Contractor Eurovia GmbH relies on slipform pavers from Wirtgen when building, repairing, and modernizing German motorways. The BAB A9 motorway leads past Brandenburg, Saxony-Anhalt, Saxony, Thuringia, and Bavaria, connecting the German cities of Berlin and Munich over 329 miles.

Expanding the A9 between Triptis and Schleiz over 12 miles was based for the first time on a new public-private partnership model. In contrast to previous models, the remuneration in this case depended on the quality of service provided. This means that any defects in quality and any limitation on availability results in a reduction of the remuneration paid to the operator by the government.

It was important to achieve the highest quality. Eurovia is responsible for planning, building, and operating the motorway section for the next 20 years, making it available to the German government.

To ensure a high load-bearing capacity and long service life, together with perfect surface evenness and skid resistance of the road surface, Eurovia elected to use the advantages of concrete surfacing. Constructing the surface course out of washed concrete reduces traffic noise by as much as two decibels.

Apart from being suitable for universal use, easy to process, and available everywhere, concrete surfacing also offers other clear advantages: Due to its high load-bearing capacity and resistance to deformation, it prevents ruts and consequently extends the necessary maintenance intervals.

This is critical in view of the increasing volume of heavy goods traffic.

Concrete paving train

Six motorway lanes extending 12 miles equates to a surface area of 601 square meters, requiring some 165,000 cubic meters of concrete. Eurovia deployed a paving train comprising Wirtgen SP 1500 and SP 1500 L slipform pavers to do the job.

On the A9 jobsite, this paving set laid down the two-layer concrete pavement in just one pass with an output of 400 to 500 meters/day.

The first slipform paver was responsible for the subgrade. The 9-inch-thick bottom layer of concrete was paved true to line and level by the SP 1500 L and completely compacted by an internal vibrator, while the paver simultaneously embedded dowels and tie bars. This yields a homogeneous base for the 3-inch-thick top layer of concrete.

Wet-in-wet paving

The top-layer concrete was installed immediately after the bottom layer to ensure optimal interlocking of both layers. The concrete for the top layer is provided via the bottom layer concrete paver from a receiving hopper with a charging conveyor and placed in front of the second slipform paver, the SP 1500. The SP 1500 then distributes this material across the entire paving width with its spreading plow, installs the top-layer concrete “wet-in-wet” when passing over it, and simultaneously compacts it. The finishing beam and super smoother produce the desired optimum surface finish. During paving, a finishing beam was deployed across the roadway while an oscillating super smoother operated in the direction of travel of the paver.

The concrete pavement is also sprayed with a TCM 1800 curing unit across the entire working width immediately after paving to prevent rapid evaporation and formation of cracks.

Eurovia and Wirtgen have been close partners for many years. Summarizing the rationale behind the decision, site manager Daniel Böhnke says, “The incredible reliability of the machines is a decisive factor for us. Wirtgen’s application advice is outstanding. Service technicians are always available without delay in the event that a problem occurs on the jobsite.”