Aquajet Hydrodemolition Robot Deconstructs a Motorway Bridge Parapet

One of Gnat UK's Aquajet Hydrodemolition Robots deconstructing a motorway bridge parapet prior to refurbishment.

Hydrodemolition is the standard method for parapet refurbishment on motorway and arterial bridges. Working at high pressure, the Aquajet selectively removes degraded concrete from around the rebar without damaging the steel — leaving a sound, key-roughened substrate ready for the recast. Mechanical breaking would damage the rebar and impart micro-cracking into the substrate that would have to be removed before the new concrete bonded properly.

Parapet work on a live carriageway adds traffic management on top of the method itself. Lane closures define the working window; the work is sequenced so that each parapet section is removed and recast within that window. The Aquajet is remotely operated, which keeps the team out of the immediate hazard zone of the high-pressure water and the live carriageway alike.