Two researchers from Delft Technical University in Holland have developed a self-healing cement that can stop microcracks from forming in concrete. The material incorporates alkaphilic bacterial spores (which thrive in the alkaline environment of concrete) plus a feeder material. When water infiltrates concrete, the spores are activated and convert the feed into limestone, sealing the crack and preventing larger cracks from forming.
Microbiologist Henk Jonkers and concrete-development specialist Eric Schlangen have been working on the project since 2006. Basements, tunnels, and transportation infrastructure are among the proposed wet environments that could benefit from the innovation, which may be commercialized in four to five years. Scientists from the South Dakota School of Mines and Technology are now cooperating in the project.
(http://www.citg.tudelft.nl//index.php?id=17205)
Dutch microbiologist Henk Jonkers explains "bioconcrete" technology:
http://www.youtube.com/watch?feature=player_embedded&v=PyBR3PDPa-c