What is the cure time required for epoxy vs concrete? (In reference to industrial equipment foundation repair)

Concrete takes 28 days to outgas (excess water leaving the foundation), it is critical for moisture to be out of the concrete because epoxy grout does not do well in presence of moisture. For jobs that require rapid turn around there are concretes that can be placed and grouted within 24 hours. Epoxies cure quite a bit faster, dependent on temperature.