Challenges of Real-Scale Production with Smart Dynamic Casting

Abstract

Digital fabrication with concrete has for more than a decade been of high interest in both research institutions and industries. A particular interest has been set on Contour Crafting, a type of layered extrusion with concrete, which in recent years has been used for the fabrication of single and multi-story buildings. However, these have been done with little proof of systematic integration of reinforcement, which until now still requires tedious post processing to obtain the structural capabilities required. Smart Dynamic Casting, a robotic fabrication process for standard and nonstandard vertical structures, has recently proven a systematic integration of reinforcement and is thereby the first digital fabrication process worldwide which has unified reinforcement and concreting in a single robotic fabrication process. This paper presents the latest developments and challenges of SDC and introduces the first architectural application in the form of structurally optimised façade mullions that are to be installed in the dfab House at the EMPA premises in Dübendorf, Switzerland.

Opportunities and challenges for structural engineering of digitally fabricated concrete

“…Smart Dynamic Casting (SDC) [37,89] is an extension of slipforming for producing bespoke concrete structures, which was used in the DFAB HOUSE to fabricate 15 slender reinforced concrete façade mullions (Figure 2, left). The architectural design concept required a variable spacing between the mullions (700 to 1400 mm), leading to different structural requirements for each mullion.…”

“…In addition, to ensure the same concrete cover throughout the mullion height and during the slipforming process, the reinforcing bars were precisely pre-bent and clamped before production. In terms of the long-term monitoring of such elements, the only remarkable observations were the shrinkage cracks reported prior to the mullions' installation [37], but they did not compromise the overall structural performance because of the presence of the reinforcement.…”

“… Process: (i) extrusion process in which concrete is automatically placed layer-by-layer through a moving nozzle, following a predefined digital path reproduced by Cartesian gantry, robotic, crane, or cable robot systems [30][31][32][33]; (ii) formwork printing in which concrete or other materials are used to fill a digitally fabricated formwork [34]; (iii) use of temporary supports which are digitally designed against applied loads, fabricated, and then, subsequently concreted [35]; (iv) slipforming consisting of a vertically moving formwork in which concrete is placed in the fluid state and allowed to harden in a controlled manner to fabricate variable cross-sectional area structures (e.g. the smart dynamic casting system developed by Lloret et al [36,37]); (v) particle bed 3d printing (also known as 'selective binding' or 'binder jetting') which is based on the selective and automated deposition of a binder onto a layer of particles (e.g. see [38]).…”

Eggshell: Ultra-Thin Three-Dimensional Printed Formwork for Concrete Structures

“…This allows the use of conventional reinforcement and design methods, but it might limit geometric freedom as the reinforcement cannot be precisely prefabricated to fit very complex geometries. 28 Further, for this to be used in a simultaneous fabrication process, the robotic arm would have to move around the preplaced reinforcement (Fig. 3A), adding complexity in robotic path planning.…”

Fabricate 2020

“…The enabling material technology consists of a batch of retarded, self-compacting concrete which is then accelerated in a mixing reactor just before deposition into the moving formwork. 15 individually shapeoptimised façade mullions were prefabricated for DFAB HOUSE with Smart Dynamic Casting (Lloret-Fritschi et al, 2018;Scotto et al, 2018;Lloret et al, 2015) (Fig. 11).…”