Study on the durability of 3D printed calcium sulphoaluminate cement-based materials related to rheology control

Since 3D printed structure is conducted by the style of dimension reduction, the defects typically occur between the printing layers due to the poor rheological properties, which affects the durability most. This study focuses on exploring the durability of 3D printed calcium sulphoaluminate cement-based materials (CSACMs) with slag powder based on the correlation between printed structures and rheological parameters. Experimental results show that both the static and dynamic yield stress of 3D printed CSACMs exhibits a gradual increase with the slag powder content increases, while the thixotropy improves continually until reaching a maximum content at 15%. In this case, an increase in slag powder content leads to a significant reduction for structure deformation. However, poor printability occurs when the content of slag powder exceeds 15%. Besides, the chloride migration coefficient and maximum electric flux decreases from 7.28 × 10−12to 3.27 × 10−12 m2/s and 1347 to 711 K, respectively, when the content of slag powder increases from 0 to 10%. Meanwhile, the freezing resistance and linear shrinkage are improved. Based on the radar map correlation, structure deformation is significantly influenced by thixotropy, which is a crucial factor that can impact the durability of 3D printed CSACMs. In conclusion, the controllable rheology of 3D printed CSACMs are advantageous for improving the printed structures and durability.