Pioneering work in the BT-43 and -44 milling processes
Wilhelm Knepper GmbH & Co. KG removes large areas of asbestos-containing plaster and filler in barracks
20,000 sq m refurbished in a short time
It is 32 m long, 20 m wide and proudly 7 m high. The “ballroom” is the most imposing room of the two barracks buildings in the west of Soest, where, among other things, modern condominiums are to be built in the future. And just like the smaller neighbouring rooms, it is plastered from floor to ceiling with a resistant but extremely dangerous covering. “We have about 20,000 sq m of asbestos-containing area here that we have to take care of, divided into more than 200 rooms,” explains construction manager Hendrik Schäfer, who coordinates the pollutant cleanup by the Knepper company.
Actually, the former soldiers’ quarters in Soest are a typical case of black areas and months of manual chiselling and milling by hand, in time-consuming vacuum decontaminated areas. However, the demolition and decontamination specialists from Lippstadt have invested in low-emission milling processes for wall (BT 43) and ceiling surfaces (BT 44) newly developed by ASUP GmbH, which are being used in Soest for the first time on this scale. “On this construction site, a large number of innovative techniques are used and combined to achieve maximum economic efficiency”, says Achim Bräutigam from ASUP, who equipped the Knepper company with technology and know-how.
Using rail-guided milling machines, trained employees can remove large areas of plaster and fillers from walls and ceilings in a short time. “With two people we can manage about 400 sq m in two days. That would be unthinkable in the conventional way,” says Schäfer, who is particularly proud of the exceptionally fast renovation of the “ballroom” with its high ceilings. In order to free the latter from the pollutants using the BT-44 process, a rolling scaffold was specially constructed, which also allows precise work at height without the release of asbestos fibers.
The new technology eliminates the need to set up pipes and working areas with negative pressure. Instead, negative pressure monitoring is performed directly at the milling machine. Expensive free measurements, which would be necessary for each room in the conventional renovation, can be largely eliminated. “The new BT procedures are a self-contained system. No one comes into contact with the dangerous waste any more, it ends up via pipes directly in easily removable big bags in front of the building,” explains Bräutigam, who sees the biggest advantage in this in addition to the fast set-up times. Furthermore, the removal is precise to the millimeter, which only removes contaminated wall and ceiling cladding. Up to 12 millimeter can be milled off concrete walls or screed in one process. Only in corners and at windows does the rail-guided milling machine reach its limits, which is why the BT-43 and -44 processes provide for combined use with conventional corner milling machines, which have also been modified to form self-contained systems.
More renovation in less time
An average of five people carried out the asbestos work with hand milling machines and mortising equipment. With the new method only two skilled employees are sufficient to operate the wall milling machine ergonomically and in a relaxed manner and, if necessary, to rework the work by hand. “This is a great saving in terms of personnel, material and time”, explains Holger Hölscher, foreman of the company Knepper and expert in the field of pollutant cleanup. A showcase project for all involved.
“The certified milling systems will be of interest to many because of their advantages and will be used more and more”, Schäfer and Bräutigam agree. The work is to be completed in autumn and the buildings are to be handed over to the client free of pollutants.