Jagvir Goyal

November, 2006

OVER the last few years, the world has seen a remarkable development in cement production. Earlier, there used to be just cement in name of cement. Then industrial wastes were put to use and pozzolana cements were developed. Then, use-specific cements such as low heat portland, high strength portland, blast furnace slag cement, rapid hardening portland, high alumina cement, super sulphate cement and many other varieties were developed.

Discovery of better quality limestone further led to various grades of Ordinary Portland Cement. Now these grades have become so popular that there are numerous queries from the layman asking which grade he should use for various components of his building.

All cement plants now use dry process for manufacture of cement. This is a better process and power consumption is lesser than in wet process. Availability of dry flyash from the thermal plants has attracted the cement manufacturers to produce more quantity of Portland Pozzolana Cement (PPC) and curtail Ordinary Portland Cement (OPC) production. Manufacture of PPC is much cheaper to that of OPC as substantial component of PPC is flyash which is freely available from the thermal plants while the market rate of OPC and PPC is the same.

Some manufacturers have altogether stopped production of OPC and are concentrating on PPC only. PPC being produced by the manufacturers is giving good strength, even better than OPC in some cases. Therefore the general consumer has no complaint if PPC is produced and made available.

Less heat of hydration in PPC is also enhancing its use in mass concreting and in water retaining structures. Less shrinkage in it is helping in reducing the commonly noticed hair cracks in roof slabs. Thus PPC is becoming popular day by day.

However, there are no grades specified by Bureau of Indian Standards for PPC. It has only one grade, manufactured as per IS 1489 and considered equal to OPC 33 Grade howsoever high strength it may be giving.

This deficiency is holding the engineers and users from economising on cement usage. In OPC, there are three grades, 33 Grade as per IS 269, 43 Grade as per IS 8112 and 53 Grade as per IS 12269.