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"Chemistry might be important" Conc is nearly all about chemistry. You mention curing rather than drying so you surely have some idea about what is going on.

"Chemistry might be important" Conc is nearly all about chemistry. You mention curing rather than drying so you surely have some idea about what is going on. The Romans did not have electron microscopes so could not watch the way the matrix develops around the aggregate etc etc from the get go. To be fair, I fried my first sample in the beam at college by over focussing. They didn't use rebar because they generally built in compression - arches etc. Rebar and pre-stressing enables members to cope much better under tension. A PS beam or slab is a modern marvel and even protects the steel from fire - bonus. Cure times: weather/environment. In hot climes you need to stop the water buggering off the surface and leaving cracked and spalling surfaces before it even cures. It may also over heat (exothermic reaction). Cold - slower curing, too cold - no cure and frozen water (total disaster). Underwater - watch your fines wandering off and going for a smoke behind a reef and your structure collapsing, unless you keep them in place. Concrete curing is not like smoking a joint of meat! A quick or slow cure may be indicated depending on conditions. We have admixtures and all sorts to fiddle with parameters. Then you have things like grading and composing your agg. and other exciting stuff. I could go on at some length - it is really, really complicated. Roman engineers managed to invent an ancient wonder of chemistry and physics that was concrete. Their approach to its use and improvements was obviously rather better than what passed for science and medicine at the time! They do seem to have experimented and gone with what worked best but it was never deliberately developed from first principles. The self healing thing was probably a happy accident. A Roman engineer had some rather different design constraints than a modern Civil. For starters, failure could quite legitimately be blamed on the god's displeasure. "When that bridge was commissioned, we made all the correct sacrifices and anyway, you are holding it wrong, I mean walking on it incorrectly". (sp)

UncleEntity 4y ago
> Roman engineers managed to invent an ancient wonder of chemistry and physics that was concrete. Technically, the ancient Egyptians used concrete in construction long before the Roman engineers were a thing. The difference is they used it for mundane things like wine cellars while the Romans integrated it into their whole architecture system. Once in a while that art history degree comes in handy…
Spooky23 4y ago
I worked on a campus where they were building a building that had to be incredibly stable - they had to coordinate arrivals of like 30 trucks making 4-5 trips a day. Each truck had like 180 seconds to unload. Because of the coordination requirements, they embedded sensors in the structure and adjusted the water for curing and would slow down or speed up the flow of trucks based on how the process went. One of the engineers told me that a thousand years from now, someone would wonder why this slab is here. I’m sure he was mostly kidding, but it seemed believable.
_0w8t 4y ago
In Ancient Rome blaming gods was never an excuse. For example, there an architect or a chief builder had to spent several nights under the bridge after its opening. In general they followed a rule similar to one in ancient Babylon which explicitly required to put the architect to dearth if a building collapse would kill the owner. And if the collapse would kill a son of the owner, then the son of the architect would be put to death. That puts rather different perspective on the quality and longevity.

UncleEntity 4y ago

> Roman engineers managed to invent an ancient wonder of chemistry and physics that was concrete. Technically, the ancient Egyptians used concrete in construction long before the Roman engineers were a thing. The difference is they used it for mundane things like wine cellars while the Romans integrated it into their whole architecture system. Once in a while that art history degree comes in handy…

Spooky23 4y ago

I worked on a campus where they were building a building that had to be incredibly stable - they had to coordinate arrivals of like 30 trucks making 4-5 trips a day. Each truck had like 180 seconds to unload. Because of the coordination requirements, they embedded sensors in the structure and adjusted the water for curing and would slow down or speed up the flow of trucks based on how the process went. One of the engineers told me that a thousand years from now, someone would wonder why this slab is here. I’m sure he was mostly kidding, but it seemed believable.

_0w8t 4y ago

In Ancient Rome blaming gods was never an excuse. For example, there an architect or a chief builder had to spent several nights under the bridge after its opening. In general they followed a rule similar to one in ancient Babylon which explicitly required to put the architect to dearth if a building collapse would kill the owner. And if the collapse would kill a son of the owner, then the son of the architect would be put to death. That puts rather different perspective on the quality and longevity.