When it comes to experience in hydro-demolition, Barry Bros. has earned its stripes.

After building its own high pressure water blasting rig to remove the unsound concrete on Nauru House in Melbourne, Barry Bros. decided to buy a specialised rig using the latest technology and capable of greater production. After looking at machines around the world, it settled on the Swedish Aquajet HV450 rig.

One of the features of hydrodemolition is that it is able to detect unsound concrete and selectively remove it while leaving the sound concrete. This makes it much more efficient than the traditional jack hammering method.

Barry Bros. has undertaken some unusual work and projects including:

> Removing concrete work not to specification while leaving the re-inforcing steel in place for use in the replacement structure.

> Removing epoxy asphalt from the steel deck of the Westgate bridge.

> Removing paint and rust from ships and tanks prior to recoating.

The Barry Bros. rig has an input of 450 hp, operates at a pressure at 1,000 bar and requires 180 litres of water per minute.

Technical Services Manager, Robert Hare, believes hydrodemolition is now better accepted but the full scope of uses for the technique in Australia has not yet been explored.