Mechanism analysis of rheological properties of 3D printed steel slag cementitious composite based on low field nuclear magnetic relaxation test

Rheological properties play a crucial role in characterizing 3D printed cement-based materials. To further investigate the mechanism behind rheological evolution, this study employs low-field NMR relaxation time measurement to characterize the microstructure evolution of 3D printed steel slag cementitious material within the first 6 hours. This is combined with rheological parameters to explore the relationship between the mixture's rheological properties and pore microstructure over time. The results demonstrate that relaxation time effectively represents the temporal characteristics of rheological parameters, while pore throat distribution (0–0.1μm) exhibits a positive correlation with plastic viscosity. Low-field NMR relaxation characteristics can effectively describe early properties of 3D printed cementitious materials and provide valuable data support for future exploration of non-destructive testing during early stages.