Yes it can. It actually cures harder under water then above it.
True.
what is the purpose of reinforcing bars in a spread footing
no, not normally. It will cure more slowly and how much slower depends on how much dirt is piled on it.
all things that need to dry are based on 72 degrees concrete needs 30 days to fully cure.
Concrete never fully cures, but a non-quicksetting concrete should be firm on the surface in about 4-8 hours, and usable for foot traffic or post setting in 36 hours.
Not much you can do if the concrete is already hard, but if you are talking about plastic concrete (still in its wet state), there's lots you can do to hurt/weaken it:If you had the wrong chemical admixturesAny addition of water at the job site will weaken the concreteFailture to properly cure the concrete
If you hit it hard enough.
28 days is the usual cure time for structural concrete. For street pavements and driveways made with 6-Sack concrete, 3 days of cure will support a car, but 7 to 10 days is required for it to support trucks. All concrete continues to cure forever, as long as moisture is present.
When they invented concrete. Roman concrete set underwater and was used to build harbours.
about 1/6 of that on land
what is the purpose of reinforcing bars in a spread footing
Yes and many so ask the supplier of your concrete.
If it's applied to a dry surface it will continue to 'cure' underwater.
Yes.
no, not normally. It will cure more slowly and how much slower depends on how much dirt is piled on it.
all things that need to dry are based on 72 degrees concrete needs 30 days to fully cure.
To build underwater foundations for the docks of some ports the Romans used concrete.
At least 3 days