Design and fabrication of optimised ribbed concrete floor slabs using large scale 3D printed formwork

•Developed a design-to-fabrication workflow for optimised ribbed concrete floor slabs.•Fabricated an optimised 2.7×2.7m reinforced concrete floor slab.•Achieved a material reduction of up to 40% compared to a flat slab.•Demonstrated the potential of 3D printed formwork for ribbed concrete floor slabs.