Rheological Response of Magnetorheological Cementitious Inks Tuned for Active Control in Digital Construction (2021-11)¶

Systematically designed cement mixtures incorporating various proportions of portland cement (PC), high-ferrous Class F fly ash (FA), nanosilica (NS), and nanoalumina (NA) were blended and characterized for rheological response with and without the application of a magnetic field to better understand the effects of doping cement with magnetic material for application in four-dimensional (4D) printing of cementitious smart materials (SM). Control groups doped with industrial-grade magnetite powder (primarily used as pigment) were likewise mixed and characterized to provide contrast to coal-combustion byproduct FA. Mixtures supplemented with ferromagnetic particles showed increased yield stress when exposed to applied magnetic field, leading to non-Newtonian rheological models exhibiting ‘sticky particles’ paradigms as discussed herein. These results suggest that the principle of using an applied magnetic field to modify the flow and slump of cementitious materials extruded through a three-dimensional (3D) printing apparatus is worthy of further pursuit and development.