A review of the factors affecting the properties and performance of hemp aggregate concretes

New energy-efficient materials are increasingly used in architecture and civil engineering today. Many of these are based on the reuse of plants and plant residues from industry and agriculture for the production of bio-sustainable insulation materials, and as aggregates in concretes. This paper presents the results of our study of research into hemp concrete, an emerging material in the green building sector, since it first appeared about twenty-five years ago to the present day. The study centres on a growing bibliography over this period, emphasizing some fundamental parameters of hemp raw materials and related building materials, the binders used in the production of hemp aggregate concretes and assessments of different aspects of their performance. The most important properties of hemp concrete vary according to the quality of the plant aggregates, the choice of binders (typically aerial or hydraulic lime), the proportions of the raw materials and the application techniques. Organic aggregates are less stable than inorganic aggregates and are therefore more difficult to use in a concrete mix with both inorganic and organic binders. Among other reasons, this is due to the disproportionate amount of water required in the mixing of plant-based concretes and to the release of organic compounds, which can have serious effects on the hardening process. This problem was identified in scientific studies on the use of hemp concrete in sustainable, bioclimatic construction, whether applied as a semi-liquid mass or as a precast element. This new biomaterial offers excellent results in terms of its application on site and has important physical properties, such as high durability and easy conservation. This study seeks to provide a useful tool for future research into sustainable building materials, better use of available energy and plant-based resources and more efficient recycling of the waste produced by human activities. © 2020 Elsevier Lt