Influence of Technological Factors on the Interlayer Bond Strength of 3D-Printed Concrete.

This paper presents an analysis of mathematical models developed from experimental data to describe the effects of concrete mixture workability, the time interval between the deposition of adjacent layers, aggregate size, and concrete mixture composition on the interlayer bond strength of 3D-printed concrete. The models enable a quantitative assessment of the nature and degree of influence of the investigated technological factors on the interlayer bond strength of concrete. The results demonstrate that the interlayer bond strength, evaluated based on concrete splitting tensile strength, exhibits an extremal relationship. The range of optimal technological parameters within which the maximum interlayer bond strength is achieved has been determined. The effects of interactions between the investigated technological factors on the interlayer bond strength are also examined. The influence of these factors on interlayer bond strength is associated with their effect on the concrete mixture water demand, which is described by the developed mathematical model. In addition, a relationship between the interlayer bond strength of concrete and the water-to-cement ratio is established.