Adaptation of Concrete Model to 3D Printing Technology

This study presents the results of adapting an existing mathematical model of concrete, originally based on the isotropic properties of traditional cast concrete, to the conditions of 3D printing technology using layer-by-layer horizontal extrusion. The adaptation of the mathematical model is grounded in experimental investigations of the deformation and failure processes of 3DCP concrete samples under various loading schemes. These experiments take into account the structure of the concrete and compare the results with the loading behavior of samples produced using traditional concreting methods. The research findings reveal that the mechanical properties of 3DCP concrete exhibit pronounced anisotropy, determined by the layered structure of the material within the construction. Concrete in structures produced via horizontal layer-by-layer extrusion is a piecewise-homogeneous, layered orthotropic material with differing mechanical properties along mutually orthogonal axes. The experiments demonstrate that under compression and tension perpendicular to the extrusion layers, the behavior of the concrete can be described using mathematical expressions similar to those for traditional concrete, albeit with adjusted key constants reflecting the actual properties. Conversely, under tensile loading parallel to the extrusion layers, the stress–strain relationship can be approximated as a straight line from the onset of loading to failure, with the limit corresponding to the adhesion strength (Radh). In this regime, failure occurs in a brittle manner. The specific deformation and failure mechanisms of 3DCP concrete under tensile loading parallel to the extrusion layers represent a critical distinction from traditional cast concrete. This characteristic prevents the direct application of existing calculation methods to justify the strength and reliability of 3DCP concrete structures.