Rock crusher and compactor in one
Blasting work during road and tunnel construction often produces large volumes of rock rubble. The blasted material often needs to be crushed and compacted for further use. Hamm offers a smart, cost-effective solution for this task: the H 25i VC rock crusher-compactor. It crushes and compacts rock in a single operation. During the construction of the Hirschhagen tunnel near Kassel at the end of 2015 / early 2016, the machine demonstrated its capabilities in continuous operation over many weeks. The Hirschhagen tunnel, around 4.2 kilometres in length, through which the A 44 motorway will pass in a few years’ time, will be the second-longest tunnel in Germany. Around 1.8 million m³ of material was excavated from the tunnel in the course of construction. A large part of the material is calcareous limestone, unweathered, not very porous and with a high compressive strength.
Part of the rock rubble produced by the blasting was used on-site as a foundation for the new access roads. The remainder will not be needed until later construction phases. Accordingly, the general contractor for this project, Osnabrück-based Köster GmbH, wanted to be able to store this rock as compactly as possible until it was required for use. Its most important tools in attaining this goal were Hamm H 25i VC rock crusher-compactors. These 25 t machines have a special feature: welded to their drums are 150 tool holders. They can hold different tools, such as cutting tools used in mining. In addition, the roller can be equipped with special padfoot inserts and used to compact cohesive soils.
Hamm wins out in a head-to-head comparison
At the start of the project, Köster GmbH put various machines to the test. From this it became apparent that the H 25i VC with cutting tools was the optimum solution: “The compactor achieved by far the highest crushing performance. One reason for this is without doubt the very powerful power train, another is the exceptional climbing ability of this machine,” said Jürgen Schlüter, special engineering foreman, reporting on the tests.
The H 25i VC replaces three machines
One of the machine’s tasks was to crush the material excavated from the tunnel to a size of 0/200 mm for interim storage. “Previously, we used a jaw crusher for this job. It is now being dealt with by the rock crusher-roller. This makes the process simpler and faster. Where we would have needed a crusher, excavator and wheel loader, the job is now being done with just the H 25i VC,” explains foreman Schlüter. The VC compactor enables a considerable reduction in personnel and machine requirements. That cuts operating and maintenance costs, simplifi es the organisation and is also exceptionally environment-friendly thanks to the greatly reduced transport requirement. Jürgen Schlüter has identified yet another benefit: “The VC compactor can even work productively in weather conditions that would test the capabilities of a jaw crusher. For example in heavy rain or at sub-zero temperatures, the vibrating screens of jaw crushers clog up with fi ne material or may freeze.” That problem does not occur with the H 25i VC.
Optimum use of storage capacity
The overall performance of the Hamm H 25i VC compactor is impressive: in the storage area alongside the tunnel, the calcareous limestone is compacted in 60 cm thick layers. In the course of an 8-hour shift, the rock crusher-compactor processes around 180 truckloads of 8 m³ each. Simultaneous compaction with vibration compresses the rock to such an extent that water is unable to penetrate and Köster GmbH is able to make optimum use of the storage capacity.
Perfect support thanks to WITOS FleetView
WITOS FleetView, the Wirtgen Group telematics solution, was used for maintenance of the compactor. This system informs the owner automatically when a fi lter needs to be replaced, for example, or when servicing is due based on the number of operating hours. On request, a service technician will come to the machine with the appropriate materials – thanks to GPS tracking, he always knows where the machine is. A useful feature that also helps to pinpoint the machine immediately in the event of theft.