Imagine a world where sidewalks never crack and potholes never form. Sounds like something straight out of a utopian sci-fi novel, right? Well, thanks to a team of microbiologists led by Henk Jonkers of Deft University, Netherlands, self-healing concrete is no longer just a futuristic concept — it actually exists in the real world now.
Basically, these guys have developed a special kind of “bio-concrete” that’s imbued with a specific strain of bacteria. When the concrete fractures, the bacteria will spring into action and fill the crack back up with limestone.
While the concept seems fairly straightforward, developing this self-healing concrete wasn’t exactly a walk in the park. Thing is, concrete isn’t a very hospitable environment for life. It’s dry, stone-like, and extremely alkaline — so Jonkers’ first task was finding a species of bacteria that could survive in such surroundings.
After some searching, he and his team eventually chose bacillus for the job; a species that thrives in alkaline conditions, and produces spores that can survive for decades without food, water, or oxygen. But that was only half the battle. Once they had the right bacteria, they needed to provide it with a food source (lactate) that would allow it to produce limestone.
Sugar was the best option — but adding sugar directly into the concrete mixture would produce soft, weak concrete. So, instead of adding it directly, the team decided to encapsulate the sugar and dormant bacteria in tiny biodegradable beads. These beads are mixed in with the wet concrete, and designed to break open whenever the dried structure develops cracks.
The resulting mixture is pretty remarkable. Basically, whenever the hardened concrete forms fractures, it splits open the beads, releasing the sugar and bacteria. The fracture of course also allows water to seep in, and this moisture activates the dormant bacteria, which then begin gobbling up the sugar, multiplying, and slowly filling up the crack with limestone.
You probably won’t have it in your driveway anytime soon, but the material has a massive number of potential applications. In the future, it could be used for anything from self-repairing freeways to earthquake-proof houses.