The problem is simple — concrete cracks. And when it cracks, it doesn’t just look bad, it starts to lose its strength. Water and chemicals get in, the steel inside begins to corrode, and the whole structure slowly gets weaker. Fixing these cracks isn’t cheap either. Over 20 years, repairs on just one mid-sized structure can cost around $140,000. And every time we repair, we also create huge emissions — about 5 to 20 kilograms of CO₂ per square meter for routine maintenance, and up to 200 kilograms when heavy repairs are needed. Multiply that across thousands of bridges, tunnels, and buildings, and you see billions wasted and enormous damage to the environment, all because concrete was never designed to heal itself

We’ve developed self-healing concrete — concrete that can repair its own cracks, the same way your body heals a cut. Here’s how it works: inside the concrete, we place microscopic hydrogel capsules containing Bacillus bacteria. These bacteria can stay dormant for decades, almost like tiny immune cells waiting on standby. When a crack forms and water seeps in, the capsules break open, and the bacteria wake up. They use the water and a nutrient source to produce calcium carbonate — which is basically natural limestone. This mineral grows inside the crack, sealing it tightly and restoring the concrete’s strength