Design and Fabrication of a Non-standard, Structural Concrete Column Using Eggshell: Ultra-Thin, 3D Printed Formwork

Abstract

This paper describes the design and fabrication process of a concrete column cast in ultra-thin, 3D printed formwork, using a process known as Eggshell. The column was prefabricated as part of a real-world construction project, serving as the main load-bearing element for a reciprocal timber frame structure. The fabrication of the column required upscaling of the Eggshell process, to allow for the fabrication of elements of an architectural scale. Furthermore, several challenges had to be addressed such as: integration of reinforcement, establishing the formwork design space, and scaling up the 3D printing process. For the production of the final column a 1.5 mm thin formwork was 3D printed, after which it was combined with a prefabricated reinforcement cage and filled with concrete in a set-on-demand casting process. The successful realization of the project provides a first example of a full-scale building element produced with the Eggshell fabrication process. By 3D printing the formwork, geometrical freedom in concrete construction is greatly expanded, as well as formwork waste reduced.