Pedant: Cement != Concrete. Cement is one component of concrete. Concrete is composed of water, aggregate, and cement.
The video linked to by Gates' blog says[0] "The most important material in terms of sheer mass in our civilization is cement made into concrete" "The chinese poured into their buildings and roads [...] as much concrete in just 3 years as United States in 1 century".
"In modern times, researchers have experimented with the addition of other materials to create concrete with improved properties, such as higher strength, electrical conductivity, or resistance to damages through spillage."[1]
There's more available[2] to concrete these days than what the US infrastructure used up to 2000[3]. Not that 3 years consumption > 100 years consumption isn't impressive, but:
1) not only are we not comparing the same period
2) it's not clear we're comparing the same material
I often hear cement and concrete used interchangeably, but had the difference drilled into me when I worked (doing computer work) in the industry briefly. For that reason (cement != concrete) and potential advancements in concrete (maybe there are new composites that let us use a fraction of what used to be necessary?) it's not entirely clear what the numbers mean, outside of "China is growing fast".
Anybody that does not understand the difference between cement and concrete is going to be in for a surprise when they mix up a batch of dark gray goop and try to use it for something in construction.
The shrinking alone will cause some interesting effects.
There are a lot of lay-man misconceptions about concrete, one of the more persistent ones is that concrete needs to 'dry'. It doesn't, it needs to cure, it's a chemical reaction that gives concrete its strength, not something going into solution to allow pouring that then dries and solidifies.
Concrete is very interesting material, its history is fascinating and the materials science behind it as well.
Such a simple thing in principle, so incredibly complex. Just like glass another one of those materials with vast depth.
> Concrete is very interesting material, its history is fascinating and the materials science behind it as well.
It's one of those deceptively 'unsexy' materials too from an outsider's perspective: think of steel and someone may think of, what, swords? watches? but think of concrete and someone thinks of brutalist architecture and urban decay. But there's no reason why concrete is any less fascinating and complex than steel.
What I suppose I'm saying is that it has a PR problem, and I'm glad people like yourself are leaving comments like that to help solve it :)
Maybe it's not entirely a PR problem. Concrete is what it is. Its not very sexy to work with. In fact it's a mess and it can be back breaking. You need to make a mould for it or it will get out of hand quickly and in some situations it's not so easy to make a mould so you have to make do.
In fact having recently had to deal with both concrete and JavaScript one reminds me of the other. With js, instead of a mould you need to write tests for absolutely everything or it will start to break down (I wont push the analogy, just saying that it reminds me of concrete)
Now timber is different because it has some inherent structure built in. Much less frustrating and still quite flexible.
My neighbor when I was in grad school did her PhD on concrete. Even after being around for, what, a couple of thousand years, there's still a lot to learn. She basically went to work every day and destroyed concrete (and, of course, spent a lot of time studying the measurements to identify failure modes and causes).
The consequences of getting concrete wrong can range from expensive to devastating.
I believe the Pantheon dome was, not sure about the Parthenon though. But it's definitely very old. A lot older than some people realise I think. But yes, not disagreeing that it can be beautiful. I've seen many beautiful concrete sculptures, but I don't think it's the first thing that springs to mind for many.
The replica in Nashville, TN has concrete in its construction. The original, I believe, is made of marble. (but I'm less certain. I've never seen the real one, sadly.)
You are thinking of the Pantheon. It is a temple in Rome built in the first century, and it has a dome made of concrete. (The Parthenon on the other hand is a temple in the Acropolis in Athens, but not related to concrete)
The video linked to by Gates' blog says[0] "The most important material in terms of sheer mass in our civilization is cement made into concrete" "The chinese poured into their buildings and roads [...] as much concrete in just 3 years as United States in 1 century".
"In modern times, researchers have experimented with the addition of other materials to create concrete with improved properties, such as higher strength, electrical conductivity, or resistance to damages through spillage."[1]
There's more available[2] to concrete these days than what the US infrastructure used up to 2000[3]. Not that 3 years consumption > 100 years consumption isn't impressive, but:
1) not only are we not comparing the same period
2) it's not clear we're comparing the same material
I often hear cement and concrete used interchangeably, but had the difference drilled into me when I worked (doing computer work) in the industry briefly. For that reason (cement != concrete) and potential advancements in concrete (maybe there are new composites that let us use a fraction of what used to be necessary?) it's not entirely clear what the numbers mean, outside of "China is growing fast".
[0] https://www.youtube.com/watch?v=xi7O9pmM_A0&feature=youtu.be...
[1] http://en.wikipedia.org/wiki/Concrete#Modern_additives
[2] http://www.columbiatribune.com/editorial_archive/pollution-e...
[3] https://img.washingtonpost.com/blogs/wonkblog/files/2015/03/...