Construction Joints in Poured Walled
Construction Joints in Poured Walled
(OP)
Why is that most structural engineers specify in their notes that concrete poured walls shalled not be poured more than 40'-0" (or close to that) in one single pour. Is this a curing issue? Does this need to be true in control joints are placed every 20'-0"? Thanks






RE: Construction Joints in Poured Walled
I’m a bridge engineer and in bridge applications we typically require a vertical construction joints every 25’ in an abutment or pier walls.
RE: Construction Joints in Poured Walled
RE: Construction Joints in Poured Walled
Please note that control joints are often not 100% effective (in relieving shrinkage stesses) since we often run either all the steel thru or cut every other bar. Even construction joints are not 100% effective especially when several days later the next section is poured (while the shrinkage is still happening).
RE: Construction Joints in Poured Walled
RE: Construction Joints in Poured Walled
Placing temperture and mix design have a major effect on concrete's initial set time and on shrinkage stresses.
Mary Hurd's book "Formwork for Concrete" has many good suggetions and details for concrete wall forming and placing, including a table of placement speed vs. formwork loading.
A 40' long section of 12" wall, 10' high contains 14.8 cy of concrete, which is basically two ready-mix truck loads. If it is placed at the rate of 5'/hr, then it takes 2 hours.
Placing stronger wall ties at the bottom section of the wall forms allows a faster pour rate.
Equipment makes a big difference in placing time too. Is the concrete placed by chute directly into the forms, with a pump or bucket or conveyor?
RE: Construction Joints in Poured Walled