The Hampton Roads Bridge-Tunnel on I-64 is the oldest and busiest underwater crossing between Norfolk and Hampton, Virginia. Both the east and westbound structures consist of an underwater tunnel with two elevated approach structures. The first tunnel tube was opened in 1957 and a second opened in 1976. In 1958, an average of 6,000 vehicles per day used the bridge-tunnel. Today, an average of 6,000 vehicles a day use the crossing, with peak volumes exceeding 98,000 during the tourist season.
Given the high frequency of vehicles in the bridge-tunnel, the selected method of rehabilitation should provide the longest service life possible. Ongoing inspections by the Virginia Department of Transportation (VDOT) indicated that chloride levels had increased in the deck slabs of the older structures. The highest concentrations were reported in the bottom of the slabs as a result of seawater splashing. In certain areas the chloride levels had exceeded the threshold for corrosion, resulting in delamination of the concrete.
A major widening project associated with the older eastbound structure was planned. In conjunction with the widening, the existing bridge decks would also be rehabilitated. As part of the overall repair strategy, VDOT bridge engineering personnel determined that cathodic protection would provide the longest service life to the structures. A latex modified concrete (LMC) overlay would also be specified on the riding surface.
The ELGARD™ titanium anode mesh system was selected for this project. The mesh is installed beneath the LMC overlay on the topside of the slabs. Testing indicated that current would flow to the bottom of the slab and fully protect both top and bottom mats of steel from corrosion. Corrpro, the worldwide licensee of the ELGARD™ system, provided the titanium anode mesh for this project on over 400,000 ft2 of concrete deck.
Project Data:
Owner: |
Virginia Department of Transportation |
Client Contact: |
Dr. Gerry Clemena
telephone: (804) 293-1949 |
Structural Consultant: |
Concorr, Inc |
Corrosion Consultant: |
Southern Cathodic Protection |
Prime Contractor: |
McClean / Archer-Western Joint Venture |
CP Contractor: |
Cathodic Systems, Inc. |
Anode Type : |
ELGARD™ 210 Anode Mesh |
Installation Date: |
1997-1998 |
Size: |
38,600 m2 (415,000 ft2) |
Leading governmental and independent trade organizations have monitored, tested, and reported on corrosion control strategies over the past three decades. These groups include the American Concrete Institute, National Association of Corrosion Engineers, and Federal Highway Administration. They advocate CP as the only rehabilitation technique that effectively stops corrosion in salt-contaminated structures, regardless of the chloride content in the concrete.
ELGARD™ is a trademark of Eltech Systems Corporation. |
