Towards a better understanding and knowledge of biobased materials through a new acoustic database
In this work, the acoustical performances of building elements including natural sustainable fibrous and granular materials have been evaluated to create a new database. These characterisations have been carried out at two scales. On the one hand, the physical parameters of the considered biobased materials have been characterised in Cerema laboratory at the material scale; the sound absorption and transmission loss were mainly obtained in normal incidence from Kundt tube measurements, following the three microphones method. On the other hand, measurements have been performed in CSTB facilities in diffuse field conditions to characterise the acoustical performances (sound absorption, airborne sound insulation) of larger scale elements.
The parameters evaluated at the material scale have then been injected into a prediction software in order to predict the acoustic performance of the building elements. In the present case, the CSTB software AcouSYS based on a transfer matrix approach and integrating a spatial filtering method to take into account the finite size of building systems and a coupling with a SEA approach to take into account structural paths, has been mainly used.
Several types of biobased materials have been considered, including wood, cotton and hemp wools, but also hemp concretes and cellulose wadding. The acoustic performance of building elements including biobased fibrous materials are compared to similar ones including more standardly used material such as mineral wool.