Printability and particle packing of 3D-printable limestone calcined clay cement composites

This study develops a modified limestone calcined clay cement (LC3) composite for 3D printing, by introducing silica fume (SF) and particle packing theory. Interactions between particle packing density, rheological properties, and printability of the composites were synergistically investigated. Moreover, the ratio of the sand-to-binder (S/B) was also analyzed to explore the performance response. Results show that when composites contain 33.33 wt% calcined clay, 16.67 wt% limestone powder and 5 wt% SF with S/B ratio of 2.5, the dynamic yield stress, static yield stress, and structural recovery can be significantly improved. The proposed mortar can be continuously extruded with few defects and exhibited an excellent shape retention during printing process. Furthermore, the embodied energy (EE) and embodied carbon emissions (ECO(2)e) per cubic meter of optimal mortar respectively decreased by 50.2% and 45.2% with respect to the plain mortar. Finally, the employment of LC3 containing SF together with optimum particle packing system mutually contributed to lower the cement content of composites that eventually led to the development of eco-efficient printable materials. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A modified limestone calcined clay cement composite for 3D printing is developed by introducing silica fume and particle packing theory, which significantly improves dynamic yield stress, static yield stress, and structural recovery. The embodied energy and embodied carbon emissions per cubic meter are greatly reduced, contributing to the development of eco-efficient printable materials.