Effect of introducing dummy layers on interlayer bonding and geometrical deformations in concrete 3D printing

Abstract

This paper presents the effect of dummy layers in concrete 3D printing to enhance interlayer bonding and reduce geometrical deviations. The specimens were printed by varying numbers of dummy layers at different layer heights using the optimized printing parameters. The impact of dummy layers on interlayer bonding was determined using a split tensile test and the geometrical deviations were analyzed using a 3D-scanning technique. Results demonstrate that significant improvement was found in interlayer bonding, notably at the top layer. For instance, by adding two dummy layers in specimen H10D2, the difference between the top and middle layers bond strength was reduced from 42.57% (i.e., for specimen H10D0) to 0.79%. Moreover, the dummy layers effectively minimized the geometrical deviations by achieving the desired layer dimensions in the top layer of specimens.