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Basalt Fiber-reinforced polymer (BFRP) bars

 
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Dr. N. Subramanian
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PostPosted: Wed Dec 08, 2021 5:17 pm    Post subject: Basalt Fiber-reinforced polymer (BFRP) bars Reply with quote

Fiber-reinforced polymer (FRP) bars are a noncorrosive and long-lasting alternative to traditional steel reinforcing bars used in concrete structures. These composite bars are made of longitudinally aligned fibers embedded in a resin matrix using a manufacturing process
called pultrusion. FRP bars have been used in civil engineering structures for over three decades. Glass fiber is the most-used fiber type because of its availability and low cost. However, because the physical properties of basalt fibers exceed those of glass, and because the cost difference between the two fiber types is marginal, interest in this fiber
type has been increasing. With a growing supply of basalt fibers in the United States, basalt FRP (BFRP) bars are becoming economically feasible.

BFRP bars provide a high tensile strength (over three times higher than Grade 60 steel (Grade Fe 415) for equivalent bar diameters). As with glass FRP (GFRP) bars, BFRP bars are lightweight (one-fourth the weight of steel-), electrically nonconductive, and transparent to electromagnetic fields. The main advantage of these composites, however, is the high corrosion resistance, even when exposed to harsh environments like seawater.

As with any other FRP composite, BFRP bars are linear elastic to failure and do not exhibit a plastic plateau like mild steel. Further, the elastic modulus of BFRP bars is approximately one-third of that of steel reinforcement. When compared to other FRP types, BFRP bars fall between glass and carbon for both strength and stiffness. In comparison to FRP bars made of E-CR glass, BFRP bars have a slightly higher elastic modulus and strength as well as greater chemical stability.

Use of FRP Bars
Historically, FRP bars have been most frequently used in transportation infrastructure rather than in buildings. The main reason behind this is the goal of departments of transportation (DOTs) to increase the service life and reduce maintenance costs of bridges and other highway structures. For example, Al-Khafaji et al.  evaluated 11 GFRP reinforced bridges after being in service for 15 to 20 years and, from the extracted
coupons, almost no GFRP degradation was seen even though
the bars used in these projects were made with E glass rather than the current E-CR glass type, a more recent boron-free evolution for improved corrosion resistance. In fact, while E glass is the most widely used glass fiber formula in the world, it contains boron and fluorine, two compounds that are trapped in particles released into the atmosphere
during manufacturing, causing environmental pollution.

Conversely, E-CR glass fibers are boron- and fluorine-free and have better mechanical properties, higher heat resistance, waterproof resistance, and higher surface resistance than E-glass fibers. Since 2005, E-CR glass fiber has been produced in accordance with ASTM D578/D578M, “Standard Specification for Glass Fiber Strands.”
As per FDOT Standard Specifications, Section 932-3 and  FDOT Structures Manual, V. 4, “…The design of all concrete members containing GFRP reinforcing bars shall be in accordance with the AASHTO LRFD Bridge Design Guide Specifications for GFRP
Reinforced Concrete. For BFRP use the same design criteria as GFRP.”

Al-Khafaji, A.F.; Haluza, R.T.; Benzecry, V.; Myers, J.J.; Bakis,C.E.; and Nanni, A., “Durability Assessment of 15- to 20-Year-Old GFRPBars Extracted from Bridges in the US. II: GFRP Bar Assessment,”Journal of Composites for Construction, V. 25, No. 2, Apr. 2021.

For more info Read:
Emparanza, A.R., McMahon,B. and Nanni, A.(2022)
Basalt FRP Reinforcement in Concrete Topping Slabs in a Commercial Building-A sustainable and durable solution, Concrete International, ACI, Dec. pp.28-33
https://www.fiberglassrebar.us/basalt-rebar/



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vikram.jeet
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PostPosted: Fri Dec 10, 2021 3:27 am    Post subject: Reply with quote

FRP &BFRP BARS AS REINFORCEMENT

Very good information shared by Dr NS sir. I think use of these bars in India is still to be seen.  Also due to very less ductility compared to steel , high seismic zones structures may still require steel reinforcement in addition to these bars.

But these can be easily used for reinforcing pavements ,  and structures not dependent on ductilty in event of  seismic visits .

Hope these may find use in India , may be in combination with conventional reinforcements.
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spsvasan
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PostPosted: Thu Dec 16, 2021 12:09 pm    Post subject: Re: Basalt Fiber-reinforced polymer (BFRP) bars Reply with quote

[quote="Dr. N. Subramanian"]Fiber-reinforced polymer (FRP) bars are a noncorrosive and long-lasting alternative to traditional steel reinforcing bars used in concrete structures.


My thanks to Dr.NS for an informative post.

The fibres are held with polymer matrix. Polymers soften at temperatures of the order of 1000C.

Even though concrete is a poor conductor of heat, since the cover to steel is only 20mm, the temperature of the rebars may reach the softening point fairly quickly in the case of a fire.

Will this not lead to a catastrophic failure? Has any research been carried out on this aspect?

S.P.Srinivasan
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vikram.jeet
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PostPosted: Fri Dec 17, 2021 2:32 am    Post subject: Reply with quote

The temperature sensitivities of fiber Reinforcement is to be seen as very rightly pointed out by Er spsvasan.  Fire can raise high temperatures and resistance to fire depends on fiber Reinforcement  sensitivity .

Also in areas of snow bound , sub zero temperatures upto - 40 ℃ for prolonged durations can affect .
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Dr. N. Subramanian
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PostPosted: Sun Dec 19, 2021 9:47 pm    Post subject: Re: Basalt Fiber-reinforced polymer (BFRP) bars Reply with quote

[quote="spsvasan"]
Dr. N. Subramanian wrote:
Fiber-reinforced polymer (FRP) bars are a noncorrosive and long-lasting alternative to traditional steel reinforcing bars used in concrete structures.


My thanks to Dr.NS for an informative post.

The fibres are held with polymer matrix. Polymers soften at temperatures of the order of 1000C.

Even though concrete is a poor conductor of heat, since the cover to steel is only 20mm, the temperature of the rebars may reach the softening point fairly quickly in the case of a fire.

Will this not lead to a catastrophic failure? Has any research been carried out on this aspect?

S.P.Srinivasan

Dear Er SPS

Please check this paper:https://www.sciencedirect.com/science/article/abs/pii/S0263822313000111#:~:text=These%20results%20indicate%20that%20concrete,under%20moderate%20fire%20exposure%20conditions
Warm regards
Subramanian
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spsvasan
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PostPosted: Mon Dec 20, 2021 2:26 am    Post subject: Re: Basalt Fiber-reinforced polymer (BFRP) bars Reply with quote

Dear Er SPS

Please check this paper:https://www.sciencedirect.com/science/article/abs/pii/S0263822313000111#:~:text=These%20results%20indicate%20that%20concrete,under%20moderate%20fire%20exposure%20conditions
Warm regards
Subramanian[/quote]


Dear Dr.NS

The information contained in this paper and also in the other papers cited in this paper were useful

Thanks and regards
S.P.Srinivasan
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