Perth city link rail project hydro-demolition

When the Perth city link rail alliance needed specialist concrete preparation work on the new rail tunnel, they turned to Jetcut.

The diaphragm retaining wall in the new tunnel has "cast in" couplers at the very base of the tunnel which are used to tie in the top and base slab of the tunnel to the walls. As the walls are cast in the earth, these couplers would need to be exposed after the pouring and excavation was complete. That meant demolishing the layer of concrete that was over the couplers.

In addition to revealing the couplers, the concrete from the pour was contaminated with bentonite and other spoils and needed to be cleaned back to exposed aggregate.

Enter hydro-demolition, a process where high pressure jets of water are used to "wash away" concrete, leaving re-enforcement (the couplers) and aggregate (the bonding surface) exposed without any damage.

Pressures in excess of 20,000psi are required to perform this type of work. This presents some risks to operators, particularly on larger demolition projects where fatigue becomes a real issue. Because of the fatigue issues Jetcut decided to use one of its robotic hydro-demolition units for this work. Robotic units have many advantages the main one of course being that the operator is remote from the 20,000psi water jet which can pose dangers. Another big advantage is that production can be increased, as the robot can "hold" much more water flow than an operator with a hand held tool, speeding up the work.

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