Cracking in concrete is a perpetual headache for engineers, as it requires additional amounts of internal steel reinforcement and/or ongoing repairs. It can also cause the internal reinforcements to rust, which can cause unsightly additional cracking and structural instability.
To find a solution, where the concrete can actually heal itself, the team of researchers, led by microbiologist Dr Hendrick Jonkers, looked in some unlikely places for inspiration, including rock formations close to volcanos.
This self-healing ability comes into play when water enters concrete through open cracks. The water awakens the bacteria which then consumes its accompanying food. As a by-product they secrete limestone - which just happens to be the main component in concrete.
The bacteria can heal cracks in just three weeks.