Delaminated concrete on Pearl Harbor's Wharves F12 and F13 was removed as part of the U.S. Navy's ongoing effort to bring all of the harbor's wharves, dry docks, and piers up to date. General contractor Nova Group Inc., Honolulu, headed the project. Project manager Tim Couch called on subcontractor Triton Marine Construction, Bremerton, Wash., to use its AquaJet Systems Aqua-Cutter HD-6000 hydrodemolition machine, which was able to remove the delaminated concrete without damaging the good concrete.

The Aqua-Cutter HD-6000, distributed by the Water Technology division of Putzmeister America Inc., offers power, flexibility, and control. The 3500-pound machine, with its computer-controlled system, maneuverability, and efficient cutting head, can operate on almost any horizontal surface and reduces the number of laborers needed, increases safety, and reduces costs.

The machine's parameters were reset for each differently shaped section and the Aqua-Cutter removed concrete to the specified depth with only one or two passes. “The passage of the machine's jet is determined by adjusting the traveling range of the lance and the distance moved by the machine,” says Bret Gordon, superintendent with Triton Marine Construction. “This means hydrodemolition is only carried out on the deteriorating concrete with no harm to the surrounding, good concrete.”

The HD-6000 removed 3000 square feet of the 6000 psi concrete from the decks at a rate of 1 cubic foot per minute, says Eric Zimmermann, general manager of Putzmeister Water Technology. Demolition concluded in March 2007.