looking for a repair product for a concrete dam riser

[dmcutter]

We have a 9 ft diameter riser made out of precast sections with tongue and groove joints, with mastic and Hydrotite water stop in the joints. We lost the waterstop at a joint about 14 ft down and it's losing about 40 gpm. We need to seal the joint from the outside. The joint is about 1/2" high and 4" deep. We plan to stuff oakum into the joint and then seal around the circumference with some type of cementitious material. All the materials we have been looking at, e.g. Ram-Nek, need to be applied in the dry, which obviously won't happen 14 ft down. We are looking for something that can be mixed at the surface in a boat and then lowered to us, so it needs to have a working life of somewhere around 10 minutes and needs to be appliable by hand or hand tools. All the swimming pool repair product makers tell us their stuff won't work with 14 ft of head. Anyone have a specific hydraulic cement/plug/marine caulk that they can recommend?
Thanks

 

[dumpsterDiver]

5200? Very messy and gooey, expensive.. I've used it underwater, but never at depth... Maybe in a caulk gun?


http://www.amazon.com/3M-Marine-Adh...31697&sr=8-2&keywords=3m+marine+adhesive+5200

 

[Heliumthief]

Dont know if it's just a UK trade name, but google 'speedcrete'. It's a fast curing cement, you make up a small bucket at a time, and quickly send down to the diver, who will usually get one good fist-full out of the bucket, and hold at the edge of the seam, and it will harden in just a few minutes after mixing.

There are quite a few plasticisers and accellerators you can add to a normal grout mix that cures incredibly quickly. My advice would be to talk to a large ready-mix quarry- anyone in the concrete buisiness will know about these. I remember trying to use an additive which said it cured in 60 seconds (specialist water board stuff) which set in the bucket around the mixing auger while the tender was reading the pack!)

the trick with speedcrete, which I've used quite a bit in Dams etc, is to be totally prepaired, mix a small amound in a disposable bucket, and make it up as quite a 'runny' consistency, certanly more liquid than looks right. Hold one fist full into the crack, until it feels like it goes off, and you might get one more out of the bucket, but probably not, so dont mix up too much or its wasted.

you could always look at something more temporary- make up a 'shutter' the same shape as the circumference of the riser, maybe out of plyboard, or if you have the means, light steel, tin, etc, use soft neoprene stuck to the inside of the patch, and get a couple of cargo straps around above the leak. When youve got everythin installed above the leak, then tap it down till its over the leak and tighten the hell out of it. If thats too temporary for the client, or if it's still leaking, then you will at least have reduced the flow of water, and you can use the speedcrete/grout repair without it getting pushed out, or just necase the whole patch with concrete. Also, you could wrap the patch, etc with 'Denso' tape, sticky wrap, which hardens over time to make a good bond.

 

[ajtoady]

Any way to have a partial saddle with a neo gasket surface made or purchased? Place it over the leak on the outside and hold it in place with a ratchet strap around the riser. We used to fix water mains like that back when!

 

[Heliumthief]

Underwater Repair - Euclid Chemical

 

[Bob3]

well... how'd the job turn out?

 

[dmcutter]

We ended up using the oakum to good effect. It looks like rope when dry, but underwater it's like Rappunzel's hair. We took 2 ft lengths and staged it under bungee cords around the circumference. I would take a bit and hold it in place with my flashlight, then stuff it into the joint with my dive knife. It took us an hour and forty minutes to do the whole thing and we got it down to a trickle. We then had guys in the boat mixing balls of hydraulic cement that we tried to take down and pack on the outside, but when we broke a ball apart it rendered visibility totally zero and just wasn't packing. Since we got it down to about nothing we're satisfied for the time being, but will probably end up getting something like what ajtoady suggested-a thin gauge metal band, probably in 4 pieces, with solid neoprene on the inside that we can bolt into place around the outside. I hadn't checked this post for a while and didn't see the link to Euclid. Some of those products look promising.