Pouring concrete under water

AlbertC · Nov 18, 2015

I built a wood duck house to go beside my fishpond. I dug the hole where I want to put the post but before I could get the post installed we got 3" of rain and now my hole is underwater.

I have heard that you can pour concrete underwater but I'm not sure how to do this. Tried dipping the water out of the hole but it filled back up quicker than I could dip it out. If I mix the concrete and pour it in the 36" deep hole that I have dug the concrete will dissolve before it gets to the bottom of the hole.

Any ideas how to do this. I don't want to dig another hole further away from the edge because I want to put the duck house where I dug the original hole. Also don't want to wait till next summer to put up the duck house.

I thought about putting a garbage bag in the hole then putting in the post and then pouring the mixed concrete in the bag which will force the water out of the hole.

Any other ideas appreciated.

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eray1066 · Nov 18, 2015

You could use a sonotube to deliver the concrete to the bottom unadulterated and it will force the water out similar to a "sock" we would use on a concrete bucket to deliver cement to the bottom of a flooded excavation. On a big job, We sometimes do the same with the cement pump hose to the bottom

GPintheMitten · Nov 18, 2015

Why couldn't you pour dry redi-mix in the hole?

AlbertC · Nov 18, 2015

I think if I were to just pour it in dry the rocks would sink to the bottom of the hole and most of the dry would float to the top and I would not get a good pour. The mix would be off. But I don't know if this is the case or not. Has anyone ever just poured the dry mix in the hole. I can see where thi might not be a proble if the hole was not very deep, but this hole is 36" deep.

AlbertC · Nov 18, 2015

If I put a sono tube in the hole it will just be full of water also. Wouldn't I have to try to pump the water out of the tube.

GPintheMitten · Nov 18, 2015

I'm picturing the duck house like a fence post with a box on it. Maybe it is more substantial than that.

I wouldn't pour dry mix in water filled hole for structure like deck or pole barn. I have used it for fence posts including those used to support farm gates. I haven't had problem with gate posts sagging or leaning.

MikeInEburg · Nov 18, 2015

Concrete curing is a chemical process. If you pre-mix properly, there should be no "dry" . Mix and pour into hole, and you should be fine.

texas42 · Nov 18, 2015

You need to use a method called "tremie"
The tremie concrete placement method uses a pipe, through which concrete is placed below water level. The lower end of the pipe is kept immersed in fresh concrete so that the rising concrete from the bottom displaces the water without washing out the cement content.
You can do a search and get a good idea how to do it

GPintheMitten · Nov 18, 2015

If you wanted to get most of the water out could you get a sump pump to fit in the hole? I have an old sump pump that I have used to get water out of a trench.

Or you could get a plastic hand pump like this

ConservCo, Gulp UltraMax Water Removal Suction Pump, A-G12-C at The Home Depot - Mobile