Novel sustainable hemp-based composites for application in the building industry: Physical, thermal and mechanical characterization

In this study, novel hemp-based composite materials, designed for building application as components of a multi-layer wall plug for concrete, steel or wood structures, providing both thermal insulation and physical-mechanical resistance, are presented and characterized. Composite panels were produced by bonding hemp hurds with a novel hybrid organic-inorganic binder. The panels were then characterized in terms of physical-microstructural properties (bulk density, water absorption, swelling in thickness and weight loss after immersion in water, microstructural features by means of scanning electron microscope and stereo optical microscope observation), thermal properties (thermal conductivity, reaction to fire) and mechanical properties (compressive strength, flexural strength, tensile strength, resistance to axial withdrawal of screws). The panels exhibited promising physical, thermal and mechanical characteristics, generally comparable to those of commercially available products. In addition, the novel composites have the advantage of a significantly low environmental impact (thanks to the nature of both the dispersed and the binding phase) and no negative effects on human health (contrary to many commercial materials, responsible for emission of formaldehyde). All things considered, the novel composites seem like very promising materials for application in the building industry. Further tests to assess the physical-mechanical durability of the panels are currently in progress.