Sooner or later, even the best sidewalk in the country will develop a crack or two. When this happens, workers are deployed to either fill in the damage or lay down completely new swaths of concrete. Over 7 per cent of the world’s CO2 emissions come from cement production, so any means of prolonging the material’s life would help to reduce greenhouse gasses. Researchers at Cardiff University, the University of Cambridge, and the University of Bath are taking part in a £3m project to create self-healing concrete. The material would be able to mend itself with the help of bacteria contained within microcapsules that would germinate and produce limestone when water enters a fissure.
Self-healing concrete could potentially extend the life of paving and structures by 50 percent and do away with the need for manual repairs. Researchers face several challenges in their efforts to find a suitable bacteria for their new material. Concrete is highly alkaline, making it a difficult place for bacteria to thrive. They are trying to find an organism that is not only able to flourish, but able to produce a large amount of spores. The team will also have to determine the pore size of the concrete so that it is small enough not to crush the forming bacteria as it densifies during the drying process. Micro-capsules will enclose and protect the bacteria while providing nutrients and calcium lactate, which will be converted by the bacteria once water is present.
“Self-healing materials are particularly suited to situations where safe access for maintenance is costly, so the outputs of this extended research program could reduce the life cycle costs of infrastructure.” says Dr. Andrew Heath from the Department of Agriculture and Civil Engineering.
This novel form of concrete could make steel framework less vulnerable by avoiding the corrosive effects of oxygen. The scientists are now looking at several different species of bacteria and assessing their viability. With the addition of microbes, buildings and roadways could take on an organic element that combines biology, chemistry, and architecture.