KEMROC KR 165 Drum Cutter Converts World War II Bunker to a Residential Building
Published: 16/6, 2023
“Comfortable living” is a term not normally associated with the idea of setting up a comfortable home in an old bunker. However, this is exactly what has recently become a fashion trend in Hamburg, Germany. Of the approximately 400 bunkers remaining from World War II, several dozen are mostly above-ground. For these buildings, the preferred option is not to demolish them completely at great expense, but demolish sections with no value and to convert the rest into residential buildings.
Thick and well reinforced concrete
For local contractor Wilko Wagner GmbH, the task was to demolish part of bunker closely surrounded by occupied residences. Along with demolishing a back wall facing the courtyard, the inside of the bunker—originally consisting of six floors each with a ceiling height of around 6 ft (2m)—was to be completely gutted out from top to bottom. To add penthouse apartments to be the building, the existing 86.6-in (220cm) thick massive reinforced concrete roof, weighing 400t, had to be removed
To get started, the contractor hand-cut a hole through each of the 10-in (25cm) thick floors, then used a wire saw to cut an opening through a wall on the ground floor, through which around 9,155 yd3 (7,000m3) of demolished concrete material could later be transported away by small loader. At a later stage, the interior of the building will be completely rebuilt.
Fortunately, the roof was strong enough to support a 35t excavator paired with a KEMROCK KR 165 drum cutter attachment. After removing the top bitumen layer, the excavator operator cut a “foxhole” through the concrete roof to discharge material from subsequent demolition work.
The excavator and drum cutter were also used to create openings for floor-to-ceiling windows through the bunker’s 43.3-in (110cm) thick, heavily reinforced façade walls. The bunker wall between the corners was ground out leaving a thin section of wall. The third step involved removal of the remaining thin section of wall using an excavator with shearer.
Reliable equipment
The KEMROC KR range of rotary drum cutter attachments use planetary gears which makes them very rugged and reliable and the ideal attachment for short boom carriers working in confined spaces and for low-vibration and low-noise demolition of reinforced concrete. Their hydraulic motors deliver high torque and maximum cutting force. The cutter picks are welded in the optimum pattern onto the cutter drums which are connected to the body using very heavy-duty bearings. Machines are supplied from the factory with connections for optional water spraying for dust suppression.
Following the “less is more” principle, Wilko Wagner operators ran the attachment with moderate feed pressure to achieve a smooth cutting action gave the best productivity to wear cost ratio. At the same time, running the drum cutter at this optimal level also ensured that noise and vibration levels were kept within acceptable limits. In the case of using the water spray for dust suppression, it was important to use the right amount of water in order to generate as little surface water as possible.
As a result, the bunker demolition work was completed in about six months with few noise and dust disruptions to the neighborhood.