Introduction. In recent years, there has been an active development of 3D additive technologies. This trend could not but affect the construction industry. However, printing using plastics and other organic compounds differs significantly in its technological features from printing with building compounds. Concrete and mortars used in layer-by-layer printing must have a number of technological properties, such as sufficient viscosity for extrusion by an extruder, low mobility to maintain geometry after laying, high setting speed and strength after hardening. Currently, there are a number of compositions that meet these requirements, however, they, as a rule, are not distinguished by high strength and require a wide raw material base, which may not be available in field printing conditions. As a result, it is necessary to expand the range of building materials for 3D printing, suitable for the above criteria, as well as satisfying economic indicators.Materials and methods. Research has been carried out using physical and mechanical tests, X-ray phase analysis and electron microscopy on the effect of finely ground mineral additives on the microstructure and hardening processes of composite binders with various dosages of functional additives.Results. The results of studies on the production of composite binders for 3D additive technologies using Portland cement and man-made waste - waste of wet magnetic separation of the Stary Oskol electrometallurgical plant, modified with additives accelerators (Technonikol Master) and plasticizers (Polyplast PK-R) using mathematical planning and construction of mathematical models for composite binders with different hardening times are pesented.Conclusion. The efficiency of using the obtained composite binder has been proven, the use of which provides an increase in rheological properties, and also makes it possible to save expensive portland cement.