Portland Pozzolana Cement (PPC)
Portland Pozzolana Cement is a kind of Blended Cement which is produced by either intergrinding of OPC clinker along with gypsum and pozzolanic materials in certain proportions or grinding the OPC clinker, gypsum and Pozzolanic materials separately and thoroughly blending them in certain proportions.
Pozzolana is a natural or artificial material containing silica in a reactive form. It may be further discussed as siliceous or siliceous and aluminous material which in itself possesses little, or no cementitious properties but will in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperature to form compounds possessing cement properties. It is essential that Pozzolana be in a finely divided state as it is only then that silica can combine with calcium hydroxide (liberated by the hydrating Portland Cement) in the presence of water to form stable calcium silicates which have cement properties. The pozzolanic materials commonly used are:
+ Volcanic ash.
+ Calcined clay.
+ Fly ash.
+ Silica fumes.
Portland Pozzolana Cement is ideally suited for the following construction:
+ Hydraulic structures.
+ Mass concreting works.
+ Marine structures.
+ Masonry mortars and plastering.
+ Under aggressive conditions.
+ All other applications where OPC is used.
+ The compressive strength of PPC as per BIS code at present is equivalent to that of 33 grade OPC.