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How Ancient Rome’s Concrete Has Survived 2,000 Years (2017)
- tictok4 7y agoMeanwhile the 20 year old office building I work just had extensive repairs to the concrete.
- ArminCherusker 7y agothat's the difference between europe and the usa.
- duxup 7y agoSurvivor bias, we only get to see Roman successes today ;)
- jbay808 7y agoYou're probably joking, but since "it's just survivor bias" is a popular take these days, I'll respond as though you're serious. A bridge that stands for 2000 years without (much) maintenance isn't survivor bias, it's disruptive technology. Yes, we only see the best of Roman architecture, and most Romans probably lived in wooden shacks or stone apartments that have long since crumbled or been demolished. But Roman concrete is chemically different than the Portland cement that was invented in the 1800s, and although there's certainly a distribution of building quality and workmanship that will result in a wide spread of lifetimes, we don't have any reason to expect that any concrete building built from Portland cement and exposed to the elements like Roman seawalls were will last 2,000 years. The distribution just doesn't have that long of a tail to it.
- joshspankit 7y agoAn important component to the survivor bias argument in this case is: we have no way of knowing what roman concrete didn’t survive. Maybe the ones standing are atypical, or were in some way a fluke as opposed to the marvel they seem to be.
- deleted 7y ago[deleted]
- jbay808 7y agoSure, but that's also not really the point. When we see these structures standing, our reaction should be "wow! How did they do that? What can we learn?" Not "well, I bet they also built a lot of bad buildings too; nothing to see here". When you build something twice as good as the average, it's a fluke. When you build something 20x as good as average, it's worthy of study. Even if these are atypically good examples of Roman architecture[1], you can't pull off the moon landings by launching a ton of backyard fireworks and hoping for a long-tailed success distribution. The best buildings represent the state of the art of the best architects and the best masons working with access to quality materials and an adequate budget and timeline. Not dumb luck and guesswork paying off. [1] Which there are decent reasons to not expect. For example, we know that many Roman buildings were demolished deliberately by later generations because they weren't Christian enough, rather than because they collapsed.
- shultays 7y agoSure, surviving for such a long time is a big accomplishment but compared to bridges today, they are relatively short bridges that cost more to build and allows less load. What is there to research other than figuring out how they work? They are well structured blocks of rocks that distributes the load well basically. How they were built is probably more interesting, but still would be useless
- jbay808 7y agoAs the article explains, the most interesting thing is their seaworthy cement. Although today's Portland cement is newer, it wasn't adopted because it was superior to Roman cement, but because (until recently?) no living person knew how to make Roman cement. Hence, we can indeed learn something by studying it.
- darkerside 7y ago
- petre 7y agoWe still use Roman technology or ideas today: double roman roof tiles, underfloor heating, water distribution, paved roads etc. Italian ceramic tiles, stone and adhesives for them are still the best you can get in Europe.
- sokoloff 7y agoObMontyPython “What have the Romans done for us?” clip: https://m.youtube.com/watch?v=Y7tvauOJMHo https://m.youtube.com/watch?v=Y7tvauOJMHo
- std_throwaway 7y agoUsually it's the rusting steel that cracks the concrete.
- PunksATawnyFill 7y agoMmmmm I think it's due to the crystallization of salts in it: https://www.sciencedirect.com/science/article/pii/S1044580304002013 https://www.sciencedirect.com/science/article/pii/S104458030...
- kennywinker 7y agoMy 10 year old building is just about to do a massive patch-and-seal job. Developer put the rebar too close to the surface, then evaded all attempts to get them to pay for it.
- onetimemanytime 7y agobad job by the contractors /planners. Concrete has an expiration date but not at 20...
- dang 7y agoRelated from 2017: https://news.ycombinator.com/item?id=14690329 https://news.ycombinator.com/item?id=14690329 2013: https://news.ycombinator.com/item?id=5883443 https://news.ycombinator.com/item?id=5883443
- Aloha 7y agoI really appreciate the good you do for the HN community.
- 867-5309 7y agohttps://youtu.be/3o-r1-AsmRU https://youtu.be/3o-r1-AsmRU
- cjohansson 7y agoFunny that discovering how they did concrete 2000 years ago can be seen as progress..
- nefitty 7y agoWell, imagine how much knowledge gets lost through the ages. If there aren't contemporary specialists who value or have enough time to study a technology or a cultural work, it could eventually just disappear. Add to that that different ages and societies build and create from different frameworks, then its conceivable that there are valuable pieces of information that our current society may never uncover or discover, just by virtue of working within a completely different context.
- jbay808 7y agoYeah. It is a mistake to believe that technology can only progress forward. If a generation dies without passing on certain knowledge, it's lost and has to be rediscovered the hard way, and that can certainly happen to technological know-how just like anything else.
- cbanek 7y agoThis is why even though the US already built a few Saturn V rockets, building the next one would be really hard.
- ashleyn 7y agoI'm just thinking right now about how we have terrible knowledge silos at work and how screwed we'd be if these people won the lottery. I'm pretty sure NASA had the same problem and we can't rebuild a Saturn V even if we wanted to. Didn't we also forget how to build nuclear bombs or something?
- cbanek 7y agoNo, sadly there's money in building nuclear bombs. But we might be at risk of losing track of where the nuclear waste is, and how to keep track of it. So here's the standard for that: https://en.wikipedia.org/wiki/Long-time_nuclear_waste_warning_messages https://en.wikipedia.org/wiki/Long-time_nuclear_waste_warnin...
- nullstyle 7y agoFor all of your internet-based concrete knowledge needs, I highly recommend Tyler Ley, a professor from Oklahoma State: https://www.youtube.com/watch?v=PMed3YtN-Fo https://www.youtube.com/watch?v=PMed3YtN-Fo
- kazinator 7y agoHow ancient Rome's concrete has survived that long can probably be attributed to one main factor: no inclusion of steel rebar.
- jbay808 7y agoIn case anyone mistakes this for a summary of the article, here's what it actually says: > Modern cement mixtures tend to erode, particularly in the presence of seawater, but the Roman recipe of volcanic ash, lime, seawater and a mineral called aluminium tobermorite actually reinforces the concrete and prevents cracks from expanding, researchers found.
- aswanson 7y agoRaises an interesting question: how long can modern bridges last, given they consist mostly of steel?
- jacobush 7y agoThe worst is when you combine materials who age differently or respond to temperature swings differently. If that steel bridge can be kept from rusting, it can keep a long time.
- petre 7y agoAlso steel has an endurance limit where material fatigue plateaus.
- sokoloff 7y agoWhat’s way stranger to me is that aluminum does not have an endurance limit (for non-Mech E’s, this is worse for aluminum even though it sounds like it might be better).
- namibj 7y agoBasically, there is no deformation so miniscule that it lasts forever. It just affects how many cycles/how long it takes. Steel however, if you deform it only very little, lasts practically forever. You just need to design it to not deform too much at normal operation. Incidentally, this fatigue vs. approaching the strength limit issue is why airplanes have limited flights. The fuselage/hull is made to last long enough, but not necessarily do well longer than that.
- blacksqr 7y agoThe Last Centurion of civil engineering.
- peterwwillis 7y agoThere's another ancient building technique that doesn't get considered in the modern era: cutting and moving gigantic 10-ton blocks of stone. Sure, it's expensive to cut and move, but a bunch of dudes with rickety boats did it across huge expanses of land and water, and their structures also still stand today. If the carbon footprint is a concern, it might be a perfect opportunity to propose alternatives to the carbon-intense techniques we've adopted. For example, William Fairbairn invented a hand-powered crane, whose 642-to-1 ratio meant two men turning cranks could lift 60 tons. Our land and water-born vessels could also probably be innovated on with similar efficiency, if it wasn't so damn easy to burn ancient vegetation.
- quakeguy 7y agoIf time isn't an issue, those techniques all are fine and are proven to work. Sadly, time IS an issue today, so 2 men on a paddle won't build the hoover dam. Even if they could.
- jblow 7y agoAre you claiming that construction today is fast? I don’t understand. Are you claiming that a contemporary construction project would be able to build the Hoover Dam? That was almost 100 years ago and a lot of things have changed...
- DenisM 7y agoIn an earlier thread someone working in the industry said that today the cement producers can make arbitrarily sturdy concrete, but almost no one wants to pay for the top-tier stuff. Part of it nearsighted thinking, the other part is consideration that money could be spent on like nicer decor, or maybe build larger number of 100 year buildings than a smaller number of 1000 year buildings.
- merpnderp 7y agoIsn’t it the height of hubris to believe we could plan 100 years ahead? What cities haven’t radically changed in the last 100 years, with nearly everything being replaced with something better than they could have conceived of?
- jimmaswell 7y agoWere the ancient Roman aqueducts the height of hubris?
- tedsanders 7y agoThe Golden Gate Bridge was conceived of 103 years ago, and began construction 87 years ago. https://en.wikipedia.org/wiki/Golden_Gate_Bridge#Conception https://en.wikipedia.org/wiki/Golden_Gate_Bridge#Conception Buildings and roads are technologies that have existed for thousands of years, and may continue to exist for thousands of years. If you want to protect people and things from the world, it's hard to do better than walls and a roof. If you want to get from point A to point B by land, it's hard to do better than a network of cleared spaces. Sure, we may not know exactly what people in 100 years will want, but it's likely they'll still want buildings and roads.
- m463 7y agoThat's an interesting philosophical question. I suspect monuments are the only thing that benefit from longevity. I was imaginging government buildings built for 100 years, but I figure climate control and window design has radically changed and older buildings are probably uncomfortable in these ways without retrofitting.
- 7y ago
- Sojuwa 7y agoDamn, us Blacks knew how to do things right. It's saddening how far civilization has been put back by unmelanated folk.