Hydrodemolition at the Port of Liverpool

The UK’s first Aqua Cutter Evolution 710V robotic unit from Swedish hydrodemolition specialist manufacturer, Aquajet Systems AB, is being used to speed up construction work on the project. Hydrodemolition eliminates the need for complicated scaffolding and improves concrete removal in a difficult marine environment.

The Seaforth Dock work will widen the passage by 20m to a total of 60m to allow quicker turnaround times for larger vessels. It will also see new fendering around the Gladstone Lock port entry, the existing wall demolished and a new quay wall constructed.

“Pneumatic or mechanical breaking wasn’t an option due to the vibrations it would have induced,” explained Ewan Crocker, operations director, at Core Cut. “Drilling or hand lancing would also have required the erection of elaborate and expensive scaffolding and the use of man baskets.

“We quickly recognised the potential for hydrodemolition and as such set up a sub-division to handle the business named Corejet. It’s a natural extension of our service package and completely complements our drilling and concrete sawing activities,” he said.

Wire sawing allowed Corejet to initially move large sections of concrete from both the receival locations over areas 3.5m wide and 2.5m long and also up to 3.5m deep.

In total, some 260 tonnes of concrete were then removed in around 14 lifts ranging from five to 34 tonnes, all as the busy shipping passage operated as normal.

The 710V Aqua Cutter was brought in to remove up to a depth of 500mm of concrete from both end walls to expose the rebar. In total, Corejet was able to remove more than 26m³ of concrete safely and efficiently from both receival locations.

A key benefit of the hydrodemolition process is that it removes the concrete without damaging the rebar, ensuring swift re-concreting onto clear reinforcement once the U-Tube structure is in position.

Corejet said that hydrodemolition techniques more than double the life of any repair or coating when compared with concrete removal using jack hammers.

Once all preliminary work has been completed at the Seaforth Dock, a new quay will be installed and the existing wall demolished. Completion of the whole project is expected to be around February 2015.

By Anne-Marie Causer