Saltwater Immersion Effects on Bio-Composites Reinforced With Seashell Powders

The valorization of marine biogenic waste, particularly calcium carbonate derived from mollusk shells, offers new opportunities for sustainable material development; however, investigations determining their mechanical and microstructural properties remain limited, especially under degradation conditions such as those encountered when these materials are exposed to seawater environments. This study investigates the integration of powders from mussel, oyster, and clam shells collected from the Adriatic Sea into a bio-epoxy resin matrix to assess their potential as functional fillers. The samples were subjected to simulated seawater immersion (for 7 days in salt water with a concentration of 35 g/L of NaCl at room temperature) to evaluate their mechanical, colorimetric, and morphological properties after environmental conditioning. Key findings include variations in water absorption, Shore D hardness, and tensile performance across different shell powders, highlighting the influence of biogenic species on composite behavior. Colorimetric analysis revealed slight discoloration post-immersion, more limited on clam shell powder composites, while mechanical tests indicated enhanced performance in those including mussel shell one. These results underscore the potential of mollusk shell powders as eco-friendly additives in bio-composites, paving the way for applications in marine environments and promoting circular bio-economy practices. Future studies will focus on biofouling resistance and long-term durability under real-life conditions.