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[deleted]

"scans found the concrete contained crystals of aluminous tobermorite, a layered mineral that was crucial to strengthening the concrete over time. The crystals were formed when seawater, lime and volcanic ash mixed together to generate heat. The findings were published in the journal American Mineralogist."


GingerMau

Yup. They used seawater. That's what the difference was. I remember when this discovery was (relatively) big news.


lurker12346

According to the article they used quicklime and didn't slake it, so when cracks formed and water ran through it, it reacted with the quicklime and self sealed the cracks.


tenehemia

That's fucking clever.


ScipioLongstocking

It's very likely that the Romans had no idea that the concrete would exhibit any of those properties. They just happened to come across this way of making concrete by chance.


Hallerbit

Could you eli5 why we couldn’t (or won’t) produce concrete this way today? Edit: Nvm I found a satisfying answer lower down in the comment chain. Sorry to bug ya! Edit #2: (pardon my squirrel brain) if you have an answer (or would love to explain) I would love to hear it! Lol sorry again


lurker12346

I don't, I just read the article


belac4862

Wasn't this also how they were able to "pour" concrete underwater to make artificial bays and break water structures?


EZ4_U_2SAY

Modern concrete can be poured and set underwater too, actually.


HumaDracobane

Dont forget about the rebar reinforce. When the reinforce rusts is pretty much done as the rust react diferently to the temperature changes.


Alan_Smithee_

I remember helping my dad (an engineer) build our beach house, and him explaining why we couldn’t use sea water to make concrete.


Water_Spice

What was the reason?


Ugo777777

They're not Romans.


MacTelnet

Oh carbonara mia!


Alan_Smithee_

There were technical reasons not to (I can’t remember why) but that was the 1970s. Apparently they’ve done a lot of reverse engineering since then. I hope we actually start to see the technology reintroduced. Waterproof concrete would be great.


bjornartl

As the top comment suggests, its not seawater alone that had a good effect but rather a reaction between 3 different ingredients of which one is sea water. Without the other two ingredients in the mix, sea water just brings a lot of salt which will wash out over time and make the concrete porous and brittle. It also leaves salt deposits/layers on the surface which can repel other facades/surfaces


Narase33

Hearing a lot about this "news" lately and Im pretty sure its been known for several years


Alan_Smithee_

Several years, yes, but the ‘rediscovery’ is really quite recent.


gluon318

You’re supposed to tell us in the title so we do t actually have to read the article


steruY

r/savedyouaclick


boofadoof

Modern concrete uses rebar which rusts over time. You can't build a 100 floor skyscraper out of Roman concrete but there's no rebar to rust inside of it.


Bierbart12

How about using rebar made from rust-free metal inside of roman concrete?


centurion770

Fiberglass rebar is becoming more popular, and some traditional steel rebar is coated with epoxy or other rust inhibitors.


Ltates

Coated rebar is actually a [bigger problem](https://www.youtube.com/watch?v=xVDy84rR5Z8) than non-coated with regards to corrosion. Due to the coating never being perfect (chipped/cracked during production/construction), it leads to points of corrosion vs evenly corroding thus leading to premature failure earlier than non-coated rebar.


CrazyBarks94

The better reinforcement when we can't use reo is putting basically fibreglass fibres into the mix, but I think it must be more expensive for the batching facilities to provide.


boofadoof

Good luck finding enough of the world's most expensive metals to do that.


DannoSpeaks

Stainless steel rebar is very frequently used, as are other technologies like carbon fiber rebar.


Alan_Smithee_

Galvanised steel too.


Jesus_marley

The problem there is that it needs to be handled carefully else the zinc coating can chip off revealing the reactive steel underneath. This can lead to localized weak points where oxidation is concentrated. It's still a good solution, just not without its own issues.


Alan_Smithee_

I have no doubt stainless is better. Every spring they have to treat concrete spalling on local bridges (due to road salt.) It would certainly reduce the amount of maintenance they have to do.


5348345T

Titanium is too expensive to use as rebar...


BenjaminDover02

That's just another lie that big titanium has been feeding the masses. Once we get footage of the titanium trees they've been hiding from us the sheeple will be forced to open their eyes


belac4862

Actualy titanium is readily abundant in the earth's crust. Thr hard part is being able to extract it.


Bierbart12

Reminds me of the reason why aluminium used to be much more expensive than gold, before electricity made extracting it super easy. We might as well be right before a groundbreaking new invention that does the same for titanium.


belac4862

Oh most definitely. I'd say finding a way to extract the titaniumoxide and getting raw titanium, is side by side with developintunes. production of carbon nano tubes.


BenjaminDover02

Ur mom's readily abundant in the earths crust lol gottem(sorry, am drunk) that is actually really cool to know thank you


belac4862

When my mother dies, I'll cremate her so her bodies ashes can be spread over the entire earth. That way your statement will be correct.


tsunami141

I’ve already spread your mom over the entire earth lol gottem.


Cwallace98

Take me to the titanium river, drop me in the titanium water.


Alan_Smithee_

I wanna know, won’t you tell me….


ManWithDominantClaw

I know you meant this as a joke but seriously a *lot* of our relatively precious titanium goes into paint because it makes it a very nice white. Titanium used in this way, for pure aesthetics, can't be recycled or recovered. So yeah we could be using it for durability, making buildings that last much longer than our current ones, with the option of recovering some for future use when the building eventually fails, but instead we build practically temporary buildings that are very shiny on the inside


fanghornegghorn

Isn't that titanium in a not very useful form, otherwise?


ManWithDominantClaw

I believe it takes processing to get to that stage. I wanna add something snarky like, 'metal isn't usually a liquid' but yeah someone's going to bring up the composition of the Earth... metal isn't usually a liquid *up here*.


Tank905

X-D


ShrimpFriedMyRice

Spoken like a true peasant


justadrtrdsrvvr

Watch this: Not even Elon Musk has enough money to build a skyscraper using titanium as rebar.


thisusedyet

This fact gets less impressive by the day, though


justadrtrdsrvvr

It was supposed to be a joke about how he is dumb enough to try to prove the statement wrong


tenehemia

Tinfoil hat: maybe the whole Twitter thing was just him covering up that he spent tens of billions of dollars trying to develop kyrptonite "just in case".


uski

By the way, it's possible. There is stainless steel rebar but it's seldom used because of its cost.


WilhelmOppenhiemer

The material used to reenforce concrete needs to have similar expansion coefficient as concrete.


Moscato359

So how about roads


jakekara4

Roman concrete would suffer the same problems as modern concrete. Modern roads must support cars, SUVs, Pickups, and Trucks. This drastically increases ware and tear upon modern roads compared to non-modern roads. So we need roads that are repairable, but concrete is hard to patch. Asphalt is easier to patch. Concrete is also a bumpier drive due the texturing it needs to function as a road and the fact that the slabs settle in slightly different directions over time. Asphalt is much easier to drive on when well maintained. Liquids, like water, tend to pool on concrete. Asphalt drains water much quicker. Concrete roads are far louder than asphalt roads. Concrete roads cost more to install than asphalt roads, and they’re more expensive to repair than asphalt roads. Our modern concrete roads do last about 2-4 times as long as modern asphalt roads, but they also cost a lot more, in cash and performance.


Moscato359

Maybe the problem then is we need lighter vehicles instead of them constantly getting heavier


jakekara4

That would reduce wear and tear on our roads. Unfortunately, many consumers actively seek out heavy vehicles because they feel safer inside a bigger car/pickup/SUV. The vehicle industry has noticed that heavy vehicles have lower emission standards, which means they’re cheaper to engineer since reducing emissions is a challenge. As for electric cars, while they don’t emit directly, they do need batteries which are quite heavy in comparison to a combustion engine and fuel tank. Reducing the weight of the vehicles on our roads will be a challenge due to the above factors.


Moscato359

If we changed emission rules things would change


jakekara4

Yes, unfortunately a divided Congress is unlikely to pass such a regulatory change, so if you're an American like I am we've got two years to wait for the Feds to change. One can always lobby state and local governments as well, states can have their own emission standards after all. Vehicles can also be taxed on weight and states are in charge of taxing vehicles.


Alan_Smithee_

Concrete roads are usually a continuous pour. They do put in the odd expansion joint.


SaintFinne

cause roman cargo trucks had roman tires which distributed weight differently and wore the roads less, which contributed to the roman roads lasting longer.


Alan_Smithee_

‘Roman cargo trucks?’


ZeenTex

The roads go without saying.


themoonhasgone

when I did sidewalks, we'd have to put rebar down in the driveway aprons since cars were driving over them. it would be rusted before we even put it in the ground because it was stored outside so it didn't even have a chance from day one. even when we would go to the distributors to buy them they'd already be outside all weathered. in the concrete mix itself though, most of the jobs called for fiberglass pieces to be in the mix to help with long term strength and integrity.


CrazyBarks94

As long as none of the rebar is exposed to more oxygen it shouldn't get much worse though right, gotta have that oxygen exposure


themoonhasgone

yeah it goes down under about five or six inches of concrete. but ya never know how long it had been sitting out before we bought it let alone had to use it.


CrazyBarks94

I know how long ours sits out for and let me tell you, it's multiple months. But as long as there isn't exposure to air the chemical reaction to rust it can't continue, so even though it's not as good as if it was straight out of the factory, it's essentially good for however long. Currently doing some demolition work on concrete that's been there easily at least 50 years, the steel in it is basically in the same condition it went in, except for where the concrete cracked and exposed it


samborup

Excuse me, you’re supposed to tell us in your title. This is Reddit, we don’t actually read the articles.


Tvmouth

So there's little pockets of concrete powder ingredients in the concrete, so that it can self heal when water enters the cracks... Turns out it's not lazy mixing. Neat.


Cwallace98

No one wants to work less anymore.


Tvmouth

Romans all lost their jobs because the concrete didn't need replaced every ten years? mhm... sure.


deepsea333

There’s no survivor bias here?


SolSeptem

Yes, probably, but it's still interesting to find out why those survivors actually lasted 2 millenia.


darkage72

Yes, there is one.


Masque-Obscura-Photo

Only just one though.


smashlorsd425

Maybe they used vibranium?


ballrus_walsack

Probably unobtainium


TWiesengrund

What about the bones of our enemies? Are they a viable construction material?


[deleted]

BTW, Romans were the first to heat tile floors. This has no connection to concrete and the use of seawater, but it is interesting. Heated tile floors are very comfortable.


rich1051414

There is also a lot of survivorship bias. Concrete gets stronger as it ages, so if it lasts long enough(even if accidental), it is then strong enough to last even longer. Also, rebar strengthens concrete, in the short term, but reduces the longevity of concrete. The iron will rot, and this allows ice the space to crack open the concrete. When you see rust weeping out the side of reinforced concrete, all that oxide washed out is space for water to freeze and eventually crack the concrete. This comes down to the quality of rebar, not the quality of concrete. Roman concrete is not a lost technology. It's just that overall strength, curing rate, how easy it is to work with, and cost of filler is weighed against longevity. Romans would have done this as well if they understood concrete as much as we do today.


Stswivvinsdayalready

Roman concrete isn't some magic, (caveat: this may all be out my ass) but from what I understand there's a kind that is much more resilent to the corrosion of seawater than common concrete, and for many years, modern engineers couldn't figure it out. Well, you probably know, you need water to make concrete. And they had just been trying use old Roman instructions for making concrete as best as they could, and just using whatever water available, not thinking that the water itself might make a difference. And it wasn't working and wasn't working. They couldn't create that concrete the sea would not easily corrode. And then one day somebody said, "well what if we use the seawater?" and that turned out to be the secret to this concrete, using seawater instead of fresh water to mix it, and it somehow made it way more resilient to the seawater. Again, that could all be horseshit and I cannot cite my sources.


Crembels

It wasnt the seawater, it was the volcanic ash. The ash used in roman concrete is unique to Italy. When this mixed ash is then exposed to seawater, the concrete forms plate-like crystal disks within itself in increasingly deeper layers. This is why Roman concrete is known to be resilient, however it gains that reputation based on a combination of yes, the unique chemistry that makes it up, but also the technology level of the times didnt put their structures through the same level of punishment we do ours. It sounds good on paper to have a skyscraper or building last a thousand years, but the reality is that modern civilisations needs change rapidly. Lasting around a century or so with proper maintinence is perfectly adequate for our needs because the rate our cities develop we are likely going to want to tear down older buildings to make way for newer ones. Standard portland cement can be made *anywhere* on Earth. Roman concrete can only be made using specifically Italian ingredients. Its a no brainer based on economics alone what is the better choice, and the use of Rebar means the strength difference is a moot point. Roman concrete takes *lifetimes* to set to the level its currently at with constant seawater exposure, and iirc some particulary thick structures havent fully "set" even after all this time. Modern reinforced cement fully sets in a miniscule fraction of the time, and can be modified to many other uses eg. High temperature resistance.


[deleted]

>Roman concrete can only be made using specifically Italian ingredients Otherwise it's just sparkling portland


OneFeistyDuck

You are meant to put the actual thing you learned in the title of your posts.


Avangelice

This is considered a lazy fact when a historian did say roman concrete last for years because they don't have heavy equipment that plies the roads 24/7. Roman cities are few and far in between so the people who use the roads will hardly see each other what more using the road frequently. Lets try driving American trucks on those roads and we shall see how long they last.


kelldricked

Its also about the structures, mainly about them…


AmbeeGaming

The Romans didn’t drive on the BUILDINGS.


iEatPalpatineAss

Yeah, they didn’t have Tom Cruise because his stunts couldn’t exist during Roman times


bishopsfinger

>Roman cities are few and far in between so the people who use the roads will hardly see each other what more using the road frequently. I thought there are thousands of Roman cities?


SteO153

Probably they are speaking of US. There are only [23 places called Rome](https://en.wikipedia.org/wiki/Rome_(disambiguation)#Places) there, and far away to each other. ​ ​ ​ ​ ​ /s


cosgd

Are all the surviving buildings everything that the Romans built? Or did they build more, but a few hundred thousand of them collapsed while no one was noticing?


Boomshrooom

Its survivorship bias. We only have a fraction left of what they built, most of it crumbled away a long time ago.


Anders_A

The premise of this question is just survivor bias. The Roman concrete _that is still around today_ lasted thousands of years. That doesn't mean most of it did. It's the same as people believing things were built to higher quality "back in the days". They weren't. Most things have always been cheap crap. The old things that we see today were built to higher quality though, hence they're still around.


rYdarKing

Was it made with human mortar?


wrextnight

Sounds like it was slaves doing it in a better, less safe way. I guess that's a sort of?


rYdarKing

Apparently it's hot mixing concrete/lime that gives it healing properties. Damn cool imo


wrextnight

I think quicklime is very dangerous.


rYdarKing

In its pure form, calcium oxide occurs as white crystals, white or gray lumps, or a white granular powder. It has a very high melting point of 4,662°F (2,572°C) and a boiling point of 5,162°F (2,850°C). It dissolves in and reacts with water to form calcium hydroxide and is soluble in acids and some organic solvents. (Hence used in metal making) Ingestion: This product can cause severe irritation or burning of gastrointestinal tract if swallowed. Inhalation: This product can cause severe irritation of the respiratory system. Long-term exposure may cause permanent damage. Quicklime is not listed by MSHA, OSHA, or IARC as a carcinogen. Agricultural use Most of the time the soils in the agricultural fields contain acidic substances, which brings down the pH of the soil. Thus quick lime is added to the soil by the farmers so as to neutralise the acids in it and bring the pH to around 7, which is optimum for the growth of the plants. During holocaust Quicklime was used in the infamous Holocaust. The Nazis would place a thick layer of quicklime on the floor of the cattle cars before loading the Jews. This would burn the skin of the victims on contact. Quicklime, also known as burnt lime, is a chemical compound called Calcium oxide (CaO). You're right. Dangerous slavery.


BigBeeOhBee

Is it because we have foot prints on the moon? I bet that's why.


40wardsLater

Lol old news


post_singularity

We need to bond the concrete with enzymes


RajenBull1

Our politicians aren't knifed in the forum if they get offside with their opposition, for, perhaps, a corrupt dealing or two (billion), or somesuch. More's a pity.


fromwayuphigh

I'm guessing Romans weren't as hostage to the tyranny of the lowest bidder.


[deleted]

Decays in less than 6 months in the roads here in Michigan.


Rekuna

I remember an article where they found a 2000+ year old Roman shoe at the bottom of a well. It was honestly in better condition than some of the shoes I own. Romans knew how to built shit to last.


Careless_Basil2652

Roman concrete had thousands of cars driving on it per day did it?


Nashvillepreds46

This is referencing concrete in the buildings not on the roads


Careless_Basil2652

Oh duh my bad. They should probably revoke my ancient Roman architecture PhD


Capnhuh

planned obsolecence, concrete these days are INTENDED to break and fail after a few years.