Effect of Interlayer Time-Lapse and Workability Retention on Printed Concrete

Описание: Presented By: Debalina Ghosh, University of Tennessee
The rapid advancement of additive manufacturing technologies for concrete construction requires further understanding of material performance and its relationship with print parameters such as interlayer time-lapse and workability retention during the print. This study addresses the effects of the time delay between consecutive extruded layers on the mechanical performance of printed concrete using a mix designed by Quikrete. A series of specimens were prepared with printing delays of 10, 15, 30, and 60 minutes. This work correlates the change in fracture properties, mechanical performance, and workability retention with the interlayer time-lapse between two consecutive concrete layers. Understanding the differences between the processes and the effects of time-lapse are important for establishing standard testing methods and fabrication guidelines. The findings conclude that the time span between two consecutive layers plays an important role in printed concrete properties. Interlayer time-lapse affects individual properties differently based on the loading direction and test types, but it is consistent in terms of interlayer performance. In this study, the bonding strength declines with longer interlayer time-lapses. The concrete fracture behavior changes with the interlayer time-lapse. The time-lapse effects are also influenced by the properties of the concrete mix. Reduced compressive strength and fracture toughness are more prominent in the specimens with long time-lapses. Hence, the workability retention trend of the print material should be considered to ensure that the interlayer time-lapse is within the dormant hydration period.