Living concrete fixes its own cracks with built-in bacteria

Concrete is the most popular building material on the planet, probably because it's very strong, easy to work with and cheap, being made mostly of rocks. There are some durability issues with concrete, though, and to make it stronger, Dutch scientists have added self-healing capsules to help buildings heal cracks on their own.

Bacteria can fix cracks in concrete the same way that humans can, by filling them in with more concrete materials, or in this case, limestone: http://dvice.com/archives/2012/11/living-concrete.php