[Cob] Fwd: Fwd: cob shake test info

[dhowell at pickensprogressonline.com]

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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