Spent mushroom substrate boards for indoor applications

Spent mushroom substrate (SMS) from Pleurotus Ostreatus represents a challenging waste resource for recycling, as its potential use as a soil fertilizer is more limited than that of spent substrates derived from other mushroom species. In this context, the present work explores a novel and straightforward approach based on the direct use of Pleurotus Ostreatus SMS, without any pre-treatment or additional processing, for the development of bio-based boards. The study consists of the characterization of the raw material, the definition of a hot-pressing process, and the evaluation of hygrothermal, acoustic and mechanical properties of the produced boards. The aim is to provide a global characterization to investigate possible applications in building practices. The results demonstrate that the porous structure of the raw material and the production process deeply influenced the boards’ properties. The boards show densities between 292 and 485 kg/m³ , thermal conductivity less than 0.070 W/m · K, good moisture buffering capacity (MBV > 2 g/(m² %RH)), and promising acoustic performance. Furthermore, the proposed bio-composite guarantees low environmental impact, as it is derived from agro-industrial wastes, in line with the principles of the circular economy.