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Re: Spec needed for 3000 psi concrete

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It is not a good idea to increase the cement even though you will get
higher strength but if you are not careful in placement techniques you
will get lot more floor cracking than with 5 sack concrete.

Ghias Dean PE
Austin Texas

>>> sscholl2(--nospam--at)juno.com 10/8/2004 7:24:05 PM >>>
Why use "3000 psi" concrete which then requires a Deputy inspector at
a
cost of about $75/hr? 
Instead specify 5.5 or 6 sack mix, limit the water and you will end up
with about 4000 psi but won't have to pay for the inspector.

This is especially important for smaller jobs.

Stan Scholl, P.E.
Laguna Beach, CA

On Fri, 8 Oct 2004 11:57:05 -0600 "David Maynard"
<davemaynard(--nospam--at)ceincorp.com> writes:
Dennis,

I tend to agree with Joe on this one.  Really let your contractor do
the
work.  The more guidance you give him, the more liability you accept
on
the project.  Typically for our concrete specs, we call out the
following
things:
1. Portland Cement type and ASTM spec.
2. Fly Ash type, content, and applicable ASTM spec.
3. 28-day Compressive Strength
4. Max. Course Aggregate
5. Max. Water/Cement Ratio
6. Air Content
7. Slump

Based on this information, you contractor should be able to come up
with
the proper mix design.  Anything more, and you start obtaining
liability.
 I hope that helps.

Dave Maynard, PE
Consolidated Engineers, Inc.
Gillette, Wyoming

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