Experimental investigation of fresh and time-dependent rheological properties of 3D-printed cementitious material

Unlike traditional construction processes, three-dimensional cementitious material printing requires more accurate control of the pumping flow rate. To this end, the predictability of the rheological properties of fresh cementitious mixtures and the property change over time are critical for the fabrication process. In this paper, the fresh rheological properties of twenty different mixtures were measured in the large gap viscometer, and three non-Newtonian fluid models (Bingham model, modified Bingham model, and Herschel-Bulkley) were applied to predict the dynamic yield stress and plastic viscosity of each material. The applicability of these models was assessed, and their relative deviation was quantified and discussed. Using the well-established Bingham model, the temporal evolution of the dynamic yield stress and plastic viscosity of the material was then characterized. Based on the measured and predicted rheological properties, an open loop control method was then implemented to harmonize the flow volume per unit length during printing processes to improve the printing quality and buildability of the material.