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From: cognos!geovision!pt@dciem (Paul Tomblin)
Newsgroups: sci.military
Subject: Re: Pouring concrete (as regards Iraqi shelters)
Keywords: concrete
Message-ID: <1991Feb15.065035.8570@cbnews.att.com>
Date: 15 Feb 91 06:50:35 GMT
References: <1991Feb9.025948.389@cbnews.att.com>
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From: cognos!geovision!pt@dciem (Paul Tomblin)

andrem@pyrman2.pyramid.com (Andre Molyneux) writes:
>In response to:
>>>From: MEDELMA@CMS.CC.WAYNE.EDU (Michael Edelman)
>>Message-ID: <1991Feb8.012544.15685@cbnews.att.com>
>>Thos Cohen asks "how long does it take for 36m of concrete to cure?",
>>with regards to Iraqi shelters. The answer: No longer than it takes
>>1m to cure.
[stuff deleted]
>several people raised their hands, he told us that such stories were hogwash
>since concrete won't cure correctly if it is poured more than 8 inches at a
>time.  To emphasize this, he pointed out pictures showing the building of
>the dam.  Sure enough, you could see concrete being poured into wooden-sided
>molds that couldn't have been more than 1 foot high.

Yes, it's still true.  As a matter of fact, one of the most common uses
of finite element analysis is to model the heat flow out of curing concrete
in large structures such as dams.  (Or as we called it in school, 
Damn Finite Elements)

The major problem with pouring big blocks of concrete is that heat is
generated by curing.  Lots of it.  If you pour a big block in one go,
the thermal expansion is enough to crack it.
-- 
Paul Tomblin, Department of Redundancy Department.       ! My employer does 
The Romanian Orphans Support Group needs your help,      ! not stand by my
Ask me for details.                                      ! opinions.... 
pt@geovision.gvc.com or {cognos,uunet}!geovision!pt      ! Me neither.