A Fungi Fix: Self Sufficient Concrete that Fixes Itself
It’s hard to imagine modern life without concrete. Thanks to its incredible strength and versatility this man-made material is used to build everything from superhighways to kitchen countertops. Also, if you’ve got an older concrete floor, you’ve got cracks- its…. natural.
Concrete structures 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. Even a slender breach just the width of a hair can allow enough water in to undermine the concrete’s integrity. And considering the aging nature of much of the infrastructure that are in place, we may be soon reaching a time when a large number of structures will need either massive
repairs or a complete rebuild, both of which are costly and lengthy processes.Ingeniously simple and inspired by nature, this “self-healing” concrete could mean cracked roads and potholes will soon become a thing of the past.
Yes, the solution to all our infrastructural problems is fungi!
A new technique uses fungi to fill the cracks in concrete—creating a self-healing concrete.
“The idea was originally inspired by the miraculous ability of the human body to heal itself of cuts, bruises and broken bones,” Congrui Jin, mechanical engineering professor at Binghamton University—State University of New York, said in a statement.
“Our work is to explore a revolutionary self-healing concept in which fungi are used to promote calcium mineral precipitation to heal cracks in concrete infrastructure,” she said. “The fungal spores, together with their nutrients, will be added into concrete during the mixing process. When cracks appear and water finds its way in, the dormant fungal spores will germinate, grow, and precipitate calcium carbonate to heal the cracks. When the cracks are completely filled and ultimately no more water can enter inside, the fungi will again form spores. As the environmental conditions become favorable in later stages, the spores could be wakened again.”
The researchers’ plan involves embedding spores of a certain fungus, Trichoderma reesei, into the concrete while it’s manufactured. The fungus can stay dormant for months or years, consuming virtually no nutrients. Eventually, when the concrete cracks, the spores are exposed to air and water, and they become active.
The fungus grows inside the concrete, producing calcium carbonate as a byproduct. While calcium carbonate—better known as limestone—isn’t exactly concrete, it does fill the cracks and prevent the concrete from further degrading. Such a system would dramatically extend the lifespan of concrete structures.
The research is still in fairly early stages with the biggest issue being the survivability of the fungus within the harsh environment of concrete. However, Jin is hopeful that with further adjustments the Trichoderma reesei will be able to effectively fill the cracks.
“There are still significant challenges to bring an efficient self-healing product to the concrete market. 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,” said Jin.
