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Re: Foundation on Expansive Clay

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     It seem's to me that the WHOLE structure will need treating because if
you simply stabilize the colums and footings and the clay lifts the rest of
the building then that is the same as the columns settling.
     Maybe piers and grade beam with degradable (cardboard) forms under the
gradebeams - and/or - consolidate the site (calcium).  Also post tensioning
as a suggestion.

Greg

----- Original Message -----
From: "Fountain Conner" <fconner(--nospam--at)pcola.gulf.net>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, April 04, 2001 12:01 PM
Subject: Re: Foundation on Expansive Clay


> Unfortunately, it appears that these expansive clays extend to China.
>
> 1.  What would a couple feet of undercut and backfill gain me?
>
> 2.  How likely am I to get differential movement in excess of 1/2" in a
> yard foundation 7ft x 8ft?
>
> Fountain
>
> ----------
> > From: Bill Polhemus <bill(--nospam--at)polhemus.cc>
> > To: seaint(--nospam--at)seaint.org
> > Subject: RE: Foundation on Expansive Clay
> > Date: Wednesday, April 04, 2001 11:02 AM
> >
> > Oops, I didn't catch that (I'm used to an active zone of 10 ft or so
here
> in
> > Southeast Texas).
> >
> > You're right, John. If it's only a 6 inch active zone, excavating it out
> is
> > the best alternative. In fact, I'd recommend doing that up to about 5 or
> 6
> > feet or so. After that, it's worth looking at a cost comparison.
> >
> > William L. Polhemus, Jr., P.E.
> > Polhemus Engineering Company
> > Katy, Texas
> > Phone 281-492-2251
> > Fax 281-492-8203
> >
> >
> > -----Original Message-----
> > From: John P. Riley [mailto:jpriley485(--nospam--at)peoplepc.com]
> > Sent: Wednesday, April 04, 2001 9:55 AM
> > To: seaint(--nospam--at)seaint.org
> > Subject: Re: Foundation on Expansive Clay
> >
> >
> > "My thinking is to turn down the outside edge of the footing an
> additional 6
> > inches.  If this clay is expansive, it shouldn't be given to capillary
> > action, and will provide a seal, preventing the soil beneath the
> foundation
> > from seeing the varying moisture content."
> >
> > Is the expansive clay layer only 6" thick?  If this "turn-down" method
is
> > effective in protecting the soil within the 6" zone, what about the soil
> > beneath IT?
> >
> > My first inclination is to overexcavate and backfill.
> > __________________
> > John P. Riley, PE, SE
> > Riley Engineering
> > 20 Oakwood Drive, Blue Grass, Iowa 52726
> > Tel & Fax:  319-381-3949
> > jpriley485(--nospam--at)peoplepc.com
>
>