Experimental Investigation on Surface Performance and Acoustic Absorption

Porous European mixes and open-graded friction courses are wearing courses with well-known advantages in terms of noise reduction due to the balance between generation factors (surface texture) and absorption properties. Unfortunately, noise-oriented mix design still calls for further research and the relationship between composition and acoustic performance is mainly unknown. Consequently, the objective of this paper was to study the relationship between acoustic absorption coefficient and pavement surface performance (surface texture and drainability). The acoustic absorption coefficient was measured according to the ISO 13472-1. Acoustical absorption coefficients were analysed by taking into account contract specifications and requirements. Surface texture was investigated according to the standards ISO 13473-1; ISO/CD TS 13473-4; ISO 13473-3. In order to assess the overall state of the surface, also drainability was measured in the same points. Results were compared and analysed in terms of averages and standard deviations, studying in-depth how acoustic absorption properties vary as a function of surface texture and drainability, for a given friction course. A theoretical framework based on texture and acoustic properties was formulated. Results showed that the maximum acoustic absorption (f = 800-1000 Hz) was well correlated with drainability and Sand Height; some texture indicators (profile-based) resulted well correlated with several parameters derived from acoustic absorption spectra and/or macrotexture performance