Practice-Oriented Buildability Criteria for Developing 3D-Printable Concretes in the Context of Digital Construction

aInstitute of Construction Materials, Von-Mieses-Bau, 3 O.G., Georg-Schumann-Str. 07, Technische Universität 4 Dresden,01087 Dresden, Germany 5 bInstitute of Construction Management, Nürnberger Ei, 4. O.G., Nürnberger Straße 31A, Technische Universität 6 Dresden, Dresden, Germany 7 * corresponding author, tel.: +49 351 463 35922, fax: +49 351463 37268, e-mail: nerella@msx.tu-dresden.de 8 Abstract 9 Buildability, i.e. the ability of a deposited material bulk to retain its dimmensions under increasing 10 load, is an inherent prerequisite for formwork-free digital construction (DC). Since DC processes 11 are relatively new, no standard methods of characterization are available yet. The paper at hand 12 presents practice-oriented buildabilty criteria by taking various process parameters and 13 construction costs into consideration. In doing so, direct links between laboratory buildability tests 14 and target applications are established. A systematic basis for calculating the time interval (TI) to 15 be followed during laboratory testing is proposed for the full-width printing (FWP) and filament 16 printing (FP) processes. The proposed approach is validated by applying it to a high-strength, 17 printable, fine-grained concrete. Comparative analyses of FWP and FP revealed that to test the 18 buildability of a material for FP processes, higher velocities of the printhead should be established 19 for laboratory tests in comparison to those needed for FWP process, providing for equal 20 construction rates. 21 Highlights: 22 Practice-oriented criteria for characterizing buildability are proposed. 23 The applicability of the model in quantifying the economic viability of 3D-printing is 24 demonstrated. 25 Specimen height and time interval are specified as parameters for buildability tests on 26 printable concretes. 27 Proposed buildability criteria are validated by tests on a printable concrete. 28 Variations regarding buildability test specifications for full-width and filament printing 29 techniques are described. 30

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