Not a bridge, but there is an urban legend about the ship ** The Great Eastern** (Snopes seems undecided) having had workers sealed up in the hull by mistake.
One thing I’ve wondered for a long time. How do you start building a dam? How do you keep the water away while you’re building?
In Iona and Peter Opies book of Nursery Rhymes, they mention the superstition in their discussion of “London Bridge Is Falling Down,” speculating that “We’ll set a man to watch all night” might refer to this. According to the Opies, a medieval bridge in England was found to have the skeleton of a child bricked up inside.
With great difficulty approaching, if not equalling, that of the dam construction itself. The high points:
Decide where to put dam.
Dig huge tunnels through surrounding rock on both banks to re-route river.
Build cofferdams (temporary dams) upstream and downstream of dam site to keep any remaining river flow out.
Build dam.
Remove cofferdams.
Close tunnels.
Watch Lake Mead appear.
Diversion.
The curing of concrete IS an exothermic process. The chemical reaction gives off heat, the heat is the result of curing.
However… as curing is a chemical reaction, it is sped up by higher temps, just like most chemical reactions. In a huge monolithic pour, the heat generated in the center of the pour causes the center to cure faster than the outside. This differential curing will cause lots of nasty stresses in the concrete leading to the problems mentioned by others. Removing the heat slows the chemical reaction of curing. If I remember properly, for a given concrete mix, too rapid curing also makes weaker concrete because all the cement in the concrete is reacted before each individual crystal can grow very long. More but shorter crystals are weaker.
In cold weather the isulating blankets are used to retain the heat generated by the concrete, increasing the reaction rate, and allowing it to cure in a reasonable amount of time.