Closed-loop valorisation of glass fibre reinforced plastic waste

The primary objective of this study is to investigate the feasibility of fully replacing aluminium trihydrate (ATH) with glass fibre reinforced plastic (GFRP) waste dust in resin-based composite formulations while ensuring mechanical integrity, fire performance, and impact resilience. For the first time, ATH was substituted with GFRP waste, and the composites were comprehensively assessed. Viscosity increased due to the heterogeneous and complex particle size distribution of GFRP waste, as confirmed by scanning electron microscopy and particle size analysis. Despite this, the optimised formulation R²₁₀₀ retained properties very close to the control (R₀), with a tensile strength of 118.56 MPa (95% retention), a cross-breaking strength of 188.04 MPa (98% retention), and an interfacial shear strength of 32 MPa (91% retention). Fire testing confirmed compliance with industrial safety benchmarks, achieving a Limiting Oxygen Index (LOI) of 29, a smoke density of 260 Ds, and a toxicity index of 5. Finite element analysis of laminate was carried in accordance with ASTM D7136 boundary conditions, revealed comparable stress distributions and dent depths for both ATH- and GFRP-based formulations. This unique substitution underscores the industrial viability of GFRP waste as a sustainable alternative filler, aligning with circular economy principles. Sustainable Composite Development using glass fibre reinforced plastic (GFRP) waste dust.Mechanical Performance of optimised formulation offers comparable mechanical properties in response to ATH-based control formulation.Finite element analysis confirms that use GFRP waste instead of ATH does not compromise the impact resilience.Fire Safety Compliance is achieved.Supports circular economy by valorising GFRP waste in composite manufacturing with TRL 8 for industrial adoption. Sustainable Composite Development using glass fibre reinforced plastic (GFRP) waste dust. Mechanical Performance of optimised formulation offers comparable mechanical properties in response to ATH-based control formulation. Finite element analysis confirms that use GFRP waste instead of ATH does not compromise the impact resilience. Fire Safety Compliance is achieved. Supports circular economy by valorising GFRP waste in composite manufacturing with TRL 8 for industrial adoption.