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Re: Concrete crack control

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Try ACI 350 for environmental concrete. There is a good treatment of mix
design, joint spacing, re-inforcing, etc.

Randy Russ, P.E.

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> From: Jeff Smith <smthengr(--nospam--at)sirius.com>
> To: seaint(--nospam--at)seaint.org
> Subject: Concrete crack control
> Date: Friday, December 11, 1998 7:44 PM
> 
> Can anyone suggest a good reference for concrete crack control in exposed
> concrete walls. Are there any rules of thumb for crack control as a
function
> of strength, w/c ratio, type of aggregate, type of forms, spacing and
size
> of control joints, etc.
> 
> We just finished a 20 foot section of 11' tall, 10" wall, double curtain
> reinf,  that will not be exposed, but was used as a mock up for a future
> pour.
> 
> We had a .43 w/c ratio, 3/4 aggregate, 5500 psi mix with poly fibers,
using
> mahogany forms on one side and ac ply on the backfill side. The finish
looks
> like it was steel troweled, glassy smooth. However, there are two 8' long
> vertical hairline cracks that occur between snap ties about 4-6' apart.
The
> crack does not extend to the back side of the wall.
> 
> The 4.1 Point Richmond quake was a few days after the pour, I can't
believe
> that was what caused it. We already completed an orthogonal wall that was
> about 40' long that was board formed, no control joints, using pea gravel
> that has no cracks in it. 17 day compression test was 4300 psi.
> 
> Thanks,
> 
> Jeff Smith
> 
> 
>