Mechanical properties of 3D printed concrete: a RILEM 304-ADC interlaboratory study – compressive strength and modulus of elasticity
Viktor Mechtcherine, Shravan Muthukrishnan, Annika Robens‐Radermacher, Rob Wolfs, Jelle Versteege, Costantino Menna, Onur Öztürk, Nilüfer Özyurt, Josef Roupec, Christiane Richter, Jörg Jungwirth, Luiza Rodrigues Meira de Miranda, Rebecca Ammann, Jean‐François Caron, Victor de Bono, Renata Monte, Iván Navarrete, Claudia Eugenin, Hélène Lombois-Burger, Bilal Baz, Māris Šinka, Alise Sapata, Ilhame Harbouz, Yamei Zhang, Zijian Jia, Jacques Kruger, Jean-Pierre Mostert, Mateja Štefančič, Lucija Hanžič, Abdelhak Kaci, S. Rahal, Manu Santhanam, Shantanu Bhattacherjee, Chalermwut Snguanyat, Arun R. Arunothayan, Zengfeng Zhao, Inka Mai, Inken Jette Rasehorn, David Böhler, Niklas Freund, Dirk Lowke, Tobias Neef, Markus Taubert, Daniel Auer, C. Maximilian Hechtl, Maximilian Dahlenburg, Laura Esposito, Richard Buswell, John Temitope Kolawole, Muhammad Nura Isa, Xingzi Liu, Zhendi Wang, Kolluru V. L. Subramaniam, Freek Bos
Abstract
Abstract Traditional construction techniques, such as in-situ casting and pre-cast concrete methods, have well-established testing protocols for assessing compressive strength and modulus of elasticity, including specific procedures for sample preparation and curing. In contrast, 3D concrete printing currently lacks standardized testing protocols, potentially contributing to the inconsistent results reported in previous studies. To address this issue, RILEM TC 304-ADC initiated a comprehensive interlaboratory study on the mechanical properties of 3D printed concrete. This study involves 30 laboratories worldwide, contributing 34 sets of data, with some laboratories testing more than one mix design. The compressive strength and modulus of elasticity were determined under three distinct conditions: Default, where each laboratory printed according to their standard procedure followed by water bath curing; Deviation 1, which involved creating a cold joint by increasing the time interval between printing layers; and Deviation 2, where the standard printing process was used, but the specimens were cured under conditions different from water bath. Some tests were conducted at two different scales based on specimen size—“mortar-scale” and “concrete-scale”—to investigate the size effect on compressive strength. Since the mix design remained identical for both scales, the only variable was the specimen size. This paper reports on the findings from the interlaboratory study, followed by a detailed investigation into the influencing parameters such as extraction location, cold joints, number of interlayers, and curing conditions on the mechanical properties of the printed concrete. As this study includes results from laboratories worldwide, its contribution to the development of relevant standardized testing protocols is critical.