A multi-scale analysis of hemp-based insulation materials

Abstract

Biobased materials are increasingly used for building insulation. Hemp concrete (mix of hemp aggregates and mineral binder) is an efficient thermal insulation material containing renewable resources. It provides also comfort in habitation thanks to its acoustical and hygrothermal properties. In this study, two hemp concrete “wall” formulations are manufactured with one type of hemp shiv and two commercial binders: a rapid setting natural cement and a formulated binder based on lime. 90 days of curing ensures the hardening of the materials. The influence of binders on the microstructure and its relation with functional properties is investigated in this paper. Similar behaviors in thermal conductivity, acoustical performances and hygroscopic properties are observed for the two binders. No differences are measured through porosity, which can explain the similar functional properties behaviors as they partly depend on porosity. Both formulations have low compressive strength compared with hemp concretes in literature. This could be due to the shiv extractible compounds that impact the hydration of the mineral binders.