Recommendations for quality control in industrial 3D concrete printing construction with mono-component concrete: A critical evaluation of ten test methods and the introduction of the performance index

The critical assessment of the applicability of fresh concrete test methods for characterizing printable concrete quality and its structural build-up rate is rare in the literature. To address this gap, this study evaluates the potentials and limitations of eight offline test methods (hand vane, rheometer, compressive strength, squeeze flow, penetrometer, ultrasonic pulse velocity, slump, and flow table) and two inline test methods (slug test and extruder torque measurement). This research proposes a new parameter called "performance index" to assess the capability of any test to detect structural buildup. The study establishes a ranking of the eight offline tests on the proposed performance index and evaluates the advantages and disadvantages of each test in terms of portability, price, required human labor, and material. The results of this study can be used as a first guideline to select a proper quality control test for industrial 3D concrete printing construction.