Effect of Magnetic Intervention Time on the Buildability of Printable Cement and Limestone Pastes Containing Fe3O4 Particles

Magnetic field has the potential to modify the rheological properties of cementitious materials containing magneto-responsive particles in the post-mixing phase, which is also known as active rheology control. In this paper, the influence of the magnetic intervention on the buildability of printable materials was experimentally investigated by means of a squeeze flow test. Magnetic field interventions with six different periods (0 s, 30 s, 45 s, 60 s, 120 s, and 300 s) were applied and its effect on the buildability of cement and limestone pastes was compared. The results show that the squeeze flow method was able to characterize the effect of magnetic fields on the buildability of cement and limestone pastes with low slump values. In addition, magnetic fields were found to decrease the displacement of pastes under loads and thus improve their buildability, which can be attributed to the organization of Fe3O4 particles. An optimal magnetic intervention time existed depending on the mixture design for different materials.