Natural additives as reinforcement for mortars: Comparative evaluation of gypsum-based plasters with pistachio shells and orange peels

This research explores the use of waste from agriculture and food production (agro-food waste) as a green additive in building gypsum plasters. The focus is on lightweight mortars made with bio-based materials, aiming for a solution that aligns with green building principles and circular economy practices. Current research prioritizes examining the physical and mechanical properties of these bio-based mortars. These mortars often have high porosity and lower weight, making them good thermal insulators and sound absorbers. While not yet widely used in construction, they hold promise as a sustainable alternative with performance comparable or even exceeding conventional plasters in thermal and acoustic insulation. In particular, the cultural premises of this study refer to the shared identity between Sicily and Tunisia, focused by a recent strategic cross-border cooperation project CUBÂTI, Culture du bâti de qualité: recherche, innovation et entreprise pour la durabilité, funded by Italy-Tunisie Programme 2014-2020. In fact, the present experimental research has focused on two materials easy to find in these countries, applying a replicable method to other regions in the Mediterranean area. In this study, the performances of gypsum-based plasters with pistachio shells and orange peels as additives were evaluated. Several tests were carried out on the developed materials to optimize their mix design, verify their mechanical and physical properties and the results of the comparative investigations showed interesting results in terms of mechanical resistance, thermal conductivity and reduction of water absorption.