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#10274 - 09/21/01 05:32 PM Impermeable concrete
Anonymous
Unregistered


Is a wall of concrete waterproof or is there extra steps that have to be done?

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#10275 - 09/21/01 05:38 PM Re: Impermeable concrete
ken Offline


Administrator

Registered: 04/12/01
Posts: 1228
Loc: Austin, Texas
Concrete is permeable. Based on the mix design and how it was placed, it could be almost impermeable, or it could be really permeable. Adding a synthetic fiber, air entrainment, a pozzolan like fly ash or silica fume, ground slag and a superplasticizer to the concrete mix would really help reduce the permeability. Placing an impervious cover such as polypropylene sheeting would be a way to keep water from migrating through, or there are coatings that could be added, similar to roofing tar, that helps as well. I would contact a local concrete contractor supply store to find out what kind of coatings are available in your area for your project.
_________________________
Concrete is good.

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#10276 - 09/22/01 12:13 PM Re: Impermeable concrete
boulder352 Offline
Member

Registered: 06/09/01
Posts: 35
Loc: United States of America
There are products out there like Thoroseal and hydroseal. I have found that a mix of 1 part sand and 1 part masonry cement mixed with a resin of no less than 30% solids works great. The reason for the masonry cement (I have used both type S and type N) is because I beleive it to be much less permeable than portland cement.

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#10277 - 09/22/01 12:17 PM Re: Impermeable concrete
boulder352 Offline
Member

Registered: 06/09/01
Posts: 35
Loc: United States of America
I forgot to finish!
I make this in a slurry mix and brush it on over the finished wall. Also I apply atleast 2 coats allowing the first coat to cure over night. The reason is that if there were any unseel air bubbles or pinholes the second coat would be sure to seal it.

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