 Researchers at the University of Bath aim to develop a concrete mix that contains bacteria within microcapsules, which will germinate when water enters a crack in the concrete to produce limestone (calcite), plugging the crack before water and oxygen have a chance to corrode the steel reinforcement. Richard Cooper, from the Department of Biology and Biochemistry, said, “Cement is highly alkaline, making it a hostile environment for bacteria. We’ll be assessing different species of bacteria to find one that is able to form abundant spores and which will survive and germinate in this environment. The work will involve finding alkaline-tolerant isolates and testing their biology and physiology.” Kevin Paine, from the Department of Architecture and Civil Engineering, added, “Concrete densifies as it hardens, so the pore size decreases to a level where bacteria may be crushed. We’re looking at enclosing the bacteria in microcapsules, along with nutrients and calcium lactate which the bacteria will convert when water becomes present and use to fill cracks in the concrete.”