Bacteria-laden concrete helps cracks fix themselves

Inspired by the human body, Jonkers, who works at the Delft University of Technology in the Netherlands, created self-healing concrete. He embeds the concrete with capsules of limestone-producing bacteria, either Bacillus pseudofirmus or Sporosarcina pasteurii, along with calcium lactate. When the concrete cracks, air and moisture trigger the bacteria to begin munching on the calcium lactate. They convert the calcium lactate to calcite, an ingredient in limestone, thus sealing off the cracks.  — smithsonianmag.com