Abstract: For 3D printing concrete produced by a printing process of pumping, extrusion and stacking-up layer by layer, its interlayer bonding performance is a key point in structural analysis. This paper presents a statistical comparison and analysis of the interlayer bonding properties based on the previous test data in literature, and reveals the mechanism of interlayer bonding influenced by the parameters of the printing process. A two-stage model considering hydration process is developed to simulate the variations in interlayer bonding strength with the printing time interval; the influences of nozzle shape, size and height on interlayer bonding are clarified. We construct a model of interlayer bonding strength degrading with printing speed to optimize and improve the 3D printing process of concrete.

Key words: 3D printing, interlayer bonding, theoretical model, process parameters, influence mechanism