Method of formulating geopolymer for 3D printing for construction applications

An innovative methodology is presented for formulating geopolymer-based material for the requirements and demands of commercially available powder-based 3D printers. Different key powder parameters such as particle size distribution, powder bed surface quality, powder true/bulk densities, powder bed porosity, and binder droplet penetration behavior were used to quantitatively evaluate the printability of prepared geopolymer-based material. Results indicated the prepared geopolymer-based material achieved sufficient printability to be used in a powder-based 3D printer. 3D printed specimens from the geopolymer were assessed for printing accuracy, apparent porosity and mechanical property. All printed cubic specimens exhibited an anisotropic phenomenon in dimensional accuracies and mechanical properties. Before further post-processing, the printed cubic structure gained compressive strength of up to 0.9 MPa with an acceptable low dimensional expansion of <4%. Post processing by immersion in saturated anhydrous sodium metasilicate solution at 60 degrees C gained compressive strength of up to 16.5 MPa. (C) 2016 Elsevier Ltd. All rights reserved.