Attach dock to cement foundation - How?

[menhir]

Hello!

I don't know if this is the right forum for the question, but I hope it is.

I have an old demolished pier on the Baltic coast. The pier consisted of submerged foundations made of cement and stone cast in oil barrels. Smaller "railway rails" were cast into the foundation, which protrude from the water and on which the wooden pier was mounted. The wooden pier (-deck?) has been gone for a long time, and the railway rails protruding from the water are severely rusted.

The simplest thing would be to reuse the existing foundations when I renovate the pier, but I can't think of how to attach a new pier to the old foundations. Since the foundations are in the water (at low tide, the tops of the foundations are at the level of the water surface), it is not possible to drill with a machine to set plugs or the like, which has stopped all my ideas. Do you have any good tips on how to attach vertical wooden posts or metal pipes to stone-mixed cement under water?

Thanks in advance!

 

[anaitis]

I could imagine that it would be possible to use something similar to what one attaches TV antenna masts with on a chimney.
That is, strong bands of, for example, stainless steel that you tighten around the barrels.

 

[LLLVäxjö]

There are quite long concrete drills, so with one of those plus a decent cordless rotary hammer, you could attach whatever you want to the concrete using expansion bolts.

 

[anaitis]

There are quite long concrete drills, so with one of those plus a nice battery-powered hammer drill, you could attach whatever you want to the concrete using expansion bolts.

Not a bad idea!
Just to improve a bit by suggesting a motor-driven drill, often called "Cobra" regardless of the actual brand.
Drill proper holes and then cast galvanized pipes in place!

 

[menhir]

Thanks for the tips! I've googled a bit about cobra now and watched some videos on YouTube. Seems to be quite powerful, to say the least... And it should be available to rent at Cramo, I hope. Drilling larger holes on top of the cement boulders and then casting in new galvanized pipes should be strong, but what type of cement is used that can cure in saltwater?

 

[cheetah1]

Cobra is Atlas Copco's name for what is otherwise called a "rock drill".

 

[Tossegubbe]

Depending on the circumstances, if it works well, I would probably rent a hydraulic core drill and drill, for example, 50mm holes that are 30cm deep in the concrete and then just insert galvanized or stainless steel pipes to hang the dock on.
Start with a hole at the innermost point and then one at the outermost point, stretch a string between these to drill along so you get a nice line.
The advantage of the hydraulic drill is that it is not sensitive to water and is easy to handle, you can even use it underwater if needed and if you don't have electricity nearby, there are petrol-driven hydraulic units available.

 

[menhir]

What do you think about attaching these in the concrete and then building the dock on posts of pressure-treated wood? http://www.jula.se/tt-stod-131874

Then you should be able to manage with a battery-powered impact driver and expansion bolts. A simple solution, but how long do you think it will last? Is the support galvanized enough to not start rusting immediately and how long can pressure-treated wood posts last compared to galvanized pipes?

 

[cheetah1]

Btw, don't take offense now, but see this as some free general knowledge:
http://sv.wikipedia.org/wiki/Betong
http://sv.wikipedia.org/wiki/Cement

 

[anaitis]

What do you think about attaching these in the cement and then building the pier on posts of impregnated wood?
[link]

Then you should manage with a battery-powered impact driver and expansion bolts. A simple solution, but how long do you think it will last? Is the support sufficiently galvanized to not start rusting immediately and how long can impregnated wood posts last compared to galvanized pipes?

I would not choose these fittings.
Even in Skåne, it gets icy sometimes, right?

 

[menhir]

Thanks for the links. I know the difference, but I'm terribly careless when it comes to using the correct term. Shame on me. I'll try to improve and from now on write concrete instead of cement in this thread...

 

[menhir]

anaitis: Why can't the fittings handle a little ice?

 

[LLLVäxjö]

What do you think about attaching these to the cement and then building the dock on posts of impregnated wood?
[link]

Then you should manage with a battery-powered impact driver and expansion bolts. A simple solution, but how long do you think it will last? Is the support sufficiently galvanized not to start rusting immediately and how long can impregnated wood posts last compared to galvanized pipes?

Probably works with that model. They won't last forever but for a good while at least. You need a hammer drill to drill the holes for the expansion bolts. An impact driver can only be used for screwing.

 

[menhir]

Will probably work with that model. They won't last forever, but for a pretty long time at least. You will need a rotary hammer to drill the holes for the expansion bolts. An impact driver can only be used for screwing.

Aha, I have never used an impact driver (only those without impact) but imagined that the impact driver was like a hammer drill, but with a battery. You learn something new every day!

 

[anaitis]

anaitis: Why can't the fittings handle a little ice?

Very large forces when the ice starts to move.
So it's not the freezing effect that's the problem, but the movements.
Have personal experience...