Systematic approach for printability evaluation and mechanical property optimization of spray-based 3D printed mortar

Abstract

Systematic approach for evaluation and optimization of spray-based 3D (S-3D) mortar printing technology are explored. Effects of different fly ash (FA), silica fume (SF) and water-binder (W/B) ratios on the rheological properties of mortar are firstly evaluated by orthogonal tests. The mortar with excellent rheological properties is then adopted to assess the S-3D printability. The test results show that proper additions of FA, SF and W/B can prolong the printing window to 120–135 min as well as improve the printing accuracy. Single layer and accumulative thickness tests are innovatively used to quantify the morphological sustainability of S-3D printed mortar. The mechanical strengths of S-3D printed mortar are remarkably higher than those of the cast counterparts in view of maximum increase of 72.64% compressive, 45.83% flexural and 33.33% splitting strengths, respectively. The high spraying pressure of S-3D printing procedure avails small pore size, therefore the compactness of the internal microstructure of S-3D printed mortar. A special-configured convex nameplate “HEBUT” with size of 2200mm × 500mm × 30 mm (X × Z × Y directions) is successfully printed on a vertical platform, which proves the applicability and dexterity of S-3D printing technology in spatial context.