The concrete corner of our foundation is spalling. Pictures inside


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Old 04-11-13, 11:50 AM
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The concrete corner of our foundation is spalling. Pictures inside

So this has been going on for a while now, but the concrete corners on the exterior part of our foundaiton is spalling or crumbling off. Its right on the outside of the garage. Actually there are two corners where this is happening.

We are doing research and trying to figure out how to fix this problem. People on this forum seem to have a lot of knowledge about this kind of thing, so I thought I would come to you guys for some help.

I've created an album in imgur since the pictures were too large to load on here.

concrete problem - Imgur
 
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Old 04-11-13, 12:11 PM
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Welcome to the forum.
From your pictures, it looks like there has been one or more attempts to patch the concrete.
The concrete looks like it's getting water behind the surface, which is causing the exterior finish to crumble away.
Unfortunately I'm not an expert in this area, so I am not sure what type of morder product to suggest.
I will mention that the wood frame around the garage bay door looks like it's got a bit of rot near the concrete floor.
 
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Old 04-11-13, 07:51 PM
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corners

first i would repace the rot around the door, then clean out loose concret clean real well with the dep hole i would use brick to bring to even with the rest of foundation, i would use portland cement take 6 shovels of masonary sand to 3 shovels of portland cement mix up for you can plaster over the brick put on 2 coats with a concret binder the first coat is a sracth coat and the 2nd coat is floated out
 
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Old 04-12-13, 04:06 AM
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6 shovels of masonary sand to 3 shovels of portland cement
Unless I'm mistaken this is the same as the 'sand mix' bags sold at most big box stores ...... which would be easier when needing small amounts
 
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Old 04-12-13, 03:41 PM
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One possibility is the differential movement between brickwork and concrete.
It goes like this; after the initial set, concrete gradually shrinks as the chemical changes within it occur. On the other hand, newly-laid brickwork expands as the initially-kiln-dry bricks take up atmospheric moisture.

Both these movements (ie the shrinkage of concrete and the expansion of brickwork) eventually slow down and stop, but are irreversible.

When these two materials are put together, problems can occur. In your case, the brickwork will eventually oversail the concrete base by a small amount, and this puts tension on the concrete, which splits at the end, where the tension is greatest.

If the concrete was of poor quality to start with, that would not help. If the house is more than a few years old, the movement will probably have stopped.
As pointed out, it looks like someone has tried to patch it, but not very well.
 
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Old 04-13-13, 08:06 PM
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That concrete looks very much like it was exposed to freezing temps when it was first placed, years ago. Hence the (repeated?) attempts at repairing it, instead of just removing and replacing it. Do you happen to have any history on the house, such as what time of year the foundation was placed? Corners are the first locations to deteriorate if uncured concrete is exposed to freezing conditions, because the cold exposure comes from two directions instead of just one. There's also far less mass, for getting help from heat of hydration, to prevent the concrete from freezing. Give it the sniff test--frozen concrete has somewhat of a "green" uncured smell to it, very different from sound concrete (which has very little odor).

Proper repair is not easy, but neither is it impossible. All unsound concrete has to be completely removed while adequately supporting the brickwork. A system of temporary, diagonal braces is usually used, with each brace using a spreader piece with a lip to catch several bricks along their bottom (front) corners. When finally reached, the sound concrete surface that will be bonded to with new concrete may be a foot or more into the garage slab. Front faces of the repair areas are formed with slight, outward offsets to enable new concrete to be placed under and behind the brickwork. Lots of vibration, and either using a mix with water reducer or using self-consolidating concrete, are helpful for proper placement and consolidation.
 
 

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