How to repair a crack in a concrete pond

[Laaf]

I have a concrete pond that is 2 feet deep and over 30 years old. It has one crack all the way through it with minimal displacement. It does slowly leak water.

What can I fix /fill the crack with?

Lowes recommended Dry Lok Hydraulic cement. It comes as a powder and you have to mix it.

The pond store recommended a pond caulk material that comes in the kind of tube that uses a caulk gun. But the tube says it is ready for painting with a pond sealant after 12 hours. And I was not planning to paint the pond.

Any tips on which to use and why?

I do not want to convert to a liner pond because it has a steep drop off and no shelves to it would be too hard to hide the liner all the way around.

It is empty and dry now. But it will get a fresh life once the crack is fixed. I bought all ingredients to make a bog filter with a waterfall and bring it back.

It is 2 feet deep, 4 feet by 5 feet x 2 sections with a 6 feet long by 2 feet wide x 1 foot deep connecting section between them with a bridge over it to the back yard. It was a selling feature for the house.

Thanks for any help!

 

[zeuspaul]

I would use Rapid Set Mortar Mix. You would have to drain the pool and clean the crack. It is similar to Portland cement products but stronger and doesn't shrink. I have used it with good success. It sticks to concrete. I would use a trowel and extend about 6 inches beyond. If there is a structural issue and the crack continues to grow this wouldn't be the solution. The advantage of the product is you still have a concrete surface and can still apply concrete fixes in the future. It is also available at Lowes.

Product Mortar Mix | CTS Cement

www.ctscement.com

 

[Laaf]

Thank you for your comment. Do you have any experience or comparison of mortar mix to hydraulic cement?

 

[zeuspaul]

I have experience with Portland cement products, most common cement/concrete/mortar mixes are made with Portland cement. Portland cement is considered a hydraulic cement because it cures with/under water. There could be a lot of different additives in Portland cement mixes which will change some characteristics, drying time for example.

Either way you choose I would clean the crack with a chisel by scraping along the crack. Muriatic acid can be used to clean concrete. I think 3 inch overlap when applying would be enough.

Rapid Set Mortar Mix has a compressive strength of 6500 psi. Portland cement mixes start around 2000 psi and max out around 5000 psi. Rapid Set shrinks very little. Portland cement may not shrink too much depending on the additives.

https://www.ctscement.com/assets/doc/products/MORTAR_MIX_SPEC_EN.pdf

 

[Laaf]

Thank you for the helpful detail. The only concrete type product I've ever used is Quickrete......pour the powder in a hole and add water, to set a post.

 

[SarahT]

I've found RapidSet to be fairly easy to work with, and has the least "shrink" of the various mix products I've used. It is a better grip with a well-chiseled and cleaned finish. I've never used a pond-crack-caulk on ponds.

Good luck, keep us posted with the leaky-solution.

 

[GBBUDD]

All loose material needs to be removed . if the concrete when tapped with a hammer sounds hollow keep going. For a solid repair they also sell a fiberglass mesh that i would install over the crack but that will require some grinding to get the area recessed a bit so when the repair is made it can be flushed out.

If the crack is like a hair then you will want to take a grinder or a saw with a masonry blade and cut the crack so it's wider and deeper Then using a quality silka caulk would be my preferred solution

 

[poconojoe]

Would it be advantageous to use some of that liquid acrylic bonding agent? You know the white stuff that some people in the trade call "milk"?
It acts as a sort of primer. It helps the cement stick better. You paint it in and around the crack. You can even add it to the cement when you mix it up.

Also, maybe carve the crack with a chisel so that it's wider inside to lock the cement in.

 

[GBBUDD]

I'll take a silka acrylic mix mortar any day you can't go wrong with silka

 

[Laaf]

Thank you all for the comments.

I may regret not chipping or chiseling or cutting the crack deeper.......but it was just too many steps for me.

I washed and scrubbed the crack with a stiff brush and strong stream of water. Then I filled it in with Dry Lok Hydraulic cement. It was kind of like putting on frosting that got harder fast.

The employee at Lowes said he had personally used it on his concrete pond and recommended it. It came in a convenient small container.

I should have taken before and after pics.....but didn't even think of it until now.

I was able to fill the pond and I have it running through my new home made bog. I am hoping to add plants tomorrow, or at least this week. I am going to cut out aquatic mint and gravel from my bog and plant it. That will help bring some good bacteria as well.

I used a whiskey barrel liner as my in pond bog and waterfall. It was too hard for me to build an external waterfall. And I was doing the bog for sure. So not the bog waterfalls back into the pond. It should be hidden by plants soon.

This pond is about 600 gallons.

Here are after pics. Note the water in the top of the bog is clear, the pond itself still has all of the sediments from the new pea gravel and volcanic rock. (The guy at the pond store really pushed the volcanic rock in the bog. So I did the bottom portion volcanic rock and the top section pea gravel). This was after I had just filled it up, so almost no cycling or running through the bog yet.

 

[Laaf]

I found these before pics from last week. It was nasty. No fish were found in it. Gold fish were there when I last lived here 10 years ago. You can see the crack to the left of the bridge.

It is basically a bone or barbell shaped pond with 2 foot sections bridged by a 1 foot deep section with a bridge over it to the back yard.