JOB REPORT

Concrete links Europe.

Dual-layer concrete paving in one single pass

A gap of about 14 km in length disrupted the new A20 motorway near the hanseatic town of Lübeck in the north of Germany. The motorway is an important link between East and West Europe. A slipform paving train from Wirtgen closed the gap not far from the former border between East and West Germany. This road construction plant type SP 1500 L comprises two machines, a bottom-layer concrete paver and a top-layer concrete paver.

The job site placed high demands on the machines, even though the job site parameters – a paving width of 11.50 m in each direction, and a paving thickness of 20 cm for the bottom layer and 7 cm for the top layer of concrete – did not stretch the slipform pavers to the limits of their capacity. The paving train placed up to 1,800 m³ of concrete per day, advancing at a speed of 1.1 metres per minute. The correct grade and slope were ensured by previously pulled stringlines.

An on-site mixing plant produced the required quantities of concrete, which was dumped and roughly pre-spread by an excavator ahead of the bottom-layer paver. The leading paver inserted dowel bars automatically in the direction of travel, every 25 cm on the main lane and every 50 cm on the hard shoulder. The top-layer paver then placed the second, thin layer of high-quality concrete on top of the bottom concrete layer. A TCM 1800 texture curing machine followed behind the pavers, applying the characteristic broom finish, as well as a thin film of curing agent to prevent premature shrinkage cracks.

Similar to the project itself, the construction material had European dimensions as well: the different aggregate fractions came from Sweden, Norway and Germany.