Use of noise-absorbing asphalt
The numerous backups on the A 9 were not the only reason for expanding this stretch of motorway. The motorway runs through a densely populated area and traffic noise was a nuisance to many of the local residents. That was why a special noise-absorbing asphalt was to be used for the surface course across the full width of the motorway.
The mix responsible for the sound damping effect is a special material for thin overlays known as DSH-V (0/5) with PmB 65 (70/100) polymer-modified bitumen. This material is characterized by a high content of double broken and double screened chippings and sand, which results in a sufficiently high voids content in the finished layer, allowing a share of the sound waves to be absorbed. In combination with the PmB 65 (currently: 45/80-50) binder, the DSH-V (0/5) material is able to withstanding the heaviest traffic loads.
The two SUPER 1800-2 with SprayJet Module applied emulsion (type C67) and paved asphalt in a single pass. The rate of spread for the emulsion was 800g/m2, thus ensuring reliable interlocking of layers.