Concrete on soft buffer - NAUE Secutex® concrete nonwoven ensures the durability of concrete pavements
Location of work/project:
Germany – A4 near Kirchheim
NAUE GmbH & Co. KG
Concrete pavements in highway construction have many advantages, including strength and durability. To ensure this, however, a soft nonwoven fabric is required beneath the hard pavement. The use of NAUE Secutex® concrete nonwoven on the A4 near Kirchheim in Germany exemplifies this roadway-improving application.
The A4 autobahn was completely renovated between the Kirchheim junction and the Bad Hersfeld exit. It was widened from four to six lanes and a hard shoulder was added. A special feature of the 6-km-long section was the rehabilitation of the Asbachtal Bridge. Built from 1938 to 1942, the viaduct with its distinctive limestone base structure was preserved and given a new superstructure. Because the pavements were widened from 9 to 14.5m, they now cantilevered almost 5m over the old bridge structure. The pavement was constructed with concrete, due to the high volume of traffic. Concrete pavements require longitudinal and transverse expansion joints (in contrast to asphalt). Water can infiltrate through these and damage the substructure at the interface between the road base and the concrete pavement.
To avoid damage and erosion by water penetrating into the structure, NAUE Secutex® R 501 is the special concrete nonwoven fabric that was used on the A4. It is made entirely of polypropylene (PP) and is resistant to the alkalis present in cement concrete. Additional defined properties are, for example, the behavior under load, the minimum strength and the extensibility and, of course, the drainage and filter properties.
A total of 64,000m² of NAUE Secutex® R 501 was professionally installed directly under the concrete. These nonwoven fabrics are capable of conducting water in their plane (in accordance with the German ZTV Beton-StB 07 and TL Beton-StB 07). The benefits are:
• Complete separation between base layer and concrete
• "Soft" buffer between base layer and concrete and, thus, a softer bearing layer
• Drainage of penetrating liquids
• Prevention of erosion in the road base, in particular in the area of the joints
• Prevention of crack propagation in both directions, both from the joint into the base layer and from the base into the concrete pavement