ICRI 2004 Project Award Winner
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Award of Excellence: Longevity Category

Coral World Ocean Park
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St. Thomas, U.S. Virgin Islands

Submitted by Matcor, Inc.


Coral World Ocean Park

Owner
Coral World Ocean Park
St. Thomas, U.S. Virgin Islands

Project Engineer/
Designer

Matcor, Inc.
Doylestown, Pennsylvania

Repair Contractor
Matcor, Inc.
Doylestown, Pennsylvania

The Coral World reinforced concrete, underwater observation tower sits in the ocean, subjected to the salt-laden trade winds. The structure was built in stages using salt contaminated sand and water. Over time, the reinforcing steel severely corroded and cracked the concrete. The structure underwent one major conventional repair. Corrosion continued and major cracks/spalls reappeared. The owners and their engineers decided that a permanent solution was required. A cathodic protection (CP) company was chosen to provide a CP system for the structure. Except for the roof, the entire structure is reinforced concrete. The system had to be easy to install on all surfaces and easy to maintain. A conductive coating system was chosen. Except for a few cable connections to the reinforcing steel and the placement of reference electrodes, the entire system was placed on the surface of the concrete. The cables and control wires ran to the existing control room and terminated at the CP controller.

The severest damage was on the radial beams. The owner’s structural engineering firm specified the spalled concrete be removed, a new epoxy coated reinforcing steel cage placed over the beam, and new concrete poured. This was difficult—some beams were over water and the reef tank had to be sectioned, the fish removed, and the tank drained.

Much of the exposed steel was badly corroded and not electrically continuous. The original steel was extensive, and additional steel was not required. A series of electrical bonds was necessary for the CP system.

With repairs made and instrumentation in the concrete, the surfaces were covered with the conductive coating. The CP company’s platinum anodes were placed on the surface with special, self-adhesive fiberglass tape. A second coat of conductive coating embedded the anode. The surface was painted with a white acrylic paint.

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