Currently only 32 per cent of the total cement produced in India is blended cement. The savings can be brought about by effectively utilising otherwise environmentally hazardous materials such as fly ash, blast furnace slag etc.Blended cements, as the name suggests, consist of a mix of fly ash, slag or other pozzolanic material with binding properties and clinker. These materials basically replace clinker to the extent they are added.

High grade cements consist of 95 per cent clinker and 5 per cent gypsum. According to Bureau of Indian Standards, fly ash can be mixed up to 25 per cent while slag can be mixed upto 65 per cent.

Blending of these materials while on one hand ensures that environmentally unfriendly materials(otherwise difficult to dispose off) are productively used and also at the same time results in saving precious limestone reserves which are not expected to last till the 22nd century.

INSWAREB has calculated the quantum of savings that the country can make by effectively utilising fly ash and slag. The country, it says, presently has about 30 million tonnes of cement grade fly ash and 10 million tonnes of blast furnace slag.

If the 40 tonnes of fly ash and slag are used then limestone deposits to the extent of 60 million tonnes amounting to Rs 12 billion can be saved. Energy savings to the tune of 36 trillion kilocalaries would also be possible which would save 10 million tonnes of coal costing another Rs 12 billion.

Clinker production involves substantial emission of carbon-di-oxide, a major source for global warming and for every tonne less of clinker used carbon-di-oxide is emitted less. The savings in carbon-di-oxide can be traded as per the international practise by a developing country with adeveloped country and the prevalent emission trading value is $ 10 per ton. The aggregate value that India can earn by utilising lesser amount of clinker and the resultant trading of emmission savings is Rs 16 billion.

Power consumption is also lower and savings can be as high as 3000 million units which works out to Rs 9 billion.