31–40 of 69 posts
Earlier quoted context omitted.
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.
Interesting. Do you have any links with background information? In German is fine.
New title: Why Ancient Roman Concrete Outlasts Our Own (2017)
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?
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 par…
Only of you go for one arch right?
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.
Earlier quoted context omitted.
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 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 con…
Not to mention that concrete steel reinforcement is the main reason it doesn't last due to water eventually making its way and the rust taking expansion thus cracking the concrete.
Earlier quoted context omitted.
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 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 con…
Are you essentially saying that you don't think there are important material and chemical differences between Roman and modern concrete that might be responsible for orders-of-magnitude differences in durability, aside from the absence of rebar, and that it's basically a matter of building so many bridges, harbours, and aqueducts that some of them end up lasting for thousands of years despite being immersed in runnin…
Basically survivorship bias
Earlier quoted context omitted.
Not to mention that concrete steel reinforcement is the main reason it doesn't last due to water eventually making its way and the rust taking expansion thus cracking the concrete.
Interesting... we’re maybe a century or two into heavy use of reinforced concrete. Does it mean that eg the iconic buildings of Manhattan will eventually need knocking down and rebuilding?
Earlier quoted context omitted.
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 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 con…
Not to mention that concrete steel reinforcement is the main reason it doesn't last due to water eventually making its way and the rust taking expansion thus cracking the concrete.
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?
Now if you want to change it constantly, if a building is for living, durability is actually not that much of a value.