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Now onward to replacing the roads and bridges on freeways and highways with these new concrete.

• insane_dreamer 4y ago
  cobblestones for the roads
  • jcadam 4y ago
    That is... not a smooth ride.
    • deleted 4y ago
      [deleted]
    • cameronh90 4y ago
      Sounds like a good way to make people slow down.
      • naniwaduni 4y ago
        The problem with making people slow down is that it slows people down.
        • r00fus 4y ago
          Sometimes that's what's needed. https://en.wikipedia.org/wiki/Braess%27s_paradox https://en.wikipedia.org/wiki/Braess%27s_paradox
          • naniwaduni 4y ago
            But usually, it slows people down. > In 2012, Paul Lecroart, of the institute of planning and development of the Île-de-France, wrote that "Despite initial fears, the removal of main roads does not cause deterioration of traffic conditions beyond the starting adjustments. The traffic transfer are limited and below expectations".[4] He also notes that some private vehicle trips (and related economic activity) are not transferred to public transport and simply disappear ("evaporate").[4] > The same phenomenon was also observed when road closing was not part of an urban project but the consequence of an accident. In 2012 in Rouen, a bridge was destroyed by fire. Over the next two years, other bridges were used more, but the total number of cars crossing bridges was reduced.[4] It seems a lot like the real-world examples of the phenomenon look like close cousins of "if you remove the smallest values in a set, the average goes up".
    • insane_dreamer 4y ago
      it's not so bad; where I grew up in France many streets were cobblestone and it was fine. It's pretty rare in the US though except I've noticed it in streets where they have trams running--presumably to reduce the need for maintenance on those streets.
  • naikrovek 4y ago
    for slow neighborhood roads I see no reason why brick isn't used more often. my hometown had brick roads everywhere and once every 3-5 years a few bricks would get replaced here and there. in the 1990s I'd look around and see a lot of the bricks on those roads that were made in the 1930s, and there were probably older bricks to be found if I'd looked harder. the rough ride kept speeding down a lot more than the police could, because I watched people scream through my neighborhood all the time after they paved over the bricks. plowing snow is harder on brick roads, but it isn't so hard that it is an unsolvable problem.
    • mikeyouse 4y ago
      It's not the plowing that gets bricks in winter, or not plowing exclusively, it's the freeze-thaw cycling that kills anything with joints. Every grout joint / polymeric sand joint is an opportunity for moisture intrusion and in any climate zone that gets cold enough to freeze, those joints are going to degrade incredibly quickly. Bricks may make sense in the South, but definitely not in most of the US.
      • teucris 4y ago
        I’m not sure how this applies. Most joints are meant to flex, reducing the breakage of actual paving elements significantly. It also means that an area with significant heaving can be repaired more easily by only needing to service the affected area, and the repair has minimal impact to the surface quality, unlike concrete patching or pothole filling.
    • mcguire 4y ago
      Speaking as someone who grew up in a neighborhood with brick streets,... They're insanely slippery when wet. A freeze-thaw cycle tends to make them move, eventually leading to weird dips and ridges. They're expensive to install and more expensive to maintain.
      • naikrovek 4y ago
        they were not slippery that I noticed in my town. not sure why. my town used dirt as the "mortar" between bricks, so there was no solid joint to degrade over time. I do remember crews going around and spreading small amounts of dirt on those roads, to refill what little rinsed away after spring thaw. they'd just have a guy following behind the truck with a push broom moving the dirt so it fell between bricks. dirt is dirt cheap.
• Retric 4y ago
  Modern roads are designed to take serious abuse. 50 years of load cycling 20 ton semi at highway speeds causes mechanical damage which Roman concrete wouldn’t be effective in preventing. In ancient sites you can sometimes see the walls in high traffic areas have gotten smoothed and indented from hundreds of years worth of people gently dragging their fingertips across the surface as they walk by, tires are less gentile. Also, people vastly underestimate how cheap road surfaces need to be. Try and calculate the volume of material making up the US road system.
  • JanSolo 4y ago
    I live in Montreal; many of the concrete structures in my city are crumbling and decaying due to the constant freeze/thaw temperature cycling that they're exposed to. I wonder if the self-healing property of this new advanced concrete would help to avoid some of the cracking & flaking we're seeing in constructions from the 60s & 70s.
    • kibwen 4y ago
      Only if you take out the rebar. Concrete is porous, water penetrates to the rebar inside, the rebar rusts and expands, cracking the concrete. But if you remove the rebar, you remove much of the tensile strength of the structure, which means you need to use way more concrete to compensate (via the sheer compressive force of its own weight).
      • elzbardico 4y ago
        What about those new materials for rebar? Like fiberglass? What do you think of them?
        • bombela 4y ago
          Not the parent. My understanding is metal rebar is the cheapest. You need a lot of rebar in modern concrete construction.
    • betaby 4y ago
• naikrovek 4y ago
  modern roads and bridges are designed to decay at the rate they decay, because building in longevity is far more expensive than simply replacing the road surface or replacing the bridge at the end of its life. what we don't do today is follow through on the maintenance and replacement schedules, in an attempt to save money. we try to repeat our tradeoff after the infrastructure is built, again trading away longevity in favor of money. well, infrastructure decays if you don't maintain it or build it to last longer. skimping on maintenance after you skimped on longevity is trying to eat the cake, and still have it after you've eaten it. it doesn't work that way.
• cjohnson318 4y ago
  I worked at a geo-polymer start-up. One huge hurdle is sourcing the right kind of ash, and other ingredients, in sufficient quantities and with the right level of quality. Building a kiln or a launch pad is one thing, but building a road is orders of magnitude more expensive. Like, it's humanly possible, but it's not economically possible.
• AlexandrB 4y ago
  Only some bridge designs can use un-reinforced concrete. Many (most?) modern bridges need reinforced concrete to allow the concrete to bear tensile loads. Reinforcing concrete introduces new ways that concrete can degrade such as rusting of the reinforcing elements. I'm not really sure Roman concrete would be much help here.
• marcosdumay 4y ago
  The quick cure may be very useful for most construction. And the self-healing may be better enough for use on pavement. But most bridges and highways are quite demanding and can't simply adopt a new concrete chemistry based on an improvement in a single dimension.
• deleted 4y ago
  [deleted]