Multi-Scale Mechanical Characterization of the Interface in 3D Printed Concrete (2023-01)¶

To be printable, the cementitious ink may have contradictory properties. It must be fluid enough initially to be pumpable and extrudable, also should stiffen quickly after deposition to be buildable. This could be influential, along with other printing parameters, on its interlayer zone. Thus, the main purpose of this study is to compare experimental protocols allowing for its mechanical characterization and the assessment of a drop in bond strength. Classical microindentation tests are done perpendicularly to the interface. Furthermore, a new method to elaborate specimens on a lab-scale is proposed in this study allowing for multidirectional compression testing. Later, interfacial instrumented indentation measurements at the macroscopic scale were also performed. Results validate the new experimental procedure. Indentation profiles reveal a weakness and widening of the interface with time gap. Multidirectional compression tests show anisotropy while no influence of time gap was detected. Instrumented macroindentation indicates a lower adherence with time gap between layers.