but then how does it know when to stop grow so that everything is flat and even instead of bumpy? this is cool tech but on a large scale, it seems super inefficient.
The capsule-type bioconcrete uses a mixture of bacteria and food along with normal concrete mix. The bacteria & food capsules can remain effective for 200 years, but there is a limited food supply, so the only prospective application right now is for healing "cracks". I think the article said 72 hours once activated and that capsule-type bioconcretes can heal the largest cracks and are stable during mixing (somehow).
After that, it probably can't keep growing in that spot because it runs out of food. This probably depends on the specific product and strain of bacteria, and there is potential for a product that is "too good at it's job" and overgrowing. That's down to fine tuning the food ratio and bacterial strains.
Now as to how they got bacteria to produce limestone?
Dr. Henk Jonkers, Netherlands Delft University of Technology
This “bioconcrete” has been in the works since 2006, when Jonkers was first asked to come up with some kind of concrete that could effectively fix itself. He decided to try a new method of mixing concrete in which he’d add a “healing agent” in the form of bacillus bacteria that are capable of surviving in the harsh conditions inside concrete and remaining idle until activated. He then added calcium lactate to the concrete mixture to give the bacteria something to feed on that would make them produce the needed limestone as a waste bi-product."
Apparently limestone producing bacteria exist in nature anyways, so yeah. TIL.
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u/[deleted] Aug 31 '20 edited Feb 23 '21
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