Despite heavy investment in renewable energy and providing alternative solutions to housing crises across the U.S., the infrastructure of American cities is collapsing. Among the causes of infrastructural failure is cracks that form in a structure’s concrete, which is difficult to isolate and repair. Scientists at Binghamton University in New York, however, found that a specific fungus, when placed in concrete mix, can repair the cracks that form in concrete structures in urban infrastructure.
In 2013, assistant professor Congrui Jin of Binghamton University and her team began looking for a long-term and sustainable solution for cracked concrete. The problem with cracked concrete is that any sizable crack in a structure’s concrete can continue to expand and eventually reach the steel reinforcement.
Once the crack expands, oxygen and water are allowed near the steal, which corrodes and rusts it and eventually leading to structural failure. Cracking does not only put buildings or bridges at risk of collapse, but other structures like power plants that use concrete for radiation shielding risk the efficacy of the shielding to begin with.
In finding a solution to their debacle, Jin and her team were inspired by the human body’s ability to heal and repair itself. “The human body heal[s] itself of cuts, bruises and broken bones,” said Jin to Binghamton News. “For the damaged skins and tissues, the host will take in nutrients that can produce new substitutes to heal the damaged parts.” It wasn’t soon after that the team discovered that the fungus Trichoderma reesei, which, when mixed in concrete mix, can repair cracks that form in it.
When mixed with the concrete and supplementary nutrients, the fungus finds its way into cracks in the concrete, according to the paper Jin published with associate professor Ning Zhang from Rutgers University, and professor Guangwen Zhou and associate professor David Davies from Binghamton University. Once the fungal spores have enough water and oxygen, the dormant fungus germinates, grows, and produces calcium carbonate to repair the crack.
After repair and once the oxygen and water are depleted, the fungal spores go back to being dormant until they are activated by environmental conditions. The reliability of fungal spores in concrete repair remains uncertain granted that research of fungal-driven repair is still in its early stages.
The most difficult challenge the researchers face is ensuring that the fungus can survive in the harsh environmental conditions of concrete. “There are still significant challenges to bring an efficient self-healing product to the concrete market,” Jin said to Binghamton News.
Last year, a Delft University professor developed a self-healing asphalt mixture that allows cracks in asphalt roads to fix themselves. The mixture is used to build roads, and when cracks start appearing, an induction machine is passed over the cracks. The induction machine adds heat that warms up the asphalt and steel fibers, allowing the cracks to close on their own. The asphalt mixture has been tested on 12 different roads in The Netherlands, one of which has been operating since 2010.
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