Construction Joints in a water containing structures
Construction Joints in a water containing structures
(OP)
I am in charge of the construction management of a 35ft x 111ft water containing structure. The bottom slab is 43.5ft x 119.33ft with 2 keyed, water stopped construction joints at third points of the length. The client wants a continuous poured slab. He states they did an aeration basin in a continuous pour and thinks there will be more leakage with jointed slab. I have always done "square pours" with joints spaced at 50ft or so. I have been look at code recommendations and the older codes give more strict recommendations than the more current ones. Does anyone have a reference I can refer to when I say "because I am the engineer and I say so"?
attached is a plan view and a couple sections
attached is a plan view and a couple sections






RE: Construction Joints in a water containing structures
ACI 350 used to have more guidance on joint spacing and they said to space contraction joints at 30 ft. We've always used 30 ft. for our default spacing for construction joints, so your 50 ft. spacing is actually pretty long.
You don't say how thick your slab is. But I'd make them install joints. AND to rub it in, I'd make them wait seven days between adjoining pours.
RE: Construction Joints in a water containing structures
RE: Construction Joints in a water containing structures
The client has a point...the joints are often where most leaks occur, but that is because they are not done right. But as apsix says, if you need to restrict the width of cracks in a longer slab, more reinforcement is required.
RE: Construction Joints in a water containing structures
Another issue, it's a good idea to have a wall joint at the same location as the slab joint. That's because the wall cracks tend to transmit to the slab. But if the joint locations you show are the only wall joints, you're going to have cracks in the walls. And these will continue into the slab.
RE: Construction Joints in a water containing structures
Curing and low slump is critical...
Dik
RE: Construction Joints in a water containing structures
Building the bulkhead for the PVC is certainly more time consuming, and will require a couple people, a saw and many many pieces of dimensional lumber, but if done right It's going to be pretty tight.
RE: Construction Joints in a water containing structures
Dik
RE: Construction Joints in a water containing structures
RE: Construction Joints in a water containing structures
How do you space the joints? I use vinyl waterstops as nilapathak describes at new construction and bentonite at new to existing.
Thanks for your input!
RE: Construction Joints in a water containing structures