Re: Building steps

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On May 18, 7:57 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

From the results, some of them obviously were.
Your stance is that you can throw steel into a concrete pour and it doesn't do anything because, hell, rebar is steel. That's like saying that you can pour gas anywhere into a car since a car runs on gas. You know, nonsense.
Like I said, if you want to learn, Google the subject. I'll give you a head start. This is from Wiki on reinforced concrete:
"Common failure modes of steel reinforced concrete Reinforced concrete can fail due to inadequate strength, leading to mechanical failure, or due to a reduction in its durability. Corrosion and freeze/thaw cycles may damage poorly designed or constructed reinforced concrete. When rebar corrodes, the oxidation products (rust) expand and tends to flake, cracking the concrete and unbonding the rebar from the concrete."
And this is from the Canadian Research Council:
"PREVENTING REBAR CORROSION IN CONCRETE STRUCTURES by Shiyuan Qian
This article reviews the issue of rebar corrosion, discusses some of the preventive technologies available, and presents information on recent studies conducted by NRC’s Institute for Research in Construction.
The corrosion of reinforcing steel bars is one of the main causes of deterioration of reinforced concrete structures in North America. It has become a serious, widespread problem, with repair costs now in the billions of dollars annually. Whether the corroding rebars are seen exposed on delaminated bridge decks or piers, or observed in damaged parking garages, engineers and contractors are all too familiar with the problem, as are anxious property owners who call on them to provide solutions."
It's either odd that; 1). these guys are in collusion and making this stuff up or 2). you've never noticed it.
My bet is on the second.
The main reason that the OP shouldn't throw the scrap iron in the steps is because it is wasting money. The second reason is that the random steel "reinforcing" will eventually cause problems.
I'm taking the liberty of cross posting this to some other groups with more knowledge on construction than this one. Let's see who weighs in and which way the verdict goes.
R
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From what I've seen (& read) working in the civil structural field for since 1988, the major cause of reinforced concrete failure is inadequate coverage. Followed by poor quality concrete.
Depending on the "exposure" & environmental conditions, as little as 2" of coverage is spec'd, harsher conditons 3"+ or more.
Epoxy coated rebar is a "new, hot" thing but I'm not convinced that it is "the" solution. Epoxy coating can get damaged during placement, leaving bare steel. :(
I'll put my money on extra cover and good concrete, designed for the local conditions.
Rebar that is fully encased in sound concrete with adequate coverage will last a LONG time.
Too little coverage or poor quality concrete will allow the rebar to begin to rust....the rusting rebar will "disassemble" the rest; quickly at first as it attacks the surface rebar but much more slowly as it progresses to the deeper rebar.
The Huntington Beach, Ca pier (the original one....ca1900) needed to be replaced due to impending structural failure. One of the engineers on the project (evaluation of the old pier) told me that IF the coverage had been adequate, the peir could have been repair and served another 50 years or more. But due to poor coverage the pier had to be demo'd and replaced.
cheers Bob
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I never said that corroding rebar in concrete couldn't cause a problem -- I'm simply taking issue with your stand that putting steel into concrete *automatically* poses a corrosion problem that will necessarily destroy the concrete.
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On May 18, 3:00 pm, snipped-for-privacy@milmac.com (Doug Miller) wrote:

This is what I wrote in my first response to the OP: "Another reason is that iron has a tendency to rust. When it rusts it expands. This would put the concrete in tension and concrete really doesn't like to be put in tension. In other words it would tend to break up the steps.
Use rocks, brick, or other busted up concrete if you need some filler. "
I used the words tendency, would, tend to - there is nothing there that says in all occasions all steel rusts. I also put the rusting issue in second place in my short list of reasons. You made a massive assumption that I was somehow referring to all situations and you got snarky about it.
Your two comments; "How are they going to get bigger while they're encased in concrete?" and "Oh, for heaven's sake. Haven't you ever heard of rebar?" imply that you equated an engine block dumped in a hole in the ground, with engineered and correctly installed reinforced concrete. I took exception to that.
I appreciate that you think the OP - a guy who wants to toss a considerable quantity of scrap iron into a set of steps as filler - as being so clued in to the correct amount of concrete coverage, and would know how to suspend an engine block to insure that amount of coverage. I have no such illusions.
R
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ideally all rebar should be non magnetic stainless, which never rusts.........
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wrote:

Ideally all people should understand the various properties of 'stainless steel'... <g> Stainless rusts just fine when *not* exposed to air!
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I would like a link to that! I was told non magnetic stainless doesnt rust.
What makes this problem worse in florida was the use of beach sand containg salt.
this info courtesy of this old house episode:)
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wrote:

I'll see what I can dig up. This is 'common knowledge' among boat builders, but not others. Problem being that the stainless looks really good on the exposed surfaces, then when you try to remove it, you find a 'ton' of rust on the burried parts. You could also try searching various marine sites too, I'm sure you will find it.
FWIW, I didn't believe it when I was told first about the problem, then managed to see it as I did work on boats.

I think the entire state of Florida contains salt! <g> WHere in Florida are you, I'm frequnently in Tampa, and when to high school in NPR.

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Oxygen is inseparable from oxidation (rusting). I think it's more likely that moisture was getting into those hidden areas and staying there longer.
R
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You can use stainless bolts and nuts, but there are good practices when doing so, just as everything else in life. http://www.estainlesssteel.com/gallingofstainless.html
PeterD was saying the stainless rusts when there's no oxygen, and that's what I was addressing, that you addressed, that I just addressed. Okay, I'm going to go up on a ladder now, I'm getting dizzy down here. ;)
R
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Anti sieze compund
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On Tue, 19 May 2009 11:06:59 -0700 (PDT), Pat

Stainless tends to 'gall' and freeze up. I've had stainless to stainless fastners freeze when tightening, friction welded into one piece so strong that the bolt sheared off but the nut never moved!

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SS has a huge tendency to gall......I once screwed together, by hand, a dry SS short nipple (2" pipe) into a fitting. Only a couple turns and the assembly almost seized up on me!
The pipe thread was a pipe rough, I didn't us any tape, lube or dope.....I was just doing a dry fit up.
cheers Bob
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Stainless on stainless is used VERY frequently........why else would there be a vast selection of SS bolts & nuts?
galling is a potential problem with SS on SS but the use of proper plating or lubes will help a lot
cheers Bob
PS stop using TV as an uncorroborated source of technical information
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........ Oxygen is inseparable from oxidation (rusting).
yup
..... I think it's more likely that moisture was getting into those hidden areas and staying there longer.
yup, again
first of all the term "stainless steel" though popular & widely used is not the "correct" term for the material under discussion
the more correct terminology is "corrosion resistant"
btw all "stainless steels" will rust / corrode under the "right" conditions
another little know fact, so called "non-magnetic", 18-8 stainless steels (typically 300 series) can, when "worked" by certain processes, in fact, exhibit magnetic properties
cheers Bob
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I'm late to the party but if they are really concerned about corrosion in the rebar maybe they should look into getting some of the (fairly) new stuff called MMFX rebar. It is five times as corrosion-resistant and up to three times as strong as conventional steel. He could use less steel and it would last longer than just about any other comparable product. Ameristeel is advertising a product called "Z-Bar" that is better (per their claim, not mine) than just plain epoxy coated bars, but I have not been involved with any project that used this material, so I can't say anything one way or the other about it.
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Whats the green rebar I saw a while back, was it a coating?
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wrote:

Yep. It's an epoxy coating. It's used in construction where the rebar will be subjected to harsh conditions and rusting is an issue.
R
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The main culprits in attacking the rebar, salt and water, don't have nearly as much effect on concrete. Protecting the concrete would require protecting large areas, and periodic reapplication of whatever it was you were using to protect it. The epoxy coated rebar has a much smaller area (in general) and it's a one shot deal.
Your bones are encased in meat, but you can still break your bones even through the meat. That's why Wolverine has an admantium skeleton - I'm amazed I have to tell you this!!!! ;)
R
R
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My son has been a Logan fan since day 1 and has 100 copies of Wolverine#1 in Wizard archival bags with boards. (I only have 1 copy) Just yesterday he emailed me a picture of a razor he purchased - Wolverine version, Gillette brand, for keeping nice crisp corners on those 50's style sideburns Logan sports that the ladies find so appealing.
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