The United States Defense Advanced Research and Planning Agency (DARPA) is seeking the involvement of industry and universities in a new study aimed at achieving 3D-printed concrete in shallow and near-shore areas for the rehabilitation and construction of key port facilities. It is envisaged that the system will make direct use of sand, clay and seawater on the seabed and reduce the reliance of traditional underwater construction on the transport of specialized equipment and external materials.
Target points to military ports and offshore installations.
DARPA states that, although available underwater concrete construction techniques already exist, they are complex, costly and highly disruptive to the environment, and are not suitable for expeditions or military operations. The new programme aims to carry out construction work in the shallow coastal zone and at a depth of 100 metres, which could be used in the future for the construction of facilities such as ports, sea walls and artificial reefs, as well as for undersea oil and gas pipeline protection and submarine communications cable protection.
The longer-term objective of the plan is to lay the foundation for “a fully autonomous system capable of operating deep water”. As envisaged in DARPA, the system could in the future carry out direct repairs in the vicinity of damaged maritime installations, reduce logistical pressures and increase the speed of combat and disaster recovery.
AI to judge the ratio of material
The project also plans to introduce AI to determine the best ratio of seawater to sediment in different marine environments. As sand, clay and water conditions vary significantly from location to location, the combination of materials can have a direct impact on concrete formation and durability. DARPA hopes to improve the adaptive capacity of on-site construction through algorithms rather than relying on a single fixed formulation.
In recent years, the United States military has consistently increased its investment in autonomous systems, extending from unmanned aerial and ground platforms to logistics and engineering. The 3D printing building on land was previously tested, but underwater construction with robotic systems is still considered a new technological direction.
The context is the ageing of maritime infrastructure.
The DARPA contribution to the study is also related to the ageing of the United States maritime infrastructure. Salt water, humidity, storms and corrosives continue to erode installations such as wharfs, troughs and sea dykes, which are both normal logistics nodes and important naval support points in wartime.
Public reports indicate that the condition of some United States maritime military installations has been under constant pressure. A report released last year mentioned that about 45 per cent of the United States Coast Guard ' s maritime facilities, including docks and mooring facilities, have exceeded the expected length of service.
In addition to this underwater construction programme, DARPA is advancing another early study to try to predict more accurately how concrete infrastructure has ageing and failed over decades. In 2023, the Agency also provided $10 million to the University of Colorado for a study for nearly five years to explore the “self-rehabilitation” of damaged facilities such as airports, missile wells and naval docks with similar biological systems.