Biologists Create Self-Healing Concrete

Mr.Intel writes: A team of microbiologists from the Delft University of Technology claims to have invented "bioconcrete" — concrete that heals cracks and breaks using bacteria. The goal was to find a type of bacteria that could live inside concrete and also produce small amount of limestone that could re-seal cracks. This is a difficult prospect because concrete is quite dry and strongly alkaline. The bacteria needed to be able to stay alive for years in those conditions before being activated by water. The bacteria also need a food source — simply adding sugar to concrete will make it weak. The scientists used calcium lactate instead, adding biodegradable capsules of it to the concrete mix. "When cracks eventually begin to form in the concrete, water enters and open the capsules. The bacteria then germinate, multiply and feed on the lactate, and in doing so they combine the calcium with carbonate ions to form calcite, or limestone, which closes up the cracks."