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RE: Shrinkage in Concrete

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Mike,

Sorry for the previous post.  I was cleaning my send button and it went off
by accident.

The first thing that you need to do is determine what level of shrinkage is
acceptable.

Re: "Shrinkage and Curling of Slabs on Grade", by Ytterberg, Concrete
Intentional, April May June of 1987.  If you send a request to Kalman Floor
Company (800) 525-7840, they will send you a reprint.  The article lists all
the contributors for shrinkage, and puts together recommendations for mix
design and testing.
If you opt for shrinkage compensating concrete, approach with caution.  It
may expand slightly, the details become very important.  
Use as big of an aggregate as possible, and uniformly grade the aggregates
all the way through the fines.  Check out various articles by Jim Shilstone.
Use a stony mix.  An 8-18% is what is generally recommended on each sieve.
I like to reduce the water as much as possible (super plasticizers) more to
reduce the volume of cement than for anything else.  Reduce the cement as
much as possible also (use no more than you need for strength).  I really
like the polycarbonate super plasticizers.  Reducing the water for a given
volume of cement does not help reduce shrinkage.  The goal is to reduce
cement.  The super plasticizers help handling the stony mixes that finishers
are not accustomed to.  Use a cement with a C3A in the range of 8 to 10
percent.
Do field testing for shrinkage.  The Kalman people have a modified field
test.  Call them to see if they will share the information.

Regards,
Harold Sprague


> -----Original Message-----
> From:	Michael Zaitz [SMTP:zmanpe(--nospam--at)bellsouth.net]
> Sent:	Thursday, May 04, 2000 7:11 PM
> To:	seaint(--nospam--at)seaint.org
> Subject:	Shrinkage in Concrete
> 
> Hello,
> 
> I have a project for a foundation that will need to be pumped due to lack
> of
> access.  A big concern of the equipment supplier is shrinkage of the
> concrete and achieving tight tolerances for the placement of the concrete.
> What all can I do to eliminate shrinkage in a pumped concrete?  Type 5
> cement? shrinkage reducing admixtures?  Super plasticizer?  Any other
> ideas?
> 
> Thanks
> 
> Mike
>