What is FRP rebar? Why don’t we use it?
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- เผยแพร่เมื่อ 25 มิ.ย. 2024
- FRP rebar or fiber reinforced polymer rebar does not corrode in concrete and so it is an important alternative to steel rebar. This rebar can be made with glass, basalt, or carbon fibers surrounded by a plastic matrix.
This video talks about the benefits and challenges with FRP. However, FRP is not widely used for several reasons. The biggest challenges are the decreased stiffness and lack of strain before fracture. There are also concerns with fire and long term deflections. The video gives solutions on how to overcome many of these issues but it will require an increase in the cost of the concrete. Finally, the video talks about carbon FRP and the significant potential that it has once the price decreases.
The calculations for basalt rebar are based on properties given here: www.build-on-prince.com/basal...
The cost of carbon FRP is based on prices from Alibaba in comparison to costs of steel rebar in the US for an equivalent concrete slab. This number will be different for other members but the point is that carbon FRP is a lot more expensive. I am sure it will come down in the future.
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A huge thanks to Hailey Goodale, my director of awesome, for editing this video. - แนวปฏิบัติและการใช้ชีวิต
hey Tyler just a shout out for ya. Reall appreciate the videos you do. I've worked as a a project engineer and now assistant superintendent on a number of IDOT projects in Illinois. Unfortunately I now work in MN doing commercial roofing but I still love concrete. I wish your videos/knowledge/passion for the crete was more widespread. Thanks, and please continue!
Appreciate the informative content. As a cost estimator it’s a great way of staying informed of what the industry is doing.
Just a quick rebuke those that say potato quality... i’m learning about concrete from a professor thousands of miles away, its amazing and its free... from the UK, thanks Prof Ley!
TH-cam's algorithm dropped me into this teacher's video for the very first time. Can you plesse tell me why and what the reference to "professor potato" means? Thanks.
@@danielfronc4304 - potato is a meme style descriptor of poor video quality… _”what did you film that on? A potato”_
Other benefits of FRP rebar are no electrical conductance, no RF interference, no corrosion, and reduced cost of shipping, handling, and installation due to it’s light weight.
I am planning on building a house and shop, so I am learning about materials, methods, and build science. FRP rebar in ICF structure has my intrigue.
I'm not in construction business. I did not know shit about concrete just a few months ago. But i just. cant. stop. watching.
In my town (near Racine, Wisconsin), we have some sidewalks in the older neighborhoods that were laid down from 1902 to 1905 that are practically perfect. We also have a lot of sidewalks from the 1970's-80's that are in need of replacement due to cracking/spalling. I don't know if it is the formula (the concrete is a little darker than concrete used today) or the workmanship, but those turn-of-the-20th-century guys who were using horse-drawn wagons, water from barrels and brute strength really knew what they were doing.
A large amount of survivorship bias, the only building work we see from 100 year sago is the stuff that survived. The badly made and poorly designed stuff has been replaced.
Ian Griffiths while it is true that survivorship bias is at work here, that doesn’t change the fact that the workers in 1902-1905 did a better work (or invest in better materials, etc.) than the 1970-80s. While nowadays we got better concrete technology, it doesn’t mean that poor concrete constructions (in our current age) that are worst than the ones built on the past didn’t exist
George Ford, funny you should bring this up. I just had a stucco guy tell me that stucco over the years is not as strong as it used to be. He thinks it's the quality of cement that has gone down. I wonder?
I believe the quality has went down myself. Can't help but think it's likely do to epa regulations and or faster curing formulas.
You can spec whatever concrete you want at any time. "Back then" and "not as good as" always come from people that don't know standards. People that know standards can compare apples to apples at any time. Customers are the cheap ones. They hire the cheap guy and then whine about quality.
I'm a mechanical engineer, specialize in fibreglass structures (Pat pending).. It's a perfect explanation to generally sought after questions.
But I find still something missing in all research carried out.. Hope to make necessary tests before publishing in scientific journal OR may be apply for a Pat.
But kudos to your presentation..
Please update. I have an idea for fiber structure in a totally different field.
Man, i'm from Brazil and your videos are great!! Thanks for the information!
Ive been doing a patio expansion; multiple sections (Im doing it all myself, so each section is small enough for 1 or 2 people to work.) Wrapping the patio from the back yard around the garage, and to connect to the driveway. Ive have been overbuilding much of it, so I can be confident it will last, and one of the things I was so excited about was finding this fiberglass rebar. I use regualr steel rebar inside the each slab, so I can bend it and weld it together, but then use the fiber glass to tie each section together through the expansion joint, so I dont worry about corrosion creeping into the slab as if I had used steel bar to tie each section together. Though I do run a #6 solid copper to continue the equipotential bonding plane.
I am so satisfied to be told the facts and as a bonus have these facts explained to me in detail. I have just learned about Basalt rebar yesterday and now I have the facts. I also have learned about the different matting and cloths that are made from Basalt . My hobby was building airplanes and will be in my future so I am trying to learn of every material that I can use for cost , safety , work-ability and accessibility . Thanks for the info.....
great video man, i watch many of your video and what i like about it is you show many of the latest research in the field, as new as 2019!
Like the new gray background. This was an informative video not only about concrete reinforcement but about the general idea of stress strain curves. I thought I was familiar with that but the clear cut explanation added to my understanding.
On the video before this I mentioned what appeared to me to be the very good performance of the concrete used to construct the Monterey aquarium 36 years ago. In general, what was best practice 36 years ago for building concrete structures in close contact with saltwater spray? Maybe in a future video you might talk about how well they are doing at making concrete structures on the east coast that need to contend with road salt. I noticed a lot of bridges with substantial rust damage when I was in MA recently.
Your explanation about concrete are very precise and crispy. You are doing a wonderful job by spreading required knowledge. 👍👍👍
Great video Tyler! Greeting from Scandinavia!
Amazing content delivery, Tyler. Great videos!
Your friends from Canada
As someone working in linguistics field, I can only thank Tyler for his super-enthusiastic way of explaining these things. I am now working as a translator for a huge railway system reconstruction project and many documents I work with deal with these topics. Turns out they can be interesting to a non-professional as well!
I appreciate Tyler’s knowledge, content, and enthusiasm. But in my opinion, his delivery style is exhausting. He’s got it dialed at 11, all the time. Such intensity is better used in moderation. To use a metaphor, I don’t want to watch a punk rock style presentation (fast and loud from start to finish) - I want something more akin to a storyteller style or perhaps witty stand-up comedian. Keep the delivery dynamic and interesting in the build up; save the energy for the right moments, no only really go off the rails rarely.
Great video, I work with carbon fibre and believe carbon fibre costs will continue to go down. I think we are about a decade away from seeing carbon fibre rebar in mainstream usage.
Great video, Tyler!
Thanks so much!
Thanks for informative video !
Saw this stuff at Menards for about the same price, but didn't know who to ask about whether or not it is better. Considering flatwork applications. Glad you made a video!
Yea the glass is cheaper at menards right now than steel - seems like it might be worth using in places like driveways that get constantly attacked by chlorides. Wonder if rate of expansion and contraction would be more or less of an issue with glass over steel.
Yow Tyler, I was just about to present on GFRBs as a solution to steel corrosion in concrete. but when I looked on the negatives in your video ...I had to call it off :). Thanks for the detailed info. I'm from Jamaica.
Awesome video, you perfectly explained what I was looking for, thank you. Looking for stainless steel rebars next as an alternative, you must have addressed that too.
We use to use water proofing solutions in basement areas, it was fairly toxic but it made the concrete less porous. Secondly the standard is 50mm cover in Australia and most "blowouts" are probably half that, through lack of care. In Canada they salt the roads I saw for ice and this was also an excellerent in pavements and bridges.
love your vids. Great and interesting content.
very relevant right now.
This is very informative and great for learning especially with graphs thank you!
Thanks for the comment and I am glad you like it.
This is an excellent presentation and well referenced. Time and building materials march on. Thanks much!
However, comparing two or more product's relative performance(s) down to percentages can only really be honestly made when all variables involved are removed ("zeroed-out") and that is first and foremost the differences between batches of concrete. If all the tests were made on the same day using one singular batch of concrete then yes, the results hold scientific credence. All of us who have handled building projects using concrete know all too well how one batch of concrete will vary from the next one delivered in both the mix and especially the amount of water from batch to batch.
u have awesome knowledge buddy..
Beautiful, more to think about FRP than I realized. I raise my finishing trowel to you. Cheers 🍻.
Thanks so much!
as You also mentioned, fire safety is another issue, esp with carbon fibers, as it burns pretty well. up until now I haven't thought about that. In another video You also mention galvanizing, and using micro and macro fibers - these are also interesting ideas
Thanks Tyler!
Hey Tyler!
I try to listen as often as you get your videos out. One subject I have not seen a lot of is a product call "Helix". For those of you that also read these messages, Helix is a small steel, almost toothpick like, that is added to concrete to cut down on Rebar with more strength. What are your thoughts on this?
I’d love to see a video comparing quality in steel rebar. I own a remodeling firm in Florida and it’s amazing how much harder it is to cut steel from homes built in the 1950-60s vs the new steel. The old steel and concrete is much more difficult to cut and break. When we remodel things from the 80s and newer the steel cuts like butter.
Rebar would not be the issue because the changes in the ASTM specifications have increased the tensile strength of rebar. What I believe you are see is the fact that concrete strength increases with age. Concrete hardens by hydration and never stops. We normally use the 28 day strength for the standard, but others use the 90 day stregth which can be 15% greater. If you investigate the time increase of the stregth of concrete you will find that very old concrete is significantly stronger especially if it is in a damp envionment. Water helps the hydration process and is why concrete is steam cured.
As far as the steel itself is concerned, where it was made might make a difference in it’s strength and toughness as well as to what standard or specification. What was the spec in 1960 vs contemporary?
I'm an electrician in the DC area, I've worked for a concrete cutting specialist company as well, and even as an electrician I sometimes have to drill holes for conduit or sleeves for MC. Sometimes in this area in old buildings, you will encounter concrete that is remarkably hard, and will wear out bits/blades before you finish the job. The older guys tell me that is typical of DC, when the old companies used to use dredged up Potomac River stones. Nowadays they use more sand and some other kind of pebbles.
good content. use both! basalt and steel, basalt for long lasting, steel for unexpected catastrophic forces
I know its been years now since this video was made but FRP rebar is now similarly priced if not even cheaper than steel rebar now. Some of the new FRP rebars are both strong and flexible now as well where they dont fracture as easily and will bend and flex back in place which solves some of the ductile concerns compared to steel.
wow i had never been this focused on a video. Thank you for your explanation. Btw i am doing GFRP study for my degree. Wish me luck!
This is a great content, keep going please
Asa licensed stucco contractor I share your passion for anythingI just wished I shared your intellect.Thank you.
THANK YOU for making this video! Long awaited. I love looking at the alternatives to steel.
In addition to rebar, I'm also curious about the use of chopped FRP fibers to replace steel fibers:
How does the actual cracking performance compare?
If we strive for low-permeability ultra-high performance concrete mixtures sealed with a lithium silicate hardener, can chopped FRP fibers help reduce spalling in a fire the way PVA can?
How long does FRP actually last? It's nice to say "no corrosion" but how long does it take for polymers to break down inside concrete? How does it behave as a reinforcing material after the polymer breakdown has begun? Can we monitor it?
Thanks!
I talk about fibers here: th-cam.com/video/jWFncYgbCCg/w-d-xo.html
Comparing FRP fibers and steel fibers is tough. The modulus of the fibers are very different but the amount of FRP fibers that you can add to the mix is higher. This has a lot of advantages of not changing your mixture proportions.
I have never seen FRP fibers in a fire test and so I don't know the answer to that. I would think they would perform well.
Previous versions of FRP did break down over time in pore solution. The new version is improved and I am not sure anyone knows how long they will last. I would guess hundreds of years but it is only a guess.
Once the polymers break down you will lose the bond between the fibers or bars and the matrix. This means that you are only relying on the mechanical deformations to transfer the load.
We can definitely monitor the performance over time.
Thanks for this highly informative video. I was hoping to build modest aircrete, dome-homes for poor people in typhoon ravaged SE Asia. With a 5 meter diameter floor and about 10 cm thick shell of polymer, and fiber enriched super quality aircrete. Some suggested 6 mm basalt rope as re-enforcement. Do you have any comments or suggestions ? I didn't know much about the basalt rebar, but this vid really hit the spot.
I appreciate the information, was wondering if you could do a video about concrete made from plastic and sand
as a working steel fixer (or rod buster as you call us stateside)i found this very interesting
Thanks for the comment adrian! I am glad you enjoyed it.
This was awesome Tyler! I knew you'd have useful information to share that I hadn't seen anywhere else. Thank you so much for this. For another topic suggestion, how about aircrete? It seems really interesting, I've watched other videos on youtube about people experimenting and building with it - all on small residential scale. Still, it seems like it's pretty easy for people to use.
Thanks Ryan,
Aircrete is coming. I have a few more videos coming on reinforcing. Thanks for hanging with me!
I'm curious what happens when aircrete is mixed with chopped basalt. Durability is a big issue with aircrete.
Please tel us more about advantage of crystalline additives
Tyler, you’ve blessed my life so much with these videos. God bless you and keep going 👏🏾👏🏾👏🏾
HEY Taylor, great video. Can u pls explain about the glass fiber GFRP rebar also. Thank you
I started seriously researching the use of glass about a year ago, a few months before you made this video. It was about 2 years after one of my suppliers first told me it was available. At the time they first got it the glass cost about 1/3 more than steel. Last spring the price had dropped to a bit cheaper than steel, maybe $0.25 per 20 ft bar. Seeing this video is the first I have heard of the basalt or carbon fiber bars so they apparently are not available here. My supplier told me that these bars are not even approved for vertical applications so he would only sell it to me for use in flat work, not in structural work.
I feel like FRP would be best combined with special concrete containing extra binders within the pour mix so as to mitigate the cracking issue. I would only really see a need to use FRP if the structure I’m designing is meant to be in a highly oxidizing environment
New sub here. I am currently using GFRP for slab with a combination of Steel rebars as top bars.
So would Basalt FRB be useful to reinforce the slab in a commercial shop floor? I am concerned about cracking under heavy loads. However, I am reluctant to use rebar due to corrosion (as explained in one of your videos) in Colorado where the roads a liberally treated with chlorides in the winter months. Thank you for all of your videos, I've learned a lot and they are extremely interesting.
I've been thinking about this in light of the recent Florida collapse. The codes have changed to increase building integrity after the Oklahoma City collapse but maybe we should do more. Better concrete helps with reduced corrosion and spalling but otherwise doesn't help integrity for other types of damage such as blast. Non-corrosive reinforcing prevents the corrosion and spalling but doesn't have enough ductility and wouldn't help with integrity. So I'm wondering if we shouldn't investigate dual systems. Maybe use FRP reinforcing for the strength but include supplemental reinforcing to provide ductility and resistance to fire and collapse. My mind leads me to having concrete beams with FRP primary reinforcing and a central core of PT reinforcing. PT reinforcing now is available with total encapsulation which should help with long term durability, and it would boost the ability of the structure to hang together after undergoing severe damage from deteoriation or some external event such as blast, collapse or fire. (Thinking about beams we would need a new way to provide shear reinforcing, can't easily form FRP reinforcing into stirrups and ties.
Watch the footage of the "collapse"
Could you look into the Stuttgart train station chalice/goblet pillars? They put in soooo much rebar and say the expected life span is 70 years. From a European perspective 70 years for the main part of a train station is absolutely ridiculous (also given the costs and time to build).
They said the pillars are absolutely cutting edge and "never done before". In my opinion carbon fiber would have been such a better alternative. The pillars have a complex shape that could have made far thinner (saving money) with carbon fiber. 30x more sound crazy for standard applications, but here it sounds like it could have ended up being cost competitive, given the complex shape and repetitive nature. And it would have actually been innovative.
Great video thanks! 2 questions, what's the current cost for carbon FRP these days (year 2021), and second question, you said it isn't good for most applications but does FRP work for the residential driveway in Canada & Northern USA where you have the wide temp changes.
ThankQ
Very cool!
Tyler - Thank you. Food for thought.
One unanswered question: The carbon FRP rebar material cost is 30 times higher than steel bars. But aren't steel bars themselves a small fraction of the total concrete structure cost? How much is the overall increase in structure cost (i.e cost of the finish pier, or column or floor or whatever)? If the carbon FRP-bar structures are superior, we'd have to ask how much that superiority is worth in overall cost. (Still might not seem like a great deal, but probably cheaper than the occasional occurrence of the kind of failure we recently saw in Florida.)
I don't think it's quite that much of a small fraction but it is a fraction. Obviously there is concrete cost, labor, formwork, and that is just the structure. You have to add in wiring, plumbing, air conditioning, architectural exterior and interior materials, etc.
Strain is not the deflection/length but elongation/length but a very useful video - thanks.
I think that you shall select the type of rebar depending on which part of the structure you want to reinforce and the properties of it. That way you may be able to control the way a structure fails if there's some outside force impacting the structure like an earthquake.
That is a good approach!
Great video thank you . Is rebar corrosion an issue on building structures in tropical climates? Is this even a concern?The corrosion you mention is it more an issue on cold climate bridges where salt is used? Thank you
hi tyler ley, all ur videos are very nice. i am just looking for a video which how bending moment and shear force act in the r.c.c structures. Can you please make one for us. Thanks in advance
Tyler, what do you think about using FRP rebar for residential construction with ICF, or AAC blocks?
Arguably they could do even without rebar...
Thank you!
Hello, I was watching an old mason/concrete man on TH-cam from the East Coast (I believe his name was Haddock?). He absolutely eschews steel rebar and uses nothing in its stead in pads, walks, driveways, slabs, etc. etc. Claims in rusts in less than thirty years and destroys the concrete. I have been around the residential side of that for decades and while I have seen rebar rust it has not been a huge problem in my area. Now keep in mind I am in a coastal temperate rain forest so rust is huge here. His premise is that unreinforced concrete is better than reinforced. I was somewhat amazed that any long time (the guy is in his sixties) professional would hold that view. What do you think? PS Although I have been watching you previous to discovering TexasBarndominiums I think it is a great collaboration between you two and look forward to more. Take care. Doug
That's Mike Haduck you speak of. Great guy I have watched quite a few of his videos.
There were debates years ago about rebar in roads - that's over steel wins. Yes rust is the killer but so is time and cost - all engineering is a compromise of the triple constraints.
I'm curious if different kinds of polymer could lend additional stiffness/deformation?
Galvanized Rebar Problems - Limited hot dip coating thickness (metalizing Zn-Al is better); field bending cracks galvanizing; drilling concrete for insertion of fasteners damages galvanizing at rebar contacts, requiring insertion of chemical bond for fastener to cover damaged galvanizing; drying shrinkage cracking in concrete can break galvanizing coating at crack, and, of course, there is no field welding allowed. When increased base metal strength is factored all of the above, with the possible exception of field welding, are not issues with Chromx steel, marginally more expensive than hot-dipped galvanizing and about the same as metallizing for added thickness and bond strength.
Can you make a video about soil cement? And how to do it most cost effective wzy.
Just for fun, how about a video on exotic concrete's. GFRC, Ductile, concrete countertops, ECT?
Basalt FRP seems like it could be a great product. Unfortunately, the catalyst for price reduction is product demand. People/industry wont use it until they know it will work better than steel. Great video Dr. Ley!
Thanks David!
There is a lot of energy needed to produce FRP and so it is not a cheap process. I do agree that basalt FRP is a cool product and I encourage people to find ways to use it.
@@TylerLey It takes more energy to produce Aluminum than Basalt roving! The barrier to entry is acceptance. Cost being equal, Steel Rebar: manufacturing, warehousing, sales fabrication, etc. will fight tooth and nail before they allow FRP to put them out of business. And, what if the roads, bridges and building were to cost less and last longer??? The Horror!!!
@@Dave-Pro it's very difficult to introduce new products into a market that is so dominated like this one. New and better products are squashed all the time because they will hurt a particular companies bottom line.
@@Maulakus and Dave Watson ; Good points about entrenched interests (cabals and mafias) resisting (killing) competition from better products, and also the economies of scale that work against the introduction of improvements, at least initially. A good example of both those forces acting in the concrete field, is how cheap the massively energy-hungry Portland cement is compared to the vastly superior magnesium oxide (though it takes a fraction of the energy and infrastructure), and how much effort and tap-dancing goes into propping up the fundamentally flawed D.O.A dinosaur of steel reinforcing.
Are they still designing and testing new versions of FRB or is what is currently on the market the end if it due to the issues you have mentioned?
I was there during one of your presentations at Illinois...it was amazing!!!... I can't imagine what it would be like to work with you!
That's why I mentioned graphene having a future in this situation because doing that with graphene would solve the weakness in these products. "You're the man" You are the one looking into this. Why? Because your the one that will find the answers. I know what it's like to have such a curiosity when you can see that something can be done much better and you want to find the best answers. The problems with graphene is that it's very new and production is still in the devoloping stages but it will become bigger than plastics... Solve this and you got the market for a time. Hope to see you like Elon Musk!
Hola, saludos desde Buenos Aires, Argentina. Quería preguntarte si sabés de algun método para reutilizar o reciclar fibra de vidrio. Gracias!
dude thank u .
Do make a video on GFRP as well
What do you think about "Mechanical concrete geosynthetic cylinder confinement " (road base of old tires filled with aggregate)?
Steel may be less resilient but it is still a tougher material. The graph plot you showed is engineering stress-strain curve. You should also see true stress strain curve if you are really into properties of materials.
I've been making concrete fence posts and struggling to find 8-in quarter inch rebar. What do you think about the FRP for fence posts?
Craig
If we ( somebody) could efficiently produce some sort of carbon fiber wrapped coated rebar... Rust protection for the steel... Extra scratch durability for that coating when wrapped in carbon fiber.. And perhaps that much Stiffer. While maintaining flexibility in the worst case scenarios... Obviously costly but it would be down to somebody's R&D work to be able to produce it in a cost efficient manner.
..
do you have a video regarding Alkaline application testing on all FRP rebar products compare to steel. thank you
Thanks, great lesson. I imagined fiber reinforcement would be weaker than steel reinforcement. I haven't been able to find a video showing the real-use of stainless steel reinforcement....
Davon ChadEwick White If 100% of the USA’s stainless capacity was switched to make stainless rebar it still wouldn’t supply enough to meet just the demand for all rebar much less all the other things stainless are made out of.
I remember the video you did about epoxy coated rebar and it being banned but I'm still seeing it being used in all type of projects just getting your thoughts on it. Thanks
Some good thinking here yet the base problem is corrosion, steel is strong enough and has similar expansion properties to concrete. I wonder here if using concrete additives in the concrete would make it water tight ? I have used silicon additives in mortar to prevent hydrostatic ingress of water due to capillary attraction but I don't know what the effect would be on the tensile strength of the concrete.
Any thoughts on graphene as an additive?
Why is there no link to the concrete videos that you mentioned?
Nice
Question Tyler.... Wouldn't bundling small diameter GFRP like 2 #3 GFRPs for 1 #4 blackbar address to some degree the stiffness and costs of using GFRP.... I realize it doesn't address ductility, but 2 strands do have advantages over a single thicker strand do they not?
Tyler, what is your thoughts on coated steel rebar ( something like the coating on steel gas mains and we could add an anode for cathodic protection) ?
I've often wondered why active cathodic protection isn't used on road structures around the Great Lakes. Lots of rust induced failure on bridge decks and columns. They started painting the concrete to keep the water out but that only prolongs the inevitable rust failure. For a few pennies of electricity the rebar could be kept rust free for decades.
Dear Sir, as far as I know, the concrete is an alkaline solution and the steel do not rust inside. So, indeed, best way to protect the steel rebar against corrosion inside RC concrete is to make the concrete impervious.
Does anyone have any idea on how should I design to compensate for the lack of ductility in ULS limit? Should I overdesign a bit and then accept the brittle failure mode?
Does basalt frp have the same properties as glass frp? I know gfrp is becoming more common, but after this video I wonder if cracking will be a long term issue. If the slope on the stress/strain graph is similar to steel and carbon it could be a good alternative.
Seems to me that comparing the bend tolerance of a short length of steel rebar to a short length of fiberglass rebar in a bench vice leaves out some important variables. It's clear from the demo that the gfrp rebar lacks the ductility of steel, but I believe the gfrp has superior tensile strength, so i would be interested in comparisons with different types of rebar that are imbedded in concrete and tested to failure. Also if carbon fiber rebar is 30x the cost of steel; how about instead using a good fiberglass rebar like aslan 100; only use twice as much as the carbon? Would that provide the equivalence of the strength of the carbon fiber, without the cost (while using twice the amount as carbon)? Finally I think the corosion resistance of gfrp is a major advantage over steel.
there are a lot of research papers in this field
I agree with you. The corrosion resistance is what is all about, you can use more of it and get the same strength. Totally worth it.
I am just an enthusiast. Does a hybrid approach make sense to you? Perhaps using an outer shell of steel and a core of FRP in a structure?
A few things are twisted. When you bend steel as you show using that short piece it bends however your guy bent it back physically. Steel does not return by itself like that it stays bent- basalt before cracking bends and returns like a pole vault. Remember these are encased in concrete not open air. So in a seismic event I want my building to return to straight not stay bent over. You are right about high and ultra high performance concretes. Basalt is less expensive than stainless or galvanized or epoxy MMX types of rebars and comes in 328 feet coils up to 1/2 inch so less overlaps and loss of rod in long runs, less ties time and labor AND no replacement down the road like steel almost everywhere will need. The thing no one thinks of is that there is no regulation that says only ONE type of rebar has to be used. Put the better steel when needed deep inside then use FRP (basalt is best) near the surface where forces are greatest. By code 2-3 inches of concrete are required over steel to protect it from corrosion. You can many times save using a lot less concrete because the FRP does not need that cover as it will never corrode. Basalt Chopped fibers and mesh also add great properties to the solution. basalt-rebar.com Nick
Nick,
Thanks for the comments. I don't feel anything was twisted in the video. I bent both bars the same amount. The FRP snapped and the steel bar just bent. This is called yielding and has a lot of advantages in a concrete structure in high load events like and earthquake. Because FRP does not yield then we have to use much larger safety factors in design. This is not my decision. This is what the committees at the American Concrete Institute has decided. Because of this we can't count on the full capacity of the FRP bars. This means the size of the FRP bars are not much smaller than typical reinforcing bars because you are not allowed to count on the high strengths.
At the end of your comment you talk about reducing the cover on the reinforcing. Cover is not just for corrosion. It is also for fire. I didn't talk much about FRP in fire but the data is not good. Plastics do not last in fires. Further, the few inches in the cover of the concrete do not significantly impact the capacity of the member.
I like the idea of using two types of bars but more work is needed to see if it is feasible. I am worried that once the FRP bars break will the rebar be able to have enough strength to hold it together? How much rebar is needed to do this?
Nick, basalt has good, interesting applications, and an excellent weight to strength ratio. It does not have ductility. For at least larger structures, you need that for seismic survivability etc. Your analysis and video critique appear to be based on incentive to sell basalt rather than on engineering principles.
I've always heard that basalt rebar is shipped essentially as a giant coiled up spring. It is supposed to be very bendable. I just wish that there were some video showing people actually demonstrating this property somewhere.
LOL! It just doesn't exist. Nowhere. Don't go look for it.
@@nobreighner No I was commenting on the guy bending the steel back by hand-it does not return by itself. I personally think steel needs to be deep inside concrete that has water protective additives and basalt needs to be surrounding it near the surface where all the spalling we see happens. Best of both worlds- no law says only ONE type has to be specified-it is time engineers figured that out!
I'm resident in the Caribbean. How do we access this alternative reinforcement? Basalt products, once competitive the product can take off.
Another great video! Have you looked into graphene reinforced concrete?
@@ewokjerky4508 I'm doing my own limited testing in my garage. I'm using the shear exfoliation method to make the graphene. I'm by no means a scientist but it's not really hard to make using this method. I'm testing aircrete to see if I can improve it's overall strength and dispersing nano graphene sheets throughout the Portland cement I think would also help increase it's ability to resist chemical intrusion?
Very cool! Let us know how your work goes.
@@HergerTheJoyous How are you gonna properly disperse it throughout the concrete... There is a production facility being built in Augusta GA to produce graphene nanoparticles... One of the products is an admixture for concrete... Locals are currently testing it now but getting the graphene to disperse in a solution is a bit tricky it seems
@@BracaPhoto I'm wanting to try a sonicated graphene in black tea. I'll replace the water that is normally used in mixing the slurry with the graphene in black tea solution to start with. I'm going to increase the amount I add with each sample till it improves the aircrete sample.
@@HergerTheJoyous Good idea I'm pretty sure they are using Sonic methods... Keep up the work friend!
Fyi they use about half a gallon of the solution per yard of concrete and getting AMAZING wear resistance on the surface of the concrete... There's a local Bridgestone manufacturing facility that poured a huge slab and used CNT on half of it and supposedly it's doing great compared to the untreated half... I'll try and get more information for you when I can
I have been dying to ask this question. As a fan of concrete and
Discovery Channel Curse of Oak Island. They unearth a concrete
structure. Is there a test to tell it's age, and were it's components came from?
Indeed. Yes they could.
ok so carbon fiber is 30 times more expensive but think about the long term maintenance that will save, as soon as corrosion enters into the rebar the clock starts ticking and soon it will need 2b demolished and rebuilt again and again, the highway system comes to mind as an example, bridges too, this constant teardown and rebuild cost $ but the biggest foe is the time lost, for a big power hungry city time is very important and road repairs are a nuisance
BTW, thanks for your reply. This is great! &Since Basalt is one of the Most Common rocks, merely finding a way to dusintigrate it and then Extrude it in Huge quantities - would make it so much cheaper than steel - which corrodes to failure in ?4 years. Can this really be just 4 years due to chloride?
Why can't the basalt rebar just be increased by 15 or 25%. Some amount that might take more than just one earthquake to snap it? Didn't the Roebling Brothers family improve metallurgy? Or, was it railroad rails, barbed wire, etc? No - I think it was suspended bridges - that's why good steel became cheaper. It had to work more or less Better somehow. In several ways maybe.
What engineering Department is actually working on this design problem? How can Basalt be produced. I'd like to imagine a pea sized pieces of basalt continuously being melted into Lazer extruder. Miles of rovings on spools. Braided into useful combinations. Are Chinese engineering schools doing this research? Combined braids with Bamboo? Indonesia maybe?
th-cam.com/video/tKcyrlysQwA/w-d-xo.html
If your worried about corrosion up your mpa an use 3cc....
An it's all about doing it as cheap as you can for a builder....
An the cracks are usually 30mm surface cracks...
They use a lot of fibre mesh today
Dear Sir,
That is good content. Could you please explain how to use FRP rebars in the safest ways? I have some that cost 60% less that steel. What type of FRP could that be? when they say that it is stronger than steel rebars, what exactly do they mean?
In Britain huge issues have been shown with RAAC (steel reinforced autoclaved aerated concrete). Since AAC does not protect the steel reinforcements as well as regular concrete, would using FRP be a viable alternative, especially for RAAC used in flat roofs?