Biologic Additive May Lead to Self-Healing Concrete

If you get a cut or break a bone, your body heals itself. This everyday miracle is what inspired [Congrui Jin] to try to find a way to make concrete self-healing. The answer she and her colleagues are working on might surprise you. They are adding fungus to concrete to enable self-repair.

It isn’t just any fungus. The conditions in concrete are very harsh, and after testing twenty different kinds, they found that one kind — trichoderma reesei — could survive inside concrete as spores. This fungus is widespread in tropical soil and doesn’t pose any threat to humans or the ecology. Mixing nutrients and spores into concrete is easy enough. When cracks form in the concrete, water and oxygen get in and the spores grow. The spores act as a catalyst for calcium carbonate crystals which fill the cracks. When the water is gone, the fungi go back to spores, ready to repair future cracking.

It isn’t clear to us why the fungi don’t grow on the outside, but we can imagine several solutions. The research is in early stages, so perhaps they don’t fully know yet, either. Earlier work proposed using bacteria in some sort of encapsulation to do this same trick (see the second video, below). However, the fungus creating its own hardy spore that can survive inside the concrete would simplify that greatly.

You might wonder why small cracks in concrete are a big deal. Concrete isn’t that strong, so we build steel inside it to produce stronger structures. However, water and oxygen don’t agree with steel, so cracks in the concrete eventually damage the interior steel and cause failures. If the cracks self-seal, it would limit the exposure of the steel to the elements.

Adding biological material to building material is an interesting idea and something that probably isn’t outside the realm of the common garage or basement lab. We’ve seen 3D printing filament made from algae, for example. Fungus might even help make better batteries. Not to mention, we’ve seen people experimenting with bioprinting. This could be an area where hackers get in on the action early and make real contributions. This might even help you get comfortable with the idea of starships running on mushrooms.

32 thoughts on “Biologic Additive May Lead to Self-Healing Concrete

  1. Another biohazard waiting in the wings.
    Reminds me of the cane beetle introduced into Australian cane farms. Then they brought in the cane toad to kill the cane beetles that got out of control. The cane toads are now on the march down south out of the cane fields.

    1. Well, you probably don´t know, but those fungi travels by air all around the planet within days. Anytime the combination drought + wind happens, MANY airborne microorganisms travel around the globe, carried by dust. Dig for “aeromicrobiology”

    1. For sure they need to find a way to kill the chosen bacterium before they start using it.

      It’s all a bit scary really. The thought of having a dust that can make solid concrete when left alone is somewhat worrying.

    1. Realistically I expect something will interact with the fungus causing it to have the opposite effect to intended and leading to collapsing bridges and buildings leading to billions of replacement cost and decades of ‘under construction’. Rather than any kind of disease that affects human or animal or birds.

      1. That’s a little like expecting the Y2K problem to cause airplanes to fall out of the sky, trains to derail, and grain silos to spontaneously explode.

        There’s no reason to expect a mutation or interaction to cause something to behave opposite to its previous behavior, unless you can come up with an example or two. To my thinking, the most likely outcome of an unexpected interaction would be that the fungus would stop doing what it was put there for. The consequence of that would just be that the concrete deteriorates like it did before.

        1. There is a reason, or two actually, experience of past failures and the old engineering rule of ‘anything that can go wrong will go wrong’.

          Incidentally, did you patch your intel bug yet? Or are you going to continue to assume there is no chance their little predictive trick can go wrong? >:)

  2. “and doesn’t pose any threat to humans or the ecology”

    This 100% correct and obviously completely and extensively researched statement presented as a fact was surely determined by years of extensive computer modeling followed by extensive real world testing, multi year governmental trials, widespread ecological testing and culminated in tens of thousands of in vitro, animal and finally paid human volunteer testing. Just like we do with all novel fungal spore based or even chemical products for that matter, right?

    Oh, wait.

  3. Actually, Portland cement based concrete already has the ability to heal cracks by the formation of calcium carbonate. About 20% of the hydrated cement by mass is calcium hydroxide that spontaneously reacts with atmospheric carbon dioxide when cracks form in the concrete matrix. The real trick is to eliminate the need for using Portland cement that inherently shrinks when water is added to it and it hardens. And is a major producer of carbon dioxide pollution. Shrinking causes cracks. The solution to this has already been invented. Look up Ceratech inc. to find out more.

      1. That’s the whole point. If a mutation disables the desirable concrete-healing activity, or enables something undesirable, and that 0.0001% out-competes the original strain, it could be a big problem. Sure, the odds are low, but we’re talking about distributing billions upon billions of fungal spores.

        Unintended consequences happen, even from something as innocent as uploading fitness tracker data to a website: https://hackaday.com/2018/01/28/opt-out-fitness-data-sharing-leads-to-massive-military-locations-leak/.

  4. Sounds like more of self patching or sealing rather than repairing. A repair would imply that a crack would be fixed to where normal tensile and bending strength of the concrete (such as it its) is restored across the crack.

  5. “Concrete isn’t that strong”!!!!!!! It has tremendous strength in compression, not so much in tension, but if it’s not that strong, why is it used so extensively in building? Granted, steel adds to the strength – actually, it adds to the ability to distribute load, which helps reduce cracks caused by shrinking during the curing phase, and then during its operational life – so you don’t have to use so much concrete, but still…..

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