Waterproofing Horizontal cold joint in slab

[anchorengineer]

I've seen a lot of topics regarding cold joints in concrete slabs/beams/walls that deal mostly with structural capacities but I haven't seen a solid answer to waterproofing the joint.

I've been asked by a contractor to review a slab that was supposed to be poured monolithically but the last concrete truck was late and rejected. The slab is for a vessel at a WWTP. The slab was designed to be 1 ft thick and to have a 1ft wide frost/edge beam around the perimeter. Instead of forming the frost beam he sloped the inside of it creating a large haunch and instead of a 12" slab his slab is more like 17" thick. Unfortunately the first pour was not level so the concrete rose above the top rebar mat on one side and the other side was below the bottom mat. They took pictures after the first pour and the concrete was plenty roughened.

My main concern is since this is a WWTP it will be exposed to some nasty stuff. I'm concerned more for the performance of the slab over time than anything. I considered using a waterproofing product along the sides to hold out the moisture but I'm not sure if it's lngevity.

Any thoughts?

Clarke Engineering Services, PC
Jobsite Engineering and Consulting

http://www.anchorengineer.com

 

[hokie66]

Based on your description, I think waterproofing is the least of your problems. Was there no attempt at consolidation? How could the slab have been left so out of level, even if not finished? I imagine it is "plenty roughened"...because it wasn't vibrated.

"The last concrete truck was late and rejected". Then why wasn't another load immediately ordered?

I think you should consider whether or not this slab is salvageable. Are you the design engineer? If not, what is the position of the design engineer?

 

[anchorengineer]

No, I am not the original design engineer. The GC filled the haunch/frost beam first and then started pouring the slab on one side when the first truck ran out. There are photographs showing the concrete being vibrated. A testing agency took cores samples and showed the concrete strength to be ok. I believe the 2nd truck came at the end of the day and another truck came first thing in the morning.

Structurally I was going to check the shear capacity at the joint and add vertical epoxied dowels at 12"-18" either way. This is a low siesmic area so uplift is small.

Clarke Engineering Services, PC
Jobsite Engineering and Consulting

http://www.anchorengineer.com

 

[JAE]

I think the design engineer should be involved if it is their work/seal/signature.