Case at a glance: A coastal bridge deck had experienced concrete deterioration associated with chloride exposure. The original steel reinforcement was corroding, contributing to cracking, spalling, and repeated patch repairs. For the deck replacement, HotFRP supplied glass fiber reinforced polymer (GFRP) rebar as the reinforcement material. The project used GFRP bars to avoid the steel-rebar rusting mechanism while retaining the overall concrete deck replacement approach.

Project Background

The bridge was exposed to de-icing salts and salt-laden air. Over time, chlorides penetrated the concrete cover and reached the steel reinforcement. Corrosion-related expansion contributed to cracking, delamination, and spalling, with repeated patch repairs carried out before the deck replacement.

During planning for the replacement deck, the project team considered a reinforcement material that would not undergo the same rusting mechanism as steel under chloride exposure. GFRP rebar was selected for the new deck.

Material Selection and Design

HotFRP supplied GFRP rebar in the diameters and lengths specified by the project designer. GFRP bars consist of continuous glass fibers embedded in a thermosetting resin matrix. Unlike steel reinforcement, GFRP is non-metallic and does not rust in the same way as steel when exposed to moisture and chlorides. Its lower weight also made handling and placement easier on the project.

Because GFRP has different mechanical properties from steel, including a different modulus of elasticity and bond behavior, the reinforcement layout could not be determined by directly substituting steel bars on a one-to-one basis. Bar size and spacing were established by the design engineer for the GFRP-reinforced deck.

Construction Differences from Steel Reinforcement

For the installation crew, the main differences were handling and cutting. GFRP bars are lighter than steel reinforcement, while cutting requires suitable abrasive or other approved tools rather than standard steel bar cutters. Field bending was not used on this project; required bent shapes were supplied as pre-formed bars.

The installation also required attention to bar support, spacing, and placement during concrete placement because GFRP has lower stiffness than steel. The crew adjusted handling and layout practices to keep the reinforcement in the specified position before and during concrete pouring.

Project Outcome

After concrete placement and curing, the replacement deck was completed and returned to service. The project demonstrates how GFRP rebar can be used in a bridge deck exposed to chlorides when the reinforcement design and installation approach account for the material's different properties.

The case is relevant to projects considering GFRP rebar as an alternative to steel reinforcement where chloride exposure is a design concern. It does not by itself establish a service-life duration or maintenance-free period; those outcomes require project-specific long-term performance data.