Effect of printing parameters on extrudability and buildability of ultra-low carbon cementitious material

Abstract

Cement-free cementitious materials are important for reducing the carbon footprint of 3D printing. However, for the ultra-low carbon cementitious material for 3D printing, the effect of printing parameters on its extrusion and stacking morphology has not been fully investigated. In this paper, an ultra-low carbon cement-free cementitious material (UCCCM) with ultra-fine slag and spherical fly ash as main components is developed. The influence of print head size (HS), print head height (HH), and printing speed (PS) on the extrudability and buildability are systematically investigated. Results showed that the HS had a clear influence on the extrudability, and a small print head size negatively affected the continuity of the extrudate. The HH had a greater influence on the buildability, and a low HH led to a height loss rate of more than 5 %. The PS had a greater influence on the buildability. When the PS was too slow, the mortar piled up and the printed specimens collapsed with a height loss rate of up to 35 %. When the PS was too fast, the strip cracked, and the height loss rate reached more than 10 %. The developed UCCCM for 3D printing presented optimal extrudability and buildability at a HS of 20 mm, a HH of 90 % and a PS of 20 mm/s.