Abstract
Three-dimensional concrete printing (3DCP) materials require a relatively low water-to-binder ratio (W/B) of 0.3 or less to ensure their buildability and flow properties are sufficiently maintained after mixing. In this study, the rheological properties of 3DCP materials with W/B 0.28 were evaluated up to 60 min after mixing, and the yield stress and plastic viscosity were analyzed over time. A gradual decrease in flow rate with time was observed during the transport of 200 kg of material per batch through a 20 m hose. To examine the time-dependent changes in flow rate and layer volume, a 2200 mm × 1000 mm test specimen was printed. The dependence of the layer width over time during the printing process was measured and analyzed. The experimental analyses showed that the flow rate and layer volume of the 3DCP material gradually decreased with time after mixing, which was correlated with the rheological properties.
Highlights
Three-dimensional concrete printing (3DCP) technology has recently been employed in successful construction attempts, including a two-story building in the UAE by ApisCor in 2019 and pedestrian bridges by TU Eindhoven in the Netherlands and TsinghuaUniversity in China
To derive the correlation between the two graphs, it is necessary to calculate the correlation coefficient, but in this study, there is a limit because the rheological properties and volume of the layer were measured using only one formulation
To predict this, the correlation between the rheology measurement result and layer volume must be derived through experiments and analysis of various cases
Summary
Three-dimensional concrete printing (3DCP) technology has recently been employed in successful construction attempts, including a two-story building in the UAE by Apis. To ensure buildability of layers and printing member, the yield stress and plastic viscosity of the 3DCP material were increased in a previous study [2] because these properties aid in supporting the weight of successively added layers and maintaining the shape of the structure. The initial yield stress of a material may be high, it will quickly begin to increase after mixing, which shortens the available open time for 3D printing [18]. Previous studies on the time-dependent changes in 3DCP materials have shown that the yield stress increases with time after mixing [2,15,19].
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