Bacteria Used To Fix Cracked Concrete

An anonymous reader writes "Researchers at the UK's University of Newcastle have created a new type of bacteria that generates glue to hold together cracks in concrete structures — that means everything from concrete sidewalks to buildings that have been damaged by earthquakes. When the cells have been germinated, they burrow deep into the concrete until they reach the bottom. At this point, the concrete repair process is activated, and the cells split into three types that produce calcium carbonate crystals, act as reinforcing fibers, and produce glue which acts as a binding agent to fill concrete gaps."

Gigacrete looks better

[digitaldc]

Gigacrete [treehugger.com] looks like a better material for building in my opinion. I'll just have bacteria in my yogurt for now.
-Several GigaCrete products can be made with recycled waste material such as bottom ash, fly ash, sludge, or dredged materials. And, these waste material fillers can comprise up to 80% (by volume) of GigaCrete products. Usage of such waste materials reduces the amount of these byproducts going to landfills or other waste storage sites.
- Less carbon dioxide (CO2) emissions are produced from the manufacture of the GigaCrete cement binder than compared to the manufacture of Portland cement.
- Energy savings can be achieved with the GigaCrete PanelSystem due to the high thermal efficiency and insulating value of the panel material. According to the “Structural Insulated Panel Association in Partnership with Oakridge National Labs,” structural paneled homes can achieve energy savings of up to 70%.
- The GigaCrete cement binder is 100% nontoxic.
- GigaCrete products use approximately two-thirds less water than conventional Portland-based cement products.
- High resistance to mold, mildew, insects, and vermin facilitates cleaner living environments.

Re:When does it stop?

[countSudoku()]

RTFA, it's not very long and explains just that fact you need; it does know when to stop.

Read teh article.

[mattdm]

The spores germinate only in very alkaline environments — concrete has a quite high pH. The article is vague on details, but notes that "[the bacteria] have a built-in self-destruct gene that prevents them from proliferating away from the concrete target."

Now, What Could Possibly Go Wrong and all of that, but the bases are nominally covered.

Re:Gigacrete looks better

[Skidborg]

You do realize that most waste products that can be used as you mentioned contain toxins themselves? Bottom ash and fly ash from coal plants is comparable to nuclear waste.

Re:Okay.

[camperslo]

An older article with considerably more detail. Not sure if it's the same bacteria.

http://www.newscientist.com/article/dn19386-for-selfhealing-concrete-just-ad [newscientist.com]

Re:Lungs

[mattdm]

What's the acidity of your lungs? Oh, I see. You didn't read the article. Carry on, then.

Re:Okay.

[sadness203]

The problem, with bullet wound is... they are not always clean, you can have some clothes debris, or other dirt. Closing the wound is easy (well, relatively speaking) but cleaning it well enough is another thing.

Re:Okay.

[Gotung]

Several hundred years? Try several thousand.

Re:Lungs

[mattdm]

The bacteria they made in the lab likes the acidity of concrete. What about the mutant bacteria that the bacteria in the crack makes?

It won't survive because it's still in the very alkaline concrete environment? Or as Morbo might put it: EVOLUTION DOES NOT WORK THAT WAY.

More Info From iGEM

[reverseengineer]

This engineered bacterium system was entered into the International Genetically Engineered Machine competition, so there's a lot more information about this project at the team's [igem.org]project page. [igem.org] In particular, there's a more thorough description of the kill switch [igem.org] the team engineered to prevent the spread of this bacterium beyond the target environment, the underlying mechanism being that sucrose must be available in the environment to prevent the bacterium from producing a toxin which kills itself.

Re:Gigacrete looks better

[nedlohs]

So basically, it had nothing at all do with the topic hand and your comparison "I'll just have bacteria in my yogurt for now" was completely meaningless since no one has suggested building new things with it since that wouldn't work anyway.

Re:Gigacrete looks better

[jeff4747]

Beware the press releases. You'll note that nowhere does the article discuss the strength of Gigacrete. They put up a few random things, but nothing like how much PSI it can withstand. And according to their web site [gigacrete.com], "GigaCrete manufactures some of the most innovative, functional, high-performance interior finishes on the market". Interior finish != replacement for concrete. Concrete is used as a structural material. It holds up thousands of tons of stuff. GigaCrete is an alternative to plaster. It looks pretty smeared on a wall...that's made of concrete.

Re:Okay.

[locallyunscene]

The main problem with a bullet wound is that it used to be a normal functioning part of the body and not a bullet wound...

Re:Lungs

[reverseengineer]

It turns out that the press release is not really accurate with regard to the effect pH has on this engineered bacterium. The starting bacterium, Bacillus subtilis 168 naturally prefers a neutral pH, but by growing generations of this bacteria in media with gradually increased pH, it can be acclimated [igem.org] to thrive at the pH of concrete (roughly 10). This requires no engineered genetic modification. The steps to control the spread of this bacterium have little to do with pH, actually. First, the bacterium comes from a strain of Bacillus subtilis which has been produced as the result of decades of laboratory cultures, and is a mutant which depends on many key nutrients to be present in its enviroment to survive. In the wild, it would be a massively deficient competitor to wild Bacillus subtilis, which is extremely common in nature.

Also, the concrete repair activity is produced by upregulation of genes natural to Bacillus subtilis, not by anything transgenic. The upregulation of these genes presents an energy cost to the engineered bacterium while providing no benefit- if these bacteria mutate, it is more likely to be towards the wild phenotype. In addition, the team responsible has added a kill switch [igem.org] which tells the bacteria to commit suicide if sucrose is not present.

Re:Okay.

[c6gunner]

Right, and battery acid is really good at curing the common cold.

I dunno where you're getting this info, but no, bullets certainly do not "sterilize" anything. One of the leading causes of death historically has been infection. We're better at dealing with it today, but infections still occur on a regular basis:

"A gunshot is never sutured closed as the infection rate is very high. Bullets drag clothing into the wound and along the bullet track. Since clothing is of course not sterile, the wound is prone to infection if closed. Open wounds almost never get infected."
http://www.tacticalmedicalpacks.com/files/Combat_Tactics_Trauma_article.pdf [tacticalmedicalpacks.com]

"We have presented a series of 120 consecutive operative cases of penetrating wounds of the abdomen-72 gunshot wounds and 48 stab wounds. The majority of patients were in the 18 to 40 age group. The infection rate was 22% for gunshot wounds and 4.8% for knife wounds."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2609419/pdf/jnma00480-0069.pdf [nih.gov]

Re:Concrete from thin air?

[reverseengineer]

There are three principal parts to the filler produced by these bacteria. First, the bacterium naturally produces calcium carbonate as a byproduct of breaking down urea as a nitrogen source; this activity has been greatly increased in the engineered bacterium. The second part is a "glue" made from levan, a polysaccharide that the bacterium is able to produce from sucrose; this activity is also natural, but highly upregulated in the engineered bacterium. The final part is the bacterial cells themselves; the cells are made long and threadlike by expressing a protein that halts cell division, and these filamentous cells act as reinforcing fibers. In practical usage, a solution of nutrients (including sucrose in particular) would need to be sprayed along with the bacterial spores in order for them to display this concrete-filling activity. This information comes from here [igem.org].

Re:Why use bacteria? Just insert glue directly!

[Reziac]

If you've ever tried to pump glue into a crack in concrete, you'll quickly figure that out. It's somewhere between messy and inadequate as a repair method, and certainly doesn't get into the smaller cracks, let alone the microcracks. The idea here is to have the glue self-extend, filling the air pockets and microcracks that no glue with sufficient surface tension to stick could ever manage.

However I think where this will become a more useful technique is for fixing the kinds of surface cracks that ail structures exposed to repeated wet/freeze/thaw cycles -- the typical winter climate for the east slope of the Rocky Mountains. Mount Rushmore would seem to be a good candidate, since seasonal surface cracking is what's causing damage.

Concrete roads that suffer similar winter freeze/thaw damage could also benefit -- instead of trying to patch the road one crack at a time (usually an exercise in futility, culminating in yawning potholes), or having to dig up and replace the concrete (an extremely expensive job), just wash it with a slurry of this bacteria. That could even eliminate most of the seasonal damage, by filling the microcracks that are where freeze damage starts.

Imagine if your state and local highway departments could reduce their budgets by simply needing to do less repair on concrete-based roads. Even if you don't believe in reducing taxes when need is reduced, it would free up that budget to use elsewhere.

Re:Okay.

[robot256]

The Romans invented concrete.

That's only 1600-2200 or so years ago.

The Romans started using concrete before 200 B.C. [ucsb.edu], but Wikipedia says the Egyptian pyramids [wikimedia.org] were built with concrete long before that. So that makes its invention 2200-4600 years ago.

IMO "several hundred" was correct.

From your link: "being more than two but fewer than many". Considering civilization has only been around for ~60 centuries, "several" is arguably less than twenty. Try "many hundreds" next time you go for your pedantic medal. Thanks for playing.

Re:What could possibly go wrong?

[jeff4747]

Selecting on a pH range is not a foolproof kill-switch

That depends. How many highly alkali environments are there in nature? (Answer: Very few)

Do calcium deposits in bone fall into the same pH range as the bacteria's selectivity?

Solids do not have pH. You can't have a pH without a solvent. The alkali environment present in concrete does not exist within humans...or any animal or plant I'm aware of.

How much is the bacteria's pH-range selectivity susceptible to drifting into other pH ranges over tens of thousands or millions of generations of evolution in coming years and decades?

Evolution doesn't work that way. There has to be selection pressure. Bacteria that live in concrete but thrive in a lower pH would be selected against - the "thrive in high pH" would outcompete them.

pH-range selectivity is not sufficient for impeccable safety.

You can't make this assessment without knowing the pH of the pH range of the bacteria, the pH range of the concrete, and knowing how common that pH range is in nature.

Another problem is quacks.

[Ungrounded Lightning]

The problem, with bullet wound is...[dirt].

Another problem with bullet wounds is emergency room doctors who believe the myth of "hydrostatic shock" damage and chop out a core of tissue around the bullet's path (as if it were a linear cancer), rather than treating it properly by cleaning and closing the wound (as if it were any other puncture-and-displacement trauma).

Yo, Docs! Even if the bullet somehow WAS traveling faster than the speed of sound in flesh (like about mach 4.4) shock waves aren't any big deal for soft tissue. Think Lithotripter.