Cementitious material bead extrusion system for robot for additive manufacturing of architectural structures comprising : - a cementitious material strand extrusion head comprising a cementitious material inlet mouth , an outlet nozzle configured to form cementitious material strands, and an intermediate enclosure, referred to as a mixing enclosure , arranged between said inlet mouth and said outlet nozzle , - a cementitious material feed circuit for said extrusion head comprising a storage tank containing said cementitious material, a cementitious material feed line connecting said storage tank and said inlet of said extrusion head , - a device for coloring the cementitious material present in said extrusion head , characterized in that the system further comprises : - a feed pump for said cementitious material feed line from said storage tank , and in that the device for coloring the cementitious material comprises : - a plurality of color pigment reservoirs , - a plurality of colorization lines connecting at least one color pigment reservoir to said mixing chamber of said extrusion head, each colorization line being equipped with means for adjusting the quantity of pigments injected into said mixing chamber , so that coordinated control of the adjustment means of each colorization line makes it possible to define a color of the strand of cementitious material extruded by the said outlet nozzle which results from a combination of the colors of the pigments of the said color pigment reservoirs . - a cementitious material strand extrusion head comprising a cementitious material inlet mouth , an outlet nozzle configured to form cementitious material strands, and an intermediate enclosure, referred to as a mixing enclosure , arranged between said inlet mouth and said outlet nozzle , - a cementitious material feed circuit for said extrusion head comprising a storage tank containing said cementitious material, a cementitious material feed line connecting said storage tank and said inlet of said extrusion head , - a device for coloring the cementitious material present in said extrusion head , characterized in that the system further comprises : - a feed pump for said cementitious material feed line from said storage tank , - a feed pump for said cementitious material feed line from said storage tank , and in that the device for coloring the cementitious material comprises : - a plurality of color pigment reservoirs , - a plurality of colorization lines connecting at least one color pigment reservoir to said mixing chamber of said extrusion head, each colorization line being equipped with means for adjusting the quantity of pigments injected into said mixing chamber , - a plurality of color pigment reservoirs , - a plurality of colorization lines connecting at least one color pigment reservoir to said mixing chamber of said extrusion head, each colorization line being equipped with means for adjusting the quantity of pigments injected into said mixing chamber , so that coordinated control of the adjustment means of each colorization line makes it possible to define a color of the strand of cementitious material extruded by the said outlet nozzle which results from a combination of the colors of the pigments of the said color pigment reservoirs . <EOS>