Post-processing Techniques to Enhance Strength of Portland Cement Mortar Digitally Fabricated Using Powder-Based 3D Printing Process

Abstract

The authors of this study have recently succeeded to formulate a Portland cement-based mortar as a printing material for use in commercially available powder-based 3D printers to build ‘free-form’ concrete components with complex geometries for construction applications. This study focusses on post-processing methods to enhance the strength of cement mortar specimens digitally fabricated using the powder-based 3D printing technique. The effects of type of curing medium (tap-water vs. saturated-limewater), curing time (7 days vs. 28 days), and loading direction (binder-jetting direction vs. layer-stacking direction) on the compressive strength of the printed samples were investigated. The results showed that the compressive strength of the printed samples cured in either tap-water or saturated-limewater was significantly higher than that of the ‘green’ samples. However, the 7-day and 28-day compressive strengths of the saturated-limewater-cured samples were 26% and 17%, respectively higher than those of the corresponding tap-water-cured samples. The results also showed that the compressive strength of the 3D printed cement mortar specimens depended on the loading direction. However, the degree of anisotropy in the compressive strength was reduced with the increase of curing time.