GFRP Rebar: Glass Fiber Reinforced Polymer Rebar

It features lightweight and high strength, corrosion resistance, non-magnetic properties, and fatigue resistance. Compared with traditional steel rebar, GFRP has only one-fourth the density of steel but offers 2–3 times the tensile strength of conventional steel rebar. It is resistant to acids, alkalis, and seawater corrosion, making it ideal for concrete structures requiring high durability, such as marine engineering, subways, and bridges.

This case involves a client’s self-built warehouse, with warehouse railings constructed using cement columns reinforced with GFRP rebar.

I. Pre-Construction Preparation

1. Material Inspection

Check the specifications and strength of GFRP rebar (must meet design standards such as ASTM A775/A775M or GB/T 26743).

Verify the integrity of the epoxy resin coating and check for damage during transport.

2. Mold Design

Create steel or wooden molds based on the column dimensions, reserving slots for rebar positioning.

Ensure the molds have sufficient rigidity to prevent deformation during concrete pouring.

II. Rebar Installation

1. Cutting and Processing

Cut the GFRP rebar to the designed length using a specialized cutting tool (e.g., abrasive saw) to avoid heat damage.

End Treatment: Use epoxy resin sleeves or mechanical connectors (welding is strictly prohibited).

III. Concrete Pouring

1. Concrete Selection

High-performance concrete (C50 or above) is recommended to improve bond strength with GFRP rebar.

Slump should be controlled between 180–220 mm for proper compaction during pouring.

2. Pouring Procedure

Pour the concrete in layers, each ≤500 mm thick, using an internal vibrator for even compaction.

Avoid direct contact between the vibrator and GFRP rebar to prevent damage.

IV. Curing and Formwork Removal

1. Initial Curing

Cover with plastic film or apply water curing immediately after pouring to keep the surface moist for at least 7 days.

Avoid high-temperature environments (>60°C), which may degrade GFRP rebar performance.

2. Formwork Removal and Post-Treatment

Remove the formwork once the concrete reaches 75% of the design strength, then inspect the surface quality.

Repair any local defects to ensure a smooth and even finish.

V. Key Quality Control Points

1. Bond Strength Testing

Perform a pull-out test before construction to verify the bond strength between GFRP rebar and concrete (typically ≥2.5 MPa).

2. Deformation Monitoring

Regularly measure the verticality and deflection of columns after pouring to adjust construction parameters as needed.

3. Fire Protection

For high-temperature environments, wrap GFRP rebar with fireproof materials (e.g., vermiculite concrete).

VI. Construction Precautions

Avoid Mechanical Damage: Use soft slings when lifting rebar cages to prevent scratches or damage to GFRP rebar.

Waterproofing at Joints: Apply waterproof coating at epoxy sleeve joints to prevent moisture ingress.

Temperature Control: During winter construction, take insulation measures to prevent concrete freeze-thaw cycles that may lead to GFRP breakage.

By replacing traditional steel rebar with GFRP, the risk of chloride corrosion is reduced by 90%, and the design lifespan is extended to 80 years.