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Biologists Create Self-Healing Concrete
Mr.Intel writes: A team of microbiologists from the Delft University of Technology claims to have invented "bioconcrete" — concrete that heals cracks and breaks using bacteria. The goal was to find a type of bacteria that could live inside concrete and also produce small amount of limestone that could re-seal cracks. This is a difficult prospect because concrete is quite dry and strongly alkaline. The bacteria needed to be able to stay alive for years in those conditions before being activated by water. The bacteria also need a food source — simply adding sugar to concrete will make it weak. The scientists used calcium lactate instead, adding biodegradable capsules of it to the concrete mix. "When cracks eventually begin to form in the concrete, water enters and open the capsules. The bacteria then germinate, multiply and feed on the lactate, and in doing so they combine the calcium with carbonate ions to form calcite, or limestone, which closes up the cracks."
I'm all for it, as long as nothing could possibly go wrong!
>The goal was to find a type of bacteria that could live inside concrete
If you can call that "living." Think of the bacteria!
Bacterial concrete is ideal for constructing underground retainers for hazardous waste, as no humans would have to go near it to repair any occurring cracks. For residential buildings, however, it does seem the traditional repairing of cracks will remain the most economically attractive solution for now.
Currently, our research focuses on creating the right conditions for the bacteria to produce as much calcite as possible and on optimizing the distribution of food for the bacteria.
"First they came for the slanderers and i said nothing."
It seems to me that this type of technology could be used on pre-existing concrete as well. Assuming it is strong enough, and it seems to be, it could be injected into foundation cracks. The crack would be fixed from the inside out. The savings in time and money would be enormous and it would be vastly superior to current methods of foundation repair.
If I can't stop concrete sidewalks from being cracked by tree roots over the years, something is wrong with me? Obviously, I should just chop down all nearby trees.
If I can't stop idiots with trucks that surpass expected weight limits or heavy objects falling onto the concrete, something is wrong with me? I'm not Superman.
This has nothing to do with concrete when it being formed. The worst that happens at that time are paw prints and graffiti.
My concern is, if this stuff works, how much will it work? Will it repair itself in the same area more than once? What is to stop the bacteria from forming a big lump on the surface after they bridge the crack's gap. Is the replacement material even nearly as strong as the original concrete or will it just break again under less stress? If the intended use of this for building construction or surfaces to walk on? I can see it being used in 1-3 story buildings as material, but any where solid concrete has to be used instead of those hollow cinder blocks, I can't see it being possible, much less if water is needed to activate it.
heal thyself!
Is this a theoretical development or does it have concrete uses?
Don't waste your vote! Vote for whoever you want, unless you live in a swing state it won't matter anyways
Concrete longevity has a LOT to do with preparation and maintenance.
For example tree roots - proper subsurface preparation, which isn't normally done for sidewalks, will result in roots not extending far under the concrete, and even if they do penetrate somewhat, not growing large enough to crack the concrete. Failing that, routine maintenance with certain products will kill the roots before they get too large, but leave the rest of the tree unaffected.
As for your questions -
1. It will probably only fix any given crack spot once.
2. 99% of the fixes will be practically microscopic in nature.
3. At the depths we're looking at, restoring a barrier is a bigger deal than being structural.
4. Most of the time the very cracking releases the stress that caused the crack, then water gets in and freezes, widening it. This keeps the water out(after the bacteria do their job).
I don't read AC A human right
How does it keep from activating when the concrete is initially wet from mixing?
My concern is, if this stuff works, how much will it work? Will it repair itself in the same area more than once? What is to stop the bacteria from forming a big lump on the surface after they bridge the crack's gap. Is the replacement material even nearly as strong as the original concrete or will it just break again under less stress? If the intended use of this for building construction or surfaces to walk on? I can see it being used in 1-3 story buildings as material, but any where solid concrete has to be used instead of those hollow cinder blocks, I can't see it being possible, much less if water is needed to activate it.
Being able to repair small cracks to keep water out would go a long way to minimize the freeze/thaw damage that makes small cracks into big cracks. Even without the same strength as uncracked concrete, concrete with some small filled cracks will perform much better and last much longer than concrete with growing numbers of growing sized cracks.
What keeps the surface of the concrete from "growing"?
Cementinator
Table-ized A.I.
Bacteria are no more animals than a rock or baseball bat. They're Prokaryotes, which is an entire different kingdom than Eukaryotes which include plants and animals.
You need to read some biology text that's younger than 30 or 40 years old.
Life hasn't been divided into just plants and animals in a long time. There's also fungi, bacteria, archaea, ... See here for example.
Vegans take more animal lives than non-vegans. Think about insects, small mammals etc. swept up in the harvest.
Liberty - Security - Laziness - Pick any two.
If the concrete fills it's own cracks automagically, two questions spring to mind: 1) Will the crack-filling material have the same load bearing properties or (as I suspect) it will be much weaker at those spots, and 2) will the filled cracks disguise the facts that the object may be under a load that was not anticipated by the designer (tensile or bending loads vs. compressive loads)?
Reinforced concrete is often used in bending and tensile load applications in architecture, and if the reinforcing is not stiff enough cracks often will appear on the surface. They are unsightly, but if the reinforcing is taking the load (as it should) these are not structural deficiencies. But for complex architectural domes and shells, the presence and size of these cracks is something that needs to be monitored.
If the concrete is used in a container and it cracks, we may actually want to see the crack as that is a warning that something is being loaded in an unanticipated way. Hiding it with a self-filling mechanism may not be desirable.
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