The rheological behavior of disperse systems for 3D print-ing in constrcution: the problem of control and possibility of «nano» tools application

The paper considers the problem of creating a wider class of building materials used for 3D printing. From the point of view of classical rheology of disperse systems, the application of 3D printing technology in construction has been analyzed. Theoretical analysis of the models of rheological behavior is performed according to state of their structure and the dynamic of the 3D printing processes such as mixing, pumping, extrusion, multilayer casting and structural built-up in the printing layers. The main factors and criteria for the stability of heterogeneous disperse systems in dynamic and static 3D printing processes have been identified. The general scientific concept for optimization of admixtures for 3D printable materials has been developed in terms of viscosity, consistency, and parameters of flocculation and structural built-up. The technological tools to control rheological behavior of visco-plastic admixtures are identified in all stages of 3D printing. The relevant considerations include the concentration, size, morphology, chemical and mineralogical composition, the physical and chemical activity of the solid phase’s surface, and the ionic composition, viscosity, and density of the liquid phase. It is shown that the practical engineering solutions to control the rheology, structure formation, properties of 3D printing admixtures and materials must be based on traditional factors as well as with the use of «nano» tools. According to the nanotechnological principle «bottom-up», a set of «nano» tools is proposed to control such admixture properties as extrudability, formability, and buildability. In conclusion the scientific and technical tasks to be researched have been formulated