Right now, one of the big stories coming out of the Detroit area is that of aging bridges that are slowly dropping pieces onto passing motorists.
A new kind of self-healing concrete is under development at Binghamton University, State University of New York, could help repair cracks in aging concrete permanently.
(Fungi concrete heals itself video>)
Binghamton University assistant professor Congrui Jin has been working on this problem since 2013, and recently published her paper “Interactions of fungi with concrete: significant importance for bio-based self-healing concrete” in the academic journal Construction & Building Materials.
Jin’s studies have looked specifically at concrete and found that the problem stems from the smallest of cracks in the concrete.
“Without proper treatment, cracks tend to progress further and eventually require costly repair,” said Jin. “If micro-cracks expand and reach the steel reinforcement, not only the concrete will be attacked, but also the reinforcement will be corroded, as it is exposed to water, oxygen, possibly CO2 and chlorides, leading to structural failure.”
The team found an unusual answer, a fungus called Trichoderma reesei.
When this fungus is mixed with concrete, it originally lies dormant — until the first crack appears.
“The fungal spores, together with nutrients, will be placed into the concrete matrix during the mixing process. 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,” explained Jin.
“When the cracks are completely filled and ultimately no more water or oxygen can enter inside, the fungi will again form spores. As the environmental conditions become favorable in later stages, the spores could be wakened again.”
SF writer J.G. Ballard wrote about self-healing buildings with plastex walls in his 1962 short story The Thousand Dreams of Stellavista:
It was a beautiful room all right, with opaque plastex walls and white fluo-glass ceiling, but something terrible had happened there. As it responded to me, the ceiling lifting slightly and the walls growing less opaque, reflecting my perspective-seeking eye, I noticed that curious mottled knots were forming, indicating where the room had been strained and healed faultily.