[HN Gopher] The Ancient Roman Secret to Concrete Resilience in S...
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The Ancient Roman Secret to Concrete Resilience in Seawater
Author : kvee
Score : 111 points
Date : 2023-07-04 11:39 UTC (11 hours ago)
(HTM) web link (als.lbl.gov)
(TXT) w3m dump (als.lbl.gov)
| saqadri wrote:
| It is fascinating how some ancient techniques had remarkable
| properties even though they didn't have the tools or science to
| explain it back then. I recently learnt that ancient concrete has
| self healing properties because of the reaction of air/water with
| lime and volcanic ash.
|
| Makes you wonder how far we can get with trial and error.
| sorokod wrote:
| Got us from cingle cell organisms. Just trial error and time.
| [deleted]
| peteradio wrote:
| > Makes you wonder how far we can get with trial and error.
|
| And millennia long test periods.
| nunuvit wrote:
| Old article from 2017. More advances were published earlier this
| year:
|
| https://news.mit.edu/2023/roman-concrete-durability-lime-cas...
| bloopernova wrote:
| That's really cool research. Using quicklime heats up the
| concrete a bunch more than some other methods, and the result
| is concrete that fills its own cracks.
| CoastalCoder wrote:
| The story mentions volcanic ash. If the Roman recipe became
| popular again for marine use, I wonder how much ash is currently
| available without terrible mining operations.
| ajot wrote:
| Fly ash (i.e. ash from industrial chimneys) is being used for
| this same purpose, as pozzolanic (volcanic ash) deposits are
| not that big or common around the world. The key here is, by
| the opinion of a cement researcher close to me, the
| availability of non-cristalline (i.e. an amorphous or vitreous
| form) silicon dioxide.
|
| I've been slightly following the papers on roman concrete for a
| decade or so, and as far as I remember, they've been
| discovering different cristalline aluminosilicates that would
| explain the resilience of these concretes, so maybe there still
| is some need for pozzolanic, or for adding aluminium to fly
| ash.
| AlbertCory wrote:
| There actually IS a contemporaneous source on how to do it,
| without exact proportions, unfortunately. They didn't know _why_
| it worked, of course.
|
| https://en.wikipedia.org/wiki/Vitruvius
|
| https://news.mit.edu/2023/roman-concrete-durability-lime-cas...
|
| "pozzolanic material such as volcanic ash from the area of
| Pozzuoli, on the Bay of Naples." They shipped this all over the
| Empire.
|
| Now we have a better idea why it got better in seawater, instead
| of deteriorating.
| satellite2 wrote:
| I'm completely new to ancient Roman civil engineering. So I ask
| completely innocently,could it be survivor bias?
| leoc wrote:
| Obligatory mention of leading concrete-engineering YouTuber
| https://youtube.com/@TylerLey . He's discussed Roman concrete in
| eg. https://youtu.be/U86tlUiFM1s .
| Projectiboga wrote:
| I hope they can perfect this and use it in places like coastal
| New Jersey.
| jboy55 wrote:
| We can build concrete that can withstand maritime conditions,
| we just choose not to due to cost. We also really don't know
| how much Roman concrete only lasted 100 years.
| al_be_back wrote:
| sadly no concrete evidence on the recipe - not surprised. Romans
| were excellent engineers but as so often, we're left with little
| documentation in this area (sciences). The humanities (law,
| politics, literature etc) has fared better, with way more
| surviving records.
| TechBro8615 wrote:
| I wonder how much documentation we have for the practicalities
| of modern construction methods, and how much of it is passed
| down orally by the construction workers who are actually
| building stuff, or locked within internal company manuals. I
| mean sure I can look up formulae for concrete, rebar etc. on
| wikipedia, but for actual step-by-step instructions with
| specific machines and materials? I bet that information is a
| bit more discombobulated.
| treeman79 wrote:
| Max dad worked for McDonald Douglas, later Boeing. Tons of
| little tricks to build things that weren't documented. Made
| union strong. Replacement workers couldn't reproduce parts to
| spec when following instructions. Things like adding strings
| to foam molds in just the way, etc.
| boeingUH60 wrote:
| > McDonald Douglas, later Boeing.
|
| Later Burger King :)
| MilStdJunkie wrote:
| Today's tech content would fare worse than you might imagine.
| So much is tied into byzantine ERP/PDM systems . . or
| contains specialized processing instructions for a particular
| black box editor/processor . .OR juggles _actual_ techdata
| with the entity peculiarities of a CCS (component content
| system) that itself can result from any number of nebulous
| engineering fads.
|
| I guess, short version of what I'm trying to say, is that
| today's tech data doesn't have narrative. It's a bunch of
| little pieces floating around and needs a living org to put
| it together. If you froze it, Pompeii-style, future
| generations would find themselves facing dead ends all over
| the place.
| al_be_back wrote:
| with software, it's particularly problematic - the
| dependency hell: libs, api, versions, platforms, players,
| os. your software needs documenting, and so do the deps.
| and if you want to run it/replay it, good luck getting it
| operational 20years from now let alone in year 3000.
|
| when a book, newspaper, magazine is published, a copy is
| archived with the National Library - narrative etc
| preserved.
|
| Websites get some archiving, but pay-walling is threatening
| this. Other types of software is very tricky.
| fbdab103 wrote:
| It is always interesting to me in science fiction how
| humans are able to repair/reverse-engineer ancient
| technology from aliens or pre-downfall humanity. If you
| stumbled across a non-encrypted WinXP hard drive, how
| would you possibly read the data? Figuring out the right
| power/voltage, creation of a SATA cable, constructing the
| SATA communication protocol, figuring out how to decode a
| NTFS file system, and then how to read bespoke binary
| format X.
|
| Modern humans with a very good idea of how NTFS work
| struggled to reverse engineer it for years.
| TechBro8615 wrote:
| Our best hope would be exploit devs, cryptographers and
| infosec professionals with reverse engineering skills.
| It's incredible what some people can do with a black box
| system and no tools aside from a voltmeter and logic
| analyzer. First you probe the chip with the voltimeter to
| find where data is being interchanged, then you hit it
| with a logic analyzer to look for patterns, then you
| start breaking it down with cryptanalysis, which is
| really about finding patterns in noise. I think you'd be
| surprised what the best minds would be able to decipher,
| given the right hardware and unencrypted data. If the
| data's encrypted, it gets a lot harder, especially if the
| encryption is advanced enough that it basically looks
| like noise. But even then, there has to be some
| bootstrapping process, so we'd be able to reverse
| engineer that part of it, and then would need to hope to
| find an exploit in the encryption.
|
| Regarding cables and such, you'd have to expect that you
| wouldn't just find a single isolated hard drive. Even if
| you didn't have a full system, surely there would be
| cables and auxiliary components strewn about. And if
| there weren't, their absence would probably be
| significant, since you'd know they used some material
| that didn't survive as long as the material used to make
| the hard drive, and could infer its properties from that.
| So you'd probably be able to piece together which cables
| plugged into which components and make educated guesses
| about voltages and the like.
| btrettel wrote:
| Nominally patents are supposed to describe these technical
| details, but unfortunately the law ("enablement") has no
| teeth in the US. When I was a patent examiner, I wanted to do
| enablement rejections, but couldn't. The law is supposed to
| incentivize properly documenting the invention, but attorneys
| have gamed the system, disclosing little in exchange for a
| monopoly.
| throw0101c wrote:
| See also "Why was Roman concrete so durable?" from January 2023:
|
| * https://news.ycombinator.com/item?id=34280239
| pengaru wrote:
| We have a tendency to promote premature failure of seawater-
| exposed concrete structures by reinforcing them with rust-prone
| materials.
|
| I don't think any amount of secret Roman concrete recipes is
| going to prevent crumbling apart due to the expanding forces of
| rotting rebar.
| steve918 wrote:
| The problem with modern concrete falling apart prematurely is
| usually the use of rebar as a reinforcement.
| thechao wrote:
| And we use rebar because we like long, flat bridging spans that
| can hold hundreds of tons at a time -- something Roman concrete
| has no hope of ever doing, _unreinforced_.
| otikik wrote:
| Not necessarily countering your point, but perhaps giving
| some perspective.
|
| The City I grew in (Cordoba) has a roman bridge[1],
| originally built 1st century BC and still standing. It
| supported a 2-way street until 2004, when it was
| pedestrianised.
|
| Caveats:
|
| * It has gone over a great deal of renovations/partial
| rebuilds on its history, so its durability can not really be
| attributed to roman concrete alone. Only 2 of the original 16
| arcades remain. One could argue that "it's not the same
| bridge" any more (Theseus' Bridge).
|
| * I ignore wether they used concrete to build the original
| one. I'm not an architect. For all I know, the initial
| construction could have been mortarless stone, and cement (as
| well as reinforcement) could have been added in some of the
| later renovations.
|
| That said, all bridges require periodical
| servicing/renovations anyway, in order to remain functional.
| And this one has stand for 2000 years.
|
| [1]
| https://en.wikipedia.org/wiki/Roman_bridge_of_C%C3%B3rdoba
| masklinn wrote:
| This doesn't really give perspective, it's basically what
| they're saying. Roman bridges are gravity structures, the
| entire thing is in compression and _heavy_ , the arches
| have really limited spans.
|
| Compare to the Millau Viaduct for instance.
| redandblack wrote:
| does fiberglass rebar work? I remember reading that it works
| well for horizontal layouts but was not sure about use in
| pillars.
| andromeduck wrote:
| Isn't basalt the best non-steel option all around?
| masklinn wrote:
| Yes, alternate forms of rebar work. You can also coat rebar
| with epoxy, or use stainless steel.
|
| The two core issues are cost, and limited understanding of
| the long-term properties of the material (as well as
| experience e.g. epoxy-coated rebar needs to be handled
| carefully lest you scratch off the epoxy).
|
| FWIW the Practical Engineering channel has an entire series
| on concrete which covers (the basics of) this and more: htt
| ps://www.youtube.com/playlist?list=PLTZM4MrZKfW90PdaBFt70..
| .
| fbdab103 wrote:
| >... e.g. epoxy-coated rebar needs to be handled
| carefully lest you scratch off the epoxy).
|
| That sounds impractical at scale. Whenever I pass by
| construction I see the materials haphazardly strewn
| about. How could you possibly ensure that all of the
| rebar used is never scratched when it has to pass through
| dozens/hundreds of hands before it is finally set?
| datavirtue wrote:
| I've always noticed it carefully packed and stacked on
| site. The epoxy coated rebar is usually formed and
| connected into structures that are placed/suspended in
| the forms or roadway. The epoxy is also very durable.
| AlbertCory wrote:
| I don't think anyone's ever claimed that it was better for
| all modern applications.
| lll-o-lll wrote:
| Rebar reinforced concrete fails, I assume, because the rebar
| rusts? If so, isn't the issue greatly reduced (potentially)
| if we were to use the quicklime process of the Romans? If the
| self-healing prevents water penetration, does that stop rebar
| from rusting?
| jacoblambda wrote:
| Remember that roman concrete often used iron for reinforcement.
| The Colosseum is a famous example of this. The only reason it's
| not still there today is because metal, particularly iron, was
| extremely valuable so after the fall of the Roman empire,
| people tore whatever iron they could out of the structure (akin
| to people today stealing wiring and copper piping from the
| walls of houses).
| Oarch wrote:
| Stories about Roman concrete appear to flood the Internet about
| once per year. No idea why...
|
| See also: seaweed reduces cow farts.
| AlbertCory wrote:
| Maybe because 2000 years later, some of it is still standing?
| kibwen wrote:
| And in 2,000 years there will still be some structures made
| of Portland cement still standing... although not any with
| rebar inside. The Hoover Dam could stand for 10,000 years
| (it's not even done _curing_ yet, 100 years later). Don 't
| overlook survivorship bias; the vast majority of structures
| made of Roman concrete are not still standing.
| AlbertCory wrote:
| I think you are ignoring all the civil engineers who ARE
| impressed with it.
|
| Getting better in salt water is a seriously impressive
| feat. Hoover Dam is fresh water.
| smackeyacky wrote:
| It woyld be funny to me if it turned out the secret was urine
| instead of seawater. One of the bits of received wisdom i got
| from my grandfather was peeing on your hands toughened them up.
| He claimed it as a bit of advice he was given on his first day
| chopping hardwood for a steam engine at a tin mine. I figured it
| as a first day prank like being sent to find headlight fluid in
| modern times but he said it was true.
|
| Before major industrialisation, people used what was at hand. I
| think the peeing on your hands thing has been long debunked but
| in roman concrete it may have worked.
| a_c wrote:
| Thanks for making my day
| https://www.youtube.com/watch?v=s_0THARUP9A
| nonethewiser wrote:
| Lots of baseball players used to do this. Particularly
| Dominicans. It mostly stopped in favor of batting gloves but
| some players continued doing it such as Moises Alou.
| bigbacaloa wrote:
| Lots of baseball players used to do this.
| mymythisisthis wrote:
| For most of human history pee urine was left to get stale,
| turning it into ammonia, and used for doing laundry.
|
| Washing clothes in ammonia is really great at getting out oil
| and grease stains. Though now you just buy ammonia directly
| from a good hardware store.
| qup wrote:
| Hi, nerdy hacker here, could use further advice:
|
| Can I screw the ammonia up, like how bleach ruins clothes?
| Any recommendation on amount? Do I add it to a wash cycle?
|
| I have a lot of grease-stained shirts that are some of my
| favorites.
| aerio wrote:
| Use in the laundry for regular stains: Soak stubborn stains
| on cotton, polyester, or nylon fabrics with a solution of
| 2/3 cup clear ammonia, 2/3 cup dish soap, 6 tablespoons of
| baking soda, and 2 cups warm water. Let it soak for about
| 30 minutes, then launder as usual. Never use ammonia on
| wool or silk.
|
| Here's a step-by-step guide on how to wash clothes with
| ammonia:
|
| 1. Read the garment labels: Check the care instructions on
| your clothing items to ensure they can be safely washed
| with ammonia. Some delicate fabrics or certain colors may
| not be suitable for this method, so it's important to
| follow the manufacturer's recommendations.
|
| 2. Prepare the washing machine: Start by setting up your
| washing machine as you would for a regular load of laundry.
| Sort your clothes by color, fabric type, and level of
| dirtiness.
|
| 3. Measure the ammonia: For a typical load of laundry, use
| about 1/2 cup to 1 cup of ammonia. Adjust the amount based
| on the size of your load and the level of dirt or stains on
| the clothes.
|
| 4. Add the ammonia to the washing machine: Pour the
| measured amount of ammonia directly into the detergent
| dispenser or the main wash compartment of your washing
| machine. Be careful not to spill any ammonia on your skin
| or clothing.
|
| 5. Add detergent: Add your regular laundry detergent to the
| same compartment as the ammonia. The detergent will work in
| conjunction with the ammonia to clean your clothes
| effectively.
|
| 6. Start the wash cycle: Close the washing machine lid or
| door and start the wash cycle using the appropriate
| settings for your clothing items. Follow the machine's
| instructions for temperature, water level, and cycle
| duration.
|
| 7. Complete the wash cycle: Allow the washing machine to
| complete the cycle as usual. Once finished, remove the
| clothes promptly to prevent wrinkling or odor development.
|
| 8. Rinse the clothes: If you prefer, you can run an
| additional rinse cycle to ensure all traces of ammonia and
| detergent are thoroughly rinsed out. This step is
| particularly important if you have sensitive skin or are
| concerned about potential residue.
|
| 9. Dry the clothes: Depending on the fabric type and
| garment care instructions, dry the clothes by air drying,
| using a clothesline, or by using a dryer.
|
| 10. Clean the washing machine: After completing the load
| with ammonia, consider running an empty cycle with hot
| water and a cup of white vinegar to help remove any
| residual ammonia smell or build-up in the washing machine.
|
| Remember to handle ammonia with care, follow safety
| guidelines, and avoid mixing it with other cleaning agents,
| such as bleach, as it can produce hazardous fumes. Always
| keep ammonia out of reach of children and pets.
|
| Additionally, if you have specific stains or heavily soiled
| items, it's advisable to spot treat them before washing
| with ammonia.
| Tade0 wrote:
| I only ever used it to clean floors, but word of warning:
| even a 3% solution is already noxious.
|
| A whiff of Uranus so to speak.
| shrubble wrote:
| Mixing ammonia and bleach gets you basically mustard gas,
| so be cautious about what is in any other detergent you use
| at the same time...
| mcpackieh wrote:
| Specifically it makes chloramine gas, the same stuff that
| (in fairly low concentrations) makes swimming pools
| stink. It can be lethal so definitely take it seriously,
| although it's not nearly so gnarly as real mustard gas.
|
| Here's an incident where a woman inadvertently made
| chloramine gas in an enclosed space while cleaning and
| was breathing it for 30 minutes. It nearly killed her and
| she was hospitalized for a week:
| https://www.nejm.org/doi/full/10.1056/NEJM199909093411115
| leetrout wrote:
| Here's one where a restaurant manager died after someone
| mixed cleaners right on the floor.
|
| https://www.cnn.com/2019/11/08/us/massachusetts-buffalo-
| wild...
| pfdietz wrote:
| It's not mustard gas, but it is really nasty. It produces
| a mixture of chloramines and hydrazine.
| mymythisisthis wrote:
| Don't mix it with bleach, otherwise you're o.k.
|
| Can't really go wrong. After I do some bicycle repair, I
| toss my greasy clothes into the washer, and add a cup or
| two of ammonia during the wash cycle. I don't even add
| detergent, as the grease comes out without soap.
|
| Found more professional instructions here,
| https://www.hunker.com/13422713/how-to-use-ammonia-in-the-
| la....
| tomjakubowski wrote:
| Baseball player Moises Alou famously claimed he peed on his
| hands to ward off calluses. He's one of the few modern players
| not to wear batting gloves.
|
| https://slate.com/news-and-politics/2004/05/can-peeing-on-yo...
| nonethewiser wrote:
| Jorge Posada and Vlad Guerrero too. All from the Caribbean.
| thworp wrote:
| Urea is very effective at moisturizing and is an ingredient in
| many heavy-duty lotions, so peeing is probably overkill but not
| without benefit.
| fbdab103 wrote:
| Practical questions abound. Do you wash your hands after
| peeing on them? Do you pat dry? Towel dry? How do you close
| up your pants without spreading a non-negligible amount of
| urine onto your pants? Would you want to pee on your hands
| every trip to the bathroom or more a once-per-day thing?
| twic wrote:
| I would expect the opposite - urea is a keratolytic, so it
| should break down thickened skin, and make the hands less
| tough. That said, urine is 1-2% urea, and typical medical urea
| solutions are 5% or more, so i wouldn't expect much of an
| effect.
| interestica wrote:
| You're in for a big surprise:
|
| https://www.smithsonianmag.com/science-nature/from-gunpowder...
| Eumenes wrote:
| Water jackets for machine guns would often be filled with urine
| by soldiers if water wasn't available.
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