rebar exposed on foundation

noquacks

Right, Mike. I feel so much better now. Oh, picture above- Im sure you saw it by now. I will not cut them out.

Now, new problem- this thread is morphing- all of a sudden, rebar is no big deal anymore- its the seepage of water coming through one of these walls. After a local moderate rain last wk, seepage is showing into the garage. remember, the back wall (concrete) is totally below ground, and judging by the look of my picture, when this was poured, I bet the workers did not purge all the air pockets from the slurry, and it entrained/trapped air which now, are the least path of resistance for ground water seepage.

Geez- is it even possible to fix that? Are there foundation specialists that can , with a stethescope type tool, locate these "pockets", drill, and "fill" in the voide, if thats the cause?

This MAY be the deal breaker, I dunno- I like the house. I cant have a river flowing in and then out to the front garage door to the street in heavy 3 day downpours.......

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Hardway

If it is rusty, a patch wont hold.

Hardway

the foundation is failing.

oh'mike

You will need a basement waterproofing expert or a foundation expert to look at that---

If it is rain related then a set of drain tiles might be all that is needed--
worse case? excavate and waterproof--then backfill and drain tiles--

Not likely you will get a great answer here---a good one ? Maybe--there are several foundation pros here.

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oh'mike

[quote=
the foundation is failing.[/quote]

Why did you say that? The rebar was placed to close to the forms and the concrete spalled off--

are you seeing something I missed?

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Hardway

the concrete is spalling because the rebar is rusting. when the rebar rusts it expands and cause the the concrete to expand causing spalling. The DOT is testing using carbon fibers in place of rebar in an attemp to stop the spalling from the rebar rusting and expanding. with the carbon fibers the concrete may crack but wont spall.

http://www.buildingonline.com/news/viewnews.pl?id=3782

oh'mike

I understand that ---why did you say the foundation was failing?

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Nailbags

That is a major Deal breaker for me. It is shoddy construction. Very Sub standard. What else is wrong? that has been covered up? If that happened on a foundation I would sub out I would have the whole thing redone at the expense of the SC.

oh'mike

Poster is looking at an vintage house (1948) -- a foreclosure--this is a garage foundation--

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Hardway

The OP said now there is water seeping in thru the poured foundation. If the rebar is rusting and spalling on the inside and the outside. What is the rebar doing on the inside? I can’t see inside the wall and say what is going on. But the surface is spalling as seen in the picture. Need to have someone that is an expert in foundation, I suspect they would
x-ray the wall and see what is going on.

http://concretesealerandblanket.org/blog/?p=61

“Concrete has two layers: an attractive, smooth, outer surface, and a rough, rocky interior. Concrete spalling occurs when the attractive top layer chips away, revealing that ugly interior material.”
“In my research, I’ve come across a great many explanations of what causes spalling. Some claim that damage and wear are the primary causes of spalling. Others say that spalling is caused by rebar corrosion. I have also seen it claimed that concrete spalling is caused by “carbonation of the concrete where carbon dioxide reacts to chemicals within the concrete”, while even others say that poor concrete construction habits are the culprit for most spalling issues.”
Have you ever seen this on a foundation before? See photo below.
The rebar showing in this Austin home is called a “concrete spall” Basically this situation happened because the rebar in this concrete slab was too close to the surface of the slab edge and it started to rust because it was getting moisture and oxygen.
The rust is a growth on the surface of the steel and because of this growth, the rebar is getting fatter and the rebar requires more room to expand. The expanding steel causes the concrete to crack, break and delaminate the area around the rusting steel. Many times just a little rust can cause the first cracks in the concrete surface, but then the rust growth can really pick up speed as water and air enters the small cracks and feeds the rust, which I call “cancer” to the steel.
In Austin, the climate is fairly dry, and there is no salt air from the ocean so the rebar can take a long time to cause spalling to happen. In this case, the slab edge was getting wet from years of sprinklers feeding the problem.
The solution to a spall, is to review if the steel is needed to structurally support the foundation or if it is not. In this case, the steel is multiple layers of overlapping rebar and the bar close to the surface is redundant and can be cut out. The other bars are going to have to be cleaned to bare metal. All rust has to be removed.
To remove the rust, first chip away all loose concrete around the rebar and chip the solid concrete to expose the entire rebar as best as possible. Grind, wire brush or hammer off all the rust on the rebar. The rebar will need to be coated with an epoxy paint to seal the steel from any moisture or oxygen. At that time, the concrete can be patched with a quality mortar patch with vinyl adhesive added for strength and adhesion to the existing slab. Care should be taken to keep all sprinklers from watering the sides of our concrete slabs as the water causes damage to siding, bricks, stones and concrete.
Do you have questions about your Austin Foundation – Slab on Grade or Pier & Beam? Douglas Foundation Repair of Austin is your home’s foundation doctor. Call today! 512-740-8114
Writer’s information is for discussion purpose only and should be confirmed by an independent source.
I am not an expert and don’t claim to be, these are just my views and opinions.

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Aggie67

There are methods of determining what size rebar is hidden within concrete, and what the spacing is. Cobalt x-ray technology has been around a while. But you need to put the cobalt on one side, and the film on the other side. I've had shots taken of concrete walls and piers, and the images are freakishly clear, and tell the complete story of what's inside the concrete. It's not terribly expensive either.

Fixing exposed rebar can be accomplished. Just take a drive by the Manhattan Bridge's west end abutment. Which is probably a bad example, since nearly every component on that bridge except the main cables and towers has been 100% replaced over its 100 year history. (Really shoddy construction, and complete replacement is out of the question.)

Fixing leaks can also be accomplished with epoxy injection.

However, with that said, these repairs would all be useless if the wall itself is unstable, insufficiently designed, or shoddily constructed. There are engineers out there that do nothing but inspect, assess, and recommend repairs on concrete structures. If it's an asset that you can't walk away from, hiring one of those engineers is a good first step.

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Hardway

agreed!

Hardway

in time if this get wrose the bricks will fail.

noquacks

Geez, looks like I have some reconsidering to do. Bank owns the house, of course, maybe I can throw it back to them and give them the opportunity to hire an expert, and go from there. The rear wall leakage is what bothers me, and the spalling concept. I suspect this can snowball into something too big, we'll se.......

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jomama45

That wall doesn't really scare me at all. I can't even tell if those really are rebar, may very well be part of the primitive forming system that was used. As for the water issues, one way or another, they can be solved from the exterior side of the wall.

One more thing about rusting rebar: The rebar in the center of the wall (if there is any, and it's not lightning rod material or old water pipe) is far less prone to rusting & failing than the steel that was placed directly next to the old hardwood formwork. It takes more than moisture migrating through the concrete to create rust. The term "oxidation" is a clear indication that sufficient amounts of oxygen must be present to sustain the process of "rusting"..........