Pouring concrete below a water line

leaman

I will be building a deck off of a retaining wall I constructed last year. The retaining wall is at the water line of the lake. i will be attaching one side of the deck to the retaining wall and digging and pouring concrete posts for the middle and other side of the deck. My question is: When i dig my middle posts, I will not get far before I'm below the water table. How do I set concrete if the hole I'm pouring into is full of water?

Thanks in advance for the help

Daniel Holzman

Concrete sets fine under water. Order a slightly dry mix, place it in a sonotube, the concrete will displace the water and the part of the concrete below the water table will set up very nicely.

Bud Cline

Yup, believe it or not.
Years ago I poured many a temporary concrete boat ramp for the Army Corps of Engineers. Poured right into the water and bull-floated under water. When the lake level would drop and a proper ramp could be built we removed the temporary. I was always amazed at the condition of the ramps. They weren't very pretty but they were tuff as could be to break up and remove.

BigD9

Many many bridges are built this way. If I were doing your project, I would slide the concrete down the side of the form continuously and try to keep the water and concrete from intermixing. As the concrete fills the hole the water will rise and flow out the top. Or you could make concrete piers on land, and maneuver them into place.