Abstract: Binder jetting 3D printing features the advantages of high accuracy and support-free fabrication, which offers an effective method for intelligent construction in construction field. In order to solve the problem that the strength and accuracy of binder jetting 3D printing cementitious materials are difficult to cooperate, based on the magnesium phosphate cement based cementitious material system, effects of magnesium phosphorus ratio (M/P, molar ratio), water cement ratio (W/C) and layer thickness on compressive strength, bedding, printing accuracy and microstructure of specimens were studied in this paper. The results show that the size error of specimen decreases first and then increases with the increase of M/P, and increases with the increase of W/C. With the increase of layer thickness, the bedding phenomenon of specimen becomes more and more obvious. With the increase of M/P, the W/C corresponding to the highest strength decreases. With the increase of M/P, the internal structure of specimen becomes denser and the compressive strength of specimen increases. The dimensional accuracy and compressive strength of specimen are obviously anisotropic, and the dimensional error in the moving direction of the powder laying wheel is the largest. The compressive strength of specimen is the highest when loading along the stacked direction. The optimal M/P is 6, W/C is 0.14, the layer thickness is 100 μm, the optimal size error of the material is 2.65% of the design size of specimen, and the compressive strength is 39.1 MPa. The 3D printing material has a good application effect in the ancient building skin restoration project, and is of great significance to promote the application of binder jetting 3D printing technology in the construction field.

Key words: magnesium phosphate cement, binder jetting 3D printing technology, compressive strength, printing accuracy, synergism