Acoustical dissipation in biobased granular packings

Biobased building materials have many advantages, including local availability and functional performance in terms of mechanical, acoustic and hygrothermal properties. Besides, the biobased solutions coming from plants that uptake CO2 during their growth, are good opportunities to reach carbon-neutral building construction. However, mastering their acoustical performance still raises a number of questions directly linked to their microstructure, which is characterised by a high degree of porosity spread over several scales. The work presented here aims to highlight the effect of the porosity distribution in biobased granular packings on their acoustical performances. Several plant aggregates are considered, such as hemp shiv, sunflower pith or reed as a function of their density and water content. Characterizations are performed in normal incidence and compared to fluid equivalent modellings based on various assumptions, to analyze the effective contribution of the various types of pores at the aggregate level, and between the aggregates.