Concrete Pond

[Tywais]

Thought this would be best in the DIY forum since I would like to see if I can do the repair myself.

I have a concrete fish pond on our property and now the water drains out of it quickly. Had it repaired several months ago by having new concrete layer put on the bottom of a few centimeters thick. They used some chemical mixed with the cement to water proof it and it worked fine until now. It just started quickly, one day pond was full then started dropping and now a full pond will drain nearly dry in 2-3 days.

I attached a photo (vertical side of pond) of where I believe the problem is and was wondering how one goes about fixing it. What techniques, chemicals/compounds etc. Should it be drilled and patched, etc.

[Zeid]

I am not sure if this helps but now they have fibers that you can mix with the concrete to make it stronger it is mixed in ratios of weight and depending on what you are using it for your ratio will differ, the ones we used for the pool was 3m and it worked miracles.

[Naam]

I have a concrete fish pond on our property and now the water drains out of it quickly. Had it repaired several months ago by having new concrete layer put on the bottom of a few centimeters thick.

another concrete layer without steel reinforcement won't solve your problem Tywais. even some cheap wire mesh in the concrete would have helped a lot. are those cracks/holes shown in the picture the only ones or are they all over the pond?

[Tywais]

another concrete layer without steel reinforcement won't solve your problem Tywais. even some cheap wire mesh in the concrete would have helped a lot. are those cracks/holes shown in the picture the only ones or are they all over the pond?

That's what I was concerned about is reinforcement. It was done about 12 years ago but I wasn't around but the problem only showed up in the last year. Appears no plastic liner was used and suspect no rebarb. That is the only crack that I've seen, and it is pretty significant going from top to bottom of the wall, and all the water is draining out at that end of the pond.

//edit - the initial problem were cracks where the floor of the pond met the walls. The concrete fill seemed to fix that nicely. Not sure what the waterproof additives he used though. Suspect it was both for waterproofing and flexibility of the concrete?

[Naam]

the initial problem were cracks where the floor of the pond met the walls. The concrete fill seemed to fix that nicely. Not sure what the waterproof additives he used though. Suspect it was both for waterproofing and flexibility of the concrete?

no waterproofing additives (not even the fibres mentioned by another poster) can add flexibility, especially not to the walls of a pond where it is most necessary. bottoms might hold up OK because the soil is -by the weight of the concrete- much denser compacted than the walls. in your case it might work to hack off those additional centimeters in the area of the crack and apply 3-4 thin new layers (1-2 cm each) of concrete mortar (no gravel, washed clean sand and cement only) as well as some mesh wire for EACH layer. i am not talking about rebar steel but the mesh which is used to cover concrete pillars before a house is plastered (or as the Brits say "rendered"). it's available in all builders markets.

[Rimmer]

Looks like it is a smooth screed that is cracking and breaking up. Is it gypsum rather than cement?

Assuming the structural integrity of the pond is OK and it does look to be actually OK right?

I would:

Drain the pond with a submersible pump.

Dig out all all the loose and cracked parts

Fill the holes with cement added with a waterproof membrain.

Screed the entire pond over with 3 to 5cm of waterproof cement.

Problem with using a wire mesh is that the cement can leave hollows and air pockets that can collapse leading to what you already have.

[Naam]

Problem with using a wire mesh is that the cement can leave hollows and air pockets that can collapse leading to what you already have.

that's why a suggested thin layers of concrete mortar (NOT cement only!) and no gravel = no air pockets.

[Tywais]

The previous photo was from my camera phone and not does not show the main crack clearly. This one does, as you can see it runs from the top of the wall down the side. It is all concrete pond and the only vertical crack is this one. What looks like many small fractures in the first photo is a thin layer of sand/concrete separating that my brother in-law put on in an attempt to repair it. The earth had subsided over the years and suspect shifting and/or expansion-contraction has caused it.

Thanks for your assistance guys. BTW: Would an epoxy fill do the job? You can see how much I know about this stuff.

[Rimmer]

Wow that's a good crack! Believe you are right and the earth has moved for you.

Assume you are going to do it yourself right?

Epoxy is not the right stuff to use. Cement is very easy for a DIY job like this one.

Knock out the loose stuff

Buy a bag of 3 in one cement mix

Mix up and Add some waterproof add mix

Wet the area to be repaired thoroughly otherwise the new cement won't stick.

Trowel into the crack as deep as you can.

Clean off the edge of the repair

When it has cured screed over the patch with same mix of cement and ad mix.

Color repair to match

Add water, fish, plants and sit back and enjoy.

It's could happen again but short of digging it out and re compacting the soil with foundations and mesh not much else to be done. Assuming the ground has stopped moving it should last a good while.

[Tywais]

It's could happen again but short of digging it out and re compacting the soil with foundations and mesh not much else to be done. Assuming the ground has stopped moving it should last a good while.

Thanks for that detailed DIY list. We had the old grass (dead) removed and re-sodded. We also added about 10 centimeters of new top soil due to the subsiding and believe it is fully settled in now. I suspect we have compounded the problem by continuing to put water in the pond (actually my wife even though I told her it was a waste of time and water) and the water leaking out may have weakened the foundation even more. We will have to transplant the fish, clean it out and let it dry and a visit to Global House for supplies.

[Naam]

have sent photo and details to a friend of mine (who lectures civil engineering). answer probably tomorrow. patience please!

[ozzydom]

Tywais,

There is an epoxy filler named Sikaflex, there are several types for different applications ,it is superb for under water repairs, I have used it to repair cracks in 20,000 litre concrete water tanks and also a ferro cement fishing boat.

The one I normally use is Sikaflex FC ,it is available at most of the big building supply stores,it is french made and instructions are in english.

It comes in cartridges and after initial drying it cures under water and has terrific flexability.

[RubbaJohnny]

If it persists it may be more effective to get the cheap local labour to dig out and properly seal with non organic plastic liner

Goodluck

[longball53098]

Tywais,

There is an epoxy filler named Sikaflex, there are several types for different applications ,it is superb for under water repairs, I have used it to repair cracks in 20,000 litre concrete water tanks and also a ferro cement fishing boat.

The one I normally use is Sikaflex FC ,it is available at most of the big building supply stores,it is french made and instructions are in english.

It comes in cartridges and after initial drying it cures under water and has terrific flexability.

This Sikaflex FC sound s like the solution to my small fish pond leak,,,,,,,,,,,,you say it can be applied underwater? And cures while wet? Perfect as I do not want to drain and dry my pond.

Will HomePro carry this FC type?

Thanks