2007 - Denmark - Optimized Thin Layers for Highways

There is a great need for durable noise reducing pavements for highways. The concept for noise reduction is to create a pavement texture, with big cavities at the pavement surface in order to reduce the noise generated from air pumping, and ensuring a smooth surface so noise generated by vibration of the tyres will not be increased. Open textured pavements are open only at the upper part and are not expected to need special winter maintenance. European experiences with thin layers have been further developed. Four different pavement concepts are used: Open graded asphalt concrete (DAC-open), Stone Mastics Asphalt (SMA), a thin layer constructed as an UTLAC (Ultra Thin Layer Asphalt Concrete), and semi porous pavement (PAC). In 2006 10 optimized thin layers were laid on a Danish highway near Herning. Maximum aggregate sizes were in the range of 6 to 8 mm. Dense Asphalt Concrete with 11 mm maximum aggregate size is a reference pavement. The results from the first series of SPB noise measurements are presented in this paper.