-Innovative Solutions-

Florida turns to composites for corrosion mitigation

By,

Rafiq Darji, P.E.FHWA – Florida Division

Background: The harsh coastal environment in Florida results in a heightened level of corrosion related damage on bridges, which is a constant concern that has historically lead to reduced life cycles for many bridges in Florida. The Florida Department of Transportation (FDOT) spends tens of millions of

dollars annually just to address corrosion related repairs. Therefore, the FDOT was in search of innovative materials that could not only extend service life, but also provide a long term solution to corrosion problems for marine structures.

Project Selection: The FDOT District 7 (Tampa area) maintenance office alone has spent about $100 million on corrosion repairs in the past 14 years (on an average spent $2.4 million per project (source FDOT D7)). The West Halls River Road Bridge Replacement project in Citrus County Florida was selected as a demonstration site for the state’s first ever bridge built with composite materials with no steel rebar in any of the bridge components. The bridge is located in an extremely aggressive environment and crosses over a corrosive salt water body. The project consists replacing an existing low level multi-span concrete bridge which was identified for replacement due to deterioration from the salt water.

The bridge superstructure consists of 5 spans @ 37’-2”, continuous deck with simple span beams. The substructure consists of pile bent caps. Once it opens in late summer 2017, the 186’ foot West Halls River Bridge will likely have more composite elements than any vehicular bridge in the United States (US).

Composite Materials: Most long-term maintenance costs for Florida bridges is due to rebar corrosion and degradation of substructure. FDOT spends a major portion of their bridge maintenance budget on rehabilitating bridge elements that are damaged due to salt water intrusion and corrosion. To avoid corrosion issues completely in the subject project, FDOT opted for composite technologies. The West Halls River Bridge replacement project began with focus on using Hybrid Composite Beams (HEB, built with Hillman Composite Beams by HCB Inc.). As planning and research in composite technologies progressed, FDOT engineers saw opportunities to implement other composite materials in the project. At the end, FDOT replaced all reinforced concrete with some form of composite material/fiber reinforced polymer or hybrid.

Carbon Fiber Composite Cable (CFCC) is used in place of traditional reinforcement for the piles and sheet piles on this project. The Glass Fiber Reinforced Polymer (GFRP) as the structural reinforcement is used in deck, barriers, approach slabs, bent caps and wall caps. Unlike the substructure, the superstructure can have most of the corrosion issues mitigated by simply increasing the clear height above the water line. However, due to vertical geometry constraints, this option is not available. Therefore, the use of the Hybrid Composite Beam (HCB) along with a glass fiber reinforced polymer deck reinforcement is used in this bridge. Including these experimental features, CFCC piles and HCB, within an extremely aggressive environment should increase the overall life of the bridge along with decreasing the associated maintenance costs. In addition, a monitoring and load testing program will be utilized during and after construction to ensure the constructability and structural performance of these systems are addressed.

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Research: The West Halls River Bridge Replacement project also serves as a research project for “SEACON: Sustainable Concrete using seawater, Salt-Contaminated Aggregates and Non-Corrosive Reinforcement”. The SEACON is one of the nine projects funded under INFRAVATION (An Infrastructure Innovation Program).

The objective of the SEACON (i.e. SEAwater CONcrete mid design) is to evaluate and demonstrate the use of chloride-contaminated concrete for the construction of durable transportation concrete infrastructure, such as bridges. Chloride-contaminated concrete mix is produced using seawater rather than typical fresh water. One of the key objectives of the SEACON project is to investigate the performance of recycled aggregates in chloride-contaminated concrete infrastructures to support sustainability in concrete production. The SEACON concrete mixes is being used in sheet pile wall caps at the West Halls River Bridge Replacement project. The research team will conduct long term performance monitoring of SEACON Halls River bridge components. This research work will be carried out by University of Miami and supported by FHWA Turner Fairbanks Research Center. Research findings and lessons learned from this project will benefit the transportation industry not only in US but also entire world.

Summary:

Demonstration Project with Innovative Materials – First in Florida

Structural Reinforcement: Glass Fiber Reinforced Polymer (GFRP) bars and Carbon Fiber Campsite Cable (CFCC)

Superstructure: Hybrid Composite Beams (HCB); GFRP bars in Deck, Barriers and Approach Slabs

Substructure: CFCC in Pre-Stressed Piles, GFRP bars in Bent Caps Sheet Pile Walls: CFCC in Sheet Piles; GFRP in Wall Caps

Contractor Bid Cost - $6.016 Million (Structures = $4.06 Million)

Bridge Cost = $218 / Sq. ft.(Conventional Construction = $166 / Sq.ft.)

Contract Time – 310 Days

Accelerated Construction

Light Materials – beams and rebar Faster Construction – handling lighter material

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Bridge Cross Section:

Hybrid Composite Beam (HCB) (courtesy of HCB Inc.)

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Project Photos:

Hybrid Composite Beams (HCB)

GFRP Bars

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HCB Placement

Pre-stressed Concrete Piles with CFCC reinforcement

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GFRP reinforcement pretied cages

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