Acoustic characterization of different road materials

Pavements that produce less noise at the tire/pavement interface represent an important strategic solution necessary to minimize the traffic acoustic impact. Several studies have shown how the most important parameters affecting tire noise are associated with the road surface that influences both the generation and propagation of sound waves. On this subject, the Italian National Road Agency (ANAS) sponsored a research project related to quiet pavements. The project was developed by Università Politecnica delle Marche based on a trial section where different kinds of wearing courses were laid down. The selected materials were a Splittmastix Asphalt (SMA), an Open Graded Friction Course (OGFC) and a dense graded asphalt containing Expanded Clay (EC). Furthermore, two sub-sections of SMA and of OGFC were covered respectively with a Slurry Seal with dry addition of Crumb Rubber (SSCR) and a Photocatalytic cement Mortar (PM), obtaining five different materials to be tested. In this paper the Authors present preliminary results, analyzing the acoustic characterization of the selected materials in terms of absorption coefficient. Moreover, in situ noise measurements have also been repeated at different stages in order to find possible correlations with acoustic properties of the mixes and to investigate the time dependency of the performance.