Title: Exploring the Influence of Material Characteristics and Extruder Geometry on 3-D Printing of Cementitious Binders

Author(s): Sooraj Nair

Publication: Web Session

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Date: 3/28/2021

Abstract:
The steady state extrusion pressure (equivalent to extrusion yield stress) and the dead zone length (static zone of material buildup at die entry) are determined from the pressure-displacement response to characterize the extrudability and/or printability. A unique “geometric ratio” is used to account for the effects of barrel-die geometry on paste extrusion. The ratio of extrusion yield stress to the measured shear yield stress, the dead zone length, and the measured-to-designed filament volume at a given flow rate (print speed) are found to remain relatively invariant with geometric ratio for mixtures with high degree of microstructural packing, and thus better extrudability and shape stability. This presentation discusses materials- and process-related issues and, could pave the way for test methods for 3D printable mixture qualification.