Some Insights on Role of Water Film-Thickness in Rheology of Coarse Aggregate-Based 3D Printable Concrete (2025-11)¶

Coarse aggregate inclusion through mortar replacement has a significant effect on both rheology as well as sustainability of 3D printable concrete (3DPC). Film thickness of the aggregate particle has a significant influence on 3DPC rheology and printability, and this thickness is closely related to the replacement levels of mortar with the selected coarse aggregates. In this investigation water film thickness was estimated by extending to 3DPC the procedure used in the case of conventional concrete, where in the key inputs is the wet packing method (for finding packing density of mix constituents) and sieve analysis data of the aggregate as well as of the binders (for specific surface area of mix constituents). Effects of varying water film associated with varying coarse aggregate replacement levels on rheological properties like yield stress and plastic viscosity, and printability properties like flowability and extrudability are presented and discussed. Findings of this investigation provide preliminary inputs for coarse aggregate optimization levels in 3DPC.