Abstract: Material, such as old unsound concrete material, is removed from a work surface by discharging water against such work surface at a pressure of from about 10,000 to about 25,000 psi from a rotating nozzle. During operation, the nozzle traverses the work surface along a series of linear paths and is incrementally moved in a longitudinal direction so as to pass over the work surface in a sequence of preferably overlapping transverse bands. An apparatus for carrying out the method of the invention comprises a support structure usefully in the form of a vehicle having an extendible arm driven by an extension means for incremental movement of that arm in a longitudinal direction. A rotatable nozzle is mounted on a nozzle support in turn secured to the extendible arm for bidirectional movement of the nozzle along a transverse linear path. Casters are also provided for maintaining the nozzle at a predetermined spacing from the work surface during operation of the apparatus.

Abstract: Apparatus for removing material from a surface, for use in association with a source of water at a pressure within the range of about 10,000 to 25,000 psi, the apparatus comprising, a carriage vehicle, extendable arm mounted on the vehicle and defining a free end, a nozzle being movable in a transverse direction, the nozzle including a housing and a rotatable nozzle mounted thereto, a hose connecting the source of water to the nozzle, a motor attached to the nozzle operable to rotate the nozzle, and an extender attached between the arm and the vehicle operable to extend and retract the arm relative to the vehicle.