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What is the best way to repair holes in exterior concrete walls?

I recently had a "bee problem" where a colony took up residence inside the concrete wall of my house.  We have since taken care of that issue but in order to do that, the contractor had to bust 4-5 baseball to softball-size holes in the exterior walls.  I need to seal them and I'm curious as to what is the best way to create a foundation or backing upon which I can apply concrete and what is the best product to use when filling these types of holes?
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Posted 2014-07-21T18:11:41+0000  by CLowell CLowell
I'm assuming your wall is made of concrete blocks (also called cinder or cement blocks).  I might fill most of the void with spray foam. The stuff expands pretty much so start at about a 50% fill and see where that gets you.  You'll want to fill so the foam is more or less even with the inside of the block.  Then use one of the concrete patching mix like the one from Quikrete.

Mix it up to the consistency of peanut butter and fill what's left.  It's got about a 40 minute working time.   You may even want to let it sit for 10 minutes or so to reduce the chance of slumping.

Quikrete also make a fast setting cement mix (10 minutes) but you'll want to use their latex additive with that (in place of water) for better bonding.


Posted 2014-07-22T12:58:21+0000  by Adam444
Hello CLowell.  Welcome to the Community!

I would definitely use the Quick-Setting cement along with the Concrete Acrylic Fortifier.  Yes, it has a fast (10 minute) set time, but is ideal for this kind of patch.  

Clean out any loose dirt, dust and debris before you start.  If you have a wet/dry vacuum this is a great place to use it.  Wet down the holes with water for best patch adhesion.  Don't skimp on cost.  Use the fortifier.  It provides much better adhesion and curing of the patch.  This is important as most concrete products shrink as they cure, and you want to prevent that as much as possible.

If the holes were smaller I would use hydraulic cement, which actually slightly expands as it cures, with about a 3-4 minute working time.  Holes this large make that type of fix impractical.

If you do have hollow cinder block walls, then yes you will need to use a filler like spray foam for areas the holes go all the way into the center.


Posted 2014-07-22T13:28:27+0000  by Chris_HD_CHI

Hello CLowell, welcome to the Community.

Another product you may consider is Rapid Set mortar mix.  It has excellent adhesion quality so you don’t need any additional fortifiers and because it can be mixed to stiff constituency it is excellent for patching large holes.

 Fast setting — hardens to structural strength in 1 hour

 Ultra durable — over 9,000 psi ultimate strength

 Crack resistant, non-shrink, long life formula

 Mix to a pourable or stiff consistency

 High performance, eco-friendly hydraulic cement formulation

 Bonds to concrete, brick, stone and many other surfaces

 Excellent for concrete repair, anchoring, underlayments, precision grouting, casting and more

 East to use — just add water

 Meets ASTM C1107 requirements

 One 55-lb. bag yields 0.5 cubic feet which is equal to a 12”x12”x6” thick.

View these video to how versatile this product is.1st rapid set video,  2nd rapid set video

Thank you for your inquiry.



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Posted 2014-07-22T14:38:09+0000  by Char_HD_CHI
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