Acoustical and Mechanical Impedance Measurements of PoroElastic Road Surfaces
Tuesday 2 june, 2015, 17:40 - 18:00
0.2 Berlin (90)
Different test sections of PoroElastic Road Surfaces (PERS) have been constructed in 2013 and 2014 as part of the European Project PERSUADE. In this paper measurement results of the acoustical and mechanical impedance of the Belgian test sections will be compared to the results obtained in Denmark, Sweden, Slovenia and Poland, and with measurement results found in literature. A small test section has been in place at the Belgian Road Research Center since October 2013 and a larger (140 mē) test section was installed at a regional road in Herzele in September 2014. Both the acoustical absorption and mechanical impedance (or dynamic stiffness) of the pavement contribute to the noise reducing capabilities of this experimental road type. The high absorption coefficient, compared to conventional pavements, such as dense asphalt concrete or stone mastic asphalt road surfaces, is caused by the high air void content, similar to (two-layer) open porous asphalt. The main noise reducing aspect however is the fact that the stiffness of the road surface is almost equal to the stiffness of standard tyres, drastically reducing tyre vibrations and hence the tyre/road noise. This lower dynamic stiffness is obtained by using rubber particles mixed with stone and sand, and bound with polyurethane. The acoustical absorption coefficient will be measured on the actual test sections (limited to 1800 Hz using a 100 mm impedance tube), as well as in laboratory conditions on slabs or cores which were fabricated on site together with the test sections (limited to 6300 Hz using a 30 mm impedance tube). The mechanical impedance will be measured using an impact hammer and accelerometer.
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