Inter-Layer Mechanical Performance of 3D Printed Cementitious Systems (2024-02)¶

This study delves into the interlayer mechanical performance of 3D-printed cementitious materials, exploring a variety of operational and material parameters to understand the practical effects on the performance of printed structures. To achieve this, a comprehensive battery of tests, encompassing compression, triplet shear, direct tensile, and diagonal tension tests, was conducted. Within the scope of this investigation, the anisotropic performance in perpendicular, lateral, and parallel directions was examined, along with varying printing time intervals (0, 15, 30, and 60 min between consecutive layers), material aging times (0, 30, and 60 min), and different manufacturing methodologies, including cast, horizontal-printed, and vertical-printed specimens. The research findings indicate that well-established mechanical tests, commonly utilized for evaluating masonry structures, can be effectively transferred and applied to assess 3D printed structures. A noteworthy discovery is the anisotropic behavior observed in compressive strength, characterized by diminishing results from perpendicular to parallel and parallel to lateral loading directions. Extended printing time intervals have an adverse impact on the interlayer mechanical performance of cementitious systems. Material aging time also significantly influences bond strength, particularly in mixtures aged for 60 min. In conclusion, it is evident that material aging exerts a more substantial influence on bond strength compared to printing time intervals in cementitious systems. Additionally, it was observed that vertically printed specimens replicate the mechanical performance and fracture mechanism of cast specimens, while horizontally printed specimens exhibit slightly lower performance with distinct fracture patterns.