The ancient Roman secret to concrete resilience in seawater (2017)

https://als.lbl.gov/ancient-roman-secret-concrete-resilience-seawater/

by kvee • 3 years ago

142 76 3 years ago

als.lbl.gov

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.

thworp• 3 years ago

Urea is very effective at moisturizing and is an ingredient in many heavy-duty lotions, so peeing is probably overkill but not without benefit.

fbdab1033• 3 years ago

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?

Eumenes• 3 years ago

Water jackets for machine guns would often be filled with urine by soldiers if water wasn't available.

a_c• 3 years ago

Thanks for making my day https://www.youtube.com/watch?v=s_0THARUP9A

bigbacaloa• 3 years ago

Lots of baseball players used to do this.

interestica• 3 years ago

You're in for a big surprise:

https://www.smithsonianmag.com/science-nature/from-gunpowder...

chaosjevil2• 3 years ago

It's a bit off-topic, but the role of urine in teeth cleaning reminds me one of Catullus' poems, poking fun at someone who was a bit too eager to laugh/smile as trying to show off how much urine he drunk.

For context: Celtiberians used urine to brush their teeth. The Romans were aware of that, but they thought that it was disgusting.

(The poem is Catullus 39, if anyone is interested. Link: https://en.wikisource.org/wiki/Translation:Catullus_39 )

mymythisisthis2• 3 years ago

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• 3 years ago

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.

tomjakubowski• 3 years ago

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...

nonethewiser2• 3 years ago

Jorge Posada and Vlad Guerrero too. All from the Caribbean.

twic• 3 years ago

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.

nonethewiser2• 3 years ago

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.

CoastalCoder• 3 years ago

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• 3 years ago

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.

Projectiboga• 3 years ago

I hope they can perfect this and use it in places like coastal New Jersey.

jboy55• 3 years ago

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.

throw0101c• 3 years ago

See also "Why was Roman concrete so durable?" from January 2023:

* https://news.ycombinator.com/item?id=34280239

al_be_back3• 3 years ago

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.

TechBro86152• 3 years ago

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• 3 years ago

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.

MilStdJunkie• 3 years ago

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.

btrettel• 3 years ago

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.

pengaru• 3 years ago

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.

Oarch• 3 years ago

Stories about Roman concrete appear to flood the Internet about once per year. No idea why...

The ancient Roman secret to concrete resilience in seawater (2017)

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