Effect of nanoclay on extrudability, printability and mechanical performance of extrusion-based 3D printing mortar

An extrusion-based 3D printing mortar was designed and included in this study to evaluate the printing characteristics of the cementitious materialwith a maximum aggregate size of 1.18 mm and nanoclay (nC) as viscosity modifying agent (VMA). This 3D printing mortar is also composed of cement(OPC), fly ash, basalt fibre, and a polycarboxylate polymer superplasticizer. The mechanical performance of the 3D printing mortar in the presence of nanoclay was investigated and compared to mold cast equivalents. The inclusion of nanoclay considerably reduced mortar bleeding, which was good for mortar mixture stabilisation. Even though flowability of the mortar mixture decreased considerably with an increase in the content of nanoclay, the mortar mixture remained extrudable even after 1 hour. The printability of the mortar mixture characterized here by layer settlement also improved as the amount of nanoclay increased. A decrease in the settlement of printed layers can be attributed to an increase in the yield stress of the material as the quantity of nanoclay increases in the mixture. A good correlation was drawn from both compressive strength and flexural strength testing of the 3D printed mortar and the corresponding mold cast counterparts after 1 day and 28 days of testing.