Comparative Study of Lightweight Concretes Based on Hemp and Flax Straw

Abstract The article presents the results of a study involving the properties of flax and hemp-based lightweight concretes as well as the initial characteristics of different straw-based materials. A comparison of straw-based lightweight concretes with and without ordinary Portland cement (OPC) showed that hemp concrete has a 5.6 % higher strength at a 10% deformation, and at the same time, has a 13% greater thermal conductivity coefficient than flax concrete. The physical-chemical study based on a thermal analysis in an air environment has shown that the overall picture of thermal degradation for flax and hemp concretes is similar. Nevertheless, additional peaks of mass loss have been defined for flax concrete. The demonstrated exothermal process is a positive aspect, considering the life cycle of the material and the recycling stage. The paper proposes reference points for the development of new building materials based on straw.