Differences in micro grain/fiber distributions between matrix and interlayer of cementitious filaments affected by extrusion molding
Rijiao Yang, Yi Zhu, Yan Lan, Qiang Zeng, Peng Yu, Zhendi Wang
Abstract
Extrusion molding generally causes laminar structure with obvious interfaces, however, the impacts of extrusion molding on the distributions of micro grains/fibers in the matrix and interface of filaments haven't been fully addressed. Herein, X-ray computed tomography was employed to track the cement micro particles and glass microfibers in extrusion molded cementitious composites (EMCC). Results show that small grains migrated into the interface while coarse grains stayed in the matrix of filaments. Glass microfibers in the matrix and interface were roughly parallel and perpendicular to the printing direction, respectively. The mechanisms of shearing stress gradients built in the EMCC filaments and collisions on the microfibers during pumping were proposed to account for the featured distributions and directions of the micro grains and fibers. The findings would deepen the understandings in particle redistribution in non-Newtonian liquid during extrusion molding and facilitate the design and development of 3D printing construction materials.