Case at a glance: A bridge deck in a coastal region had been experiencing concrete deterioration caused by chloride ingress. The original steel reinforcement was corroding, leading to spalling and frequent patch repairs. HotFRP supplied glass fiber reinforced polymer (GFRP) rebar as an alternative reinforcement for the deck replacement. The new deck design uses FRP bars to reduce long-term corrosion risk without changing the overall structural approach.

Project Background

The bridge is located in an area where winter de-icing salts and salt-laden air are common. Over time, chloride ions had penetrated the concrete cover and reached the steel reinforcing bars. Rust expansion caused cracks and delamination, especially along the deck edges and near expansion joints. Maintenance crews had performed multiple patching campaigns, but the repairs were short-lived.

When planning the deck replacement, the project team wanted a reinforcement material that would not corrode under the same conditions. GFRP rebar was identified as a practical option, particularly because it could be used with standard concrete placement methods while eliminating the corrosion mechanism associated with steel.

Material Selection

HotFRP supplied GFRP rebar in the diameters and lengths specified by the project designer. GFRP bars are made from continuous glass fibers embedded in a thermosetting resin matrix. The material is non-metallic, so it does not rust when exposed to moisture and chlorides. It is also lighter than steel of comparable diameter, which simplified handling and placement on the bridge deck.

Because GFRP has different mechanical properties than steel, the design considered factors such as tensile strength, modulus of elasticity, and bond behavior with concrete. The project referenced relevant industry design guidance, including ACI 440 documents, which provide procedures for using FRP reinforcement in concrete structures. The final bar size and spacing were determined by the design engineer, not by direct substitution of steel bars on a one-to-one basis.

Construction Differences from Steel Reinforcement

For the installation crew, the main differences from steel were in handling and cutting. GFRP bars are lighter and easier to carry, which reduced fatigue during placement. Cutting was done with abrasive blades or specialized tools rather than standard steel cutters. Field bends were avoided; any required bends were produced at the manufacturer’s facility or by using pre-formed shapes, since FRP bars should not be bent on site without approved procedures.

Support chairs and spacers were made of non-corrosive materials to avoid creating a pathway for moisture. Tying was done with coated wire or plastic ties. The contractor also adjusted lifting and layout plans to account for the lower stiffness of GFRP during placement, making sure the bars remained properly positioned before and during concrete pouring.

Outcome and Observations

After concrete placement and curing, the deck was finished and returned to service. Because the reinforcement is non-corrosive, the owner expects a longer maintenance-free period than with traditional steel, particularly in the chloride-heavy environment. Routine inspections have shown no signs of corrosion-related cracking or spalling in the new deck.

This case illustrates that FRP rebar can be integrated into a bridge deck replacement when the design accounts for its different material characteristics. Proper detailing, non-corrosive accessories, and attention to handling on site all contributed to a smooth installation.