PORTLAND POZZOLANA CEMENT (PPC)
The Star Portland Pozzolana Cement is a kind of Blended Cement which is produced by either inter-grinding 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 and aluminous material which 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 cementitious 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 cementitious properties with Highest 1 day strength of around 16 Mpa. The pozzolanic materials commonly used are:
- Volcanic Ash
- Calcined clay
- Fly Ash
- Silica Fumes
The Indian Standards for Star Portland Pozzolana Cement have been issued in two parts based on the type of pozzolanic materials to be used in manufacturing of Portland Pozzolana Cement as given below:
- IS 1489 (Part 1) 1991, Portland Pozzolana Cement specification (fly ash based)
- IS 1489 (Part 2), Portland Pozzolana Cement specification (Calcined clay based)
- The quality of flyash or calcined clay to be used in manufacturing of PPC is also specified by BIS in the following standards:
- IS 3812 1981 – specification for flyash as pozzolana and admixture
- IS 1344 1981 – specification for calcined clay pozzolana
The Star Portland Pozzolana Cement is ideally suited for the following construction.
- Hydraulic structures
- Mass concreting works
- Masonry mortars and plastering
- Under aggressive conditions.
- All other application where OPC is used.