Maintenance: Fungi help concrete to self-heal cracks

Concrete cracks

CC BY 2.0 Rick

Researchers are looking to fungi to help provide a fix for crumbling infrastructure, with promising results.

A quick look around at the masses of concrete used to construct buildings, roads, bridges, sidewalks, and other infrastructure reveals that it doesn’t take that long before cracks begin to appear, which if unchecked can go on to compromise the integrity of these structures. A small crack can channel water further into the concrete, which can eventually reach the steel reinforcement within the material and cause corrosion, weakening, and possibly even failure. And considering the aging nature of much of the infrastructure in the US, 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.

However, researchers at Binghamton University may have found a workable solution for mitigating this type of damage to our modern miracle material, thanks to one of the least understood biological kingdoms, at least by the average layman — fungi. Although fungi are one of the most prolific actors on this little planet we call home, with some mycologists estimating that up to half the species on Earth are fungi, we’re just now scratching the surface of what fungi can do for us with the right conditions. However, the new research from Binghamton University assistant professor Congrui Jin suggests that we may be able to put certain types of fungi to work to help heal some of our cracking concrete infrastructure.

“This idea was originally inspired by the miraculous ability of the human body to heal itself of cuts, bruises and broken bones. For the damaged skins and tissues, the host will take in nutrients that can produce new substitutes to heal the damaged parts.” – Congrui Jin, Binghamton University

The research team led by Jin explored a number of different fungi as potential candidates for inclusion into concrete as a dormant self-healing feature, and found at least one that shows great promise for knitting cracked concrete back together again.

fungi in petri dishes© Fungi trials in petri dishes (Binghamton University)

A fungus called Trichoderma reesei was found to germinate and grow well in the high pH environment produced by the dissolving of the calcium hydroxide (Ca(OH)2) from the concrete, and to precipitate calcite crystals on its hyphae. This natural process could enable the fungus to fill in the cracks in concrete with calcium carbonate, essentially knitting it back together again by functioning as a bio-based self-healing agent.

“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.

“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.” – Jin

The research into using fungi in concrete to transform it into a bio-based self-healing version is only in its infancy, and researchers still need to work on the biggest issue, “the survivability of the fungus within the harsh environment of concrete,” before a commercial solution comes to fruition. The team published its initial findings in the journal Construction and Building Materials under the title “Interactions of fungi with concrete: Significant importance for bio-based self-healing concrete.”