Fused Filament Fabrication Printer Modifed to Dispense Cement Paste for Concrete Additive Manufacturing Studies

Additive manufacturing (AM) with cement-based materials is an emerging technology that has the potential to revolutionize concrete construction. The placement process is quite complex, requiring suffcient flow properties as the material leaves the nozzle, and suffcient stiffening properties before the subsequent layer is placed. Precise control of material proportions and in-line monitoring of the time-dependent rheology are required to ensure the successful adoption of AM in the concrete construction community. To facilitate the study of the rheological properties of cementitious materials, as they pertain to AM, a commercial bench-top fused filament fabrication three-dimensional (3-D) printer was modifed to dispense cement paste mixtures. Modifcations included the design and assembly of a pumping system and software modifcations to the 3-D printer's firmware that were necessary to accommodate the new hardware. After assembly, a series of tests were conducted to verify machine movements and to calibrate the number of step pulses required per unit volume of extruded paste. The resulting software modifications and configuration files are publicly available.