What to mix with cement to make waterproof concrete?

Sheryl · January 29, 2016

Can someone suggest a product (by local brand name, picture if possible) to mix with cement to produce a waterproof concrete?

Needed for a small "moat" around the house to keep insects at bay

Thanks!

eyecatcher · January 29, 2016

This is what i add to mortar or concrete for a bathroom floor.

Also good to add it into a weber floor tile adhesive also....even emulsion paint.

Makes the mortar or cocrete quite sticky.

This is a common brand available at many diy stores.

lovelomsak · January 29, 2016

I donot know how to water proof the cement by mixing in the cement. But I know a great product for sealing it after it is made. Crocodile Flex Shield. This stuff works great sealing concrete. Just mix and paint it on.It goes on easy and dries hard and strong.

cooked · January 29, 2016

Naam jah is available most places

NeverSure · January 29, 2016

Concrete is never waterproof. You have to seal it. It's really important to work the concrete to compact it and force out tiny air bubbles. This can be done with trowels.

In the West when making swimming pools the concrete is applied by spraying under fairly high pressure, and then worked soundly with trowels. It is either sprayed as a dry mix with water being added at the nozzle ("gunite") or as a wet mix simply blasted under pressure ("shotcrete"). It can be applied by hand with trowels but they have a bunch of guys really working it hard with trowels to compact it. I have never seen a swimming pool being "poured" in the USA.

The more the concrete is worked and compacted and air driven out, the stronger and more water resistant it will be. Then when it cures you can apply a sealer.

Cheers.

Jing Joe · January 30, 2016

I've used waterproofing additives that mainly have PVA in them.

You can use much less water and doesn't need water to cure.

That white waterproof woodworking glue is probably the same but dearer than the industrial quantity of concrete additive.

If you have some glue try a sample. Try using much less water.

Good luck.

P.S. Helps make small patching up jobs stronger with plain cement with small qty PVA and water.

worgeordie · January 30, 2016

For a small moat around the house !,to keep insects at bay,!

I am sure you know most insects can fly,and the moat will

turn into a breeding ground for Mosquitoes,the insects that

you really want to keep at bay, unless you were only joking?

regards Wogeordie

DMC1 · January 30, 2016

Sika-101a from Homepro. Yellow tub with red triangle logo. I use this to coat the concrete on my fish pond.

You do not mix this with the cement but mix and paint on afterwards. This product is - waterproofing slurry & moisture seal. Clear instructions on the tub.

tomyumchai · January 30, 2016

i was browsing in hardware house yesterday, there must have been 15 different waterproofers and additives on the shelves. sika and many other imported quality brands too.

Shawn0001 · January 30, 2016

You cannot make concrete which is completely waterproof but you can reduce it's permeability by about 70%.

There are two options, a concrete admixture or a paint on sealer. Admixes are the only long lasting solution.

There are four types of admixture, latex is the worst as it does not fill cracks that appear after pouring. The third from best is adding silicates to the mix to increase density, this helps but not that much. The second from best is a hydrophobic admix such as soap which can reduce water ingress by about 50%.

But the best by far is a hydrophilic crystalline admixture, such as this one from Xypex.

http://www.xypex.co.th/index.php?option=com_content&view=article&id=25&Itemid=137

That is the best, but that's what we use for tunnels and the like, for a shallow trough as I imagine you are making, just regular concrete will be fine as long as it is reinforced, I would suggest some fibers in the mix as well as steel reinforcing.

Morakot · January 30, 2016

On 1/30/2016 at 11:36 AM, Shawn0001 said:

You cannot make concrete which is completely waterproof but you can reduce it's permeability by about 70%.

On 1/29/2016 at 10:16 PM, NeverSure said:

Concrete is never waterproof. You have to seal it. It's really important to work the concrete to compact it and force out tiny air bubbles.

Absolutely correct the above two posts!

Also to reduce permeability, the water-agregate ratio should be altered carefully. Increase the grain size of the aggregate and reduce the amount of water.

Basically use less water and crushed rocks (mixture of varying sizes, between 1/4" - 2") instead of gravel.

BlindMagician · January 30, 2016

On 1/30/2016 at 10:34 AM, worgeordie said:

For a small moat around the house !,to keep insects at bay,!

I am sure you know most insects can fly,and the moat will

turn into a breeding ground for Mosquitoes,the insects that

you really want to keep at bay, unless you were only joking?

regards Wogeordie

This was my first thought too. Rethink the moat idea...don't fixate on your home being your castle.

maderaroja · January 30, 2016

Thank you for the information.

jacksam · January 30, 2016

On 1/30/2016 at 10:34 AM, worgeordie said:

For a small moat around the house !,to keep insects at bay,!

I am sure you know most insects can fly,and the moat will

turn into a breeding ground for Mosquitoes,the insects that

you really want to keep at bay, unless you were only joking?

regards Wogeordie

Agree fully. What a crazy idea. Also how do you intend to enter your home. Jump? There exist much better methods. Also what your suggesting may in future become illegal with a dengue fever bill.

steve73 · January 30, 2016

I had a small fishpond built next to my house using "traditional" methods... 70mm concrete bocks, with 10mm render (same as you'd put on any wall), and then a thin skim of pure cement slurry well worked onto the surface, and polished with a steel trowel.

No use of any admixes or PVA at all - despite my concerns and suggestions...

8 years later and it still holds totally leak free (except one area where a tree root cracked the wall - which I repaired using the same cement slurry method).

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