There is class A concrete = 90 minutes it has to be all poured
class AA concrete = 90 minutes
Minor Structure conc. = 60 minutes
Type B concrete = 45 minutes
there are admixtures to concrete that may retard setting times or shortening that time... different contracts may call for different specs...
There are probably 15 or so types of concrete that we use but most have a rejection time of 90 minutes....