Physico-chemical Characterization and Development of Hemp Aggregates for Highly Insulating Construction Building Materials

The natural hemp aggregates and their bio-composite panels which have been developed for sustainable construction with low thermal conductivity and high hygrothermal efficiency. The combination of the hemp aggregates with natural matrix materials results in exceptionally low thermal conductivity and high hygrothermal efficiency compared to conventional materials of construction as a result of their microporosity and breathability. In addition, the developed bio-based composites with nanotechnology improve resistance to liquid water and protect the hemp shiv from biodegradation without impacting the natural ability of the shiv to buffer moisture vapor. The chapter assesses the physical characteristics of hemp aggregates in terms of their density, microstructure and porosity. Hemp-concrete and novel Hemp-organic composite have been studied and compared. Measurements of the thermal conductivity of hemp-composite panels are described which confirm their highly insulating properties. Hygroscopic testing demonstrates their effectiveness in absorbing and releasing moisture. The thermal and hygroscopic performance of hemp-composite panels in test cells is reported together with their application in construction. The life cycle assessment of hempcrete and hemp organic composite were performed. This chapter is part of the output of the ISOBIO programme supported by the European Union Horizon 2020 program, within the ‘Materials for Building Envelopes’ call for Energy Efficient Buildings