347 6th International Conference on Materials Science and Restoration, MSR-VI Aedificatio Publishers 347–358 (2003) Acoustic properties of sound absorbing, poly- mer-modified porous cement mortars 1 E. Knapen, 2 R. Lanoye, 3 G. Vermeir, 3 W. Lauriks and 1 D. Van Gemert 1 Reyntjens Laboratory, Department of Civil Engineering, K.U.Leuven 2 Aspirant van het Fonds voor Wetenschappelijk Onderzoek – Vlaanderen 3 Laboratory of Building Physics and Laboratory of Acoustics, K.U.Leuven Abstract This research aims at the development of granular, porous materials, to be used in combination with floor or wall panels, as sound absorbing elements. The paper describes the frequency dependent sound absorption of porous mortars, with open porosity up to 40 %. Polymers are used to provide the necessary cohesion and mechanical properties. The polymer/cement ratio is shown to have no influence on the sound absorption quality, due to the small influence on the flow resistivity. This type of sound absorbing materials may contribute to a sustainable construction development and to the improvement of acoustical 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.