide for thousands of years and was a traditional building technique popular in England."
>> Hickson's house introduces many new technologies, but what makes his system unique structurally is the addition of internal
>> bamboo reinforcing and the use of structural diaphragms.
>> "I believe well designed bamboo reinforced cob is the answer to sustainable housing for anyone living in areas where seismic
>> activity poses a threat to safety. That's sustainable with all aspects of sustainability considered – spiritual/cultural, social/economic
>> and ecological."
>> The model tested on 17 December was based on a prototype low-cost house Hickson has built
>> in the Philippines. It was complete with windows, first floor, loft bedrooms and roof.
>> "Millions of people live in inadequate and temporary houses and many thousands of people,
>> sometimes tens of thousands, die in the collapse of buildings during devastating earthquakes,"
>> he said. "These buildings are sometimes crudely built earth homes, but often are poorly
>> constructed, using reinforced concrete, concrete hollow block or fired brick.
>> "Earth building material is abundant, widespread and freely available. Education, training or
>> sharing knowledge is all that is required to make such homes safer if people are willing to adopt
>> some simple changes to the way they build.
>> "Furthermore, by utilising local indigenous materials, vernacular styles and appropriate climate responsive designs, we will have
>> also delivered the most sustainable solution for communities with limited resources."
>> 
>> Image: Top - Peter Hickson at work on test model; Bottom - The house upon which the model is based
>> 
>> For further information, contact:
>> Nancy Gewargis
>> 
>> 
>> On Sun, May 20, 2012 at 10:34 AM, dhowell at pickensprogressonline.com <dhowell at pickensprogressonline.com> wrote:
>> 
>> 
>> Begin forwarded message:
>> 
>> From: "dhowell at pickensprogressonline.com" <dhowell at pickensprogressonline.com>
>> Date: May 20, 2012 1:33:32 PM EDT
>> To: Henry Raduazo <raduazo at cox.net>
>> Subject: Re: [Cob] cob shake test info
>> 
>> Ed,
>>       That is my primary concern also. I think it's common knowledge that dirt leaches out iron. One thing I think is suspicious is that bamboo has been tested to out perform steel rebar and it's a fraction of the weight, yet there's never a mention of that. I think bamboo dowels in cob walls (just laid across the wall and cobbed around) would have the same function as steel rebar and probably would keep the integrity of the wall.
>>       It's a good time for proposing such a thing because there is almost no new construction and the inspectors may be more willing to take the time to learn about cob just to have something to do. I just can't scare the daylights out of them by proposing an American style cob house. Although they look cool and are sufficient, they look like a nightmare to an inspector that looks at straight lines and 90 degree angles in homes all day.
>> Damon
>> 
>> 
>> On May 18, 2012, at 9:41 PM, Henry Raduazo wrote:
>> 
>> Damon:
>>       You are of course absolutely right, and cob is vastly superior to adobe. That does not make it easy to get approval. Usually to get approval there is such a huge safety margin that the net effect is to be almost prohibitive to natural building.
>>       People doing rammed earth structures used to put a little concrete in their mix just to make the inspectors feel happy. There was so little concrete in the mix and so much time between mixing and pouring the mix into the form that there was no strength imparted to the mix, but making inspectors feel good is important.
>>       I have done it both ways. I had one project where the inspector required me go go in and get special approval for a wall, and my other projects have been the "Don't ask don't tell" format.  I have a huge respect for people like David Eisenberg who have devoted their lives to trying to get reasonable building codes that include natural building materials.
>>       I have been through the whole college routine too with strength of materials and concrete design... I understand how engineers think, and I wish I had an answer to this problem other than just doing it under the table. I think the adobe got approved just because the prior situation was intellectually embarrassing.  Native people could not build and finance traditional structures in their homeland, but they were allowed to build and finance structures built with imported materials and technology foreign to their native culture and traditions.
>> 
>>       I wonder: if we took apart some of the 1000 year old Pueblo structures and randomly tested some of the 1000 year old bricks, do you suppose that these bricks would pass current Adobe code? I don't think current adobe code has anything to do with a realistic assessment of what is required for a structure to last 1000 years. The strength that a wall has the day it is manufactured and the strength it has 100 or 1000 years from now depends on the chemical and mechanical stability of the materials. That is why putting steel in cob or adobe bothers me. It is not chemically stable and it expands as it reacts with moisture or minerals in the wall material. Think about all the possible impurities in clay soil.
>> 
>> I wish Good Luck to the Alpha Testers,
>> 
>> Ed
>> 
>> 
>> 
>> On May 17, 2012, at 2:52 PM, dhowell at pickensprogressonline.com wrote:
>> 
>> Ed,
>>       Understood about quality control. I must point out concrete mixes from scratch in a wheelbarrow can also have vastly different strengths according to the amount of water used. Adobe bricks? New Mexico Earthen Building Materials code states, "each of the tests prescribed in this section shall be applied to sample units selected at random at a ratio of five units per twenty-five thousand bricks to be used or at the discretion of the building official." Five out of 25,000 seems like a pretty unrepresentative number for the whole. Quality control can be done by performing tests at the foundation, sill height, and lintel height of the walls. Did you know the adobe code allows a psi of 250 and one out of five can have a psi less than that? We're talking about the same material just a different building procedure. Their code is a good guideline, but some things are questionable, such as it requires concrete stucco which is an accident waiting to happen according to the Devon Earth Building Association. A healthy topic that must be discussed, don't you think?
>> Damon
>> 
>> On May 17, 2012, at 2:09 PM, Henry Raduazo wrote:
>> 
>>       The problem might be one of quality control. When you are mixing something in a large batching machine (like a concrete mixer) you have large 3-5 yard batches which are perfectly uniform. When you have small crews making 1/27th of a yard batches on a tarp asserting quality control is a nightmare. Every crew can not make every batch the same let alone getting the 5 or 6 different crews to make uniform batches.
>>       I have been able to make uniform cob batches by mixing one ton batches on a concrete slab with a rototiller. That might satisfy a quality control person, but getting such anal persons to accept hundreds of batches made by half a dozen different crews might be expecting too much even if we had a code that described the material in a way to differentiate acceptable cob from unacceptable cob.
>> 
>> Ed
>> On May 17, 2012, at 11:29 AM, dhowell at pickensprogressonline.com wrote:
>> 
>> Thanks Ron,
>>       As I mentioned; "but no paperwork which building officials will accept."
>> 
>> 
>> On May 16, 2012, at 8:17 PM, Henry Raduazo wrote:
>> 
>> but no paperwork which building officials will accept.
>> 
>> 
>> 
>> 
>> 
>> 
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