Link between Acoustic and Hygrothermal Behavior of Hemp Shiv and Pith Composites

Abstract

Bio-based materials are an environmentally friendly alternative to classic construction materials, yet their generally low density can lead to poor acoustic properties. The acoustic performance of hemp shiv and sunflower pith composites is therefore analyzed using Kundt’s tube. Although the loose aggregates present an exceptional sound absorbing behavior, it can be notably worsened in the presence of certain binders. The Transmission Loss is nevertheless enhanced by the binders, although it does not exceed 20 dB in most cases. For both properties, the type of binder has been found to be the most influential parameter. Through the Kundt’s tube method, it is also possible to determine the geometrical parameters of the composites’ microstructure, which have been observed to be similar for materials presenting comparable hygrothermal properties and containing the same binder. In a previous work, an experimental correlation was found between the thermal conductivity and the interparticle porosity of the aforementioned composites, which is compared to theoretical thermal conductivity models from literature without finding any apparent correspondence.