Sound absorption by polymer-modified porous cement mortars: Fid-Bau Portal

Sound absorption by polymer-modified porous cement mortars

Knapen, E. / Lanoye, R. / Vermeir, G. / Lauriks, W. / Gemert, D. van

This research aims to provide a theoretical background for the development of granular, porous materials to be used in combination with floor or wall panels, as sound absorbing elements. The acoustic model of Biot-Johnson-Allard for predicting sound absorption of porous materials is applied to polymer-modified porous cement mortars with an open porosity up to 40 %. The theoretical model uses several material parameters to predict the acoustic behaviour: the porosity, flow resistance, tortuosity and characteristic viscous and thermal length. The conventional test procedures are adapted to measure these parameters. The model of Biot-Johnson-Allard is found to deliver a very strong similarity with the measured absorption coefficient. This theoretical model can be used to study the influence of the material parameters on the acoustic behaviour and to develop granular sound absorbing surfaces having high sound absorption values for a broad frequency range. Polymers are added to the fresh cement paste to provide the necessary cohesion and mechanical properties. The polymer/cement ratio seems to have no influence on the sound absorption quality, due to the small influence of the flow resistance. This type of sound absorbing materials may contribute to a sustainable construction development and to an improvement of acoustic conditions. This will allow to reduce sound propagation in interior spaces or to improve the control of outdoor noise propagation by use of sound absorbing screens. The analysis is valid for sound absorbing road surfaces as well.