A new self-healing fungi concrete,
co-developed by researchers at Binghamton University, State University of New
York, could help repair cracks in aging concrete permanently, and help save
America's crumbling infrastructure.
Congrui
Jin, assistant professor of mechanical engineering at Binghamton University,
has researched concrete and found that the problem stems from the smallest of
cracks.
"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. 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 professor Guangwen Zhou and associate professor David Davies, both
from Binghamton University, and associate professor Ning Zhang from Rutgers
University. Together, the team set out to find a way to heal concrete and 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 the 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.
