Comparative Analysis of Structural Build-Up in One-Component Stiff and Two-Component Shotcrete-Accelerated Set-on-Demand Mixtures for 3D Concrete Printing (2024-06)¶

3D Concrete Printing (3DCP) is undergoing a shift from stiff printable mixtures towards set-ondemand mixtures. Nonetheless, there remains a significant gap in understanding the rheological behaviour as well as efficiency of the test methods for characterising rheological properties of set-on-demand mixtures. To address this gap, this study conducts a thorough examination of the suitability of four different characterisation test methods on a set-on-demand mixture. A stiff mixture is also tested for comparison purposes. An in-depth analysis is conducted on the strengths and weaknesses of each method in capturing the rheological evolution of both mixtures. Additionally, direct printing tests were also conducted for both mixtures. The external stresses, specifically those resulting from the self-weight during printing, were calculated. The evolving rheological properties of mixtures, measured from the instruments, were compared with the external stresses due to the printing process. Furthermore, variations in failure modes between the mixtures are revealed, with a significant discrepancy in the predicted number of printable layers based on the characterisation tests. This study offers valuable insights into the rheological characterisation and performance of test methods for the set-on-demand approaches.