Inspired by examples of self-healing in nature, like skin and bones that heal their own damage and vines that repair themselves when broken or torn, scientists at the University of Michigan were determined to create a smarter building material. What they came up with is new a form of concrete that uses microfibers in the place of coarser bits of sand and gravel that traditional cement mix uses. The fibers allow the final composite to bend with minimal fracturing and if fracturing does occur, the cracks tend to be less than 50 microns wide.