9e53c149__Cement___Pavement_Interactive__ASTM_Types_of_Portland_Cement_2
[0] III [1] High Early Strength [2] 
Used when high early strength is needed. It is has more C3S than Type I cement and has been ground finer to provide a higher surface-to-volume ratio, both of which speed hydration. Strength gain is double that of Type I cement in the first 24 hours.
Portland Cement | Pavement Interactive
2