Jan 18 2018
America’s crumbling infrastructure could be saved by a new self-healing fungi concrete, which can help repair cracks in aging concrete permanently. This novel concrete was co-developed by researchers at Binghamton University, State University of New York.
Congrui Jin, assistant professor of mechanical engineering at Binghamton University, has examined concrete and found that the issue arises from the smallest of cracks.
Without proper treatment, cracks tend to progress further and eventually require costly repair. 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.
Congrui Jin, Assistant Professor of Mechanical Engineering
These cracks can cause enormous and sometimes hidden problems for infrastructure. One potentially critical instance is the case of nuclear power plants that may utilize concrete for radiation shielding. While remaking a structure would replace the aging concrete, this would only be a short-term solution until more cracks crop up again. Jin was keen to see if there was a way to fix the concrete permanently.
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, Assistant Professor of Mechanical Engineering
Jin worked with Professor Guangwen Zhou and Associate Professor David Davies (both from Binghamton University) and associate professor Ning Zhang from Rutgers University. Together, the team aimed to discover a way to heal concrete and found a strange answer: a fungus called Trichoderma reesei. When this fungus is mixed with concrete, it initially 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.”
The research is still in the fairly initial stages, with the biggest concern being the survivability of the fungus within the tough environment of concrete. However, Jin is hopeful that with further modifications the Trichoderma reesei will be able to excellently 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.
The paper titled “Interactions of fungi with concrete: Significant importance for bio-based self-healing concrete,” was published in Construction and Building Materials.