Can concrete set up under water?

Question

My concrete dock has been undermined by wave action and there's a huge area underneath with no rocks there. It's the front side, facing the water that needs repair. Apparently, the bottom part was filled with rocks, then the conrete was poured in. The top foot or so is solid concrete. The water level is quite low right now, so only about 8" would be under water. I'm planning to put more rocks in there to help fill the space. Is this going to work, or would I be wasting my time and money?

Answer 1

Best Answer - Chosen by Asker

Yes. All concrete will set up (cure) under water. It actually cures better under water than it does above water. You can ask any State Inspector on the highway that is on a construction job pouring concrete. When they take test cylinders they let them harden enough so they can remove the cylinder casing, then they put them in water to cure for a period of time before they break them. You do not want your concrete to soupy, it should be on the dry side. Because as you put it into the water it will thin out some. Have your rocks already put down when you do so that you can use them as forms kinda like. Plus some for extra, if you know what I mean.


Ex-Concrete Truck Driver

Asker's Rating:

Asker's Comment:

Great answer!, and so were the others. He gave good advice and sounds like he has a lot of experience. This is a fresh water dock on a large pond, so the waves aren't always a problem. Thanks to everyone.

Answer 2

portland cement cures chemicaly so yes it will harden under water just make a form to help hold it in place while it sets.

Source(s):

http://www.cement.org/basics/concretebas…

Answer 3

hydraulic concrete sets underwater. very expensive but commonly available. the Romans invented it

Answer 4

Hydraulic cement will cure underwater. Sometimes it is called wet plug. You can get it at home improvement stores/

Answer 5

Slowpoke (the prevoius answer-er) is exactly right. Follow his advice.

Source(s):

Maintenance Director of a resort/country club

Answer 6

concrete will set under water but if i was you i would try and consolidate the whole area with mass concrete ..if you could put a shutter in front to stop wave action while the concrete sets it will help ..either speak to your local ready mixed plant about the types of concrete available ..or try adding rapid set to mix

Answer 7

Concrete cured in water will be stronger in the end; however there should not be any strong current which might erode it, or agitation, as it needs time to set initially . By adding a certain calcium additive however to the wet concrete you can cause it to set off slightly faster; or moderately faster; or ALMOST INSTANTANEOUSLY. Be careful if you are going to mix it yourself, as it can happen in a flash; do a test mix.

If you're going to order the concrete, then the company will add whatever you want; they are fully familiar with the process.

Are you talking about SALT water? This I must say would be different, as salt is not a friend of concrete. If you are----well....I might do this either way-----i'd order the concrete with the calcium additive so that it cures quicker (but again.... be careful, as the cement will then stiffen up VERY QUICKLY, and if you're only halfway through the mix, you're screwed.... I wouldn't do such a thing as this without the help of an experienced concrete man.

Source(s):

Years of construction experience

Answer 8

yes `fondu`cement.

Answer 9

Just a thought, if your present dock has been undermined by wave action, so will the new one be. You need to contrive some sort of protection from the waves for it.