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.