A critical examination of the influence of material characteristics and extruder geometry on 3D printing of cementitious binders
A critical examination of the influence of material characteristics and extruder geometry on 3D printing of cementitious binders
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DOI：
10.1016/j.cemconcomp.2020.103671
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发表时间：
2020-09
影响因子：
10.5
通讯作者：
Sooraj A.O. Nair;S. Panda;M. Santhanam;G. Sant;N. Neithalath
中科院分区：
文献类型：
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作者：
Sooraj A.O. Nair;S. Panda;M. Santhanam;G. Sant;N. Neithalath
本文报道了具有多种起始材料和不同颗粒填料的胶凝体在不同挤压几何形状下的挤压压力-位移试验。稳态挤压压力（相当于挤压屈服应力）和死区长度（模具入口处材料堆积的静态区域）由压力-位移响应决定，以表征挤压性和/或印刷性。一个独特的“几何比”被用来解释筒模几何形状对膏体挤压的影响。在一定流速下（打印速度），挤压屈服应力（25-75 kPa）与实测剪切屈服应力（50-300 Pa）之比、死区长度和实测到设计的长丝体积与几何比保持相对不变，因此具有较高的微结构填充程度的混合物具有更好的挤压性和形状稳定性。本文结合了材料和工艺相关问题，可以为3D打印混合物资格的测试方法铺平道路。
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.