From printing to performance: a review on 3D concrete printing processes, materials, and life cycle assessment

A paradigm shift in the construction sector has been driven by 3D concrete printing (3DCP), offering automated alternatives to conventional building methods. 3DCP enhances precision, efficiency, and consistency through robotic control and advanced printhead systems while reducing material waste and enabling design flexibility. This review examines the working principles, printer classifications (gantry-based and robotic arm-based), and operational parameters, highlighting printing speed, interlayer gap time, and nozzle size and shape as critical parameters for buildability, interlayer bonding, and extrusion quality. Their influence is discussed in relation to fresh properties (flowability, pumpability, extrudability, shape retention, and buildability) and hardened properties (compressive, tensile, and flexural strength, interlayer bonding, and durability). Mix design strategies for optimizing rheology, printability, and sustainable material selection are critically reviewed. Key durability concerns such as shrinkage, cracking, and weather resistance are addressed. Reinforcement methods, including steel bars, fibers, and embedment techniques, are also discussed. A life cycle analysis reveals that 3DCP reduces carbon dioxide emissions by up to 89.2% and construction costs by 30–40% through formwork elimination. Environmental impacts (waste generation, carbon footprint, and energy use) are assessed using regional and global data, considering embodied energy, transportation, and maintenance costs. Challenges such as regulatory hurdles, high initial investment, and the absence of standardized guidelines are identified. This review covers developments from the past decade, offering valuable insights for researchers, industry professionals, and policymakers regarding the advancements, limitations, and future directions of 3DCP.