Exploring Key Aspects and Sustainable Benefits of 3D Concrete Printing (3DCP): a Selective Review

The construction industry, traditionally conservative, lags technologically advanced sectors adopting automation. The utilization of additive manufacturing, specifically 3D printing, in civil infrastructure, particularly with cementitious materials, is bringing about a transformative change. This technological advance presents numerous opportunities, including flexible geometry, reduced manpower, faster construction, and decreased waste. Despite the inception of 3D concrete printing (3DCP) in 1995, research on 3DCP mixes with supplementary cementitious materials (SCM), viscosity modifiers, accelerators, retarders, and nanomaterials has been limited. This paper addresses the gap by providing an overview of 3DCP incorporating fly ash, silica fume, calcium sulfoaluminate (CSA), and other SCMs. It extensively reviews the effects of SCM on workability, extrudability, printability, buildability, and the sustainable benefits of 3DCP. Additionally, properties such as viscosity, yield stress, and Young's modulus in 3DCP are discussed. Literature reviews indicate that the yield stress for 3DCP mixes ranged from 1.5 to 2.5 kPa. Fly ash emerges as a cost-effective and energy-saving binder in 3DCP. However, there remains substantial room for developing high early strength 3DCP mixes with SCM due to limited codes of practice and literature providing guidelines for digital construction practices.