Pouring concrete under water

[GPintheMitten]

Put a 2x4 in the hole and wait til it freezes and then pull the Popsicle out.

 

[GreenYellow]

I used to work for a billboard company. I've seen it done several times... Just pour the properly mixed concrete in. Don't overthink it.

 

[texas42]

The idea behind the tremie method is you are displacing the water by adding the concrete to the bottom of the hole thru the pipe. That way the water can not dilute the concrete that much. You must keep the tremie pipe in the concrete. Don't pull it up out of the concrete till you have the hole filled. You can ease it up as you add concrete just don't pull the very end out of the concrete. This method is commonly done on casions only much bigger scale.

 

[4570Man]

Put a 2x4 in the hole and wait til it freezes and then pull the Popsicle out.

Around here you would be waiting a LONG time for that to freeze. Even if it did free it would be equally as hard as a hole full of concrete to pull out. Even if it did work now he is pouring concrete below freezing which is bad.

 

[GPintheMitten]

Around here you would be waiting a LONG time for that to freeze. Even if it did free it would be equally as hard as a hole full of concrete to pull out. Even if it did work now he is pouring concrete below freezing which is bad.

Yah, I know. I was just kidding. I already offered a few ideas on real solutions so I thought I would add a silly one.

 

[papa4fofox]

Typical in tremie concrete pours using a longer pipe is to put an inflatable ball in the tremie pipe before concrete is added. This ball provides a separation between the water in the pipe and the concrete. The weight of concrete pushes the ball down the pipe forcing the water ahead of it. When the ball pops out you know the concrete is flowing and as long as you keep the end of the pipe in the concrete there will not be any washout of the cement in the concrete.

 

[jaotguy]

or . if you really want to keep them separate , line the hole with a cheap plastic sheet. keep the sides of the plastic higher than the hole , pour the concrete onto the plastic and it will sink to the bottom , continue pouring along the hole till the water rises and runs out , replaced by concrete . ... flip the rest of the plastic over the top to cover the fresh concrete against any further water ....

 

[timster2]

Just thinking outside the box, How about taking a large heavyweight trash bag put it over the hole and fill the bag displacing the water as it fills. No problem with the mix, concrete is heaver than the water so it should displace and sink as the bag fills. A little help from a tamper and your done.

 

[Red Horse]

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

Texas 42 is right on-only way to do it-get a piece of 4" pvc, big funnel on top, run pipe to bottom and start pouring!

 

[PILOON]

I have done it making piers for clients to anchor docks.
Some dilution will want to take place so I have used thin plastic bags and pour into the bag which holds it together with minimal dilution.
The bag follows the lake bottom contours to make a perfect fit.
Stuffing gaps with old insulation wool also helped.
For posts I simply pour the concrete which displaces any water.
Actually the constant presence of water makes for a much harder concrete.
Note that on hot days contractors usually spray the concrete and often cover with burlap and sometimes straw to retain moisture.
AS said, concrete is a chemical reaction and not a drying one.

Reason for bagging is to not get over dilution which does make for a weaker mix.

 

[MossRoad]

If he uses a pipe to fill the hole with concrete, how's he going to get the post into the hole afterwards? :confused3: You ever see anyone put the concrete in the hole before the post? This is for a birdhouse. Just stick the post in the hole full of water, mix up your concrete in a 5 gallon bucket or a wheelbarrow as normal and put it in the hole around the post. Its heavier than water. It will sink right down well before it gets enough dilution to make a difference. All the excess water will come to the top and spill out around the ground. Don't over think it. Its not like you have to be concerned about structural strength on a house or building.... its just a duck house on a post!

 

[MossRoad]

From cement.org

"Will concrete harden under water?

Portland cement is a hydraulic cement which means that it sets and hardens due to a chemical reaction with water. Consequently, it will harden under water."

FAQs

 

[eray1066]

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.

Perhaps the first little bit of concrete could get wet from the water but once it is above the water in the sauna tube you can just move the sono tube loaded with concrete which will displace the water away. The trick is to get the well mixed concrete to the bottom to displace the water up Is we use this technique a lot in submerged footings

 

[Ford850]

Ha, I missed the part that this is for a duck box. OP, I thought you meant it was a duck house, as in chicken coop, and you were putting in piers for it to sit on. The tremie method would still work if you have a large enough hole for a pipe to fit in next to the duck box post, but not really necessary for setting a post IMO.
Mix the concrete, bail out as much water as you can, add the post to the hole, then fill with concrete. Even if it fills most of the way, there isn't much volume of water to disperse the concrete mix as if settles to the bottom.
The reason for the tremie is to keep the mix from separating as it falls to the bottom. If you get it in place without separating, water won't hurt anything.

 

[GPintheMitten]

In post 4 I brought up that I thought it was a box on a fence post. It doesn't need over-engineering.

But it is interesting to read all the various ideas that might help in the future for real structures.

 

[jix]

properly mixed concrete will displace the water .

Agree..Use a slightly stiff mix, pour it in on top of the water. It will displace the water as it fills the hole and harden normally and fully under water, no problem.

 

[ernieo]

To pour concrete under water use a anti washout admixture from Master Builders, Euclid Chemical, or Grace chemicals, you may be able to purchase from a local redimix producer. Usually in 5gal pails, add to concrete, it produces a film around the concrete which you can place through the water or sono tube without removing water,

you can add calcium or a concrete accelerator to speed up set times

 

[MossRoad]

Welcome to TBN!

 

[TomSeller]

If it is a just duck bird house, why even the concrete?

What kind of ducks, by the way? I have a few acres in duck ponds.

 

[lostcreekranch]

What many do here in the South is build duck houses that float, then anchor in the middle of the tank. Keeps predators away. In fact don't think I've ever heard of an elevated duck house?

Perhaps there are different strategies where you are? Your profile does not say what region you are in?

But, if this thing has to be on a pole, just mix your concrete normally and pour in the hole around your properly plumb pole / post. Nothing more, nothing less. You need no special additives. The concrete will easily displace the water.

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