Rheological and Strength Characteristics of Vertical 3D Printing

Abstract

The vertical 3D printing of concrete has recently emerged as a novel printing method for 3D concrete printing, however, it is still a great challenge to realize a balance of the rheological and mechanical properties for stable printing and layer-by-layer fabrication process. In this study, it is proposed to develop a numerical simulation framework that can assess the printability of concrete in vertical printing with respect to both rheological and strength properties without using experimental testing. A Multi-Objective Particle Swarm Optimization (MOPSO) algorithm is used to optimize five parameters such as water-to-binder ratio, dosage of superplasticizer, dosage of viscosity-modifying admixture, printing speed and layer height. The framework can anticipate the plastic viscosity, static yield stress, buildability index, maximum printable height, and compressive strength while respecting printability constraints. Printable height of 1120 mm, compressive strength of 48.9 MPa, plastic viscosity of 39 Pa·s and yield stress of 1180 Pa were obtained with the optimized mixture. This shows that the proposed simulation methodology can identify printable concrete mixtures with better rheological stability and structural performance for construction of the vertical structure printed using 3D printing.