Cement: key to infrastructure growth

Since no modern construction activity can take place without the use of cement in one form or another, it follows that the cement industry forms a vital part of infrastructure development. Not surprisingly, India, one of the world's fastest-growing economies, is the world's second largest producer of cement after China - and ahead of the United States.

In the most general sense of the word, cement is a binder, a substance which sets and hardens independently, and can bind other materials together. Cement used in construction is characterised as hydraulic or non-hydraulic. Hydraulic cements (eg portland cement) harden because of hydrating chemical reactions that occur independently of the admixture's water content; they can harden even underwater or when constantly exposed to wet weather.

A chemical reaction results when the anhydrous cement powder is mixed with water. This process produces hydrates that are not water-soluble.

On the other hand, non-hydraulic cements (eg lime and gypsum plaster) must be kept dry in order to gain strength.

The most important use of cement is in the production of mortar and concrete - the bonding of natural or artificial aggregates to form a strong building material which is durable in the face of normal environmental effects. This requires the use of hydraulic or portland cement; thus this is the most common type of cement produced in the world, and especially in India.

For the past 18 years, China consistently has produced more cement than any other country in the world. However, China's cement exports peaked in 1994 with 11 million tonnes shipped out, and has been in steady decline ever since. Only 5.18 million tonnes were exported out of China in 2002. Chinese cement is perceived to be pricing itself out of the market, as countries like Thailand sell the same for a much lower price.