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RE: Mass concrete

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Good point,Jay. Since our ambient temperatures around south Louisiana are
usually in the 90's during prime concrete-pouring season, the differential
is minimal...but I know that isn't the norm for most areas. By the way,
another rule of thumb is that if the minimum dimension is greater than or
equal to 3', then consider it mass concrete. I think that just about
exhausts all my knowledge of mass concrete without looking to ACI for
help(!).

Randall

-----Original Message-----
From: Jay Shilstone [mailto:j.s(--nospam--at)shilstone.com] 
Sent: Wednesday, August 04, 2004 2:40 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Mass concrete

It doesn't matter whether it is called mass concrete or not. The question 
is, "Is there sufficient heat differential between the interior and 
exterior concrete temperatures to cause cracking?" If the mix involved has 
a high cement content, or has a high enough initial temperature, the answer 
is probably "Yes". When in doubt, treat it as mass concrete. You can either 
keep the internal concrete temperature as low as possible or insulate the 
whole deal to slow down heat loss.

We were involved in a project with 6 foot diameter columns cast with 5000 
psi concrete. The concrete was cast in winter in Chicago. When the 
contractor stripped the forms 2 days later, the concrete rapidly formed 
alligator cracks all over.

If it looks like mass concrete and quacks like mass concrete, treat it like 
mass concrete.

Jay Shilstone

At 05:15 PM 8/3/2004, you wrote:
>I have a concrete pad, approximate 3' to 3'-6" thick, 26' wide, 100' 
>long.  Is this considered a "mass concrete"?  ACI 207 talked about the 
>cooling of mass concrete etc.  Most of the ACI mass concrete reports are 
>related to dam construction.  Is this pad "massive" enough to cause any 
>serious heat problem?
>
>Thanks for any input.
>
>Y i   Y a n g,   P. E.
>STRUCTURAL DIVISION
>SUMMIT ENGINEERING INC.
>707.527.0775.x15
>Santa Rosa, California
>
>




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