VALORIZATION OF WASTE COFFEE GROUNDS IN SUSTAINABLE GYPSUM COMPOSITES: HYGROTHERMAL RESPONSE AND CIRCULAR ECONOMY APPROACH

This study analyses the deployment of spent coffee grounds (SPENT Coffee Grounds, SCGs) as an environmentally friendly additive in composite gypsum panels intended for sustainable building applications. Two different types of SCG were used, coming from the coffee varieties Coffea arabica and Coffea canephora (Robusta), in order to evaluate the influence of botanical composition on the physicalmechanical and thermo-hygrometric properties of the materials. Four formulations containing SCG in increasing percentages (0–15%) were subjected to experimental trials to determine compressive strength and moisture regulating ability. The samples showed a significant ability to absorb ambient moisture, attributable to the increase in porosity induced by the addition of SCG. Trials conducted in a controlled environment showed an increase in density and water content, confirming the potential of panels containing SCG to contribute to the hygroscopic regulation of indoor environments. The results indicate that the Robusta variety retains a higher amount of water than Arabica, but results in a reduction in mechanical strength. This decrease, although detectable, was found to be compatible with the performance requirements required for non-structural applications. The integration of SCGs in gypsum materials is therefore configured as a promising solution for the development of building products with low environmental impact and with advanced hygroscopic functionalities