This Self-healing Concrete Repairs Itself with Bacteria

By Ashley P. Taylor | November 2, 2012 9:32 am

concrete

Concrete cracks for many reasons: just for starters, the heating and cooling of changing seasons make it expand and contract, and the stress produced as the freshly poured goo dries and shrinks in volume, pulling against its underlying metal supports, can also cause cracks. But Dutch researchers are testing a new way to deal with the problem of cracking concrete: bacteria that, when exposed to water, form limestone.

The concrete mix they’ve developed contains small ceramic pods filled with dormant spores of the bacteria and nutrients (calcium lactate) to feed them. In solid concrete slabs, these spores remain dormant, but when the concrete cracks and water seeps into the ceramic pods, the bacteria spring into action, using the calcium lactate to form calcite, one of the two primary components of limestone, which fills the crack. In the lab, the bacteria can fill cracks up to 0.5 millimeters wide, microbiologist Henk Jonkers told the BBC News. Now the researchers want to test their self-healing concrete outside for a few years before putting it on the market.

And they have some serious obstacles to work out, since in a recent paper, from 2010, they note that spores mixed with wet concrete and left to dry only lasted four months. Hopefully, they last longer when coated with ceramic, but there don’t seem to be any reports to that effect out.  For now, best just not to step on the cracks.

Image courtesy of TU Deflt

CATEGORIZED UNDER: Technology
  • Peter Ellis

    Hmm. And what effect do the embedded ceramic “pods” have on the strength of the concrete? That sponge-like thing in the picture doesn’t look particularly structurally sound to me.

  • http://www.erasetheredlist.webs.com cassidy

    Wow, i know a sidewalk that could really use it, even if only for a while. After all, any water that turns to ice in between cracks will only make it worse, and winter is coming.
    Good luck to the researchers!! :)

  • K

    I’m with Peter, what is the compressive strength of this concrete? Since it’s healing itself by filling cracks with limestone, will there be white streaks all over it? What applications are they thinking about using this for?

  • Brian Too

    I remember seeing another article about self-healing concrete. As I recall it used a purely chemical-based reaction. When I do a web search I see a number of technologies designed to achieve the same thing.

    http://www.sciencedaily.com/releases/2009/04/090422175336.htm

    http://www.sciencedaily.com/releases/2010/05/100524143421.htm

    http://www.greenbiz.com/news/2011/06/02/self-healing-concrete-could-double-lifespan-bridges

    Interest is certainly high on the R&D side. Consider the amount of concrete used in the world and the activity to develop an active repair system. This could happen, even if it is only used in specialty applications.

  • ShaneM

    Makes me wonder if you could mix it into a sand or powdery like mixture – sweep it into cracks, and then pour water on it. I guess that’s kindof like Quikrete though.

  • September Amyx

    Now you’re screwing with real live organisms independently capable of survival. And when they come into contact with all the gene mutation inducing chemicals out there being spread around by man, you know that they will not become mutant killer bacteria how??????

  • Virginia

    There is another building material that is porous and has “pods” inside it, and it works pretty well and lasts a lifetime–about 70-80 years and longer: bone.

    Bone is porous and has cells inside called osteocytes. They regulate the moving of calcium and phosporus in and out of the bone structure itself. If there is not enough calcium available for metabolic function, the osteocytes take some out of the bone and put it into circulation to help in muscle movement, etc. If the diet brings in calcium and phosphorus (eat your dark green leafy veggies!) then the osteocytes build up the bones with it.

    I think it is an interesting idea to have self-healing concrete, and it is interesting that it looks very like the physiology of living bone. Perhaps the researchers will come up with a better way to regulate the concrete repair.

  • jd holloway

    A Portland based replacement for hydrolic lime mix for old foundation repairs?

  • ML

    Incredible. This is genius.

  • Peryite

    For a second I thought it said ‘self-hating concrete’ and wondered why it would bother repairing itself.

  • floodmouse

    Self-healing concrete : civilization = sliced bread : sandwiches.

  • SpecwriterKeith

    Looking at the challenges of our infrastructure – self sealing (not so much healing) concrete would be a boon. Cracks permit water to penetrate concrete, water in contact with reinforcing steel causes rust, rust takes up 7 times the volume of steel and causes concrete to crack more and spall, exposing more steel to water… see where this is going?

    If the cracks in concrete could be effectively sealed from the outset, the maintenance cycle for our roads, bridges, dams and buildings could be greatly extended. Hoping they can solve the survivability issue and get this out of the lab.

    @7. – This is a different take on biophyllic design in engineering and architecture.
    @11. – Brilliant comparison – this is the next best thing to sliced bread in my books.

  • Steve Davis

    This is a could be a great thing to use on paths etc instead of normal concrete and it would certainly fix cracks a lot quicker. As if regular concrete cracks then a concrete repair company needs to be called out and this can take time and cost money. This new concrete that repairs itself is definitely something that I would recommend.

  • David Stevens

    This could be a great thing to use on paths etc instead of normal concrete and it would certainly fix cracks a lot quicker. As if cracks appear in regular concrete then a Concrete repair company needs to be called out. This is were this money and time can be saved.

    • JohnWayne101

      Yeah thats true, good idea david.

  • http://www.doctorconcrete.co.nz/ Concrete Repairs Christchurch

    Thanks for sharing such a great information. I know that its not at all
    easy to take care of your Concrete Crack
    Repairs
    at all it need lots of hard work &
    knowledge.

  • http://www.facebook.com/profile.php?id=72901040 Eric Michael Martin

    It’s extremely unlikely. Of the trillions of species on Earth, only a handful are harmful to humans, and fewer still are deadly. These bacterium would have to mutate an enormous amount to have any interest in humans, for one, and even more to be virulent.

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