Joris Jan Burger

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Burger

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Joris Jan

ORCID

0000-0001-6116-8091

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Publications 1 - 10 of 22

Eggshell Pavilion: a reinforced concrete structure fabricated using robotically 3D printed formwork
Burger, Joris Jan; Aejmelaeus-Lindström, Petrus; Gürel, Seyma; et al. (2023)
Construction Robotics
This paper discusses the design, fabrication, and assembly of the ‘Eggshell Pavilion’, a reinforced concrete structure fabricated using 3D printed thin shell formwork. Formworks for columns and slabs were printed from recycled plastic using a pellet extruder mounted to a robotic arm. The formworks were cast and demoulded, and the finished elements were assembled into a pavilion, showcasing the architectural potential of 3D printed formwork. The Eggshell Pavilion was designed and fabricated within the scope of a design studio at ETH Zurich. The structure was designed using a fully parametric design workflow that allowed for incorporating changes into the design until the fabrication. The pavilion consists of four columns and floor slabs. Each column and floor slab is reinforced with conventional reinforcing bars. Two different methods are used for casting the columns and floor slabs. The columns are cast using ‘Digital casting systems’, a method for the digitally controlled casting of fast-hardening concrete. Digital casting reduces the hydrostatic pressure exerted on the formwork to a minimum, thereby enabling the casting of tall structures with thin formwork. The floor slabs are cast with a commercially available concrete mix, as the pressure exerted on the formwork walls is lower than for the columns. In this research, 3D printed formwork is combined with traditional reinforcing, casting, and assembly methods, bringing the technology closer to an industrial application.
Design and fabrication of optimised ribbed concrete floor slabs using large scale 3D printed formwork
Burger, Joris Jan; Huber, Tobias; Lloret-Fritschi, Ena; et al. (2022)
Automation in Construction
This paper describes the design, fabrication, and testing process of an optimised, reinforced concrete ribbed floor slab fabricated using robotically 3D printed formwork. The design of the floor slab is based on the alignment of ribs along the trajectories of the principal bending moments. A workflow is described that generates a rib layout based on structural analysis, which is used to create a three-dimensional model of the slab. A full-scale prototype is fabricated by using an industrial robotic arm with a pellet extruder mounted as an end effector to 3D print the formwork. Reinforcement is inserted and the formwork is cast using self-compacting concrete. The successful design, fabrication, and structural testing of the full-scale floor slab prototype showed that the described workflow is suitable for realizing material-optimised, ribbed reinforced concrete floor slabs using 3D printed formwork.
Design and Fabrication of a Non-standard, Structural Concrete Column Using Eggshell: Ultra-Thin, 3D Printed Formwork
Burger, Joris Jan; Lloret-Fritschi, Ena; Taha, Nizar; et al. (2020)
RILEM Bookseries ~ Second RILEM International Conference on Concrete and Digital Fabrication
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.
Towards efficient concrete structures with ultra-thin 3D printed formwork: exploring reinforcement strategies and optimisation
Gebhard, Lukas; Burger, Joris Jan; Mata Falcón, Jaime; et al. (2022)
Virtual and Physical Prototyping
The Eggshell fabrication process combines the 3D printing of formwork with the simultaneous casting of a fast-hardening concrete. One limiting factor to reaching mass-market adoption is a suitable reinforcing strategy. In this study, a reinforcement strategy combining steel reinforcing bars with steel fibres is explored. A series of eight beams were produced using the Eggshell process or conventionally cast. The longitudinal reinforcement was provided by two reinforcing bars, and two types of fibres, either mixed with the concrete or placed and aligned between the cast concrete layers, were used as shear reinforcement. The results showed that combining conventional longitudinal reinforcement and fibres as shear reinforcement is a suitable strategy. These findings were applied to fabricate an optimised beam with a volume reduction of almost 50%. The structural performance of this beam was similar to the beam with a rectangular crosssection with the same reinforcement strategy showing the potential of Eggshell in combination with an innovative reinforcement strategy to produce material-efficient structural concrete elements.
3D printed, thin-shell concrete formwork
Burger, Joris Jan (2019)
Material-informed Formwork Geometry
Burger, Joris Jan; Wangler, Timothy; Chiu, Yu-Hung; et al. (2021)
Towards a New, Configurable Architecture (eCAADe 2021)
Fused deposition modelling (FDM) 3D printing of formworks for concrete has the potential to increase geometric freedom in concrete construction. However, one major limitation of FDM printed formworks is that they are fragile and often cannot support the hydrostatic pressure exerted by the concrete. The research project 'Eggshell' combines robotic 3D printing of formwork with the casting of a fast-hardening concrete to reduce hydrostatic pressure to a minimum. Eggshell can be used to fabricate architectural-scale building components; however, knowledge of the influence formwork geometry has on the hydrostatic pressure resistance is still sparse, resulting in unexpected breakages of the formwork. This paper presents an empirical study into the breakage behaviour of FDM printed formworks when subjected to hydrostatic pressure. Firstly, the study aims to give a first insight into the breakage behaviour of formworks with a constant cross-section by casting a self-compacting concrete into the formwork until breakage. Then, we investigate if three-dimensional patterning of the formwork can have a beneficial effect on the breakage behaviour. Finally, the preliminary results are validated through the fabrication of two full-scale columns. The empirical results point towards the fact that sharp corners in formworks are weaker compared to rounded corners. Although the presented results are still preliminary, they mark an important step in the development of reliable design and fabrication strategies using 3D printed formworks.
From Smart Dynamic Casting to a growing family of Digital Casting Systems
Lloret-Fritschi, Ena; Wangler, Timothy; Gebhard, Lukas; et al. (2020)
Cement and Concrete Research
Over the past decade innovative techniques for shaping concrete have emerged, all aiming to use less material and reduce the need for traditional formwork. One very promising method is to shape concrete dynamically: referred to as Smart Dynamic Casting (SDC), this process was pioneered in 2012 as the first robotically-driven system for slipforming bespoke concrete structures. The process has successfully been adapted to produce structures using ultra-thin formworks that are cast using our digital set-on-demand procedure. More generally we frame this approach as Digital Casting Systems (DCS), which allows the user precisely to determine the hydration rate of the material, thus eliminating formwork pressure. This paper highlights the major findings from SDC that led us to continue developing DCS. It lays out the material concepts fundamental the family of DCS, which, by eliminating the need for bulky formworks, has a large potential impact on future construction methods.
Structural design and testing of material optimized ribbed RC slabs with 3D printed formwork
Huber, Tobias; Burger, Joris Jan; Mata Falcón, Jaime; et al. (2023)
Structural Concrete
Most of the concrete volume in multi-storey buildings is cast in solid slabs, which are frequently flat slabs supported on columns. By using two-way spanning ribbed slabs, concrete consumption could be significantly reduced. However, due to the high costs associated with formwork, such a complex rib configuration is rarely used nowadays. With the advent of technologies for automated formwork fabrication, the material-saving potential inherent in this structural system could again be exploited. This paper investigates the feasibility of material-efficient ribbed concrete slabs on a building scale using conventional concrete and steel reinforcing bars cast inside a 3D-printed plastic-based formwork. To that end, the code-compliant design of ribbed slabs is first discussed, followed by the introduction of a concept for an automated design-to-production workflow. The sustainability of this slab system is compared to a solution using conventional formwork in a case study consisting of a multi-bay office building with slabs spanning 8 m in both directions, revealing that ribbed slabs use 40% less concrete than solid slabs. Several representative structural elements of the case study (ribs, slab-column transition) were produced at full-scale and tested until failure to investigate the feasibility of production and structural performance. Three T-beams with various rib shapes (straight, kinked with diaphragms, curved) were tested in a three-point bending configuration, showing a ductile behaviour with longitudinal reinforcement yielding and indicating the relevance of torsional effects in curved ribs. Punching tests on two slab-column connections (ribbed, solid) revealed that the optimised ribbed slab could prevent brittle punching failures and achieve an ultimate load 105% higher than the solid reference slab. All specimens’ load-bearing behaviour could be predicted using established design formulas, showing the feasibility of producing code-compliant ribbed slabs with the applied technology.
Eggshell
Burger, Joris Jan; Lloret-Fritschi, Ena; Gramazio, Fabio; et al. (2021)
CPT Worldwide: Construction Printing Technology
Digitally fabricated ribbed concrete floor slabs: a sustainable solution for construction
Mata Falcón, Jaime; Bischof, Patrick; Huber, Tobias; et al. (2022)
RILEM Technical Letters
The concrete used in floor slabs accounts for large greenhouse gas emissions in building construction. Solid slabs, often used today, consume much more concrete than ribbed slabs built by pioneer structural engineers like Hennebique, Arcangeli and Nervi. The first part of this paper analyses the evolution of slab systems over the last century and their carbon footprint, highlighting that ribbed slabs have been abandoned mainly for the sake of construction time and cost efficiency. However, highly material-efficient two-way ribbed slabs are essential to reduce the environmental impact of construction. Hence, the second part of this paper discusses how digital fabrication can help to tackle this challenge and presents four concrete floor systems built with digitally fabricated formwork. The digital fabrication technologies employed to produce these slab systems are digital cutting, binder-jetting, polymer extrusion and 3D concrete printing. The presented applications showcase a reduction in concrete use of approximately 50% compared to solid slabs. However, the digitally fabricated complex formworks produced were wasteful and/or labour-intensive. Further developments are required to make the digital processes sustainable and competitive by streamlining the production, using low carbon concrete mixes as well as reusing and recycling the formwork or structurally activating stay-in-place formwork.

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Joris Jan Burger

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