Impact of a microwave treatment of hemp fibers on the hemp / cement interaction

Abstract

As the need to reduce grey energies is growing, materials such as hempcrete are in development. The thermal and acoustic insulation it offers, combined with the very low carbon footprint of hemp make it a first choice material. However, the great amount of hemp in hempcrete, combined with de weakness of the interface fibers/cement binder leads to poor mechanical resistance of hempcrete. This is due to a significant absorption of water by hemp and by components such as lignin, or hemicellulose, which slow down the setting of cement. This induces a poor transfer of the applied stress and therefore poor mechanical resistance at compression tests. Several chemical and chemical & physical treatments have been investigated to solve this problem. This study  focuses on the impact of a treatment based on a microwave heating on the properties of hemp and hempcrete. The influence of such treatment will be evaluated in terms of water absorption, index of crystallinity, halo of hydration, and mechanical properties.