Small Cracks in
Aging Concrete Can Lead to Costly Repairs
By Rachel Flores
However, spending on infrastructure improvement has continually gone down. The New York Times reported in 2016, based on a report for the Bureau of Economic Analysis, that “in the 1950s and ’60s, federal, state and local governments were spending twice as much on the nation’s public infrastructure, relative to the size of the economy, as they are today.”
The hesitancy to invest inAmerica
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.
This research is the first application of fungi for self-healing concrete, a low-cost, pollution-free and sustainable approach.
Why is
infrastructure crumbling?
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.”
These cracks can cause huge and sometimes unseen problems for infrastructure. One potentially critical example is the case of nuclear power plants that may use concrete for radiation shielding.
What can be
done?
“This idea was originally inspired by the miraculous ability of the human body to heal itself of cuts, bruises and broken bones,” said Jin. “For the damaged skins and tissues, the host will take in nutrients that can produce new substitutes to heal the damaged parts.”
Jin worked with associate professor Ning Zhang fromRutgers University , and professor Guangwen
Zhou and associate professor David Davies
from Binghamton University
The team found an unusual answer, a fungus called Trichoderma reesei.
“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 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.
By Rachel Flores
January 8, 2018 -- America
However, spending on infrastructure improvement has continually gone down. The New York Times reported in 2016, based on a report for the Bureau of Economic Analysis, that “in the 1950s and ’60s, federal, state and local governments were spending twice as much on the nation’s public infrastructure, relative to the size of the economy, as they are today.”
The hesitancy to invest in
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.
This research is the first application of fungi for self-healing concrete, a low-cost, pollution-free and sustainable approach.
Why is
infrastructure crumbling?
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.”
These cracks can cause huge and sometimes unseen problems for infrastructure. One potentially critical example is the case of nuclear power plants that may use concrete for radiation shielding.
What can be
done?
While remaking a
structure would replace the aging concrete, this would only be a short-term fix
until more cracks again spring up. Jin wanted 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,” said Jin. “For the damaged skins and tissues, the host will take in nutrients that can produce new substitutes to heal the damaged parts.”
Jin worked with associate professor Ning Zhang from
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.”
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.
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