Cementitious print head, 3D printing architecture, and cementitious printing methodology

A print head for extruding a cementitious composition, the print head comprising a feed barrel, a print head nozzle, a CO2 supply, a steam supply, a selective valve assembly in communication with the CO2 supply and the steam supply, a plurality of extrusion head injectors, and a print head controller, wherein:

• the feed barrel is oriented and shaped to receive the cementitious composition and to direct the cementitious composition to the print head nozzle;
• the selective valve assembly communicatively couples the CO2 supply and the steam supply to the extrusion head injectors for selective injection of CO2 and steam from the extrusion head injectors;
• the extrusion head injectors are positioned downstream of the print head nozzle for selective injection of CO2 and steam into the cementitious composition extruded from the print head nozzle;
• and
• the print head controller is operatively coupled to the selective valve assembly and is programmed to execute a CO2 and steam injection protocol where steam is selected for injection by the extrusion head injectors into the cementitious composition as it is extruded from the print head nozzle to enhance a hydration reaction and formation of hydroxide in the cementitious composition before CO2 is selected for injection by the extrusion head injectors into the cementitious composition as it is extruded from the print head nozzle to enhance a carbonation reaction in the cementitious composition.

A method of extruding a cementitious composition from a print head comprising a feed barrel, a print head nozzle, a CO2 supply, a steam supply, a selective valve assembly in communication with the CO2 supply and the steam supply, and a plurality of dual use extrusion head injectors, wherein:

• the feed barrel is oriented and shaped to receive the cementitious composition and to direct the cementitious composition to the print head nozzle;
• the selective valve assembly communicatively couples the CO2 supply and the steam supply to the dual use extrusion head injectors for selective injection of CO2 and steam from individual ones of the extrusion head injectors;
• the plurality of dual use extrusion head injectors are positioned downstream of the print head nozzle for selective injection of CO2 and steam into the cementitious composition extruded from the print head nozzle;
• and
• the method comprises operating the selective valve assembly to select steam for injection by the extrusion head injectors into the cementitious composition as it is extruded from the print head nozzle to enhance a hydration reaction and formation of hydroxide in the cementitious composition, and to subsequently select CO2 for injection by the extrusion head injectors into the cementitious composition as it is extruded from the print head nozzle to enhance a carbonation reaction in the cementitious composition.