4D formwork for robotic concrete spraying

Abstract

Globally, concrete is the second most used material after water. On average, three tons of concrete is consumed per person per year, while each ton of concrete added to the atmosphere contributes one ton of greenhouse gases. Because of this negative environmental impact, research institutions, architects, and construction professionals seek to reduce concrete usage in the built environment. Materialoptimized structures offer one approach; however, such structures often require custom-made formworks that are disposed of after a single use and are thus expensive and waste-generating. Recently, several unconventional solutions for formwork have emerged that produce material-optimized structures without generating significant waste, including the examples of lost-, stay-in-place, and dynamicformworks. This paper examines 4D-printing technology, which is tested in terms of scalability to produce a building component through fiber-reinforced concrete (FRC) spraying. With an empirical study, we evaluate two different 4D-printing techniques: 1) textile 4D-printing and 2) thermoplastic 4Dprinting, both enabling the production of self-shaping, lightweight textile formworks. Furthermore, we present the first prototypical results and discuss the challenges and next steps for 4D-printed formworks that promise a more sustainable use of concrete.