Self-Healing Infrastructure?

The U.S. Department of Transportation estimates a $542.6 billion backlog needed for U.S. infrastructure repairs alone. Infrastructure supports and facilitates our daily lives – think of the roads we drive on, the bridges and tunnels that help transport people and freight, the office buildings where we work and the dams that provide the water we drink. But it’s no secret that American infrastructure is aging and in desperate need of rehabilitation.

Concrete structures, in particular, suffer from serious deterioration. Cracks are very common due to various chemical and physical phenomena that occur during everyday use. Concrete shrinks as it dries, which can cause cracks. It can crack when there’s movement underneath or thanks to freeze/thaw cycles over the course of the seasons. Simply putting too much weight on it can cause fractures. Even worse, the steel bars embedded in concrete as reinforcement can corrode over time.

Very tiny cracks can be quite harmful because they provide an easy route in for liquids and gasses – and the harmful substances they might contain. For instance, micro-cracks can allow water and oxygen to infiltrate and then corrode the steel, leading to structural failure. Even a slender breach just the width of a hair can allow enough water in to undermine the concrete’s integrity.

But continuous maintenance and repair work is difficult because it usually requires an enormous amount of labor and investment.

One example of a possible solution was discovered by the Engineers at Delft University who have developed bio-concrete that can repair its own cracks. Dr. Henk Jonkers, a microbiologist at Delft University discovered that mineral-producing bacteria have been found that could help mend micro-cracking in concrete.

Self-healing concrete could most certainly solve the problem of concrete structures deteriorating well before the end of their service life. Concrete is still one of the main materials used in the construction industry, from the foundation of buildings to the structure of bridges and above and underground parking lots. Traditional concrete has a flaw, it tends to crack when subjected to any sort of tension.

A healing agent that works when bacteria is embedded in the concrete converts nutrients into limestone and has been under development at the Civil Engineering and Geosciences Faculty in Delft since 2006. The project is part of a wider programme to study the self-healing potential of plastics, polymers, composites, asphalt, and metals as well as concrete.

Binghamton University colleagues Congrui Jin, Guangwen Zhou and David Davies, Ning Zhang from Rutgers University found an unusual candidate to help concrete heal itself: a fungus called Trichoderma reesei.

Here is an interesting article on the discovery: http://bit.ly/HealingConcrete