Influence of Material and Process Parameters on Hardened State Properties of Shotcrete 3D Printed Elements (2022-06)¶

The layer-by-layer nature of additive manufacturing processes creates an interface between the individual strands and can therefore affect the printed element in the hardened state. In this paper, the Shotcrete 3D Printing (SC3DP) technique is investigated. Here, the effect of process and material parameters during production, namely concrete volume flow (0.4; 0.6; 0.8 m3/h), air volume flow (30; 40; 50 m3/h), and accelerator dosage (corresponding with 0; 3; 6% bwoc) on layer geometry (width/height), interface tortuosity and flexural strength are evaluated. The results presented in this paper show that the strand geometry is essentially determined by the accelerator dosage and concrete volume flow. The interface tortuosity is influenced by an interaction of all three parameters, but the air volume flow has the greatest influence. The flexural strength is dominated by the accelerator dosage and the air volume flow. In addition, a correlation between interface tortuosity and flexural strength is demonstrated. Finally, the consequences of how to use the findings of the effect of process parameters, accelerator dosage, and the layer-by-layer nature during printing in practical application are discussed.