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RE: slab on grade

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Crazy thought.  Post-tension it to limit the cracking.

 -----Original Message-----
From: Jerry D. Coombs [SMTP:jdcoombs(--nospam--at)]
Sent: Monday, January 04, 1999 2:02 PM
To: 'seaint(--nospam--at)'
Subject: RE: slab on grade

Yeah, that's taken care of, I have soil info.  Out here in sunny NM, I
very sandy, fine granular, low (-0-) PI high bearing soil with
dry conditions.  I'll prep it to get good uniform bearing,    I just want

it to hold together when it shrinks and have a reason for what I do
than use a 5" slab with #5's @12"OCEW and call it good.  Seasonal (and
daily) temperature swings are pretty drastic.  I know it'll crack, but
where and how much.

 -----Original Message-----
From: Cain, William [SMTP:bcain(--nospam--at)]
Sent: Monday, January 04, 1999 11:47 AM
To: 'seaint(--nospam--at)'
Subject: RE: slab on grade


Before you go any further, run, don't walk to a good geotechnical
engineer to determine what your soil conditions are.  If you have an
expansive soil, the slab design will need to be quite different than if
it's not.  I imagine your fee is probably pretty low (compared to the
risk of problems) and these types of projects can go south in a hurry.

Bill Cain, SE
Oakland, CA

 -----Original Message-----
 From: jdcoombs(--nospam--at) [SMTP:jdcoombs(--nospam--at)]
 Sent: Monday, January 04, 1999 10:35 AM
 To: 'seaint(--nospam--at)'
 Subject: slab on grade

 Happy New Year, y'all
 I need to put in a good slab for outdoor basketball courts.  The
 would like for them to be free of joints.  It will be an
unloaded slab, no
 traffic.  The slabs will be 100' x 65'.  I can spec a proper
subgrade spec.
  How do I design for the slab thickness and reinforcing required
to keep
 cracking controlled.  I have reviewed  ACI 302 and 360, and the
PCA guide.
  None really address the unloaded slab except fot the "subgrade
 equation", which is not really a qualitative approach.  I'm
willing to add
 fibers to get a good crack control, but how does one balance
between that
 and steel?  How thick a slab?  How much steel?  How much fibers?
 comments are appreciated.
 Jerry D. Coombs, PE