Quick posting.
Concrete is a special chemical mix of gravel, sand, water and cement. Get the mix right and this material becomes incredibly strong but brittle. To combat this brittleness add in some strong steel rods and this gives something for the concrete to bond around.
Chemically all the ingredients slowly react with each other and glue together. Over hours the concrete becomes hard enough to walk upon, over weeks it starts to reach its full strength. After a month the concrete is about 85 percent and slowly cures for the next fifty years ! ! !
After 50 years the concrete slow starts to debond; remember humans live 100 years, so the versatility of concrete is it only has to used once in a lifetime generally. But after one hundred years concrete is almost worthless functionally.
What a role and job concrete performs for that 100 years : )
So all these dams we build 75 years ago are kind of fucked.
If your think about it it is all F***ed . . .
Steel rusts or corrodes and concrete loses its bonded integrity over about 100 years. Thus railroads, overpasses, freeways, skyscrapers street lamps, power-lines and generators . . . Almost everything is made using steel or concrete.
A simple search will show how structurally unstable thousands of America dams and dikes that protect sea walls, ports, airports, power-stations, bridges. Please take a look at the lengths they go to to keep the Empire State Building functioning ...
It is like building a house; the upfront costs are huge, then there is virtually no maintenance costs. But slowly upkeep costs become so huge it is more efficient to rip the house down and build a brand new home there. America has had the benefit of low maintenance costs for many decades now the repair bills are just going to get larger and more complex ! ! !
Sorry but someone has to pay for all this upkeep; apologies : )
/ hugz ; )