Return to index: [Subject] [Thread] [Date] [Author]

RE: Concrete: Shrinkage limit of .048?

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Harold, thank you for the reply.  The location is at South Shore, Lake Tahoe
(on the California side).  There are limited suppliers within a 90 minute
range, and they have the same aggregate sources.  To import aggregate is not
an option due to the tight budget (state job).

We had another project at the same campus about 7 years ago and had the same
issue come up.  With a similar mix we got shrinkage in the range of .06, and
had no problems with the walls, footings, beams or slabs.  These results are
consistent with much of the construction of the casinos, bridges, and other
structures built there.  We have the results of testing for 3000 psi through
5000 psi mixes, all with shrinkage around .06% at 21 days.  All these mixes
included plasticizer.

I don't know why we have the .048 requirement in the spec, and I am looking
for any type of reference as to when that would be appropriate, and what
other limits would be recommended for various situations.  I'm not convinced
it is necessary, but I don't see anything in the ACI manual of standard
practice that gives a basis for evaluating shrinkage limits...

-----Original Message-----
From: Sprague, Harold O. [mailto:SpragueHO(--nospam--at)bv.com]
Sent: Wednesday, March 21, 2001 2:44 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Concrete: Shrinkage limit of .048?

Joyce,

I have heard this from many suppliers all over the world.  And we always are
able to reduce the shrinkage.

Number 1 do ask the question of why you have the shrinkage requirement of
0.048%.  Secondly if the requirement is needed.  It is likely that it can be
obtained with the proper mix design.  There are many other variables that
can be controlled that contribute to shrinkage.

Where is this work being done?  I may be able to recommend someone that can
design a mix that can give you the performance that you need.  Let the
supplier pay a more competent mix designer.

Regards,
Harold O. Sprague


> -----Original Message-----
> From:	Joyce Fuss [SMTP:Joyce(--nospam--at)lbdg.com]
> Sent:	Wednesday, March 21, 2001 3:38 PM
> To:	SEAINT list (E-mail)
> Subject:	Concrete:  Shrinkage limit of .048?
> 
> Our specifications call for shrinkage of concrete to not exceed .048% at
> 28
> days.  We have a project for which the supplier is saying he cannot meet
> that requirement because of the locally available aggregate-he is saying
> we
> will get .065%.  The supplier and the project are located at an elevation
> of
> about 6000 feet, so the cost to import the required aggregate is
> substantial.  The concrete is 3000 psi, subjected to potential freeze thaw
> conditions at the perimeter of the buildings.  
> 
> I have been unable to locate the source of that shrinkage requirement, or
> any recommendations as to what is acceptable.   If anyone has any
> information or suggestions we would greatly appreciate your imput.
> 
> Joyce Fuss
> Structural Engineer
> Lionakis Beaumont Design Group
> phone: (916)558-1900
> fax: (916)558-1919
> joyce(--nospam--at)lbdg.com
>