Mechanical Behavior of 3D Printed Cement Materials (2019-04)¶

Given that it is a manufacturing process that is often carried out layer-by-layer, 3D printing with concrete or cement-based materials is done through the formation of a laminated material whose mechanical and physical characteristics depend on the direction in which the load falls. If we examine the 3D printing process of extrusion/deposition that has currently been studied the most, it can be observed that the material has three planes, with orthogonal symmetry between these planes. Thus, it is an orthotropic material (Figure 4.1). Hence, its mechanical behavior differs on the basis of the three axes as defined by the direction of the deposition, the width of the layer and the height of the structure to be printed. In addition, the interfacing between layers intuitively appears to be a sensitive zone, which can have a large influence on the overall mechanical behavior of the printed material. To fully understand the mechanical behavior of printed structures, we must take into account the level of orthotropy. This can be done by comparing its mechanical behavior in different directions of stress or by comparing the characteristics of a printed material with those of the same cast material that exhibits a monolithic isotropic behavior. In this chapter, after conducting a review of the literature on the performance of printed mortars, we will examine the possible origins of the orthotropic behavior of printed materials by considering the influence of process parameters on the origin of this nature. We will pay particular attention to the mechanical behavior of materials printed by the extrusion/deposition method. Finally, we will examine the mechanical behavior of materials printed by the other techniques.