Mechanical properties of 3D printable responsive cement mortar after magnetic intervention

Rheology and stiffening control can contribute in a significant way to the quality of concrete structures in general and can facilitate the promotion of 3D printing technology more specially. Active stiffening control (ASC) has the potential to solve conflicting rheological requirements of 3D printable materials during pumping, extruding and deposition. Responding to an external signal, the rheological properties of cementitious materials with mixed-in responsive com-ponents can be adjusted on demand. However, the mechanical properties of hardened responsive cementitious materials are unclear. This research investigates the mechanical properties of 3D printable cement mortar containing responsive aggregates after being exposed to a magnetic field. A customized nozzle equipped with magnetic intervention is designed. Two different magnetic field strengths (0.1 T and 0.3 T) are applied on the printing nozzle. The com-pressive and flexural strengths of specimens extracted from 3D printed wall elements printed with the help of ASC are explored at 7 days and 28 days. Magnetic field intervention adjusted the rheological properties in time and on de-mand without negatively affecting the mechanical properties after hardening when the responsive aggregates to cement mass ratio was 2.3:1. Compared with the 28-day strength, magnetic intervention has greater influence on the compres-sive and flexural strength at the age of 7 days.