Advanced hybrid nanocomposites for infrastructure renewal: enhanced shear and flexural performance in load-bearing applications

Glass fiber-reinforced polymer composites (GFRP) are widely used in engineering applications thanks to their high performance. This research investigates how various hybrid reinforcement techniques influence the flexural and shear performance of GFRP laminates. The composite materials were produced by integrating nonwoven glass tissues with woven glass fabrics, along with single and hybrid nanoscale fillers. Silica (SiO₂) and carbon (C) nanoparticles at different weight fractions were selected as nano-reinforcements for their cost-effectiveness. Seven composite variants were made by hand lay-up, including an unmodified GFRP reference and six hybrid configurations. Sonication and magnetic stirring methods were used to disperse nanoparticles in the epoxy matrix uniformly. Flexural performance was assessed by the three-point flexural test, while shear performance was assessed using the short beam shear and Iosipescu tests to measure both in-plane and interlaminar shear strength. When compared to the unmodified GFRP reference, samples with 0.5 wt% carbon black showed better shear and flexural performance. Hybrid reinforcement using 0.25 wt% carbon black combined with 0.25 wt% silica achieved the highest flexural strain increase (21%) and an 8% gain in flexural strength. This indicates improved ductility without compromising shear performance. However, higher concentrations of hybrid fillers negatively affect mechanical behavior.