Testing Prisms as a Method for Assessing Compressive Properties of 3D-Printed Structural Members (2025-03)¶

3D printing in construction has emerged as a faster method that reduces labor, carbon footprint, and cost. Despite the rapid growth of this technology and its application in construction sector, there are still no established guidelines for determining the compressive strength of printed structural elements. The current method uses testing small cubic samples with one or two interlayer joints. However, this approach may not adequately represent the behavior of walls with numerous interlayer joints, which are prone to stress concentration at these interlayers. While testing full-scale wall specimens would provide more accurate data, such tests are time-consuming, expensive, and require specialized facilities. Testing prisms for determining the compressive strength of masonry buildings is an established method; however, this method has never been used for printed buildings. The objective of this study is to propose the method of testing prism as a practical and cost-effective approach to determine the compressive properties of 3D-printed structures. The research methodology includes testing 3D-printed prisms of two different dimensions and made from two different cementitious materials, alongside identical concrete masonry prisms as reference specimens. Furthermore, numerical analysis was conducted to evaluate the effects of various material properties and width of print layer. The key findings of this study reveal that 3D-printed prism tests made of mortar and concrete achieved strength-to-material ratios of 89% and 86%, respectively, comparable to the 88% ratio observed in masonry prisms. The strain contour on the surface of the printed prisms displayed a strain pattern similar to that observed in a full-scale test, indicating that this method proposed in this paper reliably assesses the compressive properties of 3D-printed structures.