Concrete bunker demolition success for Kemroc
Kemroc milling attachments play key role in initial phases of construction project
A RANGE of rotary drum cutters and grinder attachments from Kemroc are helping to give a high-rise World War II bunker a new lease of life. Made of solid concrete, the old high-rise bunker in Koblenz, Germany, formed a striking landmark from days gone by and once offered protection to almost 1,000 people.
Now, contractors HR Abbruch have been given the task to undertake extensive preparatory work for the bunker to be transformed into a high-quality residential complex. Initial stages of the project will include removal of the roof and one side of the building. Three outer walls will remain and window openings will be cut at a later stage using wire saws.
The demolition team, led by site manager Sebastian Sommer, decided to find an alternative method for the partial demolition of the building. ‘Of course, we couldn't use explosives in the middle of the city,’ said Mr Sommer, ‘and in the immediate vicinity of the surrounding residential buildings, the use of hydraulic excavators with demolition hammers was not an option. In addition, the building was constructed with completely unreinforced concrete, which could be weakened structurally if hammers were used. The only remaining option for us was to use milling technology.’
The HR Abbruch team began the demolition phase of the project with the use of a Kemroc KR 150 drum cutter attachment (on hire), which was mounted on a 35-tonne excavator owned by the company. After several weeks of continuous use, this combination proved itself to be from a technical standpoint, a viable solution. For higher productivity, however, a more powerful excavator-milling combination was required.
Once again HR Abbruch approached plant hire equipment specialists T + M Abbruchtechnik GmbH for another solution and the latter advised and specified the use of a 50-tonne excavator together with a Kemroc KRD rotary drum cutter attachment (160kW). The combined equipment was used to create the openings in the outer walls and to demolish the roof of the building, so that wire saws could be utilized at the latter stages whilst new window openings could be created.
Commenting on the successful completion of the partial bunker demolition, Mr Sommer said: ‘With an exterior wall thickness of around 2m, creating openings into the bunker building was not an easy task for any machine configuration, but under the given circumstances, renting this equipment was technically and financially the best solution for this job.’
HR Abbruch also noted that the higher contact pressure – resulting from the heavier excavator-milling combination and a low working height – helped increase productivity and safety during demolition work, as Mr Sommer concluded: ‘Excavator-mounted milling attachments will certainly become increasingly important in inner-city demolition projects and will largely replace classic hydraulic hammers.’
