Sustainable Bio-Epoxy Fabric-Reinforced Composites for Structural Insulated Panels

The adoption of sustainable construction materials in the building sector is increasing, driven by global net-zero targets, regulatory pressures, and growing demand for low-carbon and resource-efficient construction. In this context, this research investigates the feasibility of using bio-based fibre-reinforced epoxy resin composite laminates with recycled polyethylene terephthalate cores in structural insulated panels (SIPs) as an alternative to conventional SIP systems. Laminates were fabricated via a wet layup method using two epoxy resins and five fabric types, including flax, hemp, and recycled PET fabrics. Tensile and flexural testing revealed that hemp fabric paired with a fully bio-based epoxy provided the optimum combination of strength and elastic modulus. Small-scale SIP prototypes utilizing optimum laminate and rPET cores were tested for edgewise compression and flexure against expanded polystyrene (EPS) equivalents. The rPET SIPs demonstrated compressive and flexural capacities two to three times greater than the EPS panels. These findings demonstrate the potential of sustainable fabric-reinforced epoxy resin composite SIPs for specialized high-performance construction applications where enhanced structural capacity and sustainability are required. Although further work is needed to address cost, fire performance, and scalable manufacturing, the proposed system presents a promising alternative for next-generation sustainable building systems.