Self-healing concrete is normal concrete to which bacteria and nutrients have been added. Cracks in concrete lead to leakage problems in wet environments and, moreover, to corrosion of the embedded steel reinforcement. But not in self-healing concrete. Due to the ingress of water, the bacteria wake up and convert the present nutrients into limestone. As a result, the crack is automatically repaired, stopping the leakage, and protecting the embedded steel reinforcement against corrosion damage. Self-healing concrete therefore needs to be repaired less often and lasts longer. This makes it cheaper and better for the environment in comparison to ordinary concrete.