This equipment can only be used when a free edge is available. The large C-shaped jaws are installed over the concrete to be removed. The hydraulic power unit, supplied by a power unit driven by electricity, diesel or petrol, brings the jaws come together and the concrete is crushed. This process is repeated until the whole area is removed. An angle grinder or cutter is used to cut the reinforcing steel. The main difference from hydraulic bursting (see separate entry) is that it does not need any diamond holes to be pre-drilled and the resulting rubble is much smaller.
The limitations of this method are that the jaws are heavy and the larger units over 250 mm capacity need a balancer to take much of the weight. Crushing concrete over 350 mm thick is not practical with this system. It is necessary to have a fully-boarded scaffolding below the floor area being worked upon to catch the rubble.
Further information may be obtained from the Drilling and Sawing Association