Acoustical and Mechanical Impedance Measurements of PoroElastic Road Surfaces
Invited paper
UAntwerpen
Tuesday 2 june, 2015, 17:40 - 18:00
0.2 Berlin (90)
Abstract:
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.