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[Image above] Credit: Adam Hilliker; Flickr CC BY-NC-ND 2.0

Self-healing concrete is not a new concept, but it continues to be a tantalizing one—a material that can extend its own life by fixing the cracks that tend to form over time.

Scientists, innovators, and tinkerers have devised a wide variety of strategies for self-healing concrete over the years, many of which use living bacteria to do the work.

Now, researchers at Binghamton University in New York are turning to a different kingdom of living organisms to do the work.

Using a fungus called Trichoderma reesei, the researchers are developing a self-healing concrete formulation that incorporates fungal spores. The spores remain dormant within the concrete until a crack forms.

Credit: BinghamtonUniversity; YouTube

“The fungal spores, together with nutrients, will be placed into the concrete matrix during the mixing process,” Congrui Jin, assistant professor of mechanical engineering and senior author of the new research, says in a Binghamton University news release. “When cracking occurs, water and oxygen will find their way in. With enough water and oxygen, the dormant fungal spores will germinate, grow, and precipitate calcium carbonate to heal the cracks.”

That precipitated calcium carbonate fills the empty spaces in the concrete, closing off the cracks and preventing them from spreading—but also shutting off the fungus from the outside world once again.

“When the cracks are completely filled and ultimately no more water or oxygen can enter inside, the fungi will again form spores,” Jin adds. “As the environmental conditions become favorable in later stages, the spores could be wakened again.”

In other words, the concrete could theoretically self-heal itself over and over again, offering a more hands-off approach to infrastructure maintenance. So far, however, the work is a proof-of-concept.

“There are still significant challenges to bring an efficient self-healing product to the concrete market,” Jin says in the release. “In my opinion, further investigation in alternative microorganisms, such as fungi and yeasts, for the application of self-healing concrete becomes of great potential importance.”

The paper, published in Construction & Building Materials, is “Interactions of fungi with concrete: Significant importance for bio-based self-healing concrete” (DOI: 10.1016/j.conbuildmat.2017.12.233).

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