For strength and durability, precast concrete members require adequate curing. They usually are given some type of accelerated curing for economic reuse of forms and casting space. At atmospheric pressure, curing temperatures may be held between 125 and 185F for 12 to 72 h. Under pressure, autoclave temperatures above 325F for 5 to 36 h are applied for fast curing. Casting temperatures, however, should not exceed 90F. See Fig. 9.5.
(Standard Practice for Curing Concrete, ACI 308; Accelerated Curing of Concrete at Atmospheric Pressure State of the Art, ACI 517.2R, American Concrete Institute.)
