Comparing Steel and Fiberglass Rebar - SURPRISING results

Welcome back to The Build Show! In this episode, we dive into the fascinating world of rebar with our engineer Witt Smith, comparing traditional steel rebar to the innovative glass fiber reinforced polymer (GFRP) rebar, specifically the MST bar.

We start by comparing the weight of GFRP rebar to steel. You'll discover that GFRP rebar is significantly lighter, making it much easier to handle on job sites. This difference in weight can improve efficiency and reduce strain on workers.

Next, we delve into the material properties of fiberglass rebar. Unlike steel, GFRP rebar has a higher tensile strength and bonds more effectively to concrete. This results in enhanced durability and performance of the reinforced structures.

Worker safety is a major consideration, especially in hot climates. Weitzman explains how GFRP rebar stays cooler in the sun compared to steel, reducing the risk of burns and the need for heavy gloves. This aspect makes GFRP a safer choice for construction crews.

We also discuss the design differences when switching from steel to fiberglass rebar. Our engineer explains how the change in material properties requires adjustments in the design process. It is crucial to incorporate these changes early in the project planning stages to avoid costly redesigns later.

Rust prevention is another significant advantage of GFRP rebar. Traditional steel rebar can rust over time, causing concrete structures to spall and degrade. GFRP rebar, on the other hand, is resistant to rust, making it ideal for use in areas prone to moisture and salt exposure.

In terms of cost, we explain that while GFRP rebar may not always result in immediate savings on smaller projects, it can be cost-effective on larger scales. The long-term benefits of reduced maintenance and increased longevity also contribute to its overall value.

Finally, we highlight the potential applications of GFRP rebar and the importance of early planning in incorporating new materials into your projects. Proper planning ensures that the benefits of GFRP rebar are fully realized.

Stay connected with us for more insights and updates. Follow our 24-part series on the Reisinger Build project to see this and other innovative materials in action. Don't forget to subscribe to our channel for new content every Tuesday and Friday, and stay updated by following us on Facebook and Instagram.

Join us as we explore the future of construction materials and techniques. Let's build smarter and safer together!

MSTBAR
Risinger Build

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[johnbeeck]

A buddy of mine used the fiber rebar in the Bahamas right on the coast for corrosion resistance reasons. It has worked very well for him on a home that is now 20 years old!

[jesse]

The requirement to wear gloves when handling this material implies the glass particles could be in the surrounding air. Especially when cutting it. It seems to me it would be prudent to wear respirator or mask when handling fiber glass rebar.

[benjaminledford]

As an architect, the huge advantage I see is not rusting. I'm worried about how much we've built with steel-reinforced concrete and how much of it we'll have to tear down. Once water gets to the steel it's over - you can't stop it, you can't replace it, you can't salvage the concrete it's embedded in. And eventually the water will find its way in. Our oldest buildings are unreinforced masonry because there's no steel in them to rust and destroy the structure (not that all unreinforced masonry buildings last that long, obviously). Of course, unreinforced buildings have other problems, especially with settlement and seismic loads, so we can't just leave the rebar out. That's why these alternative products seem so promising. I would love to see them become the standard for public buildings, infrastructure projects, institutional buildings, and anything along the coast.

[aliancemd]

I was looking at this stuff last year(mostly research papers and how the Germans use it) for its properties to not rust but also resistance to earthquakes. It’s generally a better material but if you don’t want it to snap in sideways motions(it can swing more and recover but snaps at its limits, unlike steel which can maintain some structural integrity), you need a lot more of it and potentially mix it with carbon reinforced rebar.

[austinhastings]

I talked to an old concrete guy who told me, "The thing about concrete work is that everything you do is simple, but every single thing is HEAVY."

[KirkWallace-lwsl]

I think one of the major benefits is spalling resistance because of no internal pressure developing from rust. This is probably ok for flatwork and foundations but I bet it'll shine in exposed columns and beams, such as bridges.

[Veritasi]

I've used the basalt, the gfrp and steel rebar on multiple projects. We've figured out the gfrp with the Kodi Clip system ends up being the Best overall solution. There's a little cost of entry but overall at about 20, 000 square feet you've broken even and you've tripled or more your speed of installation. We also have a lot less problem with blowouts from incorrectly embedded steel. We're getting to a point where as soon as we can figure out the carbon issue concrete might be back in Vogue for almost all projects.

[williamboquist]

I used a bit less than half a mile of fiber rebar in a 30' X 40' garage I built. It worked beautifully. However, as they said, for applications in which a lot of shear force will be applied to the bar, I would revert to steel.

[DIYEricAZ]

What if the framer nails it when hammer drilling for anchors, do you lose the effectiveness of the entire embedded stick, or is the damage localized? Can you tell when you've hit one like with steel rebar?

[Chad_H]

Been in the rebar business for over 2 decades. Pricing and availability limit the viability of GFRP. The only places you really see it is in extremely corrosive environments, where epoxy coated rebar won't be sufficient, or in places where you can't use steel, like foundations and walls surrounding MRI machines.

[Enonymouse_]

Worked with structural Fibre rod, installed several thousand feet of it on a 220ft radio tower in place of steel cable on a site where corrosion was a concern, mfg claimed tensile strength of 50k pounds. I was also there 15 plus years later when it had to be removed.
Long story short, the rod had begun to turn to powder on its outer layers, it was very dangerous to handle new and old. Disposal and install was annoying with handling hazards (never allow it to slide through your hands gloved or not), it had added eye and respiratory hazards during disposal from the degraded rod.
Steel is still better overall IMO and safer. My former neighbor was an iron worker who spent his career working on bridges & dams with rebar and poly coated rebar I suspect he would say the same.

[Julian_Hopf]

I would also mention building longevity. Steel rebar will corrode slowly even with proper cover, which limits the design life of cement to a couple hundred years depending on climate. In comparison, GFRP reinforced cement is expected to last for thousands of years. That may not be a factor for many projects but I think it is noteworthy.

[gclarke]

any chance you do a video on basalt reinforced polymer? great video.

[FreekHoekstra]

Would be interesting to see fiberglass reinforced concrete as a mixture.
I know some people in Switzerland were playing with this where they added, like little fiberglass threads inside of the concrete mix, allowing you to pour the concrete as though it is reinforced without actually having to do the work of the reinforcing. The other benefit is that it becomes a homogenous material. It truly is reinforced throughout the entire assembly.

[markmoreno]

It totally makes sense. The only issue I see is that buildings are torn down for one reason or another. At job sites I see piles of materials for recycling. A pile of concrete chunks here and a pile of mangled rebar there. When it comes time for crunching concrete laden with fiber-reinforced polymer bars will there be any issues? Does it even need to be separated? Perhaps some buildings are torn down due to spauling. So maybe fewer demolitions will need to happen.

[cinemaipswich]

As long as you don't bend it, glass/polymer fibre is strong. Once the polymer is crushed, the glass fibre is prone to shear.

[Ordos]

I first used this reinforcement in the Netherlands (then under the name ComBar) as a chief strucutral engineer of a precast concrete factory in concrete walls, where it supported the thinner faced concrete, thus acting as a thermal barrier (and no risk of corrosion). While some properties are better as opposed to regular steel rebar, the low adaptability on site (or even in a precast factory) is a major hindrance. That and the Eurocode has low adaptibility to replacing the steel for GFR. A lot of the formulas in the code have a basis in the fact that concrete structures warn the user before they fail (by cracking in a certain way for example) -- what does astructure say when the material stretches far more easily?

[robnowe]

I spent a bit of time researching this... positives: + higher tensile strength, +lighter, +corrosion resistance, +lower-install-costs; negatives: –fire resistance very low, –no-ductility, –low-shear-resistance, –higher-cost-of-material, -not-site-bendable.

Questions: bond strength vs black bar.

[JeremeyHowlett]

I would love to see this rebar under a load test. Any videos out there?

[ddmitch]

Steel rebar may turn into powdered iron after 50+ years in concrete. I saw concrete reinforced with steel rebar, at a 70+ year old church that was being remodeled in a west Chicago suburb. The steel rebar had turned into powdered iron and had zero added strength to the concrete floors it was in. Very scary! GFRT can be driven into the ground with no effect to rebar, unlike steel rebar which cannot touch soil.