Generally, contractors have two alternatives when partial concrete removal is specified: hydrodemolition and traditional impact methods using breakers
While breakers have incredible destructive power, that power is difficult to control; so, mistakes happen that can damage both the reinforcing steel and adjacent–and otherwise structurally-sound–concrete. In addition, the vibrations from the equipment can weaken surrounding concrete.
Removing concrete beneath the reinforcing steel can be tricky with impact methods, which do not differentiate between concrete and steel or between sound concrete that should not be removed and deteriorated concrete
Hydrojet Systems use high pressure water jets to demolish and remove concrete while not damaging the rebar. This method is mainly used to remove concrete from structures, such as dams, tunnels, turbine linings, bridges, parking decks, harbours and docks for repairs.
The effectiveness of this method is due to two main reasons:
The direct impact of the water jet on the surface
The porous nature of concrete - the high pressure water is forced into the tiny cavities and cracks within the concrete mass, causing it to fracture and split
The variable parameters of the technique, water pressure, jet size and speed of application, make it possible to remove concrete in a very precise and controlled way