Self-healing Fungi Concrete Could Provide a Sustainable Solution to Crumbling Infrastructure
New concept offers low-cost, pollution-free and sustainable approach to creating concrete without cracks.
Modern concrete has been around for over 150 years, and has really never had any competition when it comes to large construction projects, such as bridge building. However, as strong as concrete can be, it is not without weaknesses. These weaknesses stem from the smallest of cracks in the infrastructure. Creating concrete without cracks has become a desire throughout the construction industry.
Without proper treatment, cracks tend to progress further and eventually require costly repair. If micro-cracks expand and reach the steel reinforcement, not only will the concrete 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 the 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 spring up.
The idea to creating concrete without cracks is to use fungi (Trichoderma reesei) to combat this issue was originally inspired by the 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. When Trichoderma reesei is mixed with concrete, it originally lies dormant — until the first crack appears.
The fungal spores, together with nutrients, are 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.
The research is still in the early stages, with the biggest issue being the lifespan of the fungus within the harsh environment of concrete. However, hopefully with further adjustments and research the Trichoderma reesei will be able to effectively fill the cracks in concrete infrastructure.
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