Parasakti opc cement that is prepared by grinding Portland Cement Clinker and suitable proportions of Gypsum is called as Ordinary Portland cement. Small additions of performance improvers such as Fly ash, Blast furnace slag etc are permitted. 53 grade Ordinary Portland Cement is high strength OPC and provides numerous advantages where ever concrete for special high strength applications is required. The rate of development of strength is faster than 43 grade OPC. 53 Grade OPC is different from Rapid Hardening Portland Cement and their purposes of usage are different.