Underwater 3D Concrete Printing (2026-02)¶

Underwater 3D concrete printing (U3DCP) is an emerging automated construction technology with significant potential for offshore, coastal, and marine infrastructure, enabling in-situ fabrication without dewatering or formwork. Operating in a submerged environment, U3DCP involves tightly coupled interactions between material rheology, hydrodynamics, and robotic process control that fundamentally distinguish it from terrestrial additive manufacturing. This review presents a focused, mechanism-driven synthesis of U3DCP, covering its evolution, mix-design strategies, fresh-state behaviour, printing hardware and operational parameters, hardened mechanical performance, durability, and multidisciplinary applications. Particular emphasis is placed on anti-washout systems, rheological structuration, and process–material coupling governing extrusion stability, shape retention, and interlayer bonding. By integrating bibliometric analysis and unified performance frameworks, the review identifies key design windows, automation challenges, and critical knowledge gaps, including standardisation, long-term durability in seawater, and full-scale robotic deployment. The paper provides guidance for advancing automated, resilient, and sustainable underwater digital construction.