Robot Cutters Clean Concrete At 120 m . . . . . continued
The robot machines were rented by Termite Ltd, a hydro-demolition specialist that is a sister company to DUS, distributor for Sweden’s Aquajet Systems AS in Finland and Russia.
The distressed concrete was at a height of 84.5 m to 94.5 m, and the full thickness that had to be removed was about 77 m³.
The 10 m high Aqua Spine mast was lifted in place by the Kroll K320 tower cranes on hire from Viking Cranes and bolted onto each side of the pylon.
An Aqua Cutter 410A was used as the Power Control Unit to control the Aqua spine.
Max Petryov, Development Director for DUS, said:
For this project we used the Aqua Spine from Aquajet which is the most effective and flexible equipment you can find in the market for this type of job.
It is easy to build the system in the size needed by using the multi-modular Aqua Spine. The spine is made to handle the reaction force from a 700 hp pump with 262 L/min.
The height of the area to be removed was 10m so we assembled the Aqua Spine in the same length. We assembled the complete system on the ground which reduced the set up time.
ICA wanted to remove the concrete without causing any damage to the inner steel structure, and needed to save the vertical rebar to spend less time on recasting. Termite Ltd provided the two water cutters together with operators and service backup, on a rental basis.
The size of the inner steel structure of the pylon varies between 3.5 and 4.4 m in diameter. The wider sides of the pylon are covered by 55 cm of concrete, while the narrow sides have a variable thickness of between 50 and 75 cm.
The distressed concrete was at a height of 84.5 m to 94.5 m, and the full thickness that had to be removed was about 77 m³. The power pack was positioned at the bottom of the pylon and used a 120 m long high-pressure hose to access the working area.
The hose was fed upwards inside the pylon and then through a vent hole to the outside. Our water source was the Finnish Gulf. We used three-level filtration to prepare water for the plunger pump, the used water was fed back into the sea.
A caisson wall filled with sand and crushed stone surrounds the pylon. This acted as a filtration and settling tank, so the water that was pumped back into the Gulf was almost entirely clean.
Mr Petrov says that the advantages to ICA, along with the clean cutting of the concrete, was that there was no need to have a large gang of jackhammer operators working high up on the pylon or any need to build any platforms or scaffolding.
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