Concrete Clears Its Own Snow

Humans are not creatures well suited to cold environments. Without a large amount of effort to provide clothing, homes, and food to areas with substantial winters, very few of us would survive. The same is true of a lot of our infrastructure since things like ice, frost heave, and large temperature swings can all negatively impact buildings, roadways, and other structures. A team at Drexel University in Pennsylvania has created a type of concrete they hope might solve some issues with the material in cold climates.

Specifically when it comes to sidewalks and roadways, traditional methods of snow and ice removal such as plowing and salting are generally damaging to the surface material, with salting additionally being damaging to vehicles. Freeze-thaw cycles aren’t kind to these surfaces either. This concrete, on the other hand, contains a low-temperature liquid paraffin which releases heat when it has a phase change, from a liquid to a solid. By incorporating the material into the concrete, it can warm itself as temperatures drop, maintaining a temperature above freezing to melt ice and snow. The warming effect isn’t indefinite, but lasts a significant amount of time during testing.

Right now the concrete has only been used in test samples at the university, but as various levels of government look for more environment and wallet-friendly alternatives to plowing and salting roads this could be a major sea change in this area. The concrete also has difficulty melting heavy snow. As long as adding paraffin to the aggregate isn’t cost-prohibitive this could be a help in reducing costs for other snow removal methods; even if it doesn’t eliminate them. If you can’t wait for your city to start using this material for your local bike paths, you might want to try your hand at building something like this bicycle-based snowplow.

25 thoughts on “Concrete Clears Its Own Snow

    1. I was a regular commuter on I-69 in Michigan during a major NAFTA-driven rework of its route, and saw its construction during various phases. To those not from around there, the climate and traffic density is pretty rough on roads: much freeze-thaw, and plenty of salt, and a *lot* of heavy truck traffic.
      I was amazed to see how much steel rebar went into the road bed, and how thick the concrete was: at least a foot, often thicker. And then on TOP of that, was two layers of asphalt, each a couple of inches thick.
      No wonder that road cost so much.

  1. ” it can warm itself as temperatures drop” is pretty misleading.

    The phase-change material incorporated in the concrete doesn’t warm the concrete. It just increases the specific heat so it retains more thermal energy than unadulterated concrete.

    It’s not a magical heat source: it requires heat from a prior warming period to store. It is just as effective at cooling, if there is a preceding cool period.

    So, the addition of a few percent of oil, when incorporated into lightweight (i.e. porous) aggregate, can double the heat capacity of a slab of concrete, keeping it warm longer during a cooling trend. Not surprisingly, so can using a bit more conventional (non-porous) aggregate.

    I do wonder what adding oil to concrete does to its strength and other mechanical characteristics.

      1. The temperature transition would still be above freezing going the other way. It would stay cold as the environment around it heated, but that point would still be above freezing point.

        I guess as long as this additive doesn’t expand and contract much when it cycles, and also doesn’t get washed out, and also doesn’t rise to the surface and make it slippery, and also doesn’t decrease the strength of the concrete too much, and also isn’t too toxic, and also isn’t too expensive…

    1. This isn’t quite right. The phase transitions between solid and liquid paraffin either absorbs or releases the heat of fusion. So essentially it will attempt to keep the concrete mass at that temperature when going from above to below or below to above. This is different than specific heat.

      1. No it’s pretty much the same. It’s frequently modeled in heat transfer science and commercial physics solvers as a temperature dependent specific heat. A very high specific heat over a narrow range of phase transition temperature. Organic pcms, such as paraffins, usually have sloppy phase transitions so these models work well. Until you need to start modeling convection processes in the liquid state, which I don’t imagine you would when impregnated into concrete.

  2. Richers and politicians love to heat their pavement.

    IIRC Illinois Governer Whatshisthief got a large ration of shit for wasting money on a heated driveway for the Gov’s Mansion. (Ref. for fuzzy foreigners: Illinois politics is among the most notoriously corrupt in the nation. As corrupt as any small town, but a big state including a large city. Chicago police are simply a criminal gang. Nobody even notices anymore. But heat your driveway on tax$ and even Chicagoans notice…1-3 of them die _every_year_ from icicles falling from tall buildings. Generally tough, but dumb as rocks. Too dumb to move. Like Ruskys. I digress.)

    Richers in places like Vail are known to spend $1000+/month heating the sidewalks at their ski place while never/rarely visiting. Their money, better than someone on the tit (e.g. Gov above).

    1. A pretty famous political guy that practised law in Illinois apparently once said ‘There’s too many pigs for the tits’, I wonder if that came from Illinois politics?

  3. It’s Solar Freaking Roadways day!

    > I was amazed to see how much steel rebar went into the road bed, and how thick the concrete was: at least a foot, often thicker. And then on TOP of that, was two layers of asphalt, each a couple of inches thick.
    > No wonder that road cost so much.

    The reason we don’t build railways anymore is right there: Roads are much simpler and cheaper to build! /s

    1. You wouldn’t believe how much rebar and concrete goes into building a modern high speed railway.

      It’s a bit different than the old rails on wooden sleepers packed in with gravel. You couldn’t ride 200+ mph on those.

      1. It depends largely on the soil. Here in peaty Netherlands, the high speed lines have deep piles supporting them almost the entire stretch. But in rocky/sandy parts of France they are laid down on a pretty traditional roadbed of sand + crushed rock.

  4. Does the paraffin not make the concrete flamable? Probably very hard to ignite, but what happens when a wildfire reaches an area paved with this stuff?

    Or as a much happier thought, could you leave a set of burning tracks if you did a wheelspin on the road like in back to the future?

  5. According to the paper, it’s only useful down to -13C and less than 5cm of snow. So that’s pretty useless in most of Canada. And in the States where some places might be above -13 and get less than 5cm snow, those areas don’t typically invest in much snow clearing infrastructure anyway, so why would they invest in ripping up sidewalks to install this?

    I’m struggling to see who the potential market is beyond maybe some suburban developers that want to do the sidewalks in this material and tout it as a selling point.

    1. Chill out it’s academic research. Secondly, concrete gets replaced on fail which would be a more cost effective application. Thirdly, even in my snow heavy climate, certainly as snowy as much of populated Canada, plenty of small snow falls less than 5cm. Responding to those events is more costly than adding wax to concrete.

  6. This seems very low quality even for lackadaisical… sure, it may keep a bit more heat through the night in spring/fall but it also keeps the cold through the morning. Not a big deal and not a big effect but still absolutely redundant.

  7. Holland, MI uses a nice approach of keeping many roads and sidewalks clear by running the local power plants cooling loops underneath the surfaces. It’s waste heat anyways, and it saves a fortune on clearing and salting, and well as preventing slips and falls in high foot traffic areas.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.