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Anyone know anything about concrete and rebar?


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A friend of mine e-mailed me the photo below. He lives in a 20-story apartment building, and this is the condition of one section of concrete in the parking garage. The building has only been open a year, so he's a little worried that the rebar should be showing through.

Opinions? Is this normal? Is it cheap concrete that got worn away by cars, and it's a hazard?

post-1-0-41637500-1296768740_thumb.jpg

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A friend of mine e-mailed me the photo below. He lives in a 20-story apartment building, and this is the condition of one section of concrete in the parking garage. The building has only been open a year, so he's a little worried that the rebar should be showing through.

Opinions? Is this normal? Is it cheap concrete that got worn away by cars, and it's a hazard?

post-1-0-41637500-1296768740_thumb.jpg

I wouldn't think it would wear down to the rebar so quickly, it's more likely just poorly done rebar and a half-assed inspection. The area where it is visible will probably crack and erode more quickly than a proper surface, but it likely won't affect overall structural integrity. Just tires and people not looking where they walk.

EDIT: I'm not an expert by any stretch, just a random engineer (by education)

Edited by 20thStDad
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A friend of mine e-mailed me the photo below. He lives in a 20-story apartment building, and this is the condition of one section of concrete in the parking garage. The building has only been open a year, so he's a little worried that the rebar should be showing through.

Opinions? Is this normal? Is it cheap concrete that got worn away by cars, and it's a hazard?

post-1-0-41637500-1296768740_thumb.jpg

I agree with 20th, but I'd love to know what is going to happen once management finds out and be the fly on the wall to the contractor.

It's a tripping hazard and if one person falls and chips a tooth, someone is going to wind up owning that building. Red would probably cheerily take on that case. :)

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I agree with 20thStDad. Sloppy construction. It will begin to corrode and spall the concrete sooner than it otherwise would have. It'll be a maintenance hassle for a long time to come, but nothing that compromises the integrity of the structure.

As for the tripping hazard, the property no doubt carries commercial liability insurance. I'd be more concerned about the old lady that falls and breaks a hip than with the chipped tooth, but this definitey isn't the sort of thing that would create a catastrophic disruption to the course of business. Property management is most conscious of incidents that would result in a bleed-out of tenants, like fires, roof leaks, or breaks in water or sewer lines. But even a murder on an apartment property doesn't typically result in a bleed of more than a handful of tenants, so I don't think that a little bit of exposed rebar posing a risk of someone tripping is going to prompt a great deal of consternation.

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A friend of mine e-mailed me the photo below. He lives in a 20-story apartment building, and this is the condition of one section of concrete in the parking garage. The building has only been open a year, so he's a little worried that the rebar should be showing through.

Opinions? Is this normal? Is it cheap concrete that got worn away by cars, and it's a hazard?

post-1-0-41637500-1296768740_thumb.jpg

Not normal. There's supposed to be 1-1/2" to 3" cover from the rebar to the edge of slab, typically. Structural engineers design the exact dimension and it's based on code and calculations.

Concrete shouldn't wear-away from cars being driven on it after only one year. There was something else. Maybe it was just stray rebar that fell on the concrete when it was wet -- and so it really isn't anything but a tripping hazard. Maybe it's a seriously flawed slab. Either way, you were right to call attention to it. Next stop should be the building management and/or owner. If they don't respond, then go to the City.

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Not normal. There's supposed to be 1-1/2" to 3" cover from the rebar to the edge of slab, typically. Structural engineers design the exact dimension and it's based on code and calculations.

Concrete shouldn't wear-away from cars being driven on it after only one year. There was something else. Maybe it was just stray rebar that fell on the concrete when it was wet -- and so it really isn't anything but a tripping hazard. Maybe it's a seriously flawed slab. Either way, you were right to call attention to it. Next stop should be the building management and/or owner. If they don't respond, then go to the City.

Thanks for that. Good to have some numbers.

It has been brought to management's attention, but it's my understanding that the entire building has so many flaws that this will likely end up pretty low on the list. Hopefully the current owners got the building cheap from the developer.

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