Lab-scale processing of waste airbags for the development of fibre-reinforced geopolymer composite

The number of end-of-life vehicles increases every year, the processing and recycling of their parts poses an issue that should be addressed. Geopolymers are alternative binders that have emerged as a novel and eco-friendly material type, which have many advantageous properties, and their brittle nature can be improved with the addition of various fibres. During the research, waste airbags were processed to obtain fibres for the production of fibre reinforced geopolymers. The rheology of the geopolymer pastes, the flexural and uniaxial compressive strength, the specimen density and the structure of the fibre reinforced geopolymers were investigated. All geopolymer pastes exhibited Bingham plastic behaviour, but the relative yield stress grew exponentially with increased fibre addition. The flexural strength of the specimens could be increased significantly by over 150% with 3 wt.% fibres, from a relatively low value of 0.42 MPa up to 1.11 MPa. The initial 16.58 MPa uniaxial compressive strength decreased slightly after 2 wt.% fibre addition, reaching 13.73 MPa as the lowest compressive strength with 3 wt.% fibres which is still appropriate as a waste-based product. The positive effect of fibre reinforcement on the fracture behaviour and microcrack propagation could also be observed. • Fibre reinforced geopolymers were prepared from fly ash and waste polyamide fibres • Polyamide fibres were mechanically prepared from waste airbags • Fibre addition significantly increased the relative yield stress of the pastes • FRGPs exhibited improved flexural strength and microstructural properties