3D Printing of a Cement-Based Mortar in a Complex Fluid Suspension (2020-07)¶

New techniques of 3D printing bring innovations to the construction industry. However, printing cantilevered elements or complex geometries which initially need some temporary support or lost formwork to ensure their mechanical stability is still challenging with 3D extrusion printing. A possible way is to print them directly in a yield stress fluid which could ensure their stability. In this study, a cantilevered cementitious material was printed in a Carbopol gel where the stability of the element and its geometry were thoroughly investigated. The rheological properties of the Carbopol gel and mortar were tailored to sustain the gravity effect of the cantilevered structure and an analytical model has been developed to propose an optimization method of the rheological properties of both the yield stress fluid and the mortar. In order to validate the model, experimental investigations have been carried out by images tracking. The developed model is reliable with the experimental data considered of the densities, the yield stress of both materials and the geometry of the printed shape. The prediction of failure by bending is possible, implying that the model could help making better designs of complex cement-based elements and optimizing their temporary support with elasto-plastic fluids.