Bright Idea: Filling Potholes with Non-Newtonian Fluids

By Veronique Greenwood | April 12, 2012 12:34 pm

What’s something that everyone hates? That’s the question that undergrads at Case Western University asked recently while brainstorming their entry for a materials science competition. Their answer: potholes. And their answer to the problem of how to fill them cheaply and easily? Basically, corn starch and water.

It’s not as strange as it sounds: the corn starch putty is a non-Newtonian fluid, a class of fluids that behave very differently from water. In the case of the putty, when it’s placed in an oddly shaped receptacle, like a pothole, it will flow like a liquid into all the nooks and crannies. But the second you push on it, with a car, for instance (or, as you can see in the above video, your feet), it turns solid, resisting compression and giving drivers a smooth ride.

Here’s a little more on the physics involved, courtesy of ScienceNOW, including how ketchup-like non-Newtonian fluids are different from putty-like non-Newtonian fluids:

Ketchup and mayonnaise are shear-thinning fluids. When sitting on your counter, they are thick and clumpy and don’t flow because the particles have a tendency to stick together at rest, explains Graham. “Ketchup is actually mashed up tomatoes, and it’s the little particles of tomato that are interacting with one another and keeping the fluid from moving,” he says. “Mayonnaise is droplets of fat that stick together.” But pressing on a glob of mayonnaise with a knife or shaking a bottle of ketchup creates shear stresses that disrupt the particles, so the fluids become runnier and more spreadable.

The type of material the students chose is the opposite of ketchup and mayonnaise. It’s shear-thickening, meaning that when a shear stress is applied—say by the force of a car tire—it becomes stiffer and resists flowing. That’s because the particles slip and slide past each other easily when moved gently, but they get stuck when strong forces are applied. “The harder you push on it, the higher the viscosity gets. If you push it really rapidly, the particles in the corn starch don’t have time to rearrange and get around one another and they jam up,” says Graham.

Now, the physics is snazzy, but could bags full of putty beat regular old asphalt when it comes to patching potholes? The team thinks they could be a useful stop-gap, since no special equipment or training is required to lay a bag of the stuff in a hole. Any city employee with a few in their car could stop and at least temporarily fill a hole, instead of waiting for a team of workers to arrive.

Read more at ScienceNOW.

CATEGORIZED UNDER: Physics & Math, Technology
  • Jay Fox

    What happens when it rains? Does the stuff get diluted? Is there a way to make it hydrophobic?

  • Jeremy

    More importantly, what happens if a car stops on the hole… The wheel just sinks into it?

  • Chris

    And what if someone steps on it with not enough force to make it hard, but gently enough so they sink. Then when they try to pull out they’re stuck. The streets are eating people!

  • Scott

    Is it edible to animals/bugs/etc? [+roadkill]

  • Jeremy Hardinger

    I hope pedestrians are observant enough when crossing a road to avoid these, or that they wouldn’t be used in crosswalks.

    But what about when cars stop? Hopefully they don’t stop on a filled pothole. The car would sink into the pothole. I’m not certain what would happen when the car attempted to pull away. I guess it depends on what the mixture sticks to more strongly: tires or potholes. Either way it’s probably not very good.

  • Jay29

    I imagine that corn starch & water is just the illustration, and that potholes would actually be filled with a synthetic non-Newtonian liquid, and sealed with something akin to plastic wrap to prevent dilution/spreading/person-swallowing.

  • Thomas

    What about bikes? What about weather? What about slow cars or traffic?

  • http://www.midisticks.com Dub
  • Tone4d

    good for slowing traffic in low speed streets instead of a solid speed trap?

  • Peter

    There could be a problem if a car came to rest in a traffic jam on one of the repaired potholes. However it’s a great solution…….?

  • Tony

    Umm, isn’t this going to do something similar to pouring water into a pothole? (in other words what I mean is, isn’t the non-newtionian liquid still going to just soak into the ground?)

  • Venkat Anumula

    That’s a classic example of shear thickening fluid. There are even numerous fluid categories that exhibit amazing fluid behaviour. Sometimes it’s unbelievable. Good work guys !

  • jackew

    This does raise a lot of interesting questions, including cost; but I wonder what an entire road would be like, made with this starch?

  • Georg

    I wonder,
    when the US will start to use “technology” and financial
    methods proven to result in pothole-proof streets?
    (at least for much longer time).
    Georg

  • Redshift

    They are suggesting packing the goop into a bag, this will prevent both dispersal during rain and people getting stuck, but the space-filling bag of goop will still stiffen up to a near solid mass when forcefully impacted

  • Erik

    Yeah… As everyone else pointed out, there’s quite a few holes in this idea.

    Pun intended.

    Ba dum BUM.

  • http://www.midisticks.com Dub

    Actually, I’m told Halfbakers did exactly that almost exactly 2 years ago: http://www.halfbakery.com/idea/Fill_20Potholes_20with_20Oobleck

  • Josiah

    How about some wet cement, and make sure it dries up in there. Permanent solution.

  • Jeremy

    Cars coming to rest on the pothole would not be a problem. The car does not have to be moving for shear force to be applied, and the corn starch would remain solid. Rain and animals are certainly real problems with the idea, but it shouldn’t take too much to make it waterproof (maybe just tape some plastic wrap over it) and unpalatable.

  • Heather

    Or you could just go to Lowe’s and pick up a bag of QPR pothole repair material for $13.98. I’m just sayin’……

  • Vincent

    Wouldn’t the water leach out over time rendering it useless?

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