Self-Organized Mycelium-Based Biocomposites for Sustainable Buildings: From Structure to Fracture and Toughening Mechanics

This work presents the results of a combined experimental and analytical study of the structure and fracture/toughening of bioprocessed mycelium composites. The mycelium composites are reinforced with self-organized cellulose/hemicellulose hemp ducts and varying laterite proportions. In-situ studies of crack growth are used to provide insights into the underlying toughening mechanism that gives rise to resistance-curve behavior. The crack-tip shielding contributions from the observed crack bridging and crack deflection mechanisms are then quantified using fracture mechanics models. The results show that toughening is dominated by crack-bridging at low volume fractions of laterite (≤ 20%), while a combination of crack-bridging and crack deflection is observed to occur at increased laterite volume fractions (20 – 60 %). Finally, toughening is shown to occur predominantly by crack deflection at higher volume fractions (≥ 60 %). The implications of the results are discussed for the microstructural design of mycelium and mycelium-laterite composites for potential applications in sustainable buildings.