Morphological and physico-mechanical properties of mycelium biocomposites with natural reinforcement particles

Abstract

Mycelium biocomposites represent a potential sustainable lightweight alternative materials due to their low energy consumption and lack of pollution to the environment. However, the low compression strength of mycelium biocomposites limits its application. In this study, three fungal strains (Pleurotus ostreatus, Oudemansiella radicata, and Acremonium sp.) were incubated in substrates (cotton stalk, wheat bran, and natural reinforcement particles (NRPs)) to obtain mycelium biocomposites. The physico-mechanical properties, morphological properties, and thermogravimetric analysis were examined. The colonization periods of the mycelium biocomposites varied with the different fungi, and adding NRPs to the substrates obviously improved the physico-mechanical properties of the mycelium biocomposites. The Pleurotus ostreatus biocomposites with 37.5% NRP had the highest UCS strength of 508 kPa and Young’s modulus of 38.5 MPa, which satisfies the requirements of backfill materials in geotechnical engineering, and its cohesion and internal friction angle were 178 kPa and 21.8°, respectively, based on triaxial tests. Moreover, although the addition of NRP will increase the density of the material, the density of mycelium biocomposites with NRP (0%–37.5%) only ranged from 0.310 g/cm3 to 0.413 g/cm3. The water absorption characteristics of the mycelium biocomposites with NRP were similar to those without NRP. The permeability coefficient decreased slightly with increasing NRP content, and the decreased percentage was related to the mycelium growth. All mycelium biocomposites showed lower thermal stability but a higher residue mass than EPS (expanded polystyrene). The results illustrate that the mycelium biocomposites proposed in this study could be used as lightweight backfill materials that are widely needed in geotechnical engineering.