Open time and extrudability performance analysis of 3D printed concrete with recycled concrete fine aggregates using rheological and computer vision techniques

This study examines the open time and extrudability performance of 3D-printed concrete elements using recycled concrete fine aggregates (RCFA). It emphasizes the importance of fresh state properties like extrudability and open time, which are crucial for the quality of 3D-printed structures. The study introduces a novel methodology that uses conventional rheological tests and computer vision techniques to assess these properties. The rheometer tests give the understanding of the evolution of material stiffness before the printing process and the computer vision technique gives an understanding of temporal extrudability changes during the printing process. The results from both studies show a similar trend in the evolution of material stiffness, signifying the importance of combined test results in analyzing the 3D-printing concrete.