Thermo-acoustic and mechanical characterization of novel bio-based plasters: The valorisation of lignin as by-product from biomass extraction for green building applications

Every day a wide amount of wastes is generated and landfilled, without giving them any new use. Among these wastes, biomass gathered from nature, as agricultural or forest wastes are found. From collecting and treating this biomass, a new composite can be obtained, reducing its environmental footprint. In this context, the present study focuses on the use of lignin produced from a bio-residue collected from the Trasimeno lake (Italy), to form gypsum-based plasters for building applications. Several compositions were formulated considering two types of gypsum, different in purity and mechanical strength. The goal was to maximize the lignin content in a gypsum matrix maintaining acceptable mechanical and thermo-physical performance. Lignin weight contents ranging from 0% (100% gypsum) to 100% (0% gypsum) were taken into account, considering also the proportions: 30–70%, 50–50%, 70–30%. Thermo-acoustic and mechanical characterization of these materials was carried out for the first time. Results showed that the thermal conductivity of the composites was closer to the only-lignin ones, resulting in promising thermal insulation results for building application. However, from an acoustical point of view, when increasing the lignin content, acoustic insulation decreased. In terms of mechanical performance, gypsum building plaster exhibited an improved performance with 50 and 70% lignin content, significantly outperforming all other studied gypsums.