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.
Concrete is a highly versatile construction material, not only for the reason that it has excellent properties in terms of structural performance, building physics, availability and price, but also ...because it can be moulded into virtually any shape regardless of its geometric complexity. However, even though current digital design tools allow to effortlessly design and calculate structures, which are exploiting these properties, this potential remains all too often unrealized. This is due to the fact that geometrically complex concrete structures require expensive, one-of-a kind formwork, which can often not be reused or even recycled. Consequently, the current practice for producing non-standard curvilinear architecture in reinforced concrete is neither ecologically sustainable nor economically feasible for a broader range of architectural typologies. Additive Manufacturing (AM) processes, like 3D printing with concrete, on the other hand, currently struggle with the integration of structural reinforcement, limiting the technique to predominantly compression-loaded applications. This research addresses both issues and proposes Mesh Mould, a robotic fabrication process that unifies concrete formwork and structural reinforcement, and hence potentially reduces formwork waste and construction costs for non-standard reinforced concrete constructions. The development of a fully automated robotic fabrication process involved various research disciplines, including architecture, material science, mechanical engineering, robotics as well as civil engineering. This paper describes the technological developments of the Mesh Mould construction system that were necessary to meet the challenges of 1:1 construction. The results are demonstrated in a final loadbearing structure, the Mesh Mould wall of the DFAB HOUSE on NEST.
•The paper highlights a novel, ecologically and economically feasible robotic fabrication system for double curved, fully reinforced concrete elements, which is based on a historic construction system known as ferrocement.•A mobile robot, equipped with a custom developed robotic end effector, is deployed on the construction site, fabricating the structure in situ.•A seamless digital workflow, from parametric design to automated fabrication, is demonstrated in a real-scale construction project, the so-called DFAB HOUSE on Nest.•Through the highly interdisciplinary research, this paper contributes to the forthcoming digitization of the construction industry, one of the largest but least automated sectors of the global economy.
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 cross-section with the same reinforcement strategy showing the potential of Eggshell in combination with an innovative reinforcement strategy to produce material-efficient structural concrete elements.
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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