Sustainable sandwich panels from upcycled aluminium cans, galvanised steel, and biobased adhesive

This study explores the design of sandwich panels using recycled aluminium can rings as the core material. The panels are also made with galvanised steel face sheets and a plant-based castor oil adhesive. To assess different configurations, two core architectures (cubic and hexagonal) are investigated, and the steel face sheets are tested both with and without sanding treatment to increase the roughness of the bonding surfaces. The structural properties of the panels are characterised using three-point bending tests, following the ASTM standards C393 and D7250, as well as the RJS Method (an approach to measure the homogenised flexural modulus of sandwich structures). Optimal results are obtained for the hexagonal packing for the core architecture associated with skins without sanding: a maximum load of 415 N, representing a maximum bending moment of 38.4 N·m and a mean homogenised flexural modulus of 2143 MPa, demonstrating a viable and sustainable method for using aluminium cans as a core material for secondary structural applications in the construction and transportation industries. Failure analysis reveals that core–skin debonding is the primary cause of structural collapse. This indicates that interfacial adhesion is the critical design constraint for these recycled-aluminium sandwich panels.