By limiting pours to 60' you get a large amount of the shrinkage prior to
pouring the next bit of wall. I have had mixed success with the "1/2 bars"
through detail. In one case the wall had .4% horizontal steel for shrinkage
and every other bar was cut at 25' joints. The joints were to be filled
with a good sealant. The joints also were 1" deep on both sides of an 8"
wall. In a couple of instances the wall cracked 3" away from the joint.
Annoying!! The concrete was 35MPa(5000psi) and the contractor did not want
to spend the money on super-plas.
>I run 1/2 of the bars through as you mentioned. If you let me know your fax
>number, I will send you a copy of the detail I use.
>SDS Architects, Inc
>We have always limited the length of our wall pours to 60 feet to
>minimize shrinkage cracking. Is there any way a contractor can pour say
>120 feet by adding additional joints, say at 30 feet, since they would
>be only partially effective in reducing shrinkage? I do not want to add
>extra longitundinal steel to control shrinkage.
>What would that joint detail look like? Should only 1/2 the bars run
>thru those intermediate joints? Should a metal keyway be used at these
>intermediate joints or some other material?
David Handy, P.Eng.
The Thompson Rosemount Group, Cornwall, Ont. Canada
Opinions expressed are personal only.