Strength, structure, and sustainability in 3D-PrintedConcrete using different types of fibre reinforcements

Steel fibres significantly enhance the mechanical performance of 3D-printed concrete, with studies reporting compressive strengths up to 111 MPa, an increase of 17to29% over non-reinforced mixes and flexural strength improvements of up to 282%. Optimal fibre alignment, typically within 0° to 40° of the printing direction, further boosts load-bearing capacity and contributes to post-fire ductility. Glass fibres and synthetic reinforcements (e.g. polyvinyl alcohol, polypropylene) also yield notable flexural gains, such as peak loads of 7.56 kN at 1.0% glass content, while enhancing inter-layer bonding. Integration methods, including fibre dispersion and textile layering, support sustainability by reducing material use (up to 80%), construction waste (by 30 to 60%), and CO emissions through optimised mix designs and lower cement content. These findings confirm that fibre type and orientation critically influence both structural performance and the environmental sustainability of 3D-printed concrete across the building life cycle