University of Newcastle building scientists have developed a means of repairing damaged or deteriorated concrete using a genetically engineered strain of a common soil bacteria. Nicknamed "BacillaFilla," the bacteria have been modified so that they migrate into the deepest parts of cracks where they then begin to produce calcium carbonate. Calcium carbonate binds with concrete and can repair small fractures and restore broken concrete to its original strength.
This is not unlike an earlier EcoGeek story about bendable, self-healing concrete which also uses calcium carbonate to heal small cracks in concrete. But where that method called for the introduction of the calcium carbonate into the concrete when it was produced. The bacterial method allows the same process to be applied to old concrete that was not made with calcium carbonate.
A number of safeguards have been incorporated into the bacteria to ensure that they work only where it is wanted. The researchers have tweaked its genetic properties such that it only begins to germinate when it comes in contact with the highly-specific pH of concrete. Once the cells germinate, they are programmed to crawl as deep as they can into cracks in the concrete, where quorum sensing lets them know when enough bacteria have accumulated. This enables the bacteria to target the weak points of damaged concrete and to work in a useful and organized fashion only where the repair is needed. In addition, the bacteria also contains a self-destruct gene, so that it will not propogate beyond where it is intended to go.
As we noted earlier, "[Concrete] is not the most beloved green building material, [but] it has properties that make it eminently useful for engineers and architects for a number of purposes. Given that there is not going to be a sudden moratorium on using the stuff, it's better to have improvements that can keep from having it go from useful building material to landfill."
written by Daniela, November 26, 2010
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