3D-printing of architectured short carbon fiber-geopolymer composite

Developing advanced lightweight structures with both high strength and high toughness remains challenging. Herein, we provide a combined experimental and simulation method to fabricate 3D-printed geopolymer complex structures with lightweight, high strength and superior toughness for the first time. In this research, short carbon fiber reinforced geopolymer (C_sfGP) composites were printed using 3D printing technology, and the rheological properties of C_sfGP inks and the mechanical properties of hardened geopolymer composite structures were systematically studied. The C_sfGP inks exhibited obvious shear-thinning behavior, which facilitated ink-extrusion from a micro-nozzle, conserving the filamentary shape and supporting the subsequent printed layers. In C_sfGP composites, the consistent orientation distribution of short carbon fibers primarily enhanced their mechanical properties. When fiber content was 3 wt %, flexural strength and compressive strength of the C_sfGP composite were 309.2% and 375.8% higher than those of nonreinforced geopolymer, respectively. Subsequently, C_sfGP composites of the Bouligand architectures were successfully 3D-printed, and they showed superior load-bearing capacity and non-brittle failure mode due to their hierarchically ordered architectures and sophisticated interfaces. 3D printing together with Bouligand-structure designing provide a novel approach for the C_sfGP composites of lightweight, high strength and superior toughness, which would lead to a resurgence of interest in new lightweight structure design and manufacturing strategies.