Mechanical and thermal properties of lime and hemp concrete (“hempcrete”) manufactured by a projection process

Concrete blocks, made of a mixture of lime and hemp shives (also called “hemp hurds”), have been manufactured by a recently developed projection process. Lime carbonatation kinetics is determined by X-ray diffraction. Density measurements are made within blocks, and thermal and mechanical properties are measured (flexural strength, compression strength and hardness). The main observations are moderate density variations within a given block, and an influence of the projection distance on density. Both thermal conductivity and mechanical properties increase with the mortar density, which is well described by existing theoretical models. Compression tests induce a compaction, or densification, of the material.