Short answer. GFRP rebar has real limits: a lower modulus than steel, brittle (non-yielding) failure, reduced strength at high temperature or in fire, no field bending, and sensitivity to damage and long-term load. None rules it out, but each must be handled in design and on site.
The limits
| Limit | Why it matters | What to do |
|---|---|---|
| Lower modulus (about a quarter of steel) | Larger crack widths and deflections at the same area | Design to serviceability; use more bars or deeper sections |
| No yielding (brittle) | No warning before failure | Use code methods that give the concrete, not the bar, the failure mode |
| Fire and heat | The resin softens well below steel’s strength-loss temperature | Provide cover and fire design; check the code for fire-exposed members |
| Low shear and dowel action | Weaker across the bar than along it | Use detailing for FRP; do not copy steel stirrup rules |
| Cannot be bent on site | Heat or force damages the fibres | Order bent bars (stirrups, hooks) from the factory |
| Long-term (creep rupture) | Sustained load reduces allowable stress | Apply the code limit for sustained stress |
| Handling damage | Cuts or abrasion in the surface reduce capacity | Protect bars on site; reject damaged bars |
Bending and cutting on site
- Bending: straight bars can flex slightly during placement and spring back, but they cannot be permanently bent in the field. Heating to bend harms the resin; bent shapes are made in the factory.
- Cutting: cut with an abrasive or diamond blade or a fine-tooth hacksaw; avoid shearing. Wear gloves, eye protection and a dust mask; the dust irritates skin and lungs.
- Ends: seal cut ends if the project requires it.
- Tying: use plastic or coated ties; avoid cutting into the bar with steel wire.
Comparison with steel and where GFRP pays back: GFRP vs steel rebar. Manufacturing and quality tests: how GFRP rebar is made.
Frequently asked questions
Can GFRP rebar replace steel in a beam?
Only if the beam is designed for it. Using GFRP in a steel design without redesign will give excessive cracking and deflection.
Send us your requirement
Guangdong Haikuo Composite Materials Co., Ltd. (Huizhou, Guangdong) designs pultrusion moulds in-house and produces custom FRP profiles. Send a drawing, a sample or just the application and the environment, and we will tell you what is feasible.
Email: helena@frphk.cn | Phone: +86 189 5198 8522