Concrete – one of the construction industry’s most common materials – has one fatal flaw: it often develops ‘micro-cracks’ during construction (Matchar, smithsonian.com, 2015). These micro-cracks can lead to leaks and the corrosion of steel reinforcements – weakening the structure over time. Repairs are time consuming, disruptive, and costly. Research and development teams from the UK, the US, and the Netherlands have taken up the challenge. Working independently and using different technologies, the teams have developed self-healing/self-repairing concrete. The Netherlands team uses embedded capsules of ‘limestone-producing bacteria and calcium lactate’ that are activated by air and moisture. In short, the bacteria eats the calcium lactate, produces calcite, and seals the cracks. The UK team is trialling 3 technologies – a similar bacteria-embedded capsule model, a technique using shape-memory polymers, and a system that uses organic and inorganic ‘healing agents’ (Dixon, constructionglobal.com, 2015). MIT scientists have developed a concrete healing technique that uses solar power and polymer microcapsules, while a microfibre-concrete product that ‘bends instead of breaking’ is in development at the University of Michigan.