Gunite cold joint

[mdbrown]

Hello concrete experts! We shot gunite 2 days ago and the PB decided to leave a 3’x6’ hole around the deep end channel drain because it had not been set parallel to the wall. They wanted to come out later and straighten the plumbing. I think they are planning to use some kind of Quikrete type product to finish it. I am super concerned about this being a structural deficiency. There’s rebar showing, so whatever material they use will at least be held somewhat in place. But if they don’t use gunite, how do we avoid a cold joint issue? What should I be asking for? Obviously they are not going to want to bring a full gunite truck and crew just to fill a hole this size…. thanks for your help

 

[hosseisemi]

They will likely used s hydraulic cement. The key is to ensure they use a bonding agent on the surface of the gunite that will come in contact with the new hydraulic cement. This is commonly done for the weephole left during construction. Just don't let them try to fill with plaster instead of hydraulic cement.

 

[mdbrown]

They will likely used s hydraulic cement. The key is to ensure they use a bonding agent on the surface of the gunite that will come in contact with the new hydraulic cement. This is commonly done for the weephole left during construction. Just don't let them try to fill with plaster instead of hydraulic cement.

The hole is 12“ deep, so there’s something like 18 cubic feet (a bit less due to the drain displacement). You think a hydraulic cement is the right solution here? Thank you!

 

[ajw22]

Cement around the drain will be fine. The area is not structural.

 

[JoyfulNoise]

This thread is helpful -

Post in thread 'Shell All 1 Pour or 2 Stages??'
Shell All 1 Pour or 2 Stages??

@MinerJason is our resident expert on all thing cementitious …

Executive summary - as long as they prep the existing concrete surface properly and clean it well, the hydraulic cement should have no problem forming a stable and strong bond with the existing concrete shell.