Pond Boss Forums POND CONSTRUCTION Building a dam Crack in concrete dam

We built a dam this summer on a creek. It was compacted base with 5 inches of concrete on top and sides. The builder thinks the water has soaked in from the side and caused the base to swell which then cracked the concrete. I'm worried that it's going to get worse. Any ideas to maybe at least just keep it from getting worse?

Is there any steel in the concrete, or fibers for reinforcement, or both?

If the crack is wider at the surface than at the bottom of the crack, then the soil under the concrete settled, not expanced. If it's narrower at the top than at the bottom, then the soil expanded.

There is a process that injects epoxy into the crack, the full depth and length of the crack. The expoxy has more tensile strength than the concrete itself. When done properly, I've never seen the epoxy break or pull away from the concrete. The epoxy has no UV inhibitors in it, so once it's applied, it should be covered with something (even a thin layer of latex infused mortar) to keep the sun off of it.

We spent 4 months fixing all the cracks in the L.A. Coliseum after the Northridge Earthquake. It's a common practice for concrete restoration in California. I can't tell you how many house slabs and foundations we fixed, a new waste water digester, a floating 4-lane highway that was used as a pier in San Diego Shipyards, etc., etc.

There is rebar in the concrete.

If it's left alone is that bad? Should I act and do something now or just wait to see if it gets bigger?

At the least I would seal it as per esshup's comment above.

It's big enough now. There is nothing to stop water from entering the crack, and potentially washing away soil that is under the concrete. For sure, it won't get any better.........

Is this actually holding all the water in your pond? If so and you don't wanna lose your pond anytime soon I'd fix it asap. If it ain't holding all the water back in your pond I'd take my time and really do some research to fix it.. (permanent fix would be tear out and redo).. Something needs done though.

Do ya'll think it'd help if we put down a 2" cap on top of the whole dam? The dam is holding back about 1 acre of water right now. It's the main entrance to drive over to get into our ranch.

That would probably only be a bandaid until what ever caused the initial crack happened again and starts the whole process over, but then you'll have to deal with water seeping through the cold joints in your new cap. A much tougher situation to deal with. Esshup is dead on with his advise.

That crack will transfer thru the 2" cap relatively quickly. If you don't mechanically and chemically treat the dam before applying the new layer of concrete, it won't adhere to it (for very long).

Unfortunately, the only other fix that I can think of is this one:

Mechanically cut out the crack. Find out why the crack happened, and properly compact the soil so it doesn't happen again. Clean and mechanically roughen the cut surfaces. Drill holes in the existing concrete, and epoxy "coated" rebar into both sides. That's the green rebar that you see them using on roads and bridges. Tie them both together. Coat both sides of the cut areas with a bonding agent, and pour new concrete in the cut-out area.

I like using both steel for a structural aspect, be it rebar or mesh, and the fibered concrete to help control surface cracks. Overkill? Maybe; but the jobs that we did (and spec'ed out that way) didn't crack.

That makes total sense to me. Now I just need to find someone around the Hill Country or Austin that can do work like that. I want to make sure that dam doesn't end up falling apart.

Thanks ya'll.

It looks like a flaw in the design. Concrete expands and contracts, you can't stop it so the design needs to take this into consideration. I would get the crack as clean and dry as possible and seal it with a flexible sealant. The width of the crack means the concrete contracted but the top edges of the crack are chipped off indicating that at times the concrete expanded and closed the crack. If the concrete wants to move, it will, that's why you need a flexible joint there. If you cut out and replace the damaged area with concrete without a flexible joint you will find that the crack will just reappear, maybe somewhere else but it will reappear.