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Ceiling demolition - bunker demolished inside a building

The Job:

The remains of an air-raid shelter had to be demolished in a historic-society protected house in Elsenheim, France. The concrete ceiling was thicker than the ceilings in the other rooms, which caused it to project into the upper floor. The ceiling consisted of three layers, of which the upper and lower were very hard, and the middle soft and crumbly.

The Requirements:

The walls, 1.3 m thick, were very heavily reinforced. As the bunker was inside a building the work had to be accomplished without noise, pollution, excessive dust or vibrations. A conventional hydraulic breaker proved incapable of demolishing the ceiling because the outer layers were too hard. It only produced severe vibrations.

The Solution:

The work was conducted from the floor above the shelter. First, the requisite holes were drilled with a DR 086 mini drill rig. This was mounted to a small Brokk 150 demolition robot. Following this, a single C 12 N splitting cylinder was used to demolish the hard, uppermost layer of concrete (about 45 cm thick). Powered by an electric EP-type hydraulic unit, it produces the minimum of noise, dust and vibrations. It proved possible to remove the next, softer layer with a hydraulic breaker, also mounted to the Brokk 150 robot. The third, hard layer was demolished in turn with the C 12 N splitting cylinder and EP power unit. Given the specified conditions, it would not have been possible to demolish the shelter ceiling without a hydraulic rock and concrete splitter.