Composites Explained: The Four Reinforcement Fibers

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A composite is the joining of two or more materials to increase physical and mechanical performance properties. Composites date back to 1500BC when Egyptians started using a combination of mud and straw to build strong houses.

Fast forward to more recent years, composites have certainly come a long way – and with the birth of resin in the 1900s, technology has further advanced to a point where composites are used widely in industrial and recreational applications. Fiber reinforced polymers (FRP) made using the pultrusion process, have proven to be a popular material of choice and are today used in a variety of applications from fence posts to Formula1 racing car components.

Pultron is equipped to work with any fiber to meet the needs of customers and, has found glass to be the most popular based on price and performance.

Common pultrusion fibers

The four main fibers used in fiber-reinforced polymers are glass (GFRP), carbon (CFRP), aramid (AFRP) and basalt (BFRP). Each is unique in its features and uses.


Aramid fiber is an organic polymer produced by spinning a solid fiber from a liquid chemical blend. Recognized by its commercial names, Kevlar®, Twaron® and Nomex® it is commonly spun into large threads and woven.
Pros: Good tensile strength and modulus. Aramid is lightweight with excellent heat resistance. It has excellent ballistic and impact resistance.
Cons: It is expensive to produce, so only suitable for a few specific applications.
Used for: Fireproof suits, bulletproof vests, ropes, cables, and protective gear. Racing suits evolved over the years from using asbestos to aramid.
Cost: As aramid gains in popularity, prices are decreasing.


Due to price and performance, glass fiber is the most popular polymer reinforcement.
Pros: Twice the tensile strength of steel and lighter than aluminum. It is corrosion-free and highly chemical resistant.
Cons: Compared to carbon fiber, it has less strength.
Used for: GFRP is used in an ever-increasing range of applications including mining rock bolts, marinas, and grape harvesting rods to name a few. The last 30 years have seen an upsurge of civil engineers using GFRP rebar as concrete reinforcement in regions where corrosion is a problem.
Cost: A cost-effective option with excellent versatility.


Carbon fibers are primarily made from organic polymers bound together by carbon atoms. CFRP is displacing aluminum in the aerospace industry. It is lightweight resulting in less fuel consumption.
Pros: Outstanding strength-to-weight ratio. Low thermal expansion. Highly chemical resistant and does not corrode.
Cons: The high cost is its biggest hindrance.
Used for: Aircraft components, racing car components, tennis racquets, and bicycle frames. All benefit from its lightweight, strength, and high performance.
Cost: Higher overall cost.


Uses basalt rock, which is processed much like fiberglass.
Pros: Very good chemical resistance.
Cons: There is an increased carbon footprint because it needs high processing temperatures.
Used for: Basalt rebar for concrete reinforcement.
Cost: More costly than glass.

As we look further at developing new technologies and improving existing ones, composites continue to play an ever-increasing role in delivering better performance solutions and increasing durability for longer life-cycles.