Fiberglass reinforced polymer (GFRP) rebar is not just an alternative to steel — it represents a major technological advancement. Its performance depends on a strict manufacturing process that ensures high mechanical strength, durability, and long-term reliability in reinforced concrete.
In this article, discover step by step how GFRP rebar is produced — from raw materials to the finished product ready to reinforce tomorrow’s infrastructure.

1. Raw Materials: The Foundation of Performance

The quality of a composite rebar starts with the selection of its components:

• Glass fibers:

• E-glass type: general-purpose and economical.
• AR-glass type (Alkali Resistant): recommended for concrete, as it resists alkaline environments found in cement.

• Thermosetting resins:

• Unsaturated polyester: good balance between cost and performance.
• Vinyl ester: excellent chemical resistance.
• Epoxy: superior mechanical performance.

• Additives and fillers: UV retardants, pigments, and coupling agents enhance the fiber–resin bond.
👉 The balance between these materials defines the long-term durability of the rebar.

2. Manufacturing Process: Pultrusion

Pultrusion is the most common process used to manufacture GFRP rebar.

Main stages:

1. Fiber unwinding
   • Glass fibers arrive in continuous spools.
   • They are aligned and tensioned to form the main direction of strength.
2. Resin impregnation
   • Fibers pass through a resin bath, ensuring each filament is fully coated.
3. Heated die shaping
   • The resin polymerizes under heat.
   • The final cross-section (round or ribbed) is defined by the die mold.
4. Cooling and calibration
   • The bar is cooled to stabilize the resin and calibrated to ensure uniform diameter.
5. Cutting to standard lengths
   • Typically 6 m, 12 m, or custom lengths as required.

👉 This controlled process ensures perfect homogeneity and high mechanical strength.

3. Surface Ribbing and Concrete Bond

A key feature of GFRP rebar is the ribbed or helical surface pattern, which improves its bond with concrete.

• Silica sand coatings may be applied for enhanced mechanical adhesion.
• Proper ribbing is essential for composite–concrete interaction.

4. Quality Control and Standards

Each production batch undergoes strict laboratory testing:

• Tensile strength (ASTM D7205)
• Modulus of elasticity
• Fatigue resistance
• Bond strength with concrete
• Chemical durability (alkali, salt, and acid exposure)

👉 Standards & references: ASTM D7957, ACI 440.1R, and integration within Eurocode frameworks.

5. Innovations in Manufacturing

Recent research focuses on enhancing GFRP performance through:

• Fiber hybridization: combining glass and carbon fibers for greater strength.
• Nanotechnology: adding nanoparticles to improve chemical and thermal resistance.
• Advanced automation: real-time continuous production with digital quality control.

6. Tangible Benefits for Construction Sites

Thanks to this advanced process, GFRP rebars provide construction professionals with:

• Lightweight and easy-to-handle products
• Faster installation compared to steel
• Proven durability under extreme conditions
• Compliance with international standards

7. Opportunities for Tunisia and Africa

Establishing local GFRP manufacturing lines would allow Tunisia to:

• Reduce dependence on imports
• Develop an innovative industrial sector
• Position itself as an African leader in sustainable construction solutions

Conclusion

The success of composite reinforcement lies in a mastered manufacturing process, from raw materials to quality control.
Through pultrusion and continuous innovation, GFRP rebar offers superior performance and durability compared to steel.
It is not just a material — it’s an industrial revolution redefining the standards of modern construction.