Mineral composition based on cement and fluor anhydrite for 3D printing

This study presents a composition for layer-by-layer extrusion (3D printing) characterized by rapid curing. The composition is based on fluoroanhydrite and Portland cement in a ratio of 3:1. Additionally, the composition includes a powder for obtaining liquid sodium glass, a setting retarder - sodium phosphate Na3PO4, and micro-reinforcing chrysotile fibers in amounts of 3%, 5%, and 10% by the weight of the binder. The study showed that the setting time of the developed composition with a water-to-binder ratio of W/B=0.45 was 90 seconds from the start of mixing. To regulate the setting time, the water-to-binder ratio was increased to W/B=0.6. Meanwhile, the compressive strength of specimens in dry conditions was 6.9 MPa, and in wet conditions - 4.6 MPa. IR spectral and differential thermal analyses of the composition revealed the formation of gypsum dehydrate and calcium silicate hydrates in the composition structure, ensuring the necessary water resistance. These results were confirmed by the microstructural analysis of the obtained material.