Am illustrative of image of a concrete surface with patches of green lichen and moss growing in the cracks.
Researchers in the U. S. have used synthetic lichen to develop a groundbreaking self-healing concrete system that autonomously repairs its own cracks using sunlight, air, and water, offering a sustainable, low-maintenance solution that could revolutionize infrastructure and prevent catastrophic failures.
Led by Congrui Grace Jin, PhD, an assistant professor at Texas A&M University, the team designed the innovative system that mimics the natural symbiosis found in lichens by using filamentous fungi and cyanobacteria, one of the oldest photosynthetic prokaryotes on the planet also known as blue-green algae.
While the cyanobacteria harvest energy from sunlight and absorb carbon dioxide from the air, the filamentous fungi generate crack-sealing minerals that reinforce the concrete from within, thus creating a closed-loop repair system powered entirely by light, air and water.
Pricey repairs
Jin stressed that even though concrete – traditionally made by combining crushed stone and sand with powdered clay and limestone – is one the most widely used construction material in the world, second only to water, its tendency too crack remains a serious flaw.
Seemingly harmless at first, these cracks, can escalate into catastrophic failures, triggering the collapse of bridges, highways, or entire buildings. Regardless of whether small or big, the cracks occur because of a chemical reaction that takes place when water is added.
Called hydration, the process hardens the mix into a solid material strong enough to support everything from massive trucks to towering skyscrapers, however, over time, environmental factors such as freeze-thaw cycles, drying shrinkage and heavy loads cause the material to crack.
Even microscopic cracks can allow water and gases to seep in, corroding steel reinforcements and compromising structural integrity, which is why detecting and repairing these cracks before they pose a danger is crucial.
However, maintaining damaged concrete comes at a price, with annual repair expenses in the U.S. reaching tens of billions. “Microbe-mediated self-healing concrete has been extensively investigated for more than three decades,” Jin said in a press release.
But despite years of research, current self-healing concrete still relies on external nutrient supplies, preventing it from functioning fully autonomously.
A different approach
To tackle the issue, the team came up with an innovative solution that draws inspiration from lichen. Often overlooked as it quietly clings to trees and rocks, lichen is a resilient organism built on a unique symbiosis between fungi and algae or cyanobacteria, that allows it to survive in the most extreme environments.
Jin and her colleagues Richard Wilson, PhD, Nisha Rokaya, PhD, and Erin Carr, PhD, from the University of Nebraska-Lincoln, Jin developed a synthetic version of the biological partnership, which mimics the collaborative function of natural lichen.
Relying only on air, light, and water, the microbes operate completely autonomously, an innovation that sets them apart from earlier self-healing concrete technologies, which depend on external inputs. Lab tests showed the microbes could grow and form crack-sealing minerals even in tough concrete conditions.
However, Jin is now expanding her research beyond the lab by collaborating with social scientists at the university to examine public perceptions and address the ethical, environmental, and legal challenges of using living organisms in construction.
She believes the innovation could slash maintenance costs, increase the durability of infrastructure, and enhance safety, while also opening the door to sustainable construction in extreme environments, including future buildings in space.
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The study has been published in the journal Materials Today Communications.
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ABOUT THE AUTHOR
Georgina Jedikovska Georgina Jedikovska, journalist, plant engineer, oenophile and foodie. Based in Skopje, North Macedonia. Holds an MSc. degree in Horticultural Engineering, with a specialization in viticulture and oenology. Loves travelling, exploring new cultures, a good read, great food and flavorful wines. Enjoys writing about archaeology, history, and environmental sciences.
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