Concrete Column Splice
Concrete Column Splice
(OP)
I have a situation where I have two 30" X 42" concrete columns cantilevered up from a footing 25'. The contractor wants to pour the columns in 6' increments, leaving 3 construction joints in the footer. I looked in the ACI code and could not find anything that specifically said you could not do this, but my gut says that this would hinder the shear transfer in the column since the concrete would have a horizontal crack all the way through. The column sees realatively high shear and bending, while the compressive loads are small compared to the column size. This also makes me uneasy, due to the friction between the concrete faces would not be overly high, forcing the shear into the vertical bars. Reinforcement consist of 22 #8 bars vertical and #4 ties @ 10". What are your opinions on this? Please respond as soon as you can, as they are breathing down my back to give them an answer.
Thanks,
Thanks,






RE: Concrete Column Splice
1. Put a depressed key in the top of each lift.
2. Strip the forms as soon as practical, clean laitance.
3. Soak top of the concrete with water for several hours to improve bond between old and new concrete (I worked one job - rebuild of a badly damaged electric generating station tubine-generator pedestal - with a respected national concrete "expert" who insisted that the "thoroughly soaked" concrete will create a bond equal to or better than epoxy compounds - based on the results, I believe him.
4. Remove the "soaking water" and place the next lift - do this as rapidly as practical (the bond between the concrete lifts will be better the "younger" the concrete.
5. Wet cure everything, ALL the time - from the start, except when actual work is being performed.
Do it right, don't skip any steps, and relax :)
RE: Concrete Column Splice
RE: Concrete Column Splice
RE: Concrete Column Splice
Placing a shear key in area crowded with rebars is probably difficult from contractor's point of view. Hammer and chisel may be as good as shear key.
RE: Concrete Column Splice
Thanks
RE: Concrete Column Splice