Concrete crumbling how to repair?


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Old 02-27-13, 08:08 PM
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Concrete crumbling how to repair?

Hi Everyone,
Can you please take a look at my exterior concrete pictures and let me know the term for it so I can research and figure out how to repair it myself. Also if you can lead me to a link that describes how to repair it I would be appreciative.
Thanks
 
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Old 02-28-13, 01:41 PM
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What is the structure on top of the slab? Is that your house or garage? What purpose does the slab serve?
 
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Old 02-28-13, 05:38 PM
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I am assuming the slab is our foundation. The picture with the wood shingle looking things and the hose is the front of our house. The rest of our house is stucco but for some reason one of the walls at the front of the house has some wood.

The picture with the stucco wall is just a half wall in the yard. It isn't structural.
 
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Old 02-28-13, 07:08 PM
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If it's the foundation, we need to know if there is a footing under it. Secondly, does water accumulate on the slab?
 
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Old 02-28-13, 08:35 PM
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The pix showing concrete have light-to-moderate surface scaling, which could be very shallow or extend deeper into the slab/wall. Proper repairs consist of removing any loose or delaminated material, then either casting new concrete or dry-packing mortar, against the properly-prepared surfaces. The stucco looks like it debonded because of missing wire bonding fabric and/or water intrusion behind it, causing the wood to swell and exert tensile forces against the scratch coat (if there is one). If the wire is missing, everything should first be removed, then a completely new stucco system installed.
 
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Old 02-28-13, 09:40 PM
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Bridgeman45...you just said a mouth full. As I am pretty new to this game I hope you can answer a couple of basic questions for me.

When you said to remove any delaminated or loose material did you mean just going over the surface concrete and using a putty knife to scrape off anything that will come off with some effort. I have been doing that and those are the pics that I posted. I was also planning on going over it with a wire brush to remove anything I might have missed.

Second, how would I properly prepare the surface?

Finally, can you guide me to a video on how to dry pack the mortar?

As far as I can tell the crumbling doesn't extend very deep, if it were, would that be considered honeycombing?

Pluto...

As for a footing under the foundation, I have no idea. Unfortunately I don't even know what that is. That area is right near the faucet, but other that a leak I fixed a few months back, it shouldn't be getting much water. That crumbling pretty much extends around the base of the entire house. It was built in '78 and from the looks of the rest of the exterior, wasn't maintained very well for at least the past 15 years.

Thanks for the help!
 
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Old 02-28-13, 10:51 PM
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New to the game is good, as that means you haven't had time to pick up bad concrete repair habits. Starting with a clean slate, so to speak.

Sorry, but a putty knife and wire brush won't do justice for delamination (and unsound material) detection and removal. You need to use a tool that can impact the surface, either a hand-held geologist's pick hammer for small areas, or a compressed-air powered impact hammer with appropriate chisels if deterioration is more widespread. A lot of the imperfections appear to be just paint that has debonded, so yes, a vigorous wire-brushing should be able to remove all of that. Concrete (and stucco) delaminations are easily detected by simply dragging the tip of a geologist's pick over the surface--a different sound will result if the surface is not tightly bonded, somewhat lower-pitched and dull-sounding, as opposed to a higher-pitched ringing (some call it "zinging") sound. Be careful, because very thin delaminations will give off a higher-pitched sound, almost similar to sound material. It takes somewhat of a trained ear to hear the difference.

Your pictures don't show honey-combing, as that would have some of the white-colored surfacing material embedded in it, either paint or stucco. Proper surface preparation would consist of sand-blasting any and all surfaces. High-pressure water blasting is also acceptable, except in your case, living in a slab-on-grade house, such would run the risk of getting a lot of water inside, which you definitely don't need.

I don't have the time or patience to dig up a video for you on dry-packing mortar. Maybe someone else will be here shortly with such. Doing a proper search yourself should come up with many such "how-to" productions. The only cautions I'd suggest are to use a proper bonding agent (a neat Portland cement slurry works well), and don't forget to properly cure the fresh mortar to prevent it from drying out too quickly, before adequate hydration (and bonding) can take place. Just forcibly push the almost-dry mortar into the surface, working your hand float back and forth a bit until the material stays in place. I like using a wood plank to initially lay the mortar on, providing a convenient work table for pushing the material off of. And don't over-work the mud, which will ruin it.
 
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Old 02-28-13, 11:09 PM
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BridgeMan45

Great response. Nevermind that it will take me the next couple days to look up and understand everything you said, I really appricaite it. Thankfully I stopped by here to learn the right way to do this instead of doing some shoddy, half thought out patch work.
 
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Old 03-01-13, 07:39 PM
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With reference to the stucco only, the first picture. It looks like what is loose is over a concrete masonry unit. You can see a mortar joint on the left side of the hole. I bet the paper and lath terminate just above that and are probably still good. I see a lot of deterioration right at the junction of the foundation or slab and the sill plate. I have a theory about why it happens but you want to know how to fix it. Remove whatever is loose and bulged then repair as described above.
 
 

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