Digital Printing of Mortar in Carrier-Liquid (2021-05)¶

Nowadays, 3D printing of cantilevered shape poses a great challenge within the digital construction through a carrier liquid as a temporary formwork. This technique allows the printing of truss bars shapes, hollow cylinders and act as a leap reducing the utilization of materials and the global carbon footprint. To transfer this new concept to the industrial process, it is essential to predict the stability of the cementitious material’s shape in the carrier liquid. In this work, three different criteria were investigated, the printed cementitious mortar and the carrier liquid attached to the rheological properties are taken into study. Rheometry measurements have been carried out on both cement-based materials and the carrier liquids. A cantilevered shape is printed with a home-made 3D printer. A simple stability criterion which is independent of the final shape is first highlighted. It is reliable to give a first approximation of the stability at the exit of the nozzle regarding the material properties whatever was the element shape. Besides, two different approaches based on the mechanical strength approach and the final geometry of the printed shape have also been proposed. The experimental results show that the reliability of these different approaches to predict the stability of the extruded materials or final shape are finally confirmed by flow visualizations.