Self-repairing concrete

Sealing cracks

Who

An engineer at one of the Netherlands’ leading universities has invented a biological concrete that can repair its own cracks.

Technology

Dr Henk Jonkers of Delft University of Technology has produced the self-healing concrete using a special strain of mineral-eating bacteria. Found in soda lake communities, such as Wadi Natrun in Egypt, these are spore-forming bacteria tolerant of very alkaline environments.

Millions of dormant bacteria are incorporated in the aggregate during production along with packets of chemical ‘feed’. If the concrete is cracked and oxygen and water are introduced, the bacteria are activated. They go to work converting their ‘feed’ into calcite, which seals the crack. The bacteria then revert to a dormant state, leaving the concrete just as strong and impermeable as it was before.

Application

Dr Jonkers of Delft University of Technology says: “The new concrete would be perfect for structures which are difficult to maintain, such as underground buildings, motorways or oil rigs. It is extremely durable. The bacteria are specially adapted to extremely alkaline environments and can survive dormant inside the concrete for up to 50 years.”