Wirtgen crusher recycles hand-packed stone pavement in single pass

The L98, a two-lane country road in Germany, closely follows the course of the river Moselle in the shadow of the medieval castle Burg Metternich. The road must be kept in good condition as an important part of this economic region’s infrastructure.

Around 3 km of the road in the area around the municipality of Beilstein needed structural rehabilitation. After milling off the asphalt surface layer, the remainder of the asphalt binder course and the underlying hand-packed stone layer were crushed and processed in a single pass by a WRC 240i Rock Crusher from Wirtgen, Germany. The objective here was to create a new, homogeneous base layer that would provide long-term resistance to the axle loads of future heavy traffic.

Hand-packed stone layers on the L98, or base layers containing large pieces of stone, often used in the past, meant traditional rehabilitation would be extremely laborious, time-consuming and costly. Above all, the transportation of materials takes time and is expensive.

With the WRC 240i Rock Crusher, Wirtgen offered a more economical solution for this challenging task. The crushing and mixing rotor of the WRC 240i processed the existing binder course and the underlying hand-packed stone layer with its HT18 crushing tools to a depth of 35 centimeters (cm).

In the crushing process, the variable and fixed crushing stages ensured that the stone pieces were fragmented to the required size by impact crushing. The screen unit, with a mesh size of 45 millimeters in the rear part of the crushing and mixing chamber, determined the fragment size of the crushed material. In this way, a new, high-quality homogeneously mixed base layer was created in accordance with the project specifications to a working depth of 35 cm, Witgen says.

With a working width of 2.32 meters and an advance rate of around 7 meters per minute, the machine achieved a crushing volume of 600 tons per hour. On the project site, the total volume of material produced on-site by the Wirtgen Rock Crusher amounted to around 11,900 tons and eliminated the need for transporting approximately 1,200 truckloads of processed or new material to and from the site. After compaction, the new crushed stone base layer was ready for the placement of the overlying asphalt binder course and the paving of the asphalt surface layer.

According to Witgen, the Rock Crusher significantly reduced not only the transport costs but also the related carbon emissions. In this case, the CO₂ emissions were cut by around 66 percent. The construction costs for the creation of an unbound, homogeneous base layer were reduced by 75 percent and the project completion time was shortened by 55 percent. This meant that the section of the L98 was ready for asphalt paving within only two days and was very soon able to be opened to traffic again.