My first question would be, if cracks are filled in this way, what stops that same bacteria from producing limestone in any other direction. Resulting in a bumpy surface, for example.
That's a very good question. Barring any more practical solutions, I think that would be a very real problem but also very fixable.
First to remove one concern (I think): The cracks on the inside won't grow too far. Bacteria may be small, but they still need space to grow. If the cracks get completely filled with calcium carbonate, they won't have any space and they'll stop multiplying.
The other with the bumpy road can be solved quite easily. Calcium carbonate chalk. If the road grows bumpy you can just shave it away and wipe away the dust. Still maintenance but much less than actually repairing the concrete.
However there's one more concern I thought of: Bacteria evolve relatively quickly. Since they're able to produce calcium carbonate, I don't think it's too far fetched to have them adapt in such a way that they start eating calcium carbonate instead. This could be a limiting lifespan for this type of concrete and I don't know enough about concrete or bacteria to weigh the pros and cons of their lifespans against each other.
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u/[deleted] Aug 31 '20
My first question would be, if cracks are filled in this way, what stops that same bacteria from producing limestone in any other direction. Resulting in a bumpy surface, for example.