Acoustical properties of hemp concretes for buildings thermal insulation: Application to clay and lime binders

This experimental and modelling study provides a general overview of the acoustical performance of hemp-lime and hemp-clay for building thermal insulation at the material scale. It is based on statistically robust experimental results from more than 100 hemp-clay samples, together with the analysis of a large hemp-lime database. In hemp-clay mixes, our experimental results show the concentration of hemp in a mix has a first order effect on the acoustical performance, while binder fluidity and clay type have no effect. Another conclusion of this study is that hemp-clay and hemp-lime behave acoustically in a similar way. For both materials, experimental sound absorption and transmission curves can be modelled with a physical-based four-parameters approach. The close agreement between experimental measurements and modelling highlights the good level of understanding of the physical phenomena responsible for the acoustical behavior of hemp concrete. A classification is finally proposed in terms of density to be used as a general guideline to evaluate or optimize the acoustical performances of hemp-based concrete. (C) 2017 Elsevier Ltd. All rights reserved.