9 ms·

Why Ancient Roman Concrete Outlasts Our Own (2017)

54 points by NiceWayToDoIT 5y ago

Phithagoras 5y ago
In a second year class I took the prof posed us the question: why don't we do this today? Why is this not part of an ASTM standard? He ended up saying it's too tough to get a hold of proper pozzlanic ash, but I suspect its more a "this is the way we've always done it" difficulty. Does anyone know more to the story?
- leroman 5y ago
  Maybe industries “planned obsolescence” practice?
  - 14 5y ago
    But surely some company would see it as an advantage over competitors and sell it if it was easily accessible. But we don’t see that so there has to be more to it. Maybe cost is too high for the average customer?
    - masklinn 5y ago
      > Maybe cost is too high for the average customer? Well yes, and even for the non-average one. Plus the goal is generally to build things which barely stand, a building which can face the vagaries of time for thousands of years would generally be way over-engineered. Countries where pozzolanic ash is readily available do use it but that’s not usually the case. Fly ash is also being explored for that role. An other issue is understanding of the material’s properties over time. Also our modern world makes a lot of concrete.
      - metaphor 5y ago
        > Plus the goal is generally to build things which barely stand... Since when? Design criteria baked into international building code is quite robust; not just naive static load, but wind, snow, seismic activity, fire/flood/termite resistance, etc. are all considered. That's a far stretch from something that can "barely stand".
        masklinn 5y ago
        > Since when? Since always > Design criteria baked into international building code is quite robust; not just naive static load, but wind, snow, seismic activity, fire/flood/termite resistance, etc. are all considered. That's a far stretch from something that can "barely stand". “Barely stands” in this context is “Barely passes code”, as in “any idiot can build a bridge that stands, it takes an engineer to build a bridge that barely stands”. The more you go over the more money you’re wasting.
    - smt88 5y ago
      > But surely some company would see it as an advantage over competitors and sell it if it was easily accessible. This is not a guarantee. Look at manufacturers of washing machines: every company makes more money by having unreliable machines. There is no financial incentive to build a better product, and it's not easy to even prove you've built a better product.
      - eru 5y ago
        Would that logic suggest that washing machine brands are equally unreliable? If not, why not? Eg Miele benefits from having a reputation of building reliable products. They can and do charge more for that reputation, but also have to live up to it, if they want to keep it.
        smt88 5y ago
        I've never heard of Miele. If it's a US brand, it is clearly not doing well. If it's a brand in the EU, the laws there were fixed to prevent every brand from selling intentionally defective products[1]. 1. https://uspirg.org/blogs/blog/usp/you%E2%80%99re-not-crazy-your-appliances-were-built-fail-you https://uspirg.org/blogs/blog/usp/you%E2%80%99re-not-crazy-y...
        eru 5y ago
        Miele is a German brand with a long history. You can buy them around the world. https://en.wikipedia.org/wiki/Miele https://en.wikipedia.org/wiki/Miele > Miele (/ˈmiːlə/ MEE-lə; German: [ˈmiːlə]) is a German manufacturer of high-end domestic appliances and commercial equipment, headquartered in Gütersloh, Ostwestfalen-Lippe. The company was founded in 1899 by Carl Miele and Reinhard Zinkann, and it has always been a family-owned and run company.[2] There might be laws that set some minimum standards. But (a) there are still differences between companies' approaches to quality, and (b) Miele is selling around the world also in jurisdictions were EU rules do not apply, but they still deliver on their reputation for quality.
      - lakis 5y ago
        It's not that simple. The consumers do not want washing machines that last forever. Are you sure that you want a washing machine from 1900? It was probably not electric. Aaah, you want an electric one. How about one from the 1920? What do you mean you want intelligent programs, save electricity, be gentle to the clothes and use little water/soap? These are modern improvements of the washing machine. Consumers vote with their money. They stop buying old washing machines because they don't have the features that they want. So companies stop making old washing machines and make new ones with more features.
    - GhettoComputers 5y ago
      Brother printers are low cost, cheap replacing the ink/toner and make good drivers. I definitely buy them only.
  - jacquesm 5y ago
    I think designing your buildings for more than a few hundred year counts as 'excessive' and more than 250 years should not allow for being disqualified under 'planned obsolescence'.
  - smt88 5y ago
    No. An industry does not make a plan 50+ years in advance to get more business. They do, however, save on costs by delivering products that don't last as long because their customers also don't (as a general rule) care about 50+ year time horizons.
- xyzzyz 5y ago
  Concrete is typically made with local materials, because shipping them is rather expensive. Maybe that’s one reason?
  - masklinn 5y ago
    > Concrete is typically made with local materials Not really, especially jot for large contructions. Not everybody has a few thousand to million tons of sands of the right composition in their backyard, and cement comes from a factory.
    - xyzzyz 5y ago
      Yes, and these factories are many, and are not concentrated in one place, because shipping cement is expensive. It’s the same with aggregate: not everyone has sand in their backyard, but there typically is good amount of suitable sand within a few dozen miles.
      - eru 5y ago
        It's even more interesting that than! There's actually plenty of drama around sand for concrete. There's talks about 'sand mafias' in India. And Malaysia has banned exporting sand to Singapore. See eg https://www.bbc.com/future/article/20191108-why-the-world-is-running-out-of-sand https://www.bbc.com/future/article/20191108-why-the-world-is...
        jacquesm 5y ago
        Similar stuff has happened in Germany, in fairly recent times. You could make your own cement, no problem. But good luck trying to unload it anywhere in Germany without paying a fee to certain individuals.
        eru 5y ago
        Interesting. Do you have any links with background information? In German is fine.
- eru 5y ago
  First, we only see the part of Roman architecture that lasted. There's an observer bias. The Romans also made plenty of ephemeral stuff, just like we are making plenty of ephemeral stuff. See also https://www.youtube.com/watch?v=qL0BB2PRY7k https://www.youtube.com/watch?v=qL0BB2PRY7k Second, there's more to engineering than making stuff last long. There are different trade-offs. Cost being one of them, but also different material properties. Eg re-inforced concrete is awesome for lots and lots of applications that the Romans couldn't even have dreamed of. Alas, it's not economical to make re-inforced concrete that lasts forever. (Not even sure if it's physically possible.)
  - hef19898 5y ago
    Trade offs should be covered a lot more during engineering studies. I know that during my time at university, as an industrial engineer destined to work at the interface engineering and economics, that aspect wasn't covered nearly as extensive as it should have. The other question that usually get's ignored is maintenance. The Roman stuff we see lasted millennia without maintenance, we on the other hand can maintain the stuff we want to last a long time. That we don't do it, e.g. infrastructure with the particularly bad maintained bridges in Germany, is not the materials fault, or the original designs fault.
    - markvdb 5y ago
      > we on the other hand can maintain the stuff we want to last a long time. That we don't do it, e.g. infrastructure with the particularly bad maintained bridges in Germany, is not the materials fault, or the original designs fault. I have to respectfully disagree on this one. Humans in general have become spectacularly bad at maintaining physical infrastructure across longer timespans. Technological advances have enabled a cheap/fast/overbuild culture. This very much includes the design phase. Look at the evolution of design. The large majority of our infrastructure, depending on the spot on our earth, largely dates from the last 200 to 50 years. Look at infrastructure predating that. Look at evolution. The bond with local communities depending on the infra? You'll inevitably find it cut. You'll find more bloat in the design. You'll find less local involvement. To some extent, this is progress. Unfortunately, this has an impact on maintainability. Looking at your example of German bridges. I'll make it even more tangible and look at the Eifel region with so much of its infra recently destroyed by flooding. How do we get excellently maintained bridges, when we know this is very much against human nature? This means questions like: - Does this bridge really need to be (re)built? To this specification? In this place? - How much does this bridge benefit the local community where it is built? Can we think of ways to increase that? - How much of this bridge absolutely needs to be built out of reinforced concrete? - Wouldn't it make sense to build some infra in now very flood-prone areas out of less durable but cheaper, more quickly replaced materials like wood? - Can we bring the design closer to the layman? Can we for example design a bridge so that it will visually degrade in step with safety degradation? - ...
- adgjlsfhk1 5y ago
  A lot of the answer is that the types of structures you can build with concrete that isn't rebar reinforced is fairly limiting. You're pretty much stuck with arch bridges, dams, and domed buildings. Unfortunately, arch bridges don't scale that well (they take concrete proportional to length cubed), and people like buildings in shapes other than domes. As a result, you often have to have designs that hold together partially under tension, and the cost is it won't stay up for 2000 years (if you use rebar which rusts). That said, in the past few decades there has started to be experiments with fiber reinforced concrete. This has the significant advantage of not corroding, but costs a good bit more than traditional rebar. That said, it might be the future for buildings where long life is desired.
  - rightbyte 5y ago
    > Unfortunately, arch bridges don't scale that well (they take concrete proportional to length cubed), Only of you go for one arch right?
    - adgjlsfhk1 5y ago
      Multiple arches helps in some cases, but gets really expensive if you have to bridge a deep gap (especially over water where de-watering is needed) The massive advantage of a suspension bridge is that you get a really big span without anything in the middle.
- OneTimePetes 5y ago
  Because buildings change constantly.. notice how in the examples, you have building for which this requirement must not be fullfilled. Public show-off buildings, statues, temples and harbour walls, they do not change with every generation. Now if you want to change it constantly, if a building is for living, durability is actually not that much of a value.
- Animats 5y ago
  There is an ASTM standard: "ASTM C618 Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete (AASHTO M 295)."[1] Fly ash, like volcanic ash, is a pozzlanic ash. Both work in concrete. Fly ash is pulled out of the exhaust from a coal-fired power plant using electrostatic precipitators. Just like electrostatic air cleaners, but huge, they pull particles out of gases. So fly ash is cheap if there's a coal-fired power plant nearby. Convenient when there is no volcano handy. There are downsides. The concrete takes longer to cure, which can hold up the next stage of construction. Curing in cold weather is difficult. The Romans didn't have that problem in their Mediterranean climate. Concrete curing requires some air in the mix, and fly ash, for some reason, tends to entrain less air than Portland cement.[2] [1] https://www.cement.org/docs/default-source/fc_concrete_technology/is548-optimizing-the-use-of-fly-ash-concrete.pdf https://www.cement.org/docs/default-source/fc_concrete_techn... [2] https://www.fhwa.dot.gov/PAVEMENT/recycling/fach03.cfm https://www.fhwa.dot.gov/PAVEMENT/recycling/fach03.cfm
- simonh 5y ago
  >but I suspect its more a "this is the way we've always done it" difficulty. Is the construction industry really known for resisting the adoption of new materials like that?
  - adgjlsfhk1 5y ago
    Yeah. incorporating unknown materials into million dollar projects is a really good way to lose millions of dollars. New materials can get added, but especially for big projects there is a long delay between tech invention and widespread use (think decades).
- jfletch25 5y ago
  It depends on what you're building. Keep in mind that one way for politicians in office to control the number of jobs and money flowing through the economy is doing road work and other public projects.
nindalf 5y ago
I must be missing something. I’ve never used scihub before, and I can’t find the link to read the paper. All I see on this link is the name of the paper and the authors.
- toiletfuneral 5y ago
  You’re still gonna hate this, but try it in landscape.
  - nindalf 5y ago
    Thanks for the tip!
- gigglesupstairs 5y ago
  Yeah, same. Came in comments to look for alternative link but none so far.
  - ggm 5y ago
    Right hand panel for me was a clickable download of the pdf.
- solohan 5y ago
  This looks like the journal page: https://pubs.geoscienceworld.org/msa/ammin/article/102/7/1435/353606/Phillipsite-and-Al-tobermorite-mineral-cements https://pubs.geoscienceworld.org/msa/ammin/article/102/7/143... Also has a link to download the PDF for free.
- zeisss 5y ago
  There is a save button right under the sci hub logo next to a Google scholar link. Opened the PDF for me on Android chrome.
deputy 5y ago
cpach edited the year from <none> to 2017 New title: Why Ancient Roman Concrete Outlasts Our Own (2017)
ncmncm 5y ago
I am becoming partial to the ancient Egyptian concrete, that they might have used to mold the pyramid blocks in situ. It takes just limestone crumble, clay (which was already in their limestone), natron, and water. It is a fair bet the precursors to the Inka who built with the really big blocks had that, or a similar trick. Local observers report the big blocks do not show embedded marine shells at the surface, unlike native limestone. (I have not had opportunity to verify this.)
- pitspotter2 5y ago
  And while we're in the Sahara Desert with abundant sunshine, sand and carbon dioxide, let's build a silicon carbide brick factory. Sunlight to provide electrical power and, via focussed mirrors, heat. Sand to supply the silicon. Carbon from carbon dioxide to be extracted from the air at $100 per tonne (well, eventually). Silicon carbide bricks, emerging gloriously from their tungsten moulds, would possess supreme corrosion resistance and almost double the crushing strength of engineering bricks. High thermal conductivity should reduce cracking and spalling, further increasing lifetime. A short railway journey to the nearest port and water desalination plant whence they can be distributed throughout the world. We'll beat the Romans! Our public buildings will last for millennia!
  - ncmncm 5y ago
    It will take a very long time to beat the Romans, and more than twice that long to beat the Egyptians. Corundum bricks would suffice. The Egyptians knew a way to cut corundum like butter; the method apparently was lost before the pyramids were built. Solar panels have proven quite a lot cheaper than mirror-concentrated solar heat as a source of electrical power. Concentrated solar has not really been tried as a source of direct industrial heat, where it might yet excel. But choosing the bit of Sahara to site in has proven harder than expected. To make building materials economically useful, the site needs immediate sea access. Pisco, Peru might be a better choice, although Nouakchott, Mauritania is well sited. Broome, Australia might do.
    - pitspotter2 5y ago
DeathArrow 5y ago
The foot of the bridge over river Danube constructed by Apollodorus of Damascus at the request of roman emperor Trajan is still visible in the water.

54 points by NiceWayToDoIT 5y ago

In a second year class I took the prof posed us the question: why don't we do this today? Why is this not part of an ASTM standard? He ended up saying it's too tough to get a hold of proper pozzlanic ash, but I suspect its more a "this is the way we've always done it" difficulty. Does anyone know more to the story?

leroman 5y ago
Maybe industries “planned obsolescence” practice?
- 14 5y ago
  But surely some company would see it as an advantage over competitors and sell it if it was easily accessible. But we don’t see that so there has to be more to it. Maybe cost is too high for the average customer?
  - masklinn 5y ago
    > Maybe cost is too high for the average customer? Well yes, and even for the non-average one. Plus the goal is generally to build things which barely stand, a building which can face the vagaries of time for thousands of years would generally be way over-engineered. Countries where pozzolanic ash is readily available do use it but that’s not usually the case. Fly ash is also being explored for that role. An other issue is understanding of the material’s properties over time. Also our modern world makes a lot of concrete.
    - metaphor 5y ago
      > Plus the goal is generally to build things which barely stand... Since when? Design criteria baked into international building code is quite robust; not just naive static load, but wind, snow, seismic activity, fire/flood/termite resistance, etc. are all considered. That's a far stretch from something that can "barely stand".
      - masklinn 5y ago
        > Since when? Since always > Design criteria baked into international building code is quite robust; not just naive static load, but wind, snow, seismic activity, fire/flood/termite resistance, etc. are all considered. That's a far stretch from something that can "barely stand". “Barely stands” in this context is “Barely passes code”, as in “any idiot can build a bridge that stands, it takes an engineer to build a bridge that barely stands”. The more you go over the more money you’re wasting.
  - smt88 5y ago
    > But surely some company would see it as an advantage over competitors and sell it if it was easily accessible. This is not a guarantee. Look at manufacturers of washing machines: every company makes more money by having unreliable machines. There is no financial incentive to build a better product, and it's not easy to even prove you've built a better product.
    - eru 5y ago
      Would that logic suggest that washing machine brands are equally unreliable? If not, why not? Eg Miele benefits from having a reputation of building reliable products. They can and do charge more for that reputation, but also have to live up to it, if they want to keep it.
      - smt88 5y ago
        I've never heard of Miele. If it's a US brand, it is clearly not doing well. If it's a brand in the EU, the laws there were fixed to prevent every brand from selling intentionally defective products[1]. 1. https://uspirg.org/blogs/blog/usp/you%E2%80%99re-not-crazy-your-appliances-were-built-fail-you https://uspirg.org/blogs/blog/usp/you%E2%80%99re-not-crazy-y...
        eru 5y ago
        Miele is a German brand with a long history. You can buy them around the world. https://en.wikipedia.org/wiki/Miele https://en.wikipedia.org/wiki/Miele > Miele (/ˈmiːlə/ MEE-lə; German: [ˈmiːlə]) is a German manufacturer of high-end domestic appliances and commercial equipment, headquartered in Gütersloh, Ostwestfalen-Lippe. The company was founded in 1899 by Carl Miele and Reinhard Zinkann, and it has always been a family-owned and run company.[2] There might be laws that set some minimum standards. But (a) there are still differences between companies' approaches to quality, and (b) Miele is selling around the world also in jurisdictions were EU rules do not apply, but they still deliver on their reputation for quality.
    - lakis 5y ago
      It's not that simple. The consumers do not want washing machines that last forever. Are you sure that you want a washing machine from 1900? It was probably not electric. Aaah, you want an electric one. How about one from the 1920? What do you mean you want intelligent programs, save electricity, be gentle to the clothes and use little water/soap? These are modern improvements of the washing machine. Consumers vote with their money. They stop buying old washing machines because they don't have the features that they want. So companies stop making old washing machines and make new ones with more features.
  - GhettoComputers 5y ago
    Brother printers are low cost, cheap replacing the ink/toner and make good drivers. I definitely buy them only.
- jacquesm 5y ago
  I think designing your buildings for more than a few hundred year counts as 'excessive' and more than 250 years should not allow for being disqualified under 'planned obsolescence'.
- smt88 5y ago
  No. An industry does not make a plan 50+ years in advance to get more business. They do, however, save on costs by delivering products that don't last as long because their customers also don't (as a general rule) care about 50+ year time horizons.
xyzzyz 5y ago
Concrete is typically made with local materials, because shipping them is rather expensive. Maybe that’s one reason?
- masklinn 5y ago
  > Concrete is typically made with local materials Not really, especially jot for large contructions. Not everybody has a few thousand to million tons of sands of the right composition in their backyard, and cement comes from a factory.
  - xyzzyz 5y ago
    Yes, and these factories are many, and are not concentrated in one place, because shipping cement is expensive. It’s the same with aggregate: not everyone has sand in their backyard, but there typically is good amount of suitable sand within a few dozen miles.
    - eru 5y ago
      It's even more interesting that than! There's actually plenty of drama around sand for concrete. There's talks about 'sand mafias' in India. And Malaysia has banned exporting sand to Singapore. See eg https://www.bbc.com/future/article/20191108-why-the-world-is-running-out-of-sand https://www.bbc.com/future/article/20191108-why-the-world-is...
      - jacquesm 5y ago
        Similar stuff has happened in Germany, in fairly recent times. You could make your own cement, no problem. But good luck trying to unload it anywhere in Germany without paying a fee to certain individuals.
        eru 5y ago
        Interesting. Do you have any links with background information? In German is fine.
eru 5y ago
First, we only see the part of Roman architecture that lasted. There's an observer bias. The Romans also made plenty of ephemeral stuff, just like we are making plenty of ephemeral stuff. See also https://www.youtube.com/watch?v=qL0BB2PRY7k https://www.youtube.com/watch?v=qL0BB2PRY7k Second, there's more to engineering than making stuff last long. There are different trade-offs. Cost being one of them, but also different material properties. Eg re-inforced concrete is awesome for lots and lots of applications that the Romans couldn't even have dreamed of. Alas, it's not economical to make re-inforced concrete that lasts forever. (Not even sure if it's physically possible.)
- hef19898 5y ago
  Trade offs should be covered a lot more during engineering studies. I know that during my time at university, as an industrial engineer destined to work at the interface engineering and economics, that aspect wasn't covered nearly as extensive as it should have. The other question that usually get's ignored is maintenance. The Roman stuff we see lasted millennia without maintenance, we on the other hand can maintain the stuff we want to last a long time. That we don't do it, e.g. infrastructure with the particularly bad maintained bridges in Germany, is not the materials fault, or the original designs fault.
  - markvdb 5y ago
    > we on the other hand can maintain the stuff we want to last a long time. That we don't do it, e.g. infrastructure with the particularly bad maintained bridges in Germany, is not the materials fault, or the original designs fault. I have to respectfully disagree on this one. Humans in general have become spectacularly bad at maintaining physical infrastructure across longer timespans. Technological advances have enabled a cheap/fast/overbuild culture. This very much includes the design phase. Look at the evolution of design. The large majority of our infrastructure, depending on the spot on our earth, largely dates from the last 200 to 50 years. Look at infrastructure predating that. Look at evolution. The bond with local communities depending on the infra? You'll inevitably find it cut. You'll find more bloat in the design. You'll find less local involvement. To some extent, this is progress. Unfortunately, this has an impact on maintainability. Looking at your example of German bridges. I'll make it even more tangible and look at the Eifel region with so much of its infra recently destroyed by flooding. How do we get excellently maintained bridges, when we know this is very much against human nature? This means questions like: - Does this bridge really need to be (re)built? To this specification? In this place? - How much does this bridge benefit the local community where it is built? Can we think of ways to increase that? - How much of this bridge absolutely needs to be built out of reinforced concrete? - Wouldn't it make sense to build some infra in now very flood-prone areas out of less durable but cheaper, more quickly replaced materials like wood? - Can we bring the design closer to the layman? Can we for example design a bridge so that it will visually degrade in step with safety degradation? - ...
adgjlsfhk1 5y ago
A lot of the answer is that the types of structures you can build with concrete that isn't rebar reinforced is fairly limiting. You're pretty much stuck with arch bridges, dams, and domed buildings. Unfortunately, arch bridges don't scale that well (they take concrete proportional to length cubed), and people like buildings in shapes other than domes. As a result, you often have to have designs that hold together partially under tension, and the cost is it won't stay up for 2000 years (if you use rebar which rusts). That said, in the past few decades there has started to be experiments with fiber reinforced concrete. This has the significant advantage of not corroding, but costs a good bit more than traditional rebar. That said, it might be the future for buildings where long life is desired.
- rightbyte 5y ago
  > Unfortunately, arch bridges don't scale that well (they take concrete proportional to length cubed), Only of you go for one arch right?
  - adgjlsfhk1 5y ago
    Multiple arches helps in some cases, but gets really expensive if you have to bridge a deep gap (especially over water where de-watering is needed) The massive advantage of a suspension bridge is that you get a really big span without anything in the middle.
OneTimePetes 5y ago
Because buildings change constantly.. notice how in the examples, you have building for which this requirement must not be fullfilled. Public show-off buildings, statues, temples and harbour walls, they do not change with every generation. Now if you want to change it constantly, if a building is for living, durability is actually not that much of a value.
Animats 5y ago
There is an ASTM standard: "ASTM C618 Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete (AASHTO M 295)."[1] Fly ash, like volcanic ash, is a pozzlanic ash. Both work in concrete. Fly ash is pulled out of the exhaust from a coal-fired power plant using electrostatic precipitators. Just like electrostatic air cleaners, but huge, they pull particles out of gases. So fly ash is cheap if there's a coal-fired power plant nearby. Convenient when there is no volcano handy. There are downsides. The concrete takes longer to cure, which can hold up the next stage of construction. Curing in cold weather is difficult. The Romans didn't have that problem in their Mediterranean climate. Concrete curing requires some air in the mix, and fly ash, for some reason, tends to entrain less air than Portland cement.[2] [1] https://www.cement.org/docs/default-source/fc_concrete_technology/is548-optimizing-the-use-of-fly-ash-concrete.pdf https://www.cement.org/docs/default-source/fc_concrete_techn... [2] https://www.fhwa.dot.gov/PAVEMENT/recycling/fach03.cfm https://www.fhwa.dot.gov/PAVEMENT/recycling/fach03.cfm
simonh 5y ago
>but I suspect its more a "this is the way we've always done it" difficulty. Is the construction industry really known for resisting the adoption of new materials like that?
- adgjlsfhk1 5y ago
  Yeah. incorporating unknown materials into million dollar projects is a really good way to lose millions of dollars. New materials can get added, but especially for big projects there is a long delay between tech invention and widespread use (think decades).
jfletch25 5y ago
It depends on what you're building. Keep in mind that one way for politicians in office to control the number of jobs and money flowing through the economy is doing road work and other public projects.

nindalf 5y ago

I must be missing something. I’ve never used scihub before, and I can’t find the link to read the paper. All I see on this link is the name of the paper and the authors.

toiletfuneral 5y ago
You’re still gonna hate this, but try it in landscape.
- nindalf 5y ago
  Thanks for the tip!
gigglesupstairs 5y ago
Yeah, same. Came in comments to look for alternative link but none so far.
- ggm 5y ago
  Right hand panel for me was a clickable download of the pdf.
solohan 5y ago
This looks like the journal page: https://pubs.geoscienceworld.org/msa/ammin/article/102/7/1435/353606/Phillipsite-and-Al-tobermorite-mineral-cements https://pubs.geoscienceworld.org/msa/ammin/article/102/7/143... Also has a link to download the PDF for free.
zeisss 5y ago
There is a save button right under the sci hub logo next to a Google scholar link. Opened the PDF for me on Android chrome.

deputy 5y ago

cpach edited the year from <none> to 2017 New title: Why Ancient Roman Concrete Outlasts Our Own (2017)

ncmncm 5y ago

I am becoming partial to the ancient Egyptian concrete, that they might have used to mold the pyramid blocks in situ. It takes just limestone crumble, clay (which was already in their limestone), natron, and water. It is a fair bet the precursors to the Inka who built with the really big blocks had that, or a similar trick. Local observers report the big blocks do not show embedded marine shells at the surface, unlike native limestone. (I have not had opportunity to verify this.)

pitspotter2 5y ago
And while we're in the Sahara Desert with abundant sunshine, sand and carbon dioxide, let's build a silicon carbide brick factory. Sunlight to provide electrical power and, via focussed mirrors, heat. Sand to supply the silicon. Carbon from carbon dioxide to be extracted from the air at $100 per tonne (well, eventually). Silicon carbide bricks, emerging gloriously from their tungsten moulds, would possess supreme corrosion resistance and almost double the crushing strength of engineering bricks. High thermal conductivity should reduce cracking and spalling, further increasing lifetime. A short railway journey to the nearest port and water desalination plant whence they can be distributed throughout the world. We'll beat the Romans! Our public buildings will last for millennia!
- ncmncm 5y ago
  It will take a very long time to beat the Romans, and more than twice that long to beat the Egyptians. Corundum bricks would suffice. The Egyptians knew a way to cut corundum like butter; the method apparently was lost before the pyramids were built. Solar panels have proven quite a lot cheaper than mirror-concentrated solar heat as a source of electrical power. Concentrated solar has not really been tried as a source of direct industrial heat, where it might yet excel. But choosing the bit of Sahara to site in has proven harder than expected. To make building materials economically useful, the site needs immediate sea access. Pisco, Peru might be a better choice, although Nouakchott, Mauritania is well sited. Broome, Australia might do.
  - pitspotter2 5y ago

DeathArrow 5y ago

The foot of the bridge over river Danube constructed by Apollodorus of Damascus at the request of roman emperor Trajan is still visible in the water.