Methods and systems for 3D printing of reactive vaterite cement

A 3D cement printing machine comprising:

• a printing head configured to dispose reactive vaterite cement;
• a feed system, in material communication with the printing head, the feed system configured to provide a feed of reactive vaterite onto the printing head;
• a feed of reactive vaterite cement, disposed in the feed system;
• a material chamber operably connected to the feed system, configured to provide a condition to prevent transformation of the reactive vaterite to aragonite or calcite, wherein the condition comprises a pressure of 10-1,000 psi and a temperature of 20-300° C.;
• and
• a system operably connected to the 3D printing machine system and configured to produce the composition comprising reactive vaterite cement, comprising:
• a calcining reactor configured to calcine limestone to form a mixture comprising lime and a gaseous stream comprising carbon dioxide;
• a dissolution reactor operably connected to the calcination reactor configured for dissolving the mixture comprising lime in an aqueous N-containing salt solution to produce an aqueous solution comprising calcium salt;
• and
• a treatment reactor operably connected to the dissolution reactor configured for treating the aqueous solution comprising the calcium salt with the gaseous stream comprising carbon dioxide to form the composition comprising the reactive vaterite cement.