Can Self-Healing Metal and Concrete Give Infrastructure a New Lease on Life?

This summer, the Atlantic Council, a non-partisan think tank, defined programmable matter as material that changes form and function after being produced, either automatically or by command. Scientists are currently developing the technology, also known as 4D printing, in various projects. As their work evolves, it could form an industry that transforms how the government services roads, bridges, and buildings.


The idea of shape-changing substances and objects undoubtedly conjures up bizarre, science fiction-flavored possibilities. People would love tables and chairs that assembled themselves after being bought, and they’d take flights with a bit more ease knowing that their planes’ wings and surfaces automatically adjusted to wind and thunder. They’d have similar feelings about adjustable vehicles, boats, and submersibles, and who wouldn’t appreciate trash that broke down into pieces or particles for easier disposal or recycling?


Government employees could adapt 4D technology for more mundane applications that are equally important to daily life. Concrete that automatically mends, for example, could lead to streets and structures that repair their cracks from water damage, which would facilitate longer-lasting infrastructure that spared public sector budgets from hemorrhaging thousands or millions of dollars in upkeep costs over several years.


Adaptive Metal and Concrete


Scientists are examining different forms of self-healing concrete, which means that the first morphing building or street may soon be on the horizon. In fall 2013, Italian engineer Liberato Ferrara addressed malleable cement at an American Concrete Institute convention and discussed fibers that shrink inside concrete to squeeze it in tighter in response to liquid penetration. Elsewhere, engineers at the Delft University of Technology in the Netherlands are developing concrete containing a porous, vascular network that transports a substance to cracked, degraded areas and glues them back together. 


Erik Schlangen, one of the Delft scientists, demonstrated adaptive asphalt earlier in 2012 during a TED Talk. He chopped a block in two, placed the pieces inside a microwave, heated them, and when he took them out and cooled, they mended themselves back together into a complete whole again. The heat activated steel wool that melted and mixed bitumen material surrounding it, and the asphalt mended once the bitumen cooled. The Dutch government has donated roads for Schlangen’s work, and his team has developed a vehicle that places induction coils on roads to heal cracked surfaces in real-world applications, a process that could save the country millions in repair costs and extend the life of city streets. 


Perhaps most astonishing of all, experiments like these are even causing metal to repair itself. Last year, MIT scientists accidentally made cracks in nickel close back up. They experimented with applying different degrees of force onto broken nickel—tension they expected to break the material apart even further—and learned that they could “push” the cracks closed instead. Michael Demkowicz, one of the scientists, told the MIT Review that their discovery was far from practical applications, but it had incredible potential to design more efficient cars, subways, planes, and quake-resistant buildings.


A Malleable Future


The abovementioned projects don’t by any means represent the complete, exhaustive grouping of programmable, 4D printed projects. While 3D printing is a few decades old, its fourth dimension began spawning at least as early as 2007 with the Defense Advanced Research Projects Agency’s programmable matter program. The project generated millimeter-sized objects that folded themselves into complex shapes.


The Atlantic Council cited programmable matter and 4D printing as potentially world-changing technology and offered predictions of applications in its report, including morphable construction bricks for more dynamic building construction, tires with sensors that trigger mechanisms inside the rubber that make it change shape and traction based on road conditions, and clothes that change fit based on the wearer’s body shape and physical performance.


Government leaders may one-day welcome programmable matter as a solution to daunting infrastructure problems. TripNet reported last fall that more than a quarter of American major urban roads were in substandard or poor condition, and that the average motorist loses $377 annually in additional vehicle operating costs because of driving on decaying roads.