Engineers at the University of Sheffield have developed a new type of 'self-healing' concrete that uses bacteria to automatically seal cracks, potentially doubling the lifespan of bridges and tunnels.

The concrete contains micro-capsules of specialized bacteria that remain dormant until a crack appears and water enters. The water activates the bacteria, which then produce limestone to fill the gap. The technology could save the UK billions in maintenance costs over the coming decades.

"Concrete is the most used material on earth, but its maintenance is an environmental and financial nightmare," said the lead engineer. "Our goal is to make infrastructure that takes care of itself."

Several major construction firms are already trialing the material on small-scale projects. While the self-healing concrete is currently 20% more expensive than standard mixes, the long-term savings in repair costs make it a highly attractive option for large-scale public works.