(202f) Modeling of Cement Paste for 3-D Printing Applications

Additive manufacturing offers the construction industry new opportunities to reduce labor costs and waste, and increase the reliability of concrete infrastructure. The 3D printing of cement-based materials involves the, extrusion of cementitious mixtures through a nozzle to layer-by-layer build structural components. The aim of this study is to explore the relationships between printing conditions and paste physical properties using computational modeling. The key factor governing the properties of cement-based extrusion mixtures is the volumetric content and rheology of the cement paste, a non-Newtonian fluid with measurable yield stress “τ₀,” and plastic viscosity “µ₀.” COMSOL Multiphysics was used to analyze cement flows in 2-D and 3-D geometries relevant to printing of cement-based structures. The free surface flow of spherical, cylindrical, rectangular and elliptical gobs of cement paste in 2-D and 3-D wasstudied. A relationship between the fluid properties, printability metrics and scale (size of printed shapes) is suggested.