Extrusion pressure-displacement tests on cementitious pastes with multiple starting materials and differing particle packing, subjected to different extrusion geometries are reported. The steady state extrusion pressure (equivalent to extrusion yield stress) and the deadzone 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 (25–75 kPa) to the measured shear yield stress (50–300 Pa), the deadzone 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 paper marries materials- and process-related issues and, could pave the way for test methods for 3D printable mixture qualification.

报道了在具有多种起始几何形状的情况下，对具有多种起始材料和不同颗粒堆积的水泥浆进行的挤出压力位移测试。由压力-位移响应确定稳态挤出压力（相当于挤出屈服应力）和死区长度（材料在模头进入时的静态区），以表征可挤出性和/或可印刷性。独特的“几何比”用于说明桶形模具几何形状对糊料挤出的影响。挤压屈服应力（25–75 kPa）与测得的剪切屈服应力（50–300 Pa）之比，死区长度，对于高微观结构堆积度的混合物，在给定的流速（印刷速度）下测量到设计的长丝体积随几何比保持相对不变，因此具有更好的可挤出性和形状稳定性。本文结合了材料和过程相关的问题，可以为3D可打印混合物鉴定的测试方法铺平道路。