Evaluating and understanding the acoustical properties of biobased materials

Abstract

Biobased (porous) materials are key solutions to deal with current environmental issues in buildings and other fields. Many studies cover the topic of their performances today, but these studies do not systematically account for the specificities of biobased materials. The goal of this presentation is to make a global review of the acoustical properties of these new materials, and to present an adapted demarch to characterize, model and optimize their performances. Two kind of biobased materials will be principally discussed, fibrous (wools) and granular (loose particles and concrete). The fibers/particles can come from hemp as well as flax, sunflower, colza, miscanthus, and kenaf cultures. In all cases, the final materials (wool, board, concrete, ...) present specificities in comparison with conventional ones. These include a mulitscale porosity, a wide distribution of fiber/grain size, a strong anisotropy and a hygroscopic behavior. These specificities have to be taken into consideration, during the characterization process but also during the modelling step by choosing a suitable model in agreement with the effective microstructural dissipation. This presentation will start with a global review covering last decade publications on the topic, where the different kinds of materials will be classified and analyzed. Then, general guidelines will be proposed on the basis of previous works to handle with these
materials acoustical properties. Finally, the different possible ways to optimize these properties will be highlighted with various examples of application.