Direct printing test for buildability of 3D-printable concrete considering economic viability

Abstract

Buildability, i.e. the ability of a deposited material bulk to retain its dimmensions under increasing load, is an inherent prerequisite for formwork-free digital construction (DC). Since DC processes are relatively new, no standard methods of characterization are available yet. The paper at hand presents practice-oriented buildabilty criteria by taking various process parameters and construction costs into consideration. In doing so, direct links between laboratory buildability tests and target applications are established. A systematic basis for calculating the time interval (TI) to be followed during laboratory testing is proposed for the full-width printing (FWP) and filament printing (FP) processes. The proposed approach is validated by applying it to a high-strength, printable, fine-grained concrete. Comparative analyses of FWP and FP revealed that to test the buildability of a material for FP processes, higher velocities of the printhead should be established for laboratory tests in comparison to those needed for FWP process, providing for equal construction rates. Highlights:Practice-oriented criteria for characterizing buildability are proposed.The applicability of the model in quantifying the economic viability of 3D-printing is demonstrated. Specimen height and time interval are specified as parameters for buildability tests on printable concretes. Proposed buildability criteria are validated by tests on a printable concrete. Variations regarding buildability test specifications for full-width and filament printing techniques are described.

Recent Developments and Challenges of 3D-Printed Construction: A Review of Research Fronts

“…The link between the capabilities of 3D-printed construction techniques and the design of building elements allows for the effective application of this new technology. 6% [28,80,140,143 Automation/Pro ductivity 32 37% [22,29,[36][37][38]40,70,80,84,98,130,136,138,150,[153][154][155]157,164,167,168,[172][173][174]177,179,180,[183][184][185] 5 6% [55,141,142,151,152]…”

Sustainable materials for 3D concrete printing

“…3D concrete printing technology requires concrete with special characteristics. Such mixtures are designed based on three primary material parameters, namely pumpability, extrudability and buildability, which are basically the ability to be pumped, extruded and to sustain load of consecutive printed layers without failure, respectively [14][15][16][17][18]. The pumpability and extrudability are governed by the properties of consistency, cohesiveness, stability and probability of phase separation under the application of pressure [19][20][21].…”

3D Concrete Printing: A Systematic Review of Rheology, Mix Designs, Mechanical, Microstructural, and Durability Characteristics

“…Research studies that have simultaneously measured static yield stress, dynamic yield stress, and plastic viscosity for a printable concrete mix proportion are rare in the existing literature. Table 1 and Table 2 indicate that there is no absolute value of static yield stress, dynamic yield stress, and plastic viscosity values for printable concrete [ 63 , 64 ]. Even rheological values of the same concrete mix proportion measured with two different kinds of rheometers can vary.…”