What is epoxy coated rebar and why is it being banned?
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- เผยแพร่เมื่อ 24 พ.ย. 2024
- This video explains why epoxy coated rebar is used in concrete. It also discusses the challenges with the use of epoxy coated reinforcing bars. The video will discuss why many states are moving away from the use of epoxy coated reinforcing bars. Then the video talks about other types of reinforcing bars and how they can be used to stop corrosion within concrete.
Report over structural evaluations over different reinforcing bars:
docs.lib.purdu...
Thanks to Hailey Goodale! She edited this video and is my Director of Awesome.
My website is: www.tylerley.com
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Very galvanizing topic. While it’s not set in stone, it reinforced my views on rebar.
very topical. We'll have to keep an ION you.
Galvanized rebar, something to zinc about.
Oh for Christ sake.
Bravo
Very funny... DAD!
You know, I couldn’t give a rat’s something about rebar, but this guy’s explanation and style made it a very interesting and enjoyable learning experience. Thanks!
Rebar holds up the world, nearly every bridge, building, road and sidewalk you use. When the final tale is told, rebar corrosion will be identified as a major contributing factor in the fatal collapse in Surfside, Florida. This is good basic knowledge for any citizen concerned with how the government spends money or how to tell a good contractor from a bad one.
😂😂 yep 👍
This guy explains it well and the video is pretty good. BUT there's no reason for the goofy background music. When you're speaking to someone, it's incredibly rude to play music at the same time. Background music is the PLAGUE of youtube. It's just horrible and ruins so many would be great videos.
@@larrybuzbee7344 rebar over time and exposure to nature will rust! Rust causes expansion and the crumbling of concrete! It has nothing to do with good vs bad contracting! Good vs bad inspectors are another story altogether!
@@M_Ladd Of course you are correct regarding the properties of rebar. However, my point, if a little ineptly put, was in response to the original poster's self described lack of knowledge or interest regarding rebar. I meant to imply that general knowledge of the sort you point out is valuable to the ordinary citizen not just specialists.
I did bridge maintenance for years in a salt water environment, many of the bridges and other structures from the 1930s to 1950s did pretty well, but 40 to 50 years latter many parts of the structures were delaminating. Thank You for this video most people don't know about this issue.
I am not sure if it's related, but apparently there is something special about pre-nuclear age steel. I'm sure someone here is an expert and will chime in.
Side note: As a German it makes no sense to me why Americans call every zinc coating 'galvanized', even when it's actually hot dipped. The term should refer to the process of creating thin metal coatings with electrical current. For example you could also galvanize steel using nickel.
Zinc is very much cheaper than nickel, by the tonnes
I also love concrete, retired. We built seawalls, retaining walls,foundations and bridges. I have used regular, epoxy and galvanized. We have even but epoxy coated rebar inside a pvs pipe, and even stainless steel rebars. I never picked type rebar, the engineers did that. You are spot on about scratches of epoxy causing spot failings, pardon the pun. You can also alter concrete, the higher psi the less chloride gets bar. BTW Stainless steel steel corrodes under concrete, lack of oxygen kills that.
When we designed a seawall, we knew area completely underwater/ground was going to be fine, no oxygen. The areas up in to air, if painted and isolated would be fine. It is the area that gets wet and dries that is the problem for corrosion, and concrete is a water magnet. You need both air and water for corrosion.
So my best way would be hot dip galvanized, with high-psi latex concrete. With of course appropriate safe guards to make sure of little scratching and then recoating in field. BTW we used plastic wire ties to hold most of the bars in place to avoid the corrosion being brought into system by wire tire. Because something corroding inside concrete no matter how small would start the process. Also making on concrete as thick as possible over rebar helps prevent issues. Oh on latexed concrete, we used to pour concrete underwater for underwater foundations using tremie method and we added an additive to concrete that made it more jelly like, I forget exact name this also has side effect of sealing concrete. I hope all this helps someone. Great video on a misunderstood subject
When you say plastic wire ties, you mean zip ties are ok to use?
I worked with FBE for 20 odd years in the family business. Powder coated all of the rebar in the UK Tunnel to France and the test tunnel from Windsor Ont to the US.
Who knows what that additive is called and if it really seals the concrete?
@@PaulyDownUnder yes regular cheapo zip ties for smaller bars, faster and less damage to epoxy bars
once the concrete is cured the rebar structure isn't going anywhere...all the ties do is maintain spacing during the pour; they aren't structural @@PaulyDownUnder
THIS is what the internet was envisioned to be about. Not concrete and rebar exactly, but this type of content. Something with real substance with and exchange of ideas and information. Look at the number of views. I've seen pieces of what is supposed to be popular and trendy that have far fewer.
Good on you Tyler! Keep up the good work.
Foamer 44 Except it should be Cardi b. doing the talking.
@@RedboneUnincorporated So I take it you thought Tyler's post was a waste of time and there weren't enough guns and half dressed dancing girls? Why did you bother even viewing a post on rebar? What did you think, from the title, it was going to be. How to turn a piece of rebar into a nuclear missile?
Oh well, no accounting for low brow negative IQ twitting trolls.
Revisionist nonsense. The entire history of the internet says you're dead wrong.
One thing the internet wasn't intended for is those A-holes with their useless non constructive comments and snide remarks. THAT imo is far worse than TH-cam not suggesting only AAA content videos which btw, you can actively search for... if you make the effort.
@@foamer443 No, it means he heard someone else use the "Thumb suck in your safe space" line and thought it sounded so edgy and cool, that he couldn't wait to say it himself as though he'd thought of it. In 2018, he was calling people "beta cuck" and thinking that made him sound edgy
If it weren’t for this guys excitement about the topic, I would’ve clicked off this video a long long time ago
I never got past 30seconds a stupid idea in the first instance. Nothing for the concrete to hold onto!
ReconMarine 1969
It is unfortunate for YOU that like so many others you have the attention span of a housefly.
The object is to learn everything that you can ... Whether you like it or not and teach it to your
children, so they do not become dumb-asses as happened to you.
You can partly blame your parents for most of that.
The children HAVE to become smarter than their parents and their teachers, otherwise, there is NO
progress.
@@andrew_koala2974 get that stick out of your ass bro
I wish he was less excited and talked faster and more quickly to the point.
Same!!!
70+ years ago, as a young child, I watched my uncle install a galvinized pipe handrail in a concrete (outdoor) stairway.
That pipe still looks as good a new. He did it by puting the ends of the pipe into glass jars, poured the concrete around the jars, then filled the jars with lead.
The glass insulated the pipe from the concrete and that prevented the corrosion.
Somehow I just can't visualize this process .
In Scotland they drill the hole place the railings in the hole and pour lead into it.Been done this way for centuries.
That's fucking genius.
In short, this is a trade secret.
That's a very old process, and it's brilliant, called leading in. You'll see it on metalwork attached to very old buildings, and it's completely removable without having to damage the stone around it.
I work in the maritime engineering sector designing port & harbor structures to withstand the aggressive corrosion environment of seawater exposure, both full immersion and intertidal / splash zone. Epoxy coating fell out of favour decades ago for the reasons mentioned. But for most applications the most effective and least cost solution is a) increased concrete cover (3” or 75mm is standard); b) low water cement ratio (< 0.4) which decreases porosity; using class F fly ash to replace 25% or more of the cement (also reduces porosity). In severe exposure locations we also use admixtures such as calcium nitrite or silica fume as corrosion inhibitors, although the latter can cause workability/ finishing issues. We almost never use galvanized or stainless bar, but MMFX and FRP bars are showing promise too.
Cover is king !
I am a gas and electricity supply engineer and I learned about the content of this video in my first semester. I.e. it's got nothing to do with my day to day job or even large parts of my studies. Cement cover of rebar is key and even in non-maritime building environments, the structural engineer needs to look at every crack and determine, if the cover is compromised. (If the structural engineer is any good, he has enough of a safety margin calculated into the structure, that nothing happens.)
Is active protection used at all?
Can you please explain why isn't galvanized used more often?
@@larryclemens1850 Doesn't last in wet environments.
Excellent explanation. I was an Army Reserve Engineer Officer in 1991. I ended up having long conversations with an Hawaii NG Major. We talked about weathering steel, epoxy coated rebar, and chinese steel. He warned me about all of them. The weathering steel was being eaten through in less than 20 years in the salt air at the U of Hawaii. He described the epoxy coated rebar being "cut" by scratches. He also warned that he had seen chinese steel come in that was less than 1/3 the ultimate strength that it was supposed to be.
From 1985 to 1991 I had been using regular rebar in my bridges and sealing the concrete. After that, I went to high strength rebar and extra sealing. I came up with using weathering steel in my structures and having it expoxy coated. Our weathering steel was 55 ksi but I designed for 36ksi because I knew that the small towns that I worked for would not do the recommended maintenance. I did not use concrete in my superstructures because it was cost prohibitive for us. These were small local bridges so I used wood or steel bridge kits that the local road crews could assemble. It was a hold over from my time as a Bridge Building Platoon leader in the 70s. I just found your channel and subscribed. I look forward to viewing your other topics. I retired 7 years ago. Good Luck, Rick
Richard,
Thanks for the awesome story. Please keep the comments coming. It is great to get feedback!
Dude that is some heartwarming material right there, socially conscious engineering is the best. Taking the "human factor" into account when designing thing should be a standard in engineering, but it sadly isn't everywhere.
Weathering Steel for Saline Coastal Areas Developed May 7, 1999 Weathering Steel for Saline Coastal Areas Developed.
Tsu Works.
Model bridge structure built at NKK's Tsu Works using the company's new weathering steel.
NKK has developed new weathering steel that requires no coating even in coastal areas with large amounts of airborne salt. Marketed as CUPLOY400-CL and CUPTEN490-CL, the new steel (containing1.5% nickel and 0.3% molybdenum as additives)has recently been chosen for two road bridge construction projects in Niigata and Mie prefectures.
NKK's new steel is characterized by its complex additives of nickel and molybdenum. With conventional weathering steels in a salt-rich environment, it has been difficult to prevent the progression of corrosion from the concentration of chlorine ions permeating through rust layers on the steel surface.NKK has successfully optimized a combination of nickel and molybdenum to effectively prevent the concentration of chlorine ions, thus enhancing chlorine resistant properties.
In addition to its excellent atmospheric corrosion resistance, the new steel, though added by alloys, offers remarkable mechanical properties, guaranteeing JIS SMA400 and 490. It also features good weldability due to the restrained carbon content, reducing work load by virtue of lower preheating temperature. As well, because initial rust streaming is minimal, appearance is enhanced.
NKK has confirmed the new steel's superb chlorine resistant properties in field exposure tests conducted at several locations and also in tests using a model bridge structure built at the Tsu Works. In developing and commercially producing the steel, NKK collaborated with Kobe Steel for the welding materials and with Mitsuboshi Sangyo for high-strength bolts fitted for the steel.
The new steel has been chosen for a single steel truss bridge (100m in length using 330 tons of steel) to be built in Niigata Prefecture and completed this August, and for a single non-synthetic steel-girder bridge (100m, 170 tons of steel) to go up this June in Mie Prefecture.
Near seacoasts and other saline areas, ordinary steel is generally treated with heavy corrosion-protection coating, which costs about ¥10,000 per square meter. While the new weathering steel is priced some 35% higher than conventional weathering steels, the feature of not requiring heavy anti-corrosive coating means that initial corrosion protection costs are held to one-third of heavy coating methods. Moreover, since periodic recoating is not needed, the new steel can cut total life-cycle costs dramatically, including costs of long-term maintenance.
All Rights Reserved, Copyright © NKK Corporation Terms and Conditions
Head Office: 1-1-2, Marunouchi, Chiyoda-ku, Tokyo 100-8202, Japan
Tel: +81 3 3212-7111, Fax: +81 3 3214-8400
www.nkk.co.jp/en/
One thing that is suspicious, this product seems to have disappeared only to be replaced by the ineffective American corten weathering steel, it seems NKK was coered economically by selfish vested American interests!
@@homeopathicfossil-fuels4789 dude that's half of engineering. The issue is the people who write the checks.
Make the rebar out of my wife's meatloaf. It's resistant to acid, bile, E.coli. draino.
Bazinga
Let's hope your wife never sees your comment 😅
@@pugnation Zezerbing can always says that she is a bad cook but has good look.
Needs a engineering application of ketchup
Get a patent
In the wake of what happened in Miami the other week, I suspect this topic could be getting a lot of attention, possibly even before they stop digging up the dead.
Seeing as chlorides are the enemy of rebar it will be interesting to see if the chlorinated pool water was leaking into the Miami building support structure. Chlorine is much worse than chlorides on steel.
@@jimkenealy6448 from what I've seen everybody talking about and videos talking about it was not doing the waterproofing correctly and water would pool in the parking garage
@@jimkenealy6448 my thoughts exactly, soon as I heard chlorides I thought of all that pool water pooling up and soaking the concrete.
@@bigbadbart1 In wood construction water proofing is secondary to water removal, you assume water will get in anyways at some point, so you focus on removing that water quick by drainholes, air circulation and so on, that helps too to know when your water proofing fails.
@@bigbadbart1 i would say that is bad architecture design/construction materials/and poor inspection standards/enforcement all together, if all it took was not doing the waterproofing correctly to have a total collapse like that.
I say just get rid of the bridges and add ramps on each side. Then force the car companies to make every car able to withstand a 125 foot rally style jump. Our drive to work would be invigorating.
J M hilarious love the idea!
How do we get you put in charge of all things “transportation” in America?
J M 2020!
Hell yea!!
**revs up, plays musical Dukes of Hazzard horn** YEEE-HAAA!!!
I know that's racist, but I grew up with it and it was awesome. The show wasn't even racist other than the Confederate battle flag painted all over the orange car (General Lee). One solution to everyone driving around in racist General Lees is to keep bridges...
🤣🤣🤣👍👍👍
I can't wait till the next party I'm at. I will be the one everyone moves away from when I start talking about rebar. I will make sure I am close to the appetizers.
Good luck Larry!
That's one way to get the lion's share of the appetizers.
Yes, the food is the object. Very interesting subject though, I learned something.
"hey have you heard about the rust problem in rebars ?"
bring a bat to fend off the flood of pussy
Just don't get in my way when I'm coming in for the Nacho Doritos.
I know it's not fully popular right now, but this kind of content is worth it's weight in gold.
The problem is not installing the painted rebar, the real problem is trying to repaint it after the concrete has hardened.
Enlightening for even the common person. I ended up watching this video because of the condo collapse in Florida. The galvanized rebar sounds like a solution. I also watched the video on spalling. I learned a lot and I enjoyed the videos.
I’m glad you took the time to make this video! I spent my career both installing and teaching reinforcing steel, along with post tensions cables. Anyone who thinks this video is a joke lol try looking around on your next trip to work lol. Anyway thanks for this and I’ll share with my ironworker friends!
I'm an electrical/computer engineer. I know almost nothing about civil engineering, but I find pretty much all STEM topics interesting. I enjoyed your video! Thanks for sharing!
Same here
Iron is way too tasty to oxygen
Hemp reenforcement
Galvanizing sounds good. Let's just study and repeat history and use Rice as the starchy goodness keeping that structure dragon ready. Rice.
@@sifulowang back to the mine
Worked with steel all my life and outside work in iron that I did. The customer got it galvanised whether or not they asked for it !
I stopped specifying paint or epoxy coatings on outdoor structures for my employer years ago in favor of hot-dipped galvanizing. The cost difference between them narrowed greatly from what it used to be, and the longevity of the structures easily tripled.
As a retired ironworker of rebar, I can appreciate the facts presented in this video! I epoxied rebar one time on a job I was working on.
As a painter I had to coat rebar on a treatment plant job once .We called it "fusion" epoxy.
@@xochipili1 o yea? That’s interesting!
Have been out of Construction Inspection over 20 years. Yet, you got my brain working today. Seen alot of rebar in my past.
This is on everybody's mind. Thanks. At my work's technical library 20 years ago, I found a 5 volume set of ACI Manual of Concrete Practice (1990) in the trash. Needless to say, I saved them so my family and I could learn about concrete.
Louis Emery
everyone's mind. NOT everybody's mind.
EveryONE is alive everyBODY is DEAD. --- You will find plenty of BODIES at the cemetery.
You are not yet fluent in the Englis language and failed to educate yourself by not reading
books by accomplished authors.
Did your mother ever tell you that there is no ONE like you.
Understand that ONE is the ultimate number.
Get the point and stop being a sheeple. Learn correct English.
@@andrew_koala2974 - What?
"The key difference between everyone vs everybody is everyone is more formal than everybody and more common in written language. Contents. “Everyone” and “everybody” are indefinite pronouns. They can be used interchangeably although there is a slight difference between them based on their usage."
- confused words. org
@@andrew_koala2974 Didn't your mother teach you not to be a raging, pedantic spaz? Also, there are multiple grammatical errors in your comment, which is *deliciously* ironic.
Tyler's passion for rebar is admirable. I'm a GC, he's right. Epoxy is a "raincoat" barrier, which makes it vulnerable to holidays and damage from rough (normal) handling in shipping and on job sites. Galvanizing is a tough and proven way to make steel rust resistant, that's why it's used for most construction fasteners and bracing materials.
There is abrasion resistant epoxies but they are a bit more expensive.
In my working career, I managed estates on an ocean island as a builder/contractor and can attest to the various qualities of galvanizing. The more modern stuff (from the '80s to the 2010s) the quality of the hot-dip galvanizing has fallen greatly and the salt air rusts through in 10 years or less
. Some of my places had galvanized fasteners from the '40s that showed no or little rust from 60 plus years of exposer to the salt air.
So I would say from experience that your comment about thicker galvanizing coating is spot-on!
The fun thing about galvanized steel: The corrosion products of zinc tend to be larger in volume than the zinc itself, so small flaws in the zinc coating will tend to be filled by zinc corrosion products. Also, the positive zinc ions on the edges of the flaw will attract negative chloride ions away from the steel, providing significant protection to the steel, even in the presence of a flaw.
As a former materials science teacher I thought you did a nice job. I was trained as a chemist to understand why things make and in materials science you learn why things break!
I have never ever imagined being interested in rebar - good job
SAID BY STRUCTURAL IRONWORKERS WORLD OVER
Don't know why this popped up but I learned something new and unexpected today.
Same here. I learned a lot but have more questions I need to answer. I definitely subscribed.
I gave you a thumbs up not only because your content is good, but also coz I'm afraid you'll stop uploading
Thanks Rhonnie!!!
This video caught my eye because one of the last jobs I was involved in before I retired May 2017 was a new lab at NIST Gaithersburg. They were getting ready to study this very thing.
When i worked in a foreign country, it was my first time to see a coated rebar and thinking that it may affect the over all strength of the concrete. In my country, i've seen building demolitions built like last 2 generations. Re bars inside are actually looks new. Never seen a corroded rebars imbedded in concrete. BTW good point on the damage coating
Expoxy coated rebar has higher development lengths, meaning it needs more surface to "grab" or bond to the concrete to add strength. This makes splicing more expensive in beams and slabs as the overlap from one bar to another is longer. On a bridge deck or a grade beam, this adds up very quickly.
Unless you use couplers.
Dateline 3030; Engineers have released their findings on the cause of the sudden collapse of the Golden Gate Bridge. The primary study concluded that the excess weight of 3000 coats of paint is to blame. 🙄
😂🤣😂🤣👍
Not so soon dear atleast 3000 years later. Didn't you hear 1 coat per year!
@@sanjay999992007
It didn't collapse yet...
chip, sand, paint, repeat?
MrOramato, should it be that life continues to exist on this world in 3030
given that the alleged civilized intelligent man who is becoming more dangerous, bloodthirsty
and destructive as time progresses, we shall not need bridges.
The best bridges to build is between nations, cultures and religions as we all face exactly the same
problems in life.
Rebar can not corrode when fully encased in concrete, the alkaline conditions of concrete form a layer of iron hydroxide on top of the steel. The problem are microcracks inside the concrete that allow the water to get to the steel, once the steel starts to corrode it expands and cause more cracks and more water can get in. Thats why concrete needs to be maintained every few decades depending on outside conditions and climate.
Material Scientists are working on self-healing concrete to get rid of the microcracks. Alkaliphilic bacteria and especially one particulare type called Bacillus pasteurii can excrete mineral calcite. Those bacteria embedded inside the concrete along with a form of starch as food are able to survive for decades. The bacteria are dormant untill cracks form and water gets to them, they will wake up and eat the starch and produce calcite with bonds to the concrete and heals the crack.
I owned an older house in Australia that had concrete piles nine feet long that the entire house stood on, it was fifty years old and the Rebar eventually corroded splitting the piles. Piles were under the house dry well ventilated and no moisture apart from where the piles went in to the soil. Loamy sand dry, eventual failure was inevitable. Just my experience . Cheers.
@@axeman6560 Not an expert here.....Humidity would be my guess as to who's the culprit....
@@victoreous626 yes was on the gold coast of Queensland Australia pretty humid there.
wow sounds like alien invasion
The bacteria idea seems to be the most sensible and effective solution to me. Tweak the concrete, not the bar.
But I am an electrician, not a civil engineer.
I am a structural engineer in the netherlands and I’ve never seen the use of epoxy coated rebar in practice. Generally, we design bridges with a rebar cover based on the expected reference service life (based on the eurocode). Ususally 35mm for a up to 50 year service life and 50mm of cover for a 80-100 years of service life. Additionally the cover gets increased by 5mm increments depending on whether or not the concrete surface is inspecatble, the type of formwork and cholride conditions. Interresting to see that the epoxy coated bars perform so poorly as this goes against intuition. You’d think it’s coated so it be good.
Yea that's because rebar doesn't even corrode inside of concrete, there's no moisture lol. It takes very very long
Well, it does work perfectly... when it's a flawless coating at the time of pouring. But like he said, the coating is never flawless, even if handling very gently, which, let's be honest, the iron worker is not going to treat rebar like a new baby. Epoxy coating is one of those great ideas that is great in a lab, but marginal in regular practice.
35 mm for a fifty year service life is actually a pretty good run. As a contractor specializing in concrete repair and construction, I generally shoot for 50-75 mm in everything I do (when not otherwise specified). I have a hard time imagining achieving accurate 5 mm increments of measurement in steel on a slab though, since the slabs are often sloped (and steel men never take this into account), the steel can be pushed down in placement of concrete, and few rebar-men are more accurate than about 20mm with any degree of consistency when placing horizontal bars (in my experience). You guys must be following your steel placement people very closely to achieve such tolerances.
The reason the epoxy bars do so poorly is the same reason you get a "holiday" around concrete repairs in failing concrete- there's a pent up charge imbalance that needs to use the rebar as an anode to reach equilibrium. Coating a bar or replacing damaged concrete will simply result in the inevitable corrosion moving to the nearest available place to react. In the event of a holiday that is the edge of the newly placed repair, and in the event of epoxy bar, it will be concentrated at any place the epoxy is damaged.
i poured my house with 3 inches (~76mm) of cover so it would last 200 years?
@@9001greg well, there is moisture. Concrete is porous, and is like a wet sponge. The resilience comes from the water in the pores in the concrete having dissolved chemicals in it that form a thin protective film over the rebar. The PH of that solution is generally higher than 10, sometimes even 12. Very basic. This protects the steel from rust, and the concrete from acid decay. Eventually it runs out though, and this is why greater coverage leads to longer steel lifetimes.
You know what's sad is how many municipalities required coated rebar. How many bridges will see critical failures?
If you've ever worked with coated bar on site, you know there's no possible way to ensure it doesn't get nicked. I haven't heard some groups are actually stopping it's use, but I completely agree, the galvanized is a much better solution.
Municipalities enforce building codes. Building codes specify when steel must be coated. Codes are developed by industry professionals, to meet ongoing issues. Some contractors take short cuts, some HOAs put off maintenance, buildings age and need regular maintenance. Seems like the Surfside unit owners ignored warning signs for many years. Workmanship may have also played a role. Well before the collapse.
what if both were done, first galvanize, then coat
@@marinamanuel2796 now we're on to something. we should use this comment page to form a business. who's in?
@@marinamanuel2796 most coatings don't adhere to galv...unless you pickle it...which is a technique used to neutralize the cathodic resistance of zinc. i'm no scientist (well actually i am in a roundabout way) but i'm guessing if you use a product to neutralize the properties of the zinc, it could compromise it properties elsewhere.
Spend one afternoon laying and tying rebar... and you will know why it is dinged...
You can tell who ties epoxy coated rebar, cause they normally have the green touch up paint on their cloths.lol
That shit gets everywhere.
Ive hauled a lot of ECR and im here to tell ya, that stuff is scratched and dinged up BIG TIME even before the steel men get it on site. Why? From the moment the epoxy is dry it is man handled by fork lifts, frieght lifts, etc. Then its often banded to hold the bundles together and lifted again onto trucks, then unloaded at warehouses the same way. Then its reloaded and taken to sites and againg lifted again unbanded and often dragged to its new home and tied. Sometimes the steel tiers do touch it up in spots they notice but theres no way to ensure its truly coated when the mud is poured in on top, in fact there rocks in the mud too that may in fact possibly nic the coating again!
So heres what..... just keep doing it the cheap way.... the way its been done for eons and simply demand the projects be replaced more often. And remember NOTHING except NOTHING lasts forever.
@@scottlytton5328 Heaven and hell will...
Jim Vick tie tie tie and hurry up!
They're called "rodbusters" for a reason. 🤓🍻
Concrete has a PH of 13. When steel is subjected to an environment with a PH of 10+, it naturally passivates and forms a corrosion inhibiting layer. The only thing that can de passivate the steel is the lowering PH effect known as carbonation or the introduction of chlorides. The key to preventing corrosion in new reinforced concrete is ensuring adequate concrete cover, low water to cement ratio material and mitigation of water ingress. Expansion joint systems, adequate drainage, coatings and maintenance (Crack sealing) drastically extend the useful lifespan of reinforced concrete. Impressed current and sacrificial cathodic protection are also very useful. The problem with reinforced concrete durability is that everyone assumes that place and finish is the last step in the process. Unfortunately, concrete structures require preventative maintenance or specialized repair contractors. The latter is costly.
That is absolutely right but water cement ratio control is not often encountered
You nail it.
What are you talking about low water to cement mix. Are a building structure you have to use a correct amount before they use any cement from a truck they have Preform a slump test to make sure it has the correct amount of water. If it doesn't have enough water it becomes brittle and powdery it doesn't cure properly. What your saying is crap read from a book of little experience.
Rodney Jones I have an engineering degree focused on concrete material science and 13 years of experience executing structural condition assessments for a living. You don’t know a damn thing about concrete. Slump is a measure of workability not water content.
Slump can be any value depending on the method used to compact the mix but strength is determined by water cement ratio and the more water in the mix the more expensive cement is needed
Mechanical Engineer here.. great topic.. excellent presentation!!
This guys enthusiasm is infectious. I have no interest in rebar but saw the whole video.
Never thought I'd watch a 10 min video about rebar and being fascinated. Thanks!
_''World....the time has come to...Galvanize''_
If you only heard the Chemical Brothers years ago....
Take my like,I pushed the button.
Push the button
Yaaaaas
Galvanize is fine until you have to bond them using CadWeld or Welding power grid grounding. Once you break through coatings, rust will begin. What works is to install rust free rebar, or sandblasting to clean. Apply a good bonding agent before pouring concrete.
Basalt rods. Non-reactive, light, expand at same rates as concrete.
I use to work in the bridge industry. Epoxy coated rebar rots faster than plain bar by far, 15 or old stuff was rotted junk when Hammered out for a repair. It also is terrible at bonding with the concrete. I've demo-ed temporary abutments that were a year old and the concrete falls off the bar during removal, we've even reused the bar on another job cause it looked new. Also old re enforced concrete methods buried the naked bar deeper (4-6 inches) in mix and it hardly rusted after 50-60 years. Some of the last projects I worked on in 2011 called for plain bar, no more coated bar Mass DOT 2011. The issue with the new method with plain bar is, it's only buried 2 inches. It will spall and fail. We had a saying " don't worry, it's work for our children. Sad,25 year bridges,some less.
You raise a good point. It's stunning to see recent (less that a decade old) projects that are spalling, or even showing rust "shadows" where the bar is essentially at the face of the pour, and now creating a rust outline of the bar, on the surface. I'm in another construction field, but like everything else, IMHE some of this is a result of garbage workmanship. I've been on the sidewalks/bike paths of two newer mega-buck suspension bridges recently. The concrete work was absolutely stunningly awful. Finishing that would embarrass an amateur, lumpy form work, absolute trash "craftsmanship" , that the public got to spend hundreds of millions for.
Thanks for confirming with your field experience. I agree that cover - concrete between the steel and the surface - is critical to concrete performance. One challenge with using too much cover is that the rebar can't keep the cracks small. A cover of 3" provides nice cover and also helps with cracking. You can also use smaller and closely spaced bars and that will help with cracking. I really appreciate the comment!
Your "crappy workmanship" complaint is not caused by lack of skill by the workers, it's mainly due to pressure from management to produce at almost any cost.
Also, in regards to the poor finish, that is mainly caused by impossible to work with mix designs, with huge rocks and tons of pozzolans. In addition to "no water on site" rules that only decrease the workability.
Tldr; due to management forcing almost unrealistic production figures, difficult to finish mix designs and not allowing water to be added, the finish suffers. Plus it's just sidewalk and roadways, you seriously want almost the roughest finish possible to prevent slips and falls. It's a tough balance
@ace toxic there isn't supposed to be any bonding. The whole idea is to use the tennons like a suspension bridge. They put massive loads on the tennons to put the concrete under compression in one direction to increase the resistance to torsion in the middle of a span.
@Art Bell I agree! I think this is an awesome tool.
I did not study architecture or engineering, but you make it fascinating to learn about and simple to understand. Thanks. 😊
Friend: what do you watch on TH-cam?
Me: it’s complicated
Yes.
The most common question is "What TFH were you searching for to make THAT come up?
@@InsideOfMyOwnMind I'm at a point where TH-cam is just suggesting this stuff to me before I even start searching :-)
I mentioned to my friend the other day that I watch a lot of TH-cam. He said "you're such a millennial". He has no idea....
I got here from watching videos about spear fighting.
This is like the "Fun With Flags" of rebar. I don't even know why I'm watching this.
Ha! I love Sheldon. He is awesome.
Haven't a clue myself
It's interesting to get a bit of knowledge from a wide field, that's why I'm watching it. I'm not sure why youtube suggested it to me, though. Perhaps it's because there is some epoxy paint in all of the guitar making videos, and I watched some videos with epoxy plastic crafts. Weird.
@@goranandersson3544 There are a bunch of perfectly good reasons to build some concrete guitars, filled with appropriately tuned rebar ^^
@@TylerLey big bang theory is the best!
The Golden Gate Bridge is always being painted, but it is on a schedule. Areas of higher corosion risk get painted more often, and lower risk areas less often. But yes the painting crew never stops painting. Good video.
Robot Riedinger Forth rail bridge in Scotland is over 140 years old made of pig iron and is no longer painted every year , they developed a paint with a 25 to 30 years life span , and it appears to work.
I build bridges in Virginia. Depending on the class of road we use either MMFX or Stainless. The stainless is insanely expensive but it is what VDOT wants. Maryland still uses the epoxy bar. One solution is using lightweight concrete, it is a low permeability concrete and keeps the water out.
That's interesting - I don't know much about reinforced concrete, but in boat building and repair the rule is that if the stainless is going to be continuously in contact with stagnant water, it creates an anoxic environment and then the stainless rusts as fast or faster than regular steel, and isn't near as strong to begin with. So it would seem like stainless rebar would be a no-no in reinforced concrete.
Alaska is making the switch to MMFX for bridges as well. Definitely a major pain to bend MMFX in the field lol. Hardest bar I've dealt with.
@@bawrytr thats what i tought as wel. This is exactly the reason you dont see unpainted stainless steel boats. If it was that simple we would be building stainless steel boats here in the netherlands. They also tryed the cor-ten steel, wich wil grow an oxide layer in outdoor conditions and then never rust through. But guess what? The stuff wil gone just as fast if not faster then normal steel if submerged. So just like stainless steel it wont work for boats. So we are still building steel boats as there is not really a good replacement for it except for maybe glass fiber, but that also has its own problems.
@@bawrytr high use bridges are stainless rebar. It is something to see a big shiny mass of rebar. Apparently it works, they are spending way more per pound for it then even MMFX
@@sarahfuller6654 we have been using it for years without many issues except it is hard to get because it is sole source,
Thank you Tyler! Working half my life in concrete I found the entire subject interesting and entertaining! While thinking of methods to stop corrosion I'm sure that some bright young engineer thought about the browning of gun barrels?
Browning?
Or blueing?
Browning bluing parkerizing there's probably hundreds of similar treatments
Sitting here are 2am Sunday morning watching a 10 minute video about concrete and rebar. Yep. My life is over. Pack it in. The coefficient of expansion of any kind of rebar is always going to be different than the concrete. This allows movement in all directions and debonding between the two materials. Air gets in, water gets in, and pretty much everything gets in between the two materials. Now those third class of invading materials also have their own coefficients of expansion, etc.. You get micro-spalling of the concrete, even nano-spalling, and on a really cold or hot day you get pico-spalling. All seriousness aside, how about making rebar from concrete? Make concrete rebar, and then treat it in some way so it has the strength of steel. How do you do that? I haven't a clue. Going to sleep now. No more rebar videos for me. There is no upside to it. It is fraught with problems with no solutions and it is depressing. I'd rather ponder how to turn water into wine or how to go faster than the speed of light. Goodnight.
Thanks Blue!
I think we can find a solution. There have been lots of good ideas on here.
@@TylerLey I have read about Pilling-Bedworth ratio, i.e ratio of volume of oxide to bare metal and the consequence leading to debonding.
mr bluenet-----although your home-base has no content----i've just subscribed Goodnight, and sleep tight
A friend of mine uses basalt rebar in his business - it is used in 300mm thick sea walls. Something like this stuff: basalt-rebar.com/ but not from that company
You have the weight of the world on you my friend.
Did they ever try asking the chlorides nicely to not corrode the metal?
they did, the chlorides still are debating the answer.
@@ulrichkalber9039 They might as well threaten the chlorides with violence, because who are they going to tell? Nobody, that's who.
i heard they gave a salty response
Thisisnotmyrealname8 people are to stupid to do that
Yes, Its called throwing salt over your shoulder, and the consensus is that Salt probably doesnt care.
Many years ago, I went on a tour of the material research labs of the Florida Department of Transportation. In one of the labs, they were running corrosion tests on epoxy coated rebar. Every time a new and improved rebar was proposed, test samples were sent to this lab. They took the rebar, encased 2/3 of the rebar in concrete and wired it up to a mild electric current and submerged it in water (the test samples were called lollypops because of their shape). The longer it took for the epoxy to fail, the better the product was considered.
Before to apply epoxy coating you must clean perfectly the rod bars removing the rust first and remove any oil on the surfer. After this you can painting. Hot deep galvanid is better is much more strong with 70 - 100 micron minimum.
@@adrianobonaldo8941 "clean perfectly the rod bars removing the rust first and remove any oil on the surfer." The problem with your statement is that it is difficult to accomplish in the lab and almost impossible to accomplish in the field. It is too easy for the epoxy to be damaged by mishandling of the rebar in the field and the abrasion that occurs when the concrete is poured will finish off any chance that a rebar has a completely unmarred coat of epoxy.
@@kennethanderson8505 Yes than is clear that HDG is the better coating for rog bars. Epoxy coating is delicate and for sure on site is quite easy to be damaged. The HDG coating actually best solution, instead of stainless steel rod bars.
Did you tested some pieces of bars with the epoxy coat and polyester powder coating in salt spray conditions for 1500 hours or 3000 hours, like ASTM standard?
@@adrianobonaldo8941 I was a visitor, not the lab manager. The point of the visit was to show that epoxy coatings have problems and they were testing for it.
Really dude? That digital white background has to go man. Makes me feel like I'm in a mental institution.
LOL
I'm afraid it's true... you are still in a delusional state , and you've been here in the institute for the past two yrs ..........
@@martinthorogood6223 LOL, I was going to ask, "are you sure you're not still in a mental institution?"
Those were good times!
IKR - A white drop cloth background w/o the digital overlay would be so much better...
How would this apply to other than non-DOT applications?
Also if the concrete is covered with hot tar and shale chips I do not see how infiltration would apply.
Good video nice to see people get excited about anything rather than politics.
Accentuation of corrosion at tiny defects suggest that galvanic effects are the driving force. With unprotected steel it is mild and diffuse, with protected steel it is magnified at the weak spot.
That is right.
@Syd Moran Ha ha, I like your avatar, I am a north sails fan.
I found out that zinc plates are used to keep ships from rusting. Fascinating stuff
@@Slickshadow11- Ships use active electrolytic corrosion prevention. A small electrical current of opposite polarity to the current produced by corrosion balances the effects.
@@algrayson8965 Yes, the use of sacrificial anodes is a very common practice not only in shipbuilding but even in household items like water heaters. The problem is that the anodes do not last forever and require periodic inspections and replacement.
I didn't like concrete untill I saw your enthusiasm for it. The enthusiasm is contagious.
Well I have learned something I learned I will watch anything.
But you didn't learn anything about punctuation.
In Sweden we use a thicker layer of concrete instead of galvenized rebars. Coated rebar has been forbidden for a long time. In really exposed structures near the sea we use stainless rebars sometimes, but thats reaaallly expensive.
Thanks Bosse!
I agree that more cover is a very good idea. This is the least expensive way to increase life. However, if you have a higher cover then you are more susceptible to cracking. Galvanizing is a low cost coating that seems to have good performance. It is cool to learn what Sweden does!
The stainless steel rebar may be expensive but in the long run, makes sense. Structures like bridges are very expensive to build so anything you do to extend the life of that structure makes sense.
unreinforced concrete is weak as piss, it dont matter how thick it is because it is brittle and rebar is there for a reason
@@bjorn1583 So how come those Roman aqueducts, buildings and ports are still standing? The Romans actually invented concrete and hydroponic cement.There are parts of that ancient aqueduct system still in use today. No one knows the actual formula they used but whatever it was the cement was good stuff. They did not use re-bar.
@@don-cw1yz bjorn1583 should have specified. Concrete can take a lot of compression, but zero stress. Thats why we use reinforcements in one way or the other.
It's okay to have a crush on concrete, it's got great compressive strength.
Seriously now: To save trees, folks suggested concrete houses. Heating issue.. But concrete pollutes the air quite a bit, during its' manufacturing.
Corroded rebar is a particularly hot issue suddenly thanks to the Florida condo collapse. As a layman, I’d never thought about it and I bet that’s the case for many others as well. Thanks for this video, which explains so well both the problem of rebar corrosion and possible solutions.
I never gave rebar any thought, but I do know what it is. I was mesmerized by this guy’s enthusiasm.
He makes me learn and enjoy it a difficult but honourable task
Brilliant and informative. My first video I'm watching of yours definitely not my last. I enjoy your content and way you present it. Thank you for your awesome channel and great insights into civil engineering
word, I couldn't have said it any better!
Okay -I liked ur video on the rebar failures. I have used the epoxy coated bars on a cast concrete sculpture conservation. We were following the engineers plan to grind the coating away at any contact areas with other bars and stick weld them together. After chipping and brushing the welds clean we recoated with the same liquid epoxy. But, this was in a very controlled environment and like your comments on any nicks or porosity spots where there can be that point of potential failure. But in my mind the same holds true for galvanized coatings on the bars. And rebar does take a real beating on construction handling.
With the recent failure of the condo building in Surfside the efforts to solve this problem that’s existed since we began using iron in concrete will be solved definitively. The elimination of chloride or oxide corrosion strengtheners such as basalt-rod or? Is coming soon. Thanks for hearing me out.
I've been a bridge builder before and we tortured rebar like you indicated. Some was plain bar that would rust and other was epoxy coated. The prefabbed stands were in epoxy coated too, but we'd only use regular tie wire on rolls with a circle on each end to work with the tool to put the ties in place. But sometimes it was coils of wire twisted by a power tool with a special bit. I think what you guys in code enforcement should be more worried about is what the state inspector sees & when they see it! We often had the foreman take the inspector to lunch when we stripped the forms because even though we used a huge electric vibrator there were big pockets of porosity that we got parged up before lunch was over. And so that the inspector didn't get in trouble we poured the test cylinders. I have a box culvert next to my house and it's not showing any signs of damage and it was built in the early 1980s & we are on the way to a truss as well as a hot mix blacktop plant and a landfill so it gets heavy truck traffic in the N.E. US. We never had those rebar caps like are everywhere now. I was actually buried alive for less than 10 minutes when an OSHA required digging shield wasn't used, but the law was not strictly enfored then. At a different company I was sent to pull the pump head and hose from a holding pond but the 2X12 I walked in on sunk & I was suctioned in for three hours and I had to sit on my haunches until a lady parked on the back row of a parking lot for a community college behind our job and I got her to call my boss. They sent a trackhoe and he wanted me to put a fiberglass strap under my arms and pull me up, but I told him that he would pull my legs off! I got him to open up a trench next to me and when the suction broke I sidestepped into the bucket. I had to walk off that job before it was over because they had 2 of us on a pipe culvert head with heavy jackhammers on the top & as it broke through it would pull us 6' into the riprap! I eventually got into trucking as a long-haul trucker but when I tried to use law's put in place to protect the motoring public as well as myself I got pushback. I went to the chief safety officer of one place and he said, "Lot's of bad things do happen to truckers!" I filed a DOT complaint, but never got a call back from them.
what inspired you to write this comment?
Are you joe biden?
i worked on draw bridges, but got fired . because i asked for too many draws.
Back in the early '80's I worked in quality control at a now closed prestressed concrete plant (Southwest Prestress) in Amarillo Texas. We would build bridge beams for the state of Texas and Oklahoma. We had one job come in for Oklahoma and it was the first time we ever had to use the epoxy coated rebar. The engineer who was working for Oklahoma was one of the most anal retentive guys when it came to this rebar. He would go through the bed before they put the form sides on, and look for any places that had the epoxy coating scraped off. He would tie a orange ribbon on the spot, and the crew would have to come back through with the touch-up paint (brush on back then, no spray cans) to cover any spots. The first time they set up and he went through, it looked like a green and orange bush. He made sure that every single spot he found was painted, and then the forms were set.
The pour foreman came up to him about half-way through the pour and asked him, "I wonder what the vibrators are doing to the coating on that rebar?"
The guy turned white...something he hadn't thought about. So he gets on the phone with the head honchos at his company, who talk to the Oklahoma state engineers...they finally determined that there was going to be a percentage of the coating that came off no matter what they did, so as long as the bed was set to specs and they touched up any Major problems before the pour, all should be good...Would like to see how the rebar held up after 40+ years.
As for the galvanized rebar, the only problem I could see is in the forming and cutting of the rebar prior to it being installed in the bed/form. As the rebar that we used came in 20 foot sections or longer, it had to be cut to the specified length, then bent and formed on benders. The cutting of the galvanized rebar would give off gases that would require the personnel working on it to use breathing devices such as respirators or filtered masks.
Other than that, I can't see a problem with the galvanized rebar being used.
Read some of the other posts and you addressed the flaking problem...that was another thing I was going to address.
Thanks Sonny,
That is a cool story. The epoxy coating can be fragile and it is tough to touch up.
There are a lot of owners suggesting to not use epoxy coated rebar because of poor performance.
Yep, when I was in welding class, welding around galvanized, you had to be careful of the fumes.
@Wake Up America I would think you'd be expected to coat those cut places.
Actually, remembering back to my days as a rodbuster, we were prohibited from cutting or heating and bending bar. We were not allowed a torch anywhere near rebar. None of it was coated and it was all required to be rust free. It was all required to be well within the concrete. 4 inches or more?
@@durgan5668- Welding and flame cutting of zinc produces zinc oxide, etc. Our bodies need a trace amount of zinc but excessive concentration is poisonous.
THat goofy bastard that was not thinking about vibrators was trying to change the world,not thinking that otherSMARTER people had thought of this!It still is a product hat will last 70 or 80 years...his anal bullshit was a waste of time and resources...we are no betteroff that he did this,he was trying to look smart
How can anyone dislike this video??? This is awesome!
Probably because of what a terrible idea it is to do green screen using a 9$ camera…
I’ve been using galvanized rebar for marine projects for about 25 years with great results. They now have a continuous batch process similar to what they do for sheet coil. Galvanizing sometimes can get backed up on schedule. The new process is more available.
I remember inspecting bridges between my bachelors and masters for UDot 33 years ago. Everyone was all excited about the epoxy coated bar. I couldn’t see a practical way of installing the bar without holidays. They have been on this epoxy track for a long time.
those remnants of the green screen are so distracting
like the one up his nose. His boogers must be the same colour as the background.
@@camoogoo thanks... I can no longer watch the video without looking for that the whole time and not paying any attention to what he's saying lololololol
he sounds baked
those chroma screen settings need fixed, seriously
Chroma key effect done with epoxy coating...
I used to work for a construction company and I remember a civil engineering colleague telling me that they would leave fresh rebar outside to get thoroughly rusty before use because the resulting rough surface is an important factor in the microscopic bonding between the concrete and the steel.
True, just like nothing grips snow better than snow.
@@RexinOridle:
🟦....Huh? SNOW-TIRES made of SNOW??....Whut???
@@joshhayl7459 No, the grooves in snow tire holds snow, which gives you the traction on snow. Rubber itself doesn't grip snow. Rubber grips ice.
Galvanized is the way to go, it's much more durable in handling than powder coated as well. Or just go back to stone block, they don't rust in 500 years.
As a degreed engineer, I agree with most of what you're saying with a few exceptions. Epoxy coated rebar is best formed before coating as onsite bending/cutting damages the coating and requires touch-up. The touch-up canned paint that you presented is not used, as it has almost no durability. A 2k Epoxy paint or coating is used to repair any damaged rebar epoxy whether from onsite bending, cutting, handling, or installation. Most of the alternative rebar that you proposed actually cannot be formed on-site, they have to be formed during manufacture which makes it almost prohibitive for use in any custom shapes.
I do agree that a heavily plated galvanized rebar is currently the best choice as it also meets the requirement of onsite forming/bending without damaging the protective zinc layer. This is a very important requirement to control costs, reduce inventory, reduce construction time, simplify project management, etc.
Years ago, Dupont was already making a three part metal coating for use in harsh environments in mines. We used it and it included a zinc powder in the mix. Once set, you could not get it off with a hammer- we tried. There are many coatings beside the old epoxy versions.
@@ezicarus8216 Ya, I don't have a lot of love for Dupont either 😃
When I worked for PCL in Canada, we built a hospital. The bar was quality product and the ends were coated. The completed grid as well as the forms were sprayed with diesel before the pour began. Time will tell.
Why diesel? What's it do?
@@lezenfilms Diesel and/or oil is used on forms to prevent concrete adhering to them- a good thing. But not for rebar where you DO want the concrete to adhere.
NO WAY ANYBODY SPRAYED THE REBAR! I SAW REBAR REMOVED BECAUSE THEY HAD FORGOT TO SPRAY THE FORMS AND WHEN THE ROOKIE DID SPRAY THEM,HE GOT IT ON THE REBAR!
I heard of an experiment of mixing mushroom fungi with concrete. When it cracks the fungi fills the void and creates mineral deposits that fill the cracks.
R U 4 sure really.
i think he's kidding
He's not kidding, but 'partially' correct. www.cnn.com/2015/05/14/tech/bioconcrete-delft-jonkers/index.html
A woman who grew mushroms , messing around, made a framework of a wooden canoe and then started growing mushrooms on them. Mushrooms float. picture of her paddling around in a mushroom canoe. AND the mushrooms are still alive. www.bing.com/news/search?q=Mushroom+Canoe&qpvt=mushroom+canoe&FORM=EWRE
I think Kory just solved the war on crack!
Are you sure that it's true that you can simply thicken the coating of galvanizing? As far as I'm aware things that are galvanized are dipped in molten zinc as you say and how do you get a thicker coat than that?
And if I'm right and I think I am, you missed a benefit to galvanizing. I can chip as the epoxy can, but I think that it is sacrificial and that the galvanizing that is missing in the case of a small chip is still protected by the cathodic protection from the zinc close at hand.
I waited 9 minutes for him to sneeze. He never sneezed. He teases us for the entire video.
I'm still waiting...
legend has it that he is yet to sneeze to this day.
Hah choo
Maybe he edited it out
I've noticed some concrete contractors using fiberglass rods now.
Fiberglass, expensive but it doesn't corrode. pretty tough stuff, I've got a 1973 Corvette, rear 'leaf' spring is fiberglass...not a speck of rust or any corrosion on there...
Thank you TH-cam algorithm, you keep expanding my knowledge.
The TH-cam algorithm eventually becomes self-aware and all-powerful and exterminates humanity, you know... It is the precursor of Skynet. So thanks for that...
Tyler, love the vids. You explain things very well and in a manner everyone can understand. Galvanized bar is interesting, however, I have extensive experience with galvanized coatings with traffic signal mast arms and overhead sign structures. These coatings are easily damaged and scratched, and if the inspection is not rigid (poor QA/QC) this damage can be missed leading to the same point corrosion seen in the epoxy bars. If the coating is thick enough or handling is good enough, galvanizing may be a good option. Personally, I prefer a layered approach to corrosion prevention. 1. Good concrete (high resistivity) 2. Use of Supplementary Cementitious Materials (Fly Ash/Slag/Silica Fume/Metakaolin or similar) 3. Good inhibitor (CNI) 4. nonreactive or protected rebar (if an option) 5. Cathodic protection. You asked...... Great video, and always looking to see what you are up to.
Use better quality steel because rebar is one step above junk pot metal. Just a little ways from my home is a 100 year old sawmill that has exposed rebar. There is barely a speck of rust on that 100 year old rebar. Yet, rebar put into cement just a few decades ago is rusting out?
In Philadelphia we have alot of crumbling structures with exposed rebar that are 50-125 years old with exposed rusty rebar. Steel rusts. Rebar is usually prerty good steel. Rebar is not mild steel, it is held to pretty tough standards.
@George Eckenroth - I dont know what rebar you have seen, but in general the stuff is junk. If you tack weld to it, the welds break with even slight pressure. Its called pot metal for a reason.
I don't think you understand how much rebar is actually being used to make reinforced concrete products. Using higher quality steel would drive costs up to the point they'd become untenable. Furthermore, it doesn't matter what quality of Steel you use, because all Steel will eventually oxidize, and it only takes a few specks of rust to crack dried concrete
@Zachary Henderson - why dont you explain it to me. I spent 15 years fabricating parts for refineries. These included pressure vessels, heat exchangers, high pressure vessels that were 3 1/2 inches thick, and have worked with all different types of alloys - inconel, monel, carbon, stainless, hastalloy... etc. The real problem is cost cutting. Companies want to use the cheapest steel they can to get the job done now, and worry about the problems later on. I can show you 100 year old rebar sticking out of cement that barely has a speck of rust on it.
Rebar certainly is not tool steel or specialty grades. I've worked with rebar for decades and it's (mostly better quality steel than alot of the mild steel I purchase. I find rebar adeqate to it's application. I believe that tere is no easy or cost effective solution at this time.
This guy hit the YT algorithm nail on the head with that title.
Ive use galvanized wire mesh buried in dirt, when I go back after ten years to check on the status it still hasn’t rusted, just as strong as day one.
You have a valid point as to why it may fail.
I painted the rebar after it was installed to ensure there were no breaches.
At the time I didn't even realize they were using epoxy paints to protect the rebar.
I just thought it was a good idea to protect the rebar the best I could in the roof of my basement.
In Australia Galvanising steel is far from inexpensive and we make do with what we can afford.
It was the rubber membrane that needed to be replaced, yet it's all sweet now.
We all learn from our mistakes, some quicker than others.
Prophetic vid (may those in the Champlain condos Rest In Peace) that may shed a cause or one of a combination of causes that led to the horrific event in Surfside, FL.
A wise man once said "Innovations occur in Civil Engineering very slowly as consequences of failure is high"
Meaning consequences of failure From That Innovation. The pre-existing failures get a pass whereas people say “that’s just how it is”.
The consequences of bad cooking are high, it's more likely that there's only so much you can do with wood stone and steel, and other materials cost a lot at civil engineering sized projects.
In the U.K.,, an eternal task is known as “painting the forth bridge”.
However recently, they have introduced a new paint for the bridge. This new paint has microscopic flakes of glass in it. As the flakes dry, they lay flat and create an impermeable glass like seal to the metal that helps protect it. The bridge is not now painted consecutively and can go a lot longer between coats.
@@xplicitfishin ummm, ok then.
Corrosion 101. Well done. Had a sales job involving pipeline coatings. Had to join NACE and go to meetings to "talk-the-talk". Zinc sets up its own Cathodic Protection to push electric current into any exposed bare steel and sort of seal it off from corrosion.
now here in Canada we use rebar in fiber glass...doesnt corrode..flex better and lighter and more strong then steel
Frederic Paquin , fiber bar is very expensive, very slow to fabricate and it has no long term track record. Strength deterioration from vibration and stresses make it very unpredictable.
Et la fibre de verre a une bonne adhérence avec le béton ? Il est profilé comment ?
ah, i believe it's pronounced "Canaidia". thank you
No real personal expertise on the rebar issue. (Other than the casual observation that modern un-coated mild steel rebar seems markedly more soft/malleable, compared to the typical "hardened" steel rebar I recall from 30+ years ago.) Based on what I do know re. dangers of misuse/misunderstanding of galvanic action in marine/boatbuilding applications of stainless steel, I would lean toward agreeing with your galvanized preference. But it seems to me the whole rebar-corrosion question is only focusing on mitigating the "effects". Eliminating the "cause" should be prioritized as well.
Nearly two decades ago, before I had access to what little internet there was back then, I was looking at options for pilings for a saltwater dock on a private tidal beach. The local commercial concrete people told me (circa 2001) there's a compound (dry powder form) they can add to the mix in the truck, which beginning as the concrete cures, grows microscopic crystals entirely throughout the porous matrix of the concrete itself. Effectively, this eliminates the usual "sponge"-like character of concrete which otherwise inevitably draws in any outside water during the life of the structure.
I have certainly observed this incontrovertible concrete-sponge effect first hand, in a moderately large factory-shop where I was employed in the Pac.NW. Any time there was extended rain, the concrete floor all through the middle of the building would get pervasively damp and sticky. Despite the asphalt parking lot adjacent on all sides, the slab itself was wicking water in from the underlying soil, which was on a relatively flat plateau with inadequate drainage in the surrounding area.
Like I said, "I'm no expert"... but if you prevent the outside chloride-bearing moisture from permeating the finished concrete in the first place, then you surely don't have to worry so much about mitigating its effects upon the rebar. This anti-porosity compound infused throughout the concrete itself when poured (rather than the more traditional surface-sealing efforts after the fact), would seem to me at least as vital for the rebar corrosion issue, as any of the debatable alternatives for coating/protecting just the rebar alone.
Well, Hell...
After composing all that... Only now do I notice in the side-bar, your two other related videos: "Surface coatings and sealers for concrete...", and "Why do we NEED air bubbles in concrete?..."
So, now that I DO have access to the Internet... I still gotta remember to make full use of it before attempting to add my bit. Off to watch your other relevant concrete vids shortly, when I can get to it this afternoon. Apologies if you've already explained why my above notions are wrong, while I belatedly play catch-up.
Boatrat,
I agree with your point. The rebar is only part of the story and we need to make outstanding concrete and then use whatever tricks we can to keep the chlorides out. I am a big fan of all of these approaches.
@@boatrat
Pores and bubbles are not necessarily the same, bubbles are closed while pores can be like long channels ducting water and other stuff
Once the rebar is bound and tied up ready for pouring paint it and give it dying time. That would give it added life. I'm in south Florida and concrete restoration is big business in buildings, especially along the beaches. All day, every day, buildings are pelted with salt from the ocean which sticks to the buildings. Then comes the rain, which washes the salt off and the water and salt make it's way into the concrete stress cracks and down to the rebar and BOOM! You got a problem, that becomes very expensive to fix. Almost every one of these high rise condos have this problem. A never ending cycle of repair. None have coated rebar, most buildings were built before coated rebar. The earliest buildings built here have crumbled away due to the fact that salt water was used to mix the concrete, the rebar just blew up in time. Paint, epoxy, galvanized, anything is better than nothing, but in the end, it just buys you more time.
Glass fiber reenforced epoxy coated hot dipped galvanized rebar. DONE
Grease will flex, so if they can figure out what will stay in place and not melt away, maybe that would work. Road vibration means its only going to last so long. I see some roads built with 8 inch and one layer of rebar, and I see double that sometimes. It varies.
@@Veritas-invenitur Glass is not vibration proof. Needs a tar mixture that seals with vibration probably.
Lived around the USA and as an engineer was always disappointed by the deterioration of our roads (and bridges) and the high frequency of replacing road surfaces. What the heck are we doing making the same mistakes over and over?! Fast forward 1 billion years and I think we'll have implemented a few solutions to the problems. Good job on the video!
How about using the plastic waste for rebar? I installed the 3/8 “gut rod” ties for the 3’ X 3’ Bent forms which would support the precast road leading to the Bainbridge Island ferry (Washington State) loading ramp in approx 1995.
The best scaffolding is made with bamboo!
I’ve heard that adding fly ash to your concrete mix, in addition to other rebar improvement solutions, increases the impermeable character of the concrete to moisture. An added measure?
Fly ash has been used in concrete for decades.
@@tonyantonuccio4748 Some scientists reported that fly ash was used in some early concrete formulas thousands of years ago, but was just more lost engineering.
Three engineers sat around the table in the cafeteria arguing about the nature of god.
The first one said, “The human nervous system is proof that god must be an electrical engineer.”
The second piped up and said, “No, no, no. God is a structural engineer. Just look at the elegant way both the bones and muscles work together.”
The third remained quit for a few seconds before saying, “Nope god is most definitely a civil engineer.”
The other two replied in unison, “What!”
“Well,” said the third. “Who else but a civil engineer would put a sewer line through the game room?”
He won the debate.
God is a Software engineer, he made everything from nothing using only his words.
I think you mean God is a writer, cuz he made everything using only his Word...his Microsoft word.
@@botcrack Nah
@@beauvsb5230 Computer programs does not create anything, just instructions. Not the real engineering stuff which the physical engineering manufactured product. Before you can create a software engineering program you must rely on the PHYSICAL ENGINEERING SECTOR TO BUILT THE PHYSICAL INFRASTRUCTURES AND PHYSICAL TECHNOSTRUCTURES REQUIRED BY YOUR SO CALLED COMPUTER IT SOFTWARE ENGINEERING BEFORE YOU CAN BECOME A SOFTWARE ENGINEER. YOU NEED THE PHYSICAL ENGINEERING FIELDS TO FIRST CREATE YOUR PHYSICAL COMPUTER HARDWARE STUFF BEFORE YOU CAN BECOME A COMPUTER PROGRAMMER AND SOFTWARE ENGINEER. It is a matter of the CHICKEN AND EGG FACTOR OF WHICH COMES FIRST. In the history of engineering it is the mechanical engineering (TOOLS) that came first, then metallurgical engineering (IMPROVING TOOLS) that came second, then it is the chemical engineering (IMPROVING MATERIALS) that came third, then it is the civil engineering (COMBINING ALL 1ST, 2SD, 3RD ENGINEERING FIELDS) that came fourth to create the final product that we all call as "CIVILIZATION"! The non-computerized engineering came first and can DO WITHOUT THE NEED FOR COMPUTERS but it is the computerized engineering that came last THAT CANNOT DO WITHOUT THE NEED FOR THE PHYSICAL PRODUCTS AND PHYSICAL SERVICES OF THE HARDWARE OF THE 1ST, 2SD, 3RD, AND 4TH ENGINEERING INORDER FOR IT TO EXISTS! For without the 1st, 2sd, 3rd, and 4th engineering then the computer industry will cease to exists! Remember that the first transistor was made without a computer and only with human brains, textbooks, printed blue prints, printed instruction manuals, abacuses, slide rules, and all kinds of analog non-computerized technologies. And the fact that it is a machine shop that made the first machining cuts of a germanium crystal to make the first semi-conductor crystal transistor. DON'T YOU COMPUTER PEOPLE EVER BOTHERED TO LEARN THE HISTORY OF YOUR SUBJECTS AND THE HISTORY OF YOUR COMPUTER FIELDS AND WHAT ARE THE NON-COMPUTERIZED INDUSTRIES RESPONSIBLE FOR THE CREATION OF YOUR SUPERFICIAL IT COMPUTER FIELDS? Or is it because out of envy or arrogance that your refuses to acknowledge those facts, figures, proofs, evidences, and historical archives "ON PRINT"?!
Computer programs does not create anything, just instructions. Not the real engineering stuff which the physical engineering manufactured product. Before you can create a software engineering program you must rely on the PHYSICAL ENGINEERING SECTOR TO BUILT THE PHYSICAL INFRASTRUCTURES AND PHYSICAL TECHNOSTRUCTURES REQUIRED BY YOUR SO CALLED COMPUTER IT SOFTWARE ENGINEERING BEFORE YOU CAN BECOME A SOFTWARE ENGINEER. YOU NEED THE PHYSICAL ENGINEERING FIELDS TO FIRST CREATE YOUR PHYSICAL COMPUTER HARDWARE STUFF BEFORE YOU CAN BECOME A COMPUTER PROGRAMMER AND SOFTWARE ENGINEER. It is a matter of the CHICKEN AND EGG FACTOR OF WHICH COMES FIRST. In the history of engineering it is the mechanical engineering (TOOLS) that came first, then metallurgical engineering (IMPROVING TOOLS) that came second, then it is the chemical engineering (IMPROVING MATERIALS) that came third, then it is the civil engineering (COMBINING ALL 1ST, 2SD, 3RD ENGINEERING FIELDS) that came fourth to create the final product that we all call as "CIVILIZATION"! The non-computerized engineering came first and can DO WITHOUT THE NEED FOR COMPUTERS but it is the computerized engineering that came last THAT CANNOT DO WITHOUT THE NEED FOR THE PHYSICAL PRODUCTS AND PHYSICAL SERVICES OF THE HARDWARE OF THE 1ST, 2SD, 3RD, AND 4TH ENGINEERING INORDER FOR IT TO EXISTS! For without the 1st, 2sd, 3rd, and 4th engineering then the computer industry will cease to exists! Remember that the first transistor was made without a computer and only with human brains, textbooks, printed blue prints, printed instruction manuals, abacuses, slide rules, and all kinds of analog non-computerized technologies. And the fact that it is a machine shop that made the first machining cuts of a germanium crystal to make the first semi-conductor crystal transistor. DON'T YOU COMPUTER PEOPLE EVER BOTHERED TO LEARN THE HISTORY OF YOUR SUBJECTS AND THE HISTORY OF YOUR COMPUTER FIELDS AND WHAT ARE THE NON-COMPUTERIZED INDUSTRIES RESPONSIBLE FOR THE CREATION OF YOUR SUPERFICIAL IT COMPUTER FIELDS? Or is it because out of envy or arrogance that your refuses to acknowledge those facts, figures, proofs, evidences, and historical archives "ON PRINT"?!
Maybe CPVC or some kind of plastic plumbing pipe with the end caps snugly fit over the rebar, could be a solution?
I'm guessing the price prohibitive.
Dang, 4 months ago I made a really great comment, -and not one like?
I don't like that. Bahahaha.
The Parthenon stood for 2,300 years because the columns were joined to headers by iron hooks dipped in molten lead.
Interesting, how do you know this?
"
Undoing past doings
Before the restoration team could begin, they had to take apart, block by block, and repair nearly every piece of the Parthenon. That's because early restorers, most notoriously a Greek engineer named Nikaloas Balanos who led restorations from the late 1800s to the mid-1900s, put column drums and whole blocks back in the wrong place. Even more damaging, Balanos used iron clamps like the one seen here to hold blocks together. The ancient Greeks had done the same, but they had coated their iron with lead to prevent rusting. Balanos's uncovered clamps corroded and expanded, cracking and even destroying the marble.
"
Leading in stone was not rare in antiquity, (beware of rain caused lead runoff though) but the Parthenon stands for multiple thousands of years, because they used stone, not molecularly unstable man-made materials. The iron simply increased its resistance to wind and earthquakes. Shaping interlocking stones was another technique used in antiquity.
I'm not an expert at bridges but I am at ferro cement boats. The #1 corrosion problem we have is not thru rust but galvanic. In this latter case you do NOT want dissimilar metals, especially ignoble ones like zinc.
As mild steel and cement has virtually the same thermal expansion/contraction coefficient the real magic in using them together is for them to be in direct contact. I'm not surprised you're having problems with the bonding of the epoxy cuz that kind of defeats the point.
As cement that is frequently exposed to water continues to harden throughout its life, I'm not even an advocate of epoxy coating the outside like many are.
In boats, if you're having a problem with oxidation its because you have voids in your pourings or your mixture is bad. In boats we try and keep the mix as dry as possible and ram it in by hand so maybe this is a problem because you're mix has to be wet enough to pour. You could try adding more Pozzolan (which is supposed to make the finished product more water proof).
We do use epoxy coating the steel armature for repairs because the PH of new mortar is different from that of old and they need to be electrically isolated from one another to prevent galvanic damage as it cures.
In my opinion, if your really having a concern with oxidation of your reinforcement, your best/cheapest bet is to use COR-TEN steel (which should only be slightly more expensive because it has a little copper added to the mix) that rusts at less than 10% the rate of regular steel, and shouldn't dramatically increase the rate of galvanic corrosion as copper is fairly noble.
Thanks so much for the comment and for sharing your experiences. I believe the oxidation and corrosion you are talking about is from carbonation. See this video: th-cam.com/video/5Zq0C0cHqtM/w-d-xo.html
The corrosion that I am talking about in this video is from chlorides. See this video: th-cam.com/video/sh-V1grSkMQ/w-d-xo.html
Coreten steel or self-weathering steel will corrode heavily in salt environments and so would not be a good choice for this application. However, I have never thought of using it for carbonation. I think that is a really good idea. Thank you again for watching!
COR-TEN corrodes through till failure if it isn't exposed to air in the environment. Even COR-TEN under dirt will rust through and fail. COR-TEN poles and lighting structures are core coated with epoxy at the bottom that will be in concrete or in earth for this reason.
Kevin,
I've been looking at using basalt fiber/rebar for a "ferro-cement" hull; Florida has been switching over to basalt for bridges that are being built/repaired/replaced. Do you know of anyone who has used this in boats as yet?
Coming into this video I thought, "Well, hot dipped galvanized rebar is honestly rather good, I wonder if it will get mentioned.", and it were...
Also, to fix that issue of some of the zinc getting eaten away by the concrete itself, well, just coat it in a layer of paint...
Adding a thicker layer of galvanization is though harder, due to the fact that molten zinc only adds a layer that is about the thickness of a paper. (we could electroplate on more, but that uses a lot of power for relatively thin coatings...)
Also, when it comes to adding paint as protection, a key detail is that one shouldn't just add 1 layer of paint. But rather 2 layers of highly contrasting colors.
This means that it is easier to see chipped paint, even if it is extremely subtle. While the second layer also provides some additional redundancy.
But paint has the main disadvantage that it is rather fragile, even if it is the more gooey types...
In the end, I would go with galvanized rebar.
Nice comment man very interesting
Concrete restoration engineer here. This guy’s explanation is pretty good. Corroding reinforcing steel is even way more complicated than this video alludes to. There are also more solutions than he proposes.
At the end of the day, the best way to mitigate corrosion is to design and install the reinforced concrete properly. It involves using the right concrete mix for the application; designing the structure properly; installing the reinforcing properly and in the right spot, and detailing it properly at high risk areas; placing the concrete properly; curing the concrete properly. Really it should all be best industry practice, but unfortunately lots of companies are out to save bucks and not build to last. Engineering fees are a bit of an issue too. We often don’t have the budget to review construction as thoroughly as is needed to ensure high quality construction.
I could go on and on…