3D-printed military structures dot the Himalayas

  The bunker in Leh was built on site using a robotic arm and completed in five days, with the total printing time being only 14 hours.

  The conventional way of construction in such terrain is slow and labour-intensive, requiring material to be transported over difficult routes and personnel working in low-oxygen conditions. Whereas 3D printing addresses the operational challenge to quickly build durable, protective infrastructure in forward areas where terrain, climate and logistics severely constrain construction. 

  PRABAL shows how additive manufacturing – 3D printing–  can change the construction of shelters, bunkers and underground facilities across high altitude-low oxygen (HALO) conditions. On-site construction using portable robotic printers and locally sourced materials reduces timelines, eases logistical dependence on long supply chains and limits human exposure in extreme terrain. 

  “Concrete construction, the way it is done today, is very slow,” said Professor K V L Subramaniam, department of civil engineering, IITH. 

  Traditional construction also limits structural efficiency because it forces engineers into simple rectangular designs rather than free-form structures. 

  “We are always stuck with producing rectilinear shapes. Rectangular shapes are not the most efficient shapes structurally,” he said, noting that these forms are used largely because they are easier to cast with conventional shuttering. 

  “With 3D printing, robots fabricate the structure in real time without using formwork. It uses less material and still delivers a structure that performs far better than a conventional one,” Subramaniam said, adding that it helps to reduce the weight without affecting performance.

  Under PRABAL, the army deliberately set difficult conditions to test the technology. “The army wanted us to prove two things: first, we could print protective structures using indigenous technology, and second, that we could use only local materials.”  

  Need for sustainability

  The conventional construction methods were not sustainable in forward areas. Existing structures depended heavily on materials transported from distant locations, creating logistical challenges and increasing environmental costs in sensitive regions. 

  On-site construction using locally available materials, rather than relying on off-site prefabrication and long supply chains was the only option for such heights, while also reducing the logistical dependence and ensuring that protective infrastructure could be deployed quickly and responsibly in challenging terrain.

  Project Prabal is structured around four broad pillars: the development of a deployable robotic printing system, terrain-specific material design, location-based construction strategies, including concealment and overall sustainability of the system across operational environments. 

  The project was driven less by novelty than by necessity. 

  CEO and founder of Mumbai-based Simpliforge Creations, Dhruv Gandhi, explained that the army’s decision to back additive manufacturing was driven not just by innovation, but by economics and construction time. 

  “3D printing is going to be cheaper than conventional construction,” Gandhi said, pointing out that even where upfront costs are higher, lifecycle economics tilt the balance. “If you look at cost over a 10-year horizon, 3D printing consistently turns out to be  the cheapest option,” driven by lower maintenance and energy consumption.

  “3D printing is nearly ten times faster than conventional construction,” he said, noting that robotic systems can print up to six metres a day. “Time savings are an even bigger strategic advantage, particularly in high-altitude areas where construction seasons are short.”

  According to various media sources, the armed forces selected a robotic-arm-based printing system, owing to its flexibility and design freedom at high altitudes. 

  It was a strategic choice, as it helped to scale the technology from bunkers to underground structures across varied terrains. A blend of local sand, cement, water and additives went into the concrete mix. In cold and dry climates, accelerators are added in the mix to set fast enough to hold their shape; in wet and humid regions, retarders extend working time and prevent premature stiffening, with exact proportions adjusted based on terrain samples and lab tests. 

  Prof. Subramaniam, speaking about the design of these bunkers, observed, “An eggshell is one of the strongest shapes in nature. We borrow from nature.” By using shell-like geometries, the printed concrete remains largely in compression rather than bending, significantly reducing the need for steel reinforcement. 

  This design-led approach is strategic because protection is determined not by material alone but by geometry and threat-specific engineering.

  Strategic necessity

  “Not every printed structure is blast-resistant by default. Blast resistance is a design choice,” Subramaniam noted. Each bunker is designed to address specific threat profiles and weapon systems, which can be modified if the threat changes. “This technology allows us to deliver lighter, stronger, and more protective structures with minimal human intervention in places where conventional construction simply cannot work.”

  He said the bunker’s performance was rooted in its geometry rather than sheer mass. “The bunker is a functionally designed structure. The outer shell looks like a wrinkled piece of paper, and that is deliberate.” 

  The non-planar surface improves ballistic and blast resistance by disrupting impact behaviour. “Ricochet is deadly. The wrinkled surface arrests bullets instead of deflecting them,” he said. Such designs are difficult, if not impossible, to achieve using conventional construction methods.

  A robotic arm moves to make layers, helping to achieve significant reductions in material usage compared to conventional construction, without affecting performance. 

  The engineering approach adapts to terrain: in cold conditions where hydration is low, accelerators are added to reduce setting time. Whereas, in deserts, retarders are added in the concrete mix to prevent rapid moisture loss to maintain workability and strength.  

Subramaniam added that there’s no single concrete mix for different environments. “A desert deployment requires a different mix than Ladakh or Sikkim.” 

  The team conditions materials to handle extreme cold, heat, low oxygen and rapid drying, while also accounting for changes in pumpability at altitude. This is where machines offer a decisive advantage. “It is better to expose machines to extreme conditions than human beings,” he said.

  Gandhi said that beyond scale, thermal insulation is one of the most significant advantages of 3D-printed bunkers. “Earlier bunkers lost heat rapidly, even with heating systems,” 

he said. 

  Conventional fibre- or panel-based shelters lose heat quickly, even when heaters are running. In contrast, monolithic 3D-printed concrete structures retain heat. “Even when outside temperatures fall to minus 40 to 50 degrees Celsius, we can maintain an internal temperature difference of 10 to 20 degrees,” Gandhi stated, significantly reducing fuel consumption and improving living conditions at forward posts.

  Concealment is another factor. “Post-Op Sindoor (against Pakistan), the army realised that emerging threats require soldiers to go underground, even if temporarily,” Subramaniam said.

  “From the top, you would not even know a structure exists.” 

  The increasing use of drones and aerial threats in the ongoing war between Ukraine and Russia has prompted countries to look for quick and easy-to-deploy solutions worldwide to help the troops on the ground, with technologies such as 3D printing emerging as a solution. 

  The structure is designed to take on emerging threats and provide shelters for troops. It was deployed by the Army’s Trishakti Corps in Sikkim - at an altitude higher than Leh — where it was validated for operational use.

  The Army tested 3D-printed structures with live ballistic trials, confirming their structural strength, durability and protective performance in real-world combat scenarios.

  Following this success, the project was expanded across the northern and western borders, scaling from small protective structures for troops to broader protective infrastructure supporting different assets in diverse operational environments.

  Along the Line of Actual Control, Chinese military infrastructure has expanded rapidly with hardened shelters, underground facilities and high-altitude logistics nodes compressing response timelines. The situation signifies the need for protection that can be deployed quickly. 

  Gandhi said that the Indian armed forces have often been early adopters of new technologies, adding that PRABAL has already positioned India ahead globally in terms of 3D printing adoption.

  “Even the US Army uses concrete 3D printing, but they have not attempted high-altitude robotic-arm printing the way India has.” As production volumes rise, Gandhi said daily output could scale from six metres (m) to nearly 20 m, allowing the technology to be deployed across multiple sectors of border infrastructure in the coming years. 

Gandhi stressed that the technology can be extended to roads, permanent bridges, helipads and crash barriers. “Crash barriers can be built for kilometres to ensure safety infrastructure far faster than conventional methods, with minimal reinforcement and logistics.” 

  PRABAL signals a shift in how the Indian armed forces approach force protection in contested and high-altitude areas by integrating robotics and terrain-specific material. The army has moved additive manufacturing beyond experimentation into deployable military infrastructure. The emphasis is no longer just on building faster, but on building smart and lighter structures, reduced logistics dependence and minimal human exposure.

  In a battlespace where adversaries prioritise speed, concealment and safety infrastructure, India’s ability to print infrastructure at the frontline has cut the response timelines. The early investment in the technology will help in the long run in frontline areas, especially in view of China’s expanding border infrastructure.