3D printing plastic formwork can transform concrete construction and enable the production of individual freeform concrete structures quickly and cost-effectively, minimizing construction waste and labor. The degree of geometric complexity a concrete element can assume is directly linked to our ability to fabricate its formwork. Additive manufacturing can facilitate complex freeform geometries and expand design solutions for concrete elements. In particular, fused filament fabrication (FFF) 3D printing of thermoplastic, which was used to produce the formwork of the exhibited columns, is a useful method for fabrication due to the lightweight properties of the resulting formwork and the accessibility of FFF 3D printing technology. The performance of 3D printed formwork and its geometric complexity varies, depending on the type of plastic used for 3D printing the formwork and the printing technology. 

PLA (Polylactic Acid) is a common plastic material in the 3D printing industry, being both biodegradable and produced from renewable, organic starches. PVA (Polyvinyl Acetate) is a water-soluble synthetic polymer often used for support material on complex 3D prints due to its ease of removal when in direct contact with water. . Due to its high sensitivity to moisture, PVA requires airtight storage. Because of the material’s sensitivity, PVA can clog the nozzle of a 3D printer. PETG (Polyethylene Terephthalate Glycol) is a thermoplastic copolyester with high chemical resistance, durability, and ductility. It is also fully recyclable.

The design and fabrication of the three concrete columns exhibited investigated different plastics, including PLA, PVA, PETG, and the combination of PLA-PVA as a formwork material. Ultimately, this research primarily used PVA to directly 3D print the formwork parts. The three columns showcase the degree of geometric freedom achievable in concrete formwork when printing with different materials—namely PLA, PVA, and PETG—and using different 3D printing techniques—robotic fused granulate fabrication (FGF) and fused filament fabrication (FFF) cartesian machines.