Circular Formwork: Recycling of 3D Printed Thermoplastic Formwork for Concrete

Concrete construction is one of the largest producers of CO2 emissions and waste from discarded formwork. 3D printing of formwork using polymer extrusion 3D printing can increase the sustainability of concrete construction by allowing the fabrication of optimized geometry. However, polymer extrusion printed formwork must be discarded after being used several times. Therefore, this paper explores the potential of recycling 3D printed formwork. We describe a workflow in which a formwork is 3D printed, filled with concrete, removed, recycled, and reprinted into a new formwork. Two case studies are presented: filament-printed PET-G formwork for a concrete column, and pellet-printed PIPG formwork for a series of columns. The results indicate that the printing material can be fully recycled for at least one cycle.