Sustainable epoxy composites incorporating Aloe Vera and fly ash for bio derived reinforcement and circular economy advancement

Abstract This study presents the development and characterization of epoxy-based composites reinforced with Aloe Vera powder and Flyash, advancing circular economy objectives through the valorization of bio-derived and industrial waste fillers. Composite specimens were fabricated with two particle size ranges (38–53 μm and 75–90 μm) at varying reinforcement-to-matrix weight ratios (10:90, 20:80, 30:70, and 40:60). Mechanical testing revealed that the unreinforced epoxy exhibited a tensile strength of 23.53 MPa and Shore D hardness of 79.3. With reinforcement, Aloe Vera composites achieved a maximum tensile strength of 45.45 MPa (an improvement of 93.2%), while Flyash composites reached 40.71 MPa (73% increase). Hardness was significantly enhanced, with Flyash-based composites recording up to 90 Shore D (+ 13.5% compared to plain epoxy) and Aloe Vera composites reaching 85.33 Shore D. Density analysis showed Flyash composites increasing to 1.396 g/cm³, whereas Aloe Vera composites reduced density to as low as 1.142 g/cm³, offering lightweight advantages. Water absorption was higher in Aloe Vera composites (up to 2.71%) due to hydrophilic properties, while Flyash composites absorbed only 1.83% moisture, ensuring better dimensional stability. Structural analysis via FTIR and XRD confirmed strong interfacial bonding and filler incorporation, while SEM micrographs highlighted uniform dispersion with finer particles, particularly at 38–53 μm, which yielded superior performance. Unlike fiber-based Aloe Vera systems, powder form enables isotropic reinforcement and simplified processing, with Flyash synergy enhancing rigidity—pioneering dual-waste upcycling. Collectively, these results validate the reinforcement potential of Aloe Vera and Flyash, achieving strength, hardness, and sustainability gains. The dual-waste valorization strategy demonstrates promising applicability for lightweight, durable, and eco-conscious composites aligned with circular economy practices.