Development and characterization of mycelium-based biocomposites from Ganoderma lucidum using spent yerba mate and residual sunflower oil for sustainable insulation in construction

Abstract

The construction industry urgently requires sustainable alternatives to petroleum-based insulation materials such asexpanded polystyrene (EPS) and mineral wool. Mycelium-based biocomposites offer a promising solution by valorizingagricultural waste while delivering competitive thermal and acoustic performance. In this study, developed and characterized biocomposites using Ganoderma lucidum mycelium combined with spent yerba mate and residual sunfloweroil (70 g/30 mL), both commonly generated as waste in Argentine institutions. Two formulations were evaluated: highdensity (HD: 280 ± 5 kg/m3) and low density (LD: 185 ± 5 kg/m3). Samples were cultivated for 90 days at 28 °C and 65%relative humidity and tested following ASTM and IRAM standards. Results showed strong thermal insulation properties,with HD composites achieving a conductivity of 0.031 W/m·K, comparable to EPS and better than mineral wool. Thermalresistance reached 0.967 m2·K/W at 3 cm thickness. Acoustic absorption coefficients were 0.388 ± 0.019 (HD) and 0.688± 0.022 (LD) across 100–4,000 Hz. Mechanically, HD composites exhibited compressive and flexural strengths of 0.226± 0.056 MPa and 0.385 ± 0.081 MPa, respectively, while LD showed lower values. Both formulations demonstratedself-extinguishing behavior (V-1 classification) without flaming drips. Contact angle analysis revealed hydrophobicityin HD and hydrophilicity in LD. These results demonstrate that controlling density allows tailoring the balance betweenmechanical resistance, moisture response, and insulation properties in Ganoderma lucidum-based composites producedfrom agricultural residues.