Abstract

3D concrete printing (3DCP) is a new technique in the construction sector that allows the printing of concrete structures of various sizes and shapes. This article aims to present the evolution of 3DCP technology as well as the various concrete mixtures and materials that are used in 3DCP. In addition, it describes the necessary tests to determine the mechanical properties of 3DCP. There are mainly two techniques of 3DCP which are laying down concrete layer by layer or using shotcrete 3D printing. The characteristics of concrete mixtures are conducted by compression, flexural, tensile, and shear tests to determine the strength, pumpability, printability, durability, and workability of 3DCP. Furthermore, the slump flow is used to determine the flowability of concrete that passes through the printer’s nozzle. Superplasticizers, silica fume, fly ash, geopolymer and fibers such as steel, polypropylene, and glass are commonly used in mixtures to increase the strength of 3DCP and control the formation of the drying shrinkage cracking.

Keywords:3D concrete printing; 3D printing techniques; Cementitious materials; Concrete structures; Cementitious composites

Abbreviations:3DCP: 3D Concrete Printing; 3DPT: 3D Printing Technique; τD,i: Initial Dynamic Yield Shear Stress of the Material; Measured from the First Rheological Test (Pa); τS,i: Initial Static Yield Shear Stress of the Material; Measured from the First Rheological Test (Pa); τS(t): Static or Apparent Yield Shear Stress of the Material at Time t After Agitation (Pa); AM: Additive Manufacturing; Athix: Structuration Rate (Pa/sec); Rthix: Short-term Re-flocculation Rate (Pa/sec); trf: Time Period Over which the Re-flocculation Occurs and the Dominant Shear Stress Increase (sec); t: Time Since the Cessation of Agitation (sec)