[Cob] cob shake test info

[Janet Standeford]

Hi, I believe load bearing was 350 and I met or went over  that with one
sample (with the least amount of straw)  and was at 240 I think with
another sample.

The latter was loaded with straw.
Ultimately you sacrifice psi for insulation but the overall strength is
still there, just not like engineers are used to seeing it.

Plus, if you notice this house has a center stud wall. I will fill in with
cob and put windows that open in strategic places for light and direct heat.

btw To anyone interested, ALL the pages of the plans are online at
www.mystonehaven.com under the heading house on the left. They are NOT
under plans yet.

The guide book that came with the plans is very thick and not available. It
does include code that was referred to.

I guess if you come to help with the house you can read it.

On Mon, May 21, 2012 at 8:23 AM, dhowell at pickensprogressonline.com <
dhowell at pickensprogressonline.com> wrote:

> I must be recalling the wrong numbers then. As I recall, before you done
> the psi tests you said you had to come in above 350 and afterwards you said
> you came in at 360. So if that's wrong, what is the psi minimum requirement?
>
> On May 20, 2012, at 6:47 PM, Janet Standeford wrote:
>
> Did you see something I didn't see requiring over 350?
>
> On Fri, May 18, 2012 at 9:28 AM, dhowell at pickensprogressonline.com <
> dhowell at pickensprogressonline.com> wrote:
>
>>  Field tests aren't psi tests though. Thankfully you have done the
>> preliminary psi tests and that should be all that is required. Field tests
>> would be more like being sure the mix and the materials are the same as
>> they were in the beginning. Yeah, who can wait months and months for psi
>> tests when the materials have already been approved. They're just holding
>> up progress because of their cold feet. Doesn't all the cob homes and
>> outbuildings the world over offer enough proof of its strength? I guess
>> not. Adobe is only required to have an average compression strength of 300
>> psi and one out of five bricks can be less than 250. So why are they making
>> you have over 350?
>> Damon
>>
>>
>> On May 17, 2012, at 5:11 PM, Janet Standeford wrote:
>>
>> The problem here is that when you are in the middle of a wall, you cannot
>> wait for the cob to cure enough in a psi container!
>> You have to go by feel and all the preliminary tests such as determining
>> the strength through the snake test, etc.
>>
>> It took my samples at least 3 months to cure enough to get a 350 psi? I
>> can't remember the exact number at the moment but it was load bearing.
>>
>> Wet cob is not going to get anywhere near those numbers. It will simply
>> fall apart!
>>
>> When you are racing weather, you can't take this kind of time to psi test
>> periodically. That would be insane.
>>
>> On Thu, May 17, 2012 at 11:52 AM, dhowell at pickensprogressonline.com <
>> 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
>>>
>>
>>
>
>