Like a cut on skin that scabs over and heals, concrete could one day repair its own cracks — thanks to an ingenious formula from Drexel engineers.

Inspired by the body’s natural healing process, researchers have developed “BioFiber,” a bacteria-infused reinforcement that reacts to damage by sealing cracks before they grow. This self-repairing system could dramatically extend the lifespan of concrete infrastructure while reducing costly repairs and environmental impact.

BioFiber consists of a polymer fiber core coated with a hydrogel layer embedded with bacteria, all wrapped in a protective, damage-responsive shell. Placed in a grid throughout the concrete as it is poured, it acts as a reinforcing support agent.

The researchers used a hardy strain of Lysinibacillus sphaericus commonly found in soil that can survive dormant inside a cementitious matrix. When a crack forms and water reaches the BioFiber layer, the bacteria react with calcium in the concrete.

Once activated, they trigger a natural process that produces a cement-like substance (calcium carbonate) that seals the crack, similar to how blood clots help skin heal. The entire BioFiber structure measures just over half a millimeter thick but plays a crucial role in strengthening concrete.

Preliminary tests, reported in Construction and Building Materials, suggest the bacteria can complete repairs in just a few days or a couple of weeks, depending on the size of the crack.

“This is an exciting development for improving building materials using inspiration from nature,” says Amir Farnam, an associate professor in the College of Engineering and lead researcher on the NSF-funded project. “If we can extend the lifespan of concrete structures, we not only reduce repair costs but also significantly cut the environmental impact of cement production.”

Concrete production accounts for 8% of global carbon dioxide emissions due to the high-temperature and calcination processes required to make cement. Making infrastructure more durable is critical to limiting the need for new concrete, a priority for global sustainability efforts and federal agencies. Farnam’s lab is also part of a team participating in a Department of Defense effort to fortify aging structures using a nature-inspired vascularization approach to deliver self-healing agents into concrete.