Cob: Re: Cob & Steel

[Hays]

Would it not be better to put some sort of sleeve all the way around the I-beam to allow the beams
some room to move so they will not cause cracks in the surrounding walls as the structure will move
alittle with wind/earth shaking?  Perhaps the foam insulation on all sides would serve this purpose?

With wood embedded in the cob one would typically use nails or other method to allow the cob to get a
better grasp on the object.  Suppose you could do the same with the i-beam or, better yet, the sleeve.

as a side, you'll also want to make sure that you provide an electrical ground for your steel frame.

- rhays

"Matthew HALL(SED)" wrote:

> ANovelli at aol.com writes:
> >One point I have not seen discussed is a corollary of the thermal
> >transmission of steel. It is well known in bale circles that rebar pins
> >"sweat", and over time create cores of rot around them, potentially weakening
> >the steel and of course, destroying any resistance they offer to movement.
> >While you are using a much lower percentage of straw in a cob mix, the clay
> >may not help solve this problem.
> Steel rebar is commonly used in abobe and rammed earth walls to increase flexural strength
> particularly against high winds. Steel that is embedded in earth with a suitable amount of cover
> will not corrode significantly as it is kept away from pockets of air and moisture. The problems
> you speak of in a lightweight highly aerated material such as strawbale are not the same as in
> condensed subsoil where there is no provision for air pockets etc. As with reinforced concrete the
> key to corrosion resistance is adequate depth of cover, cement will also enhance this. This is all
> commonly used in western australia and has been for the past 20 years since cyclone tracy struck
> and people sought to increase the wind resistance of walls. The technology is well understood
> there; i see no reason why it cannot be translated to cob walling. If the steel columns are
> embedded to give adequate cover and the thermal mass is not interrupted by a cold bridge i think
> the idea works well.
> Regards
> Matthew
>
> ____________________________________________________________________
> Matthew Hall BSc (Hons) GradBEng
> PhD Research Student
> Centre for the Built Environment
> Unit 9 Science Park
> Sheffield Hallam University
> Pond Street
> Sheffield S1 1WB
> England
>
> Tel: +44 (0) 114 225 3200
> Fax: +44 (0) 114 225 3206
> E-mail: M.Hall at shu.ac.uk