JOB REPORT

Compacted to perfection.

Thin-layer paving in hot application on tack coat on the A99 motorway, Germany

The A99 motorway serves as ring road, conducting all traffic that uses the motorways leading towards Munich around the city. A new surface course was to be placed on the two left lanes of the three-lane motorway between Hohenbrunn and the junction München Ost (Munich East). The operations were carried out during the nights, while all three lanes were opened to traffic during the days.

It was decided to rehabilitate the motorway section by paving a “thin layer in hot application on tack coat”. This method permits the road to be reopened to traffic quickly after completion of each working step, while additionally producing a surface of excellent skid resistance and durability. The thin asphalt layer in hot application was paved on the two left lanes over a total length of 9 km and across an overall width of 7.20 m. The operation began with two W 2000 large milling machines from Wirtgen, which fine milled the pavement at a depth of around 2 cm. Two Super 1800 SF spray pavers followed right behind, paving the thin asphalt layer on top of a tack coat.

As thin asphalt layers tend to cool down very quickly, the DV 90 VO rollers from Hamm were the ideal candidates for compacting the pavement on the A99. The oscillation rollers from Hamm achieved the specified density quickly and reliably. Oscillation rollers are capable of producing excellent compaction results even at low asphalt temperatures. Extensive density measurements behind the paver and after compaction of the pavement on the A99 revealed “that densities comparable to those produced by oscillation cannot be achieved using static compaction methods only”.