Patching a concrete water tank ?

[auscab]

Any one know anything about patching a crack in a concrete water tank ?

Its 40,000 LT and has a crack that's opened down the side . Maybe 3mm ? I thought if the side had opened it would mean the bottom had to have moved as well but I cant see anything in the bottom below the crack in the wall . Ill have to get in and have a closer look as the whole thing emptied . I think it had an amount left in the bottom which then evaporated. It failed and I had a quick look and didn't go back for months.

I wondering if I chip it out on the inside and force in a mix of cement ,sand and Bondcrete ?

Or is some sort of silicon better ?

[auscab]

Here's a picture I took the other day . Looks like it runs right to the bottom and gets wider as it goes down so it must be in the bottom as well .

506010

[Beardy]

A product like Silasec will be better than bondcrete as it will crystallise and self aneal but if there is ongoing movement you will struggle to maintain a seal.
Seeing as though you have access to the inside of the tank I would be more inclined to use a flexible membrane. Open up the crack a bit more with a diamond blade about 10mm deep and caulk with a polyurethane like Sikaflex and then apply a membrane and use a reinforcement bandage over the crack. Apply a minimum of three coats to get enough of a build up to give the membrane elasticity
I would inspect the floor and the rest of the tank as well to see how far the crack has run.

[Slave]

You can get liners for tanks to repair cracks and small holes. Mate used them on 20000 lt tanks, I think they where around $1200/1400 each, sealed the tanks perfectly with no worries since. This was around 10 years ago

[Bushmiller]

Rob

You may be lucky and get away with a patch job, but long term with a water tank you need security. Concrete tanks should always maintain at least a small "bank" of water in the bottom and never be allowed to completely dry out so you are behind the eight ball already.

I would investigate the cost of a plastic liner. It may seem expensive, but the last thing you want to happen is watch 40,000l of precious water go down the paddock. Having said that, you could try patching first, and I would be inclined to coat the whole interior of the tank, but the risk is that it will still leak and then you lose the water. :(

Regards
Paul

[Bohdan]

Having had that problem with several made on site tanks and having tried all the patch repairs, which all failed eventually, I would recommend the liner as the only repair that might work long term.

I have used the crystaline external repair and the painted on internal membrain - both failed

One of the basic problems with any patch repair is that as you fill and empty the tank it expands and shrinks and the crack opens and closes. If the tank is normally kept pretty full the crystaline fix may work.

I have even tried running strapping around the tank to hold the crack closed but once the concrete cracks it exposes the internal reo to rust and this then forces the crack to grow.

The only other guarenteed fix is to replace the tank with a pair poly tanks, with which I have never had any problems. I have a pair of factory made concrete tanks. These have cracked but have somehow managed to seal themselves so I think that they are made of a different concrete mix.

[auscab]

Thanks for that info . It doesn't sound promising with the patching . A local farmer said the same sort of thing .

I didn't realize they had steel reo in their make up as well . Makes sense though .

So a decent liner or a new tank .

The good thing about a new poly tank is I could move it North 40 meters and it would be sitting 5 to 6 foot higher on a hill which would be better for getting the water to other locations with better pressure . This tank is close to a dam and water is pumped from the dam to the tank and then is fed to a stock drinking trough .

[malb]

Hi auscab, I have seen these guys (https://thetankshop.com.au/leak-repairs/concrete-tank-leak-repairs.html) advertising regularly on facebook for a few years. They appear to use a pressure injection technique and can work with the tank full and leaking. Seems to suggest installing metal bands as well to support the wall where there is evidence of a running fracture. I have no knowledge or experience of their methods, so this is information only rather than a recommendation. Hope you can something sorted.
Mal

[auscab]

Hi auscab, I have seen these guys (https://thetankshop.com.au/leak-repairs/concrete-tank-leak-repairs.html) advertising regularly on facebook for a few years. They appear to use a pressure injection technique and can work with the tank full and leaking. Seems to suggest installing metal bands as well to support the wall where there is evidence of a running fracture. I have no knowledge or experience of their methods, so this is information only rather than a recommendation. Hope you can something sorted.
Mal

Thanks Mal . That's a good link . Not just for the repair. There's a lot of stuff in there that's well explained about other things as well .

Rob

[damian]

2c..

Plastic liners are protected from UV by the concrete. I know plastic tanks claim to have UV protection but they are only guaranteed for 10 years.

Corro steel tanks have plastic coating on the inside and can be cheap. You can also get stainless but I'd be sus of corrosion around the welds, no matter how well they are done. Steel tanks are easier to dispose of when they do wear out.

The downside of steel, and plastic for that matter is site prep.

If it were me I'd have a good ring around and see what you can get a liner for, then compare the cost of a new. The trouble with a liner is if the tank loses structural integrity you've done your money.

Whatever you decide good luck.