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from the Roman-concrete-lasts-2000-years...-why-not-our-roads? dept.
The story of concrete is so ancient that we don't even know when and where it begins. It is a story of discovery, experimentation, and mystery. Emperors and kings became legends for erecting great concrete structures, some of which are still a mystery to engineers today. Many of history's most skilled architects found inspiration in slabs of the gray building material. Common bricklayers advanced the technology, and a con man played a crucial role in the development of concrete recipes.
Today, the world is literally filled with concrete, from roads and sidewalks to bridges and dams. The word itself has become a synonym for something that is real and tangible. Press your handprints into the sidewalk and sign your name to history. This is the story of concrete.
[...] Let's get this out of the way right here: cement and concrete are not the same thing. Cement, a mixture of powdered limestone and clay, is an ingredient in concrete along with water, sand, and gravel.
So ubiquitous and fundamental, that nobody thinks about it. Its inventor is unknown, but that person changed history.
Related: Volcanic Rocks Resembling Roman Concrete Explain Record Uplift in Italian Caldera
Roman Concrete Explained
(Score: 0) by Anonymous Coward on Tuesday October 17 2017, @07:48PM (1 child)
i dunno what the big deal is.
if you can find good stones and are apt at forming stones you can make pretty spectacular stuff.
thus you have to be a mediocre stone artist or a good stone mason.
with concrete it's just liquid stone. the good part is that you can pump it.
however there is still some workmanship required only this time it is (mostly) with wood.
thus you have to be mediocre wood artist or a good carpenter.
in my minds eye, cement is a "glue" and sand and stones/gravel is just "filler" so you
dont' need so much cement powder.
concrete is three (four) things: cement, sand, stone (and water)
As a whole it is as strong as the weakest element.
my guess the stones/gravel are junk.
Another perceived insight is that liquid cement is a precursor to growing your own crystal
akin to buying a pack of seamonkey and adding them to water ...
as with all crystals, a seed is required and i assume that if the stones/gravel added to
cement have crystal inclusion (quartz?) that is helps the cement settle better/stronger?
also let's not forget that concrete needs time to cure, thus it might be beneficial to keep
it from drying out to fast.
there's a (personal) notion that covering/packing fresh concrete with
ALU-SI clay (wet) will let the crystals grow from the outer direction also?
however, kaolin, says wikipedia is "destroyed" once dried ... thus adding to the heap of waste
already containing the wood form-work?
(Score: 0) by Anonymous Coward on Wednesday October 18 2017, @09:09AM
>As a whole it is as strong as the weakest element.
>my guess the stones/gravel are junk.
It's a composite material. My guess is that the inclusions (sand or gravel) tend to inhibit the growth of cracks.