Pouring concrete underwater

[greyskies99]

Great suggestions all! I think for my application the 55 gal drum makes the most sense, although I am having trouble visualizing this. Is there a link vtsnowedin? Am I correct in assuming the concrete poured to the bottom of the barrel "pushes" the first concrete up and therefore doesn't become "contaminated" by the water in the form (drum)? Would adding rebar help to preserve integrity of the concrete? I am not familiar with types of concrete. What specifically should I look for? Would a 8" ABS or PVC pipe to the bottom of the barrel work for pouring? Dock would be permanent so I would just have to trust that the ice flows will go past my little bay...

 

[vtsnowedin]

Great suggestions all! I think for my application the 55 gal drum makes the most sense, although I am having trouble visualizing this. Is there a link vtsnowedin? Am I correct in assuming the concrete poured to the bottom of the barrel "pushes" the first concrete up and therefore doesn't become "contaminated" by the water in the form (drum)? Would adding rebar help to preserve integrity of the concrete? I am not familiar with types of concrete. What specifically should I look for? Would a 8" ABS or PVC pipe to the bottom of the barrel work for pouring? Dock would be permanent so I would just have to trust that the ice flows will go past my little bay...

I'm a state guy. Can't ever say no to rebar.
An 8" pipe would work as your tremie.
Concrete mixes from the plant are sold by PSI cured strength. 3000 psi for walls and 4000psi for floors and bridge decks and even 5000psi for precast items like pipe or catch basins. Old school they went by the number of bags of cement per cubic yard. 5 bag for walls 7 bag for decks. Redimix you buy in bags at the lumber yard is about a 5 bag mix. You can make it richer by adding a few shovel fulls of straight type 2 cement to each bag of concrete mix. Add only enough water to get it to mix up into a thick plastic mass that will flow well down your 8" pipe. It will take about fifteen bags of concrete mix to fill a 55 gallon drum.
Cut the ends out of your drum and drive it down into place with a sledge hammer as far as it will go or to the water line. (Is there a low water season on this water body? If so do it then.) Then dig out all the mud you can from inside the drum with you post hole digger. Mix up your first batch of crete and have a five gallon pail full ready. Now stick an old pie plate over the end of your 8" pipe and push it down through the water and hold it on the bottom. Have your assistant pour in the bucket of concrete while you hold it down against the bottom. Then you should be able to let the pipe go and start mixing and filling. After the third batch or so pull the pipe up a couple of inches and use a rebar to tamp the crete down in the pipe and out the bottom but be careful to not pull the pipe all the way out of the crete. If you do waste another old tin pie plate and repeat the start procedure. On bridge seals they blow up a soccer ball in the end of the pipe and it pops to the surface when the crete forces it out of the end. When you get halfway up stick in your rebar #4s are all you need.When at the top finish off and you can set in anchor bolts or post brackets to hold your wooden riser post.
One note of caution. Make sure you place all the mud you dig out up on dry land and not in the water or the permit gods will frown on you.

 

[flusher]

The ancient Romans and Egyptians developed additives for getting concrete to set underwater 2000 years ago.

Roman concrete - Wikipedia, the free encyclopedia

Check it out before you try the caisson idea.

 

[vtsnowedin]

The ancient Romans and Egyptians developed additives for getting concrete to set underwater 2000 years ago.

Roman concrete - Wikipedia, the free encyclopedia

Check it out before you try the caisson idea.

I know the procedure I discribed above is overkill for the project but it is the way to do it for sure which was the original question. A casson would only be really important if there was a stong current flowing through and around the form . That current could wash out the cement and any additives as fast as they could place it leaving them with a pile of washed rock. They could just pound in a four inch steel pipe as far as it will go and build up from there.

 

[AGGIE00]

When I mentioned 55 gallon drum I meant it as a surface casing, not the actual form for the concrete. If the water is shallow enough it can be used to isolate the column/pier location from water. Then work inside the drum to dig the pier. If you pour under water you will definitely need a tremie of some sort to allow the concrete to rise from the bottom and not pile on top because the mix will dilute and seperate. I have poured many bridge piers under water and the only must is to keep the tremie inside the concrete, but not so deep it gets stuck. Slowly pull it back as the mud fills the hole, but never let it surface above the mud. You could use 6" lay flat hose for this attached to a funnel that can be rented from a construction supply rental company. You could also get some 12" cmp and water jet it down and then fill with concrete. There are so many ways to do this so chew on all the advise and do what you are capable of.

 

[greyskies99]

Thank you all for your suggestions! I think I have enough info to give it a try. I'll let you know how it all turns out. Thanks again!

 

[brin]

Use Hydraulic cement...you can buy it at big box stores..it sets up and expands in water...that is what it is made for...sets up instantly.

 

[greyskies99]

Thank you. Think I may try a test of both regular and hydraulic. Any difference in strength?

 

[Soundguy]

hyd cement will set up under water

 

[vtsnowedin]

Hydraulic cement works great but the cost is very high.
WATERPLUG Hydraulic Cement T5002 10# Can Case of 4 Cans | eBay