How to fix a crack in a concrete tank?

I would say an EPDM (rubber) liner is the only reasonable solution...

Any 'repair' wil just fail again....

But I'm sure someone will maybe have an idea which won't.

Is there reinforcing steel in the tank walls and floor? The reason for asking is that, in the limit, the steel will be doing most of the work in holding the tank together and if the concrete is still bonded to the steel it is only necessary to stop the crack from leaking. If there isn't then more drastic action needs to take place (the absence of reinforcement in a concrete slab, upon which was erected a garage, was a prominent driver for the demolition and replacement of said structure as part of a home extension project recently).

Bitumen-based roof repair compounds applied with a putty knife to damp wood from the inside have been effective in eliminating leaks in a wooden boat recently without the need to lift the boat out of the water, as a possibility (the local major home improvement outlet has a number of solutions for roofs based upon this sort of technique). On boats the task is known as 'caulking'.

Yes, there is reinforcing, though I do not know what size etc.

The tank is a commercially sold one quite commonly used in the bush, and maybe 40 or more years old.

I have tried Bentonite which acts similarly to the wood sawdust in being sucked in and then swelling, as suggested for wooden boats, but the expanding crack let it eventually get washed out.

Has anyone tried these plastic liners?

The main problem, as I see it is to get something which may be brushed on as a paint in the wet damp conditions on the floor, with a flexible "fabric" to provide stretch protection and form a flexible impervious sheet across the crack.

Couple of points.

Repairing a crack with a rigid material is no good without answering the question why it is cracking so that action can be taken to stop the expanding crack widening .

I'd aviod plastic liners as the do not have as much stretch or last as long as rubber..* EPDM has plenty of strtch so it will allow for movement, obviously you would want to fill the crack as much as possible first to avoid the liner getting forced into it too much initialy.

I've used EPDM to re-roof a flat roof which has quite a bit of seasonal movement, also to re-line apond, it's good stuff, and any offcuts can be used to make usefull 1"wide strips, great as tie downs....also makes interesting evening wear...pass the talc boys.

To use another boat analogy:

Wooden hulled vessels of all sizes develop plank seam leaks. For centuries, a short term fix, (short of hauling the vessel and reefing and caulking), is to sprinkle a fair amount of saw dust and shavings over the side in the vicinity of the leak(s). Surprisingly, the sawdust will be drawn into the open seam, get lodged, and after a fairly short while (dependent on the granule size and type of wood) will swell up and pretty much seal the leak. This is also used for vacuum leaks on steam ship's main condensers through and induction tube at the sea water inlet to the condenser.

If the cracks are quite wide, this may not work.

The water may taste a little funny for a while, but it will surly be less toxic than most commercial sealants.

This site might help solve your problem.

http://www.kryton.com/products/crackrepair.php

This site might help solve your problem.

http://www.kryton.com/products/crackrepair.php

Thank you willyap06, I have sent them an extensive email requesting better and further particulars and asking if they have their products available in Australia.

Probably costs the earth, but we shall see.

It will be good to have the windmill storing water inside the tank, instead of continuously recycling it in through the top and out the bottom and round and round and round.

Probably the best sand filtered water around.

ciao

Devcon corp, makes NSF certified "sealing" putty type of poducts. They can be spread on with a putty knife and work very good. Have you considered having a local swimming pool company spray gunite inside the tank? it should take less than 2 days and last for years.

Mike the boiler guy

Maybe a compromise/cheap fix...maybe a BIG patch of rubber.....stcuck down with suitable gunk, the water pressure should hold it in place as long as it is water tight initially, and it should have the flexibility needed?

(Or is this just being silly?)Don't cheap fixes usually bite us on the arse?)

Use a submersible pump to totally empty your tank and then make your repairs to a cleaned surface. Consider excavating (if necessary) around the tank perimeter and reinforcing the structure externally. This should also be done empty.

There are lot's of possible websites to look at. Parchem may be useful to check since they may have some relevant 'local' knowledge.

I'm surprised no one has suggested a very simple solution Hydrolic cement sounds like the solution to me simple and readily availible

traditional

I'm surprised no one has suggested a very simple solution Hydrolic cement sounds like the solution to me simple and readily availible

Thanks for the comment, but would you please tell me what is hydrolic cement? I have not heard of this type of cement, and how is it applied?

It can be used under water , where it will harden and also expand (in contast to most cements which contract).

Hey Kris...I'm feeling shunned in this thread.

Is no one interested in the innocent pleasures of rubber?

Brentford Nylons * suit me very nicely ! The static discharge is more amusing than scary.

I think the notion of filling the crack is better in principle. The membrane you suggest is viable but not without it's drawbacks. The best approach can only really be decided by site evaluation.

* I'm still singing that darned Ariston Jingle now.

I'll get you the manufacturers name and product code

The product I mentioned Hydraulic cement

Manufacturer UGL

Brand Drylock Fast Plug 10 lbs. $10.99 www.ugl.com

order # 009 24 I hope this helps

Traditional, Hello and thanks for the suggestions - I would imagine this supplier is an American one and so I asked at my local Gigantic Hardware Chain shop and they have pallet loads of what they call Quick Setting Concrete, which seems to have a different composition to the Hydraulic Cement.

It is commonly used here for the fast erection of Colorbond Fencing posts - dig a hole , fill with the Quick Setting Concrete, push in the metal post, add water, stir somewhat, keep the post vertical and 5 minutes or so later it is set, and you can let go off the post.

see below

No one here seems to have heard of the Hydraulic Cement

WARNING:

Do not use Quick-Set Concrete or Quick-Set Mortar with aluminium products.

Download:
Material Safety Data Sheet
(PDF: 158Kb)

AUSTRALIAN BUILDERS QUICK SET CONCRETE

Is a "Dry Mix" combination of quick setting aggregate, sand and cement.

NEW Warning: Do Not Use Quick-Set Concrete or Quick-Set Mortar with aluminium products.

IDEALLY SUITED FOR
Any use where a strength of up to 15mpa is sufficient and quick setting is required. For instance for fencing, pergola posts, clothes hoists and general landscaping needs. (Not suitable for structural use.)

DIRECTIONS FOR USE
When setting a post, place the post in its correct position in its posthole. Next, thoroughly soak the posthole so that none of the water in the concrete mix will be absorbed and therefore weakened by the surrounding dry soil conditions. Now, pour the required amount of water into the hole and add the Quick Set Concrete. No need for premixing. Australian Builders Quick Set Concrete Mix starts to set within minutes. Always add the concrete mix to the water. Because it's quick setting, this product should not be mixed in a cement mixer. Not recommended where a smooth trowelled finish is wanted. For proper results, add 20kg Australian Builders Quick Set Concrete Mix to 2.5 litres of water.

AVAILABLE IN 20kg and 40 kg bags.

BACK

Have a look here.

The product I suggested is important because it actually expands and therefore fixes the crack rather than a temporary patch .

I'm sure if you go on the website I provided they can send you some directly it is a superior product for your application .

I would fix the crack with hydraulic cement. Then install a swimming pool liner. EDPM would make the water taste bad for a long time.

There is a polymer which can be injected into the crack if the crack is wide enough. The polymer will then expand and seal off the crack. The company that use to sell this product is Cytec Industries (www.cytec.com). I don't know whether they still sell it. There are other companies that are selling similar products, look it up in Google.

Cracks can be around for a while allowing build up of algea in the crack. It will mess with most fixes unless you first clean it up with algeaside or pool acid and then neutralise the chemicals before you patch. Concider a few 12mm steel rebar reinforcing "staples". Go with 300 to 500mm wide and 70 - 100 legs. shallow chase a slot accross the crack and drill holes for the staple legs. Chase a groove along the crack, fill and smooth over the whole lot with a structural epoxy. Etch a wide area on either side of the crack 300 - 400mm each side. wire brush well and then apply a nontoxic water based bitumous sealant and geo-fabric, the type used for koi ponds. Allow to set up and then wash it down with bio degradable soap and water. Bushdriver South Africa

Hi Bushdriver,

Thanks for the reply - good thinking - I will do something like what you suggest, since the whole tank is obviously still settling, even though very slowly and I have a supply of 1/2" reo bar and the neccessary drills etc. etc.

Also, there is algae in the crack, as you suggest, and while I was aware of it, the "penny did not drop" about its significance, so thanks again.

Finally, may I tender my thanks to all those who sent in so many helpful suggestions and advice.

Hi hope this helps as i have used it and it works a treat!

Go to a plumbing supply shop and ask for feroprey which is a 2 pack paste and you mix it under water and apply sub water level .

best to air dry if poss.

Cheers carl

a.hill@sctelco.net.au

Dear Mr. cirreb217,

In one of the following links - you can get the answer for your Problem. I do not remember in which link the answer lies. Pl. read them and you will find the answer.

How to monitor and control temperature in order to prevent shrinkage and crack on Grade 60 (60MPa) concrete?

https://www.google.co.in/search?hl=en&newwindow=1&tbo=d&rlz=1T4ADFA_enIN339IN340&spell=1&q=How+to+monitor+and+control+temperature+in+order+to+prevent+shrinkage+and+crack+on+Grade+60+%2860+MPa%29+concrete%3F&sa=X&ei=uSLgUKjTM8j7rAeUxoCwCQ&ved=0CDEQBSgA&biw=1280&bih=657

Concrete Handbook Control of Cracking in Concrete - Transportation Research Board Curing Concrete, Chapter 12

Prediction of Cracking in Reinforced Concrete Structures - Inti

Thanks,

DHAYANANDHAN.S