Fast and clean installation

KEMROC KRD 120 drum cutter with rotation unit

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The sides of an approximately 6,000 m² pit excavated in Leonberg (Germany) were made safe by the urgent action of the Swabian demolition and construction company BERB with a retaining wall. Using a drum cutter attachment with rotation unit from KEMROC mounted on a 26 ton excavator, the pit walls were precisely and safely cut back to allow wooden planks to be fitted between girders.

An industrial area in Leonberg near Stuttgart (Baden-Wurttemberg, Germany) is changing its appearance. Here, the developer, a well-known Swabian manufacturer of electrical appliances, is replacing an outdated manufacturing center with a modern building. After demolishing the structure that stood above ground level, the company BERB from Bösingen took on the task of removing the basement structure including the concrete foundations thereby creating a 6,000 m² excavated pit that needed to be secured. Thanks to a KRD 120 (120 kW) drum cutter with a KRM 60 rotation unit – both from the manufacturer KEMROC – mounted on the company's own crawler excavator, the retaining walls constructed from girders with timber lagging were installed quickly and efficiently.

Combining assets for demolition projects

Bantle Entsorgung und Rückbau (Bantle Disposal and Demolition) in Bösingen – is the full name of the Swabian company BERB, which was founded in 2017 by graduate engineer Georg Bantle. This is a sister company of the road and civil engineering company Gebrüder Bantle from Bösingen on the edge of the Black Forest. With qualified personnel and their own machine and equipment park, BERB has completed important demolition, disposal and earthworks projects throughout southwestern Germany. KEMROC excavator attachments have been part of the joint equipment arsenal of both sister companies for some time now: for example, a patented chain cutter attachment is used for gypsum mining at a gypsum deposit owned by the Bantle brothers. BERB also use a 6 ton cutter wheel attachment from KEMROC.

With their background and experience, demolition of the remaining building structure in Leonberg was initially carried out using the classical method with excavator plus hammer and shearer attachments. However, to then create and secure the excavation pit for the future building complex, a previously untested approach was taken. A company-owned 26-ton excavator with a drum cutter attachment from KEMROC was used to install the girder and plank shoring system.

Installation of this shoring system (also known locally as Berlin shoring), requires double-T steel girders to be rammed into the ground at regular intervals and then wooden planks are used to fill the space between the girders. To create space for the shoring, the soil is normally removed using an excavator with bucket. However, if the bucket removes a large boulder, voids are left behind the shoring that need to be backfilled. To avoid this, it was decided to try a new method using an excavator with a rotary drum cutter attachment at Leonberg. In this way, flat, straight walls could be cut into the stony soil material without breaking out large sized pieces that would later create voids behind the wooden planks.

The KRD range of rotary drum cutters are a relatively new addition to the specialist range of excavator attachments from KEMROC. There are nine sizes available for excavators from 0.5 to 50 ton operating weight. These are twin head milling machines, otherwise known as drum cutters with direct drive. Robust and compact, they develop a very high power to weight ratio, making them suitable for applications such as demolition projects using long-reach excavators as well as for soil stabilization and concrete renovation. They can also be used in sewer and pipeline construction, for accurate profiling work and for the mining of soft rock.

In Leonberg, a KRD 120 rotary drum cutter was delivered to the BERB construction site.  It was mounted on the excavator together with a KEMROC KRM 60 rotation unit. This range of endlessly rotating rotation units for excavators from 2 to 70 ton enables accurate positioning of the drum cutter attachment at any angle to the material to be milled from any excavator position. While working in Leonberg from February to May 2022, the drum cutter attachment was used to remove material from between the steel girders from the bottom to the top producing straight, vertical walls, without the operator having to continuously reposition the excavator to move from one section to the next. The result was smooth, flat walls with the correct amount of space for insertion of the timber planks.

"Thanks to this combination of equipment, our operator managed to remove the correct amount of material quickly and accurately from different layers containing rocks or soils with large amounts of stones," reported site manager Florian Eisele after the completion of this project. "We also produced a very small amount of excavated material, keeping removal and landfill costs within tolerable limits. In any case, in this type of application, success is not determined by the production rate of the KEMROC attachment, but rather about accuracy." Using this combination of equipment in conjunction with a fully hydraulic quick coupler and a standard bucket had additional benefits as the civil engineer Eisele explained: "The operator could quickly and easily alternate between milling and loading the excavated material, so the excavator was utilized in the best way possible. This saved us from having an additional eight-ton excavator in Leonberg."