Friday, June 26, 2009

RE: Shrinkage of Concrete Floodwall

Reference Table in ACI 350-06, shrinkage reinf based on movement joint spacing, for liquid-containing structures.  (I recommend using the Grade 40 values even if you have Grade 60 rebar.)
Bill Sherman

From: Stan Caldwell []
Sent: Friday, June 26, 2009 1:17 PM
To: SEAINT Listserv
Subject: Shrinkage of Concrete Floodwall

Shrinkage of concrete during curing seems to me to be one of those fuzzy areas of structural engineering practice.  Perhaps some of you can help shave the fuzz.
We have to design a small concrete floodwall on top of an existing levee.  The wall will be about 300 ft. long, 12 in. thick, and 2 to 3 ft. tall.  Joint spacing will be based on shrinkage, and joint width will be based on thermal expansion (101 dF in Dallas today).  Back to the shrinkage problem, this is a flood protection wall so we do not want any cracks.  We are thinking of 20 ft. joint spacing, but are having trouble justifying this choice, or any other, based on available literature.
Any thoughts?
Stan R. Caldwell, P.E.
HALFF Associates, Inc.
Richardson, Texas