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[researchers] have found an unusual candidate to help concrete heal itself: a fungus called Trichoderma reesei.
We initially screened about 20 different species of fungi in order to find one that could withstand the harsh conditions in concrete. Some we isolated from the roots of plants that grew in nutrient-poor soils, including from the New Jersey Pine Barrens and the Canadian Rocky Mountains in Alberta.
We found that as calcium hydroxide from concrete dissolved in water, the pH of our fungal growth medium increased from a close-to-neutral original value of 6.5 all the way to a very alkaline 13.0. Of all the fungi we tested, only T. reesei could survive this environment. Despite the drastic pH increase, its spores germinated into threadlike hyphal mycelium and grew equally well with or without concrete.
We propose including fungal spores, together with nutrients, during the initial mixing process when building a new concrete structure. When the inevitable cracking occurs and water finds its way in, the dormant fungal spores will germinate.
As they grow, they'll work as a catalyst within the calcium-rich conditions of the concrete to promote precipitation of calcium carbonate crystals. These mineral deposits can fill in the cracks. When the cracks are completely caulked and no more water can enter, the fungi will again form spores. If cracks form again and environmental conditions become favorable, the spores could wake up and repeat the process.
The spores wake up when cracks form in concrete and admit moisture.
(Score: 2) by GreatAuntAnesthesia on Tuesday January 23 2018, @10:58AM (4 children)
So these spores fill the gaps in the concrete, but where do they get the materials to do so? There's only one place they can get it, and that's from the concrete itself.
Does this mean that whenever the spores fill a gap, they weaken the concrete around the gap? Could this be mitigated by somehow providing the spores with an alternate food source? Periodically spraying structures with calcium-rich liquid?
(Score: 4, Interesting) by looorg on Tuesday January 23 2018, @12:49PM (1 child)
Indeed. What happens to the structural integrity of the concrete if it becomes all fungi filled? If it is the same then why just not replace concrete with it. My guess is that it doesn't have the same (or better) properties then concrete. So the fungi would just be a temporary fix so there doesn't come more water etc down into the crack until you have time to actually repair the construct. Somehow out of sight soon becomes out of mind and then people get all shocked and surprised when something collapses.
(Score: 2) by bob_super on Tuesday January 23 2018, @08:21PM
> the structural integrity of the concrete if it becomes all fungi filled?
Peace on Earth: Looking forward to exploding heads of the conspiracy theorists who scream about jet fuel melting steel beams, when you tell them about concrete that may burn.
(Score: 0) by Anonymous Coward on Tuesday January 23 2018, @01:52PM
There should be more than enough concrete, so weakening the concrete around does not matter (plus, the material it "steals" would probably have been washed away by the water anyway).
The point is likely to prevent water from washing out tiny cracks and have them become deeper and deeper, and particularly badly if the water freezes in them.
(Score: 2, Informative) by khallow on Tuesday January 23 2018, @04:01PM
That sounds reasonable. But an unplugged gap will weaken the concrete around the gap more since it isn't a process that halts.