Determining Printable Zone of Three-Dimensional-Printable Mortar Using Flow Table Tests

In this study, 12 mortar mixtures were designed to have different flow properties using a highly flowable, rapid-set crack repair grout (CRG) for cement replacements and different water-binder ratios (w/b). Their flowability was measured using flow table tests at 0, 40, and 60 minutes after mortar mixing, corresponding to the time spent on different three-dimensional (3D) printing stages (feeding, printer setup/pre-printing, and actual printing). Feed-ability of all mortar mixtures and the extrudability, buildability, and printing quality of the printable mixtures were evaluated qualitatively. A printable zone was developed based on these results, and it was expressed in terms of initial (D-0) and final (D-25) diameters. This printable zone was then used to adjust the flow properties of a different mixture proportion containing river sand (RS). It was verified that the object printed with the mixture that met the printable zone criteria was easy to print and showed very good printing quality.