- Ordinary Portland Cement: It derives its name from the name of a stone (Portland) which resembles its colour. It is the most commonly used building material in mortar for masonry work, in mortar for plastering and pointing and as a binding medium in cement concrete, reinforced cement concrete and prestressed cement concrete construction.
- Rapid hardening cement: The rapid hardening property is imparted to the cement primarily by burning at a higher temperature and secondly by finer grinding of the particles. The initial and final setting time of the cement is the same as ordinary cement, but it attains high strength in the early stages. It is useful in emergency situations as it develops the same strength in 4 days which ordinary cement acquires in 28 days. It is comparatively costlier than Ordinary Portland Cement. The uses and advantages of this cement are:
- It can be used when the construction has to be carried out fast.
- When the formwork of the concrete has to be removed earlier.
- It is light in weight.
- It is not damaged easily.
- The structural members constructed out of this cement can be loaded earlier.
- This cement requires short period of curing.
- It allows higher permissible stresses in the design.
- Low heat cement: It is a type of Portland cement which sets and hardens with the evolution of very low heat of hydration. It contains low percentage of tricalcium aluminate, of about 5 per cent, and higher percentage of dicalcium silicate, of about 45 per cent. This is the ideal cement for construction of dams as it reduces the development of cracks in the structure.Heat of hydration is the heat produced during the chemical action between cement and water. In mass concreting like construction of dams, this heat produced will be high and will affect the stability of the structure. So, there is a necessity to control the amount of heat produced and it is in these situations that the use of this type of cement comes into play.
- Quick setting cement: It is produced by adding a small percentage of aluminium sulphate and by finely grinding the cement. It contains very little or no retarding substances like gypsum. The setting action of the cement starts within 5 minutes after addition of water and it becomes hard in less than 30 minutes. The mixing and placing of concrete should be done in a very short time. This type of cement can be used for construction under water.
- High alumina cement: It is obtained by adding bauxite (Al2O3) of about 55 per cent and lime (CaO) of about 35–45 per cent. The advantages are:
- It is highly resistant to attack by sea water.
- It rapidly hardens.
- It does not expand while setting.
- It can stand very high temperatures.
- It resists the action of frost.
- It cannot be used for massive concrete work.
- It is much costlier.
- Extreme care should be taken to see that it does not come in contact with ordinary cement or lime as it reduces the strength.
- Coloured cement: This cement will produce a surface of desired colour and is manufactured by the addition of a small proportion of some colouring material, generally a mineral pigment to the clinker. The amount of colouring material may vary from 5 to 10 per cent. Chromium oxide gives green colour and cobalt imparts blue colour. Iron oxides in different proportions give brown, red and yellow colour and manganese dioxide produces black and brown colour.
- Expanding cement: This cement is used to neutralize the effect of shrinkage of ordinary concrete. It is produced by adding an expanding medium like sulpho-aluminate and a stabilizing agent to the ordinary cement. It is used for the construction of water-retaining structures and also for repairing damaged concrete surfaces.
- Hydrophobic cement: It contains admixtures which decrease the wetting ability of cement. The admixtures usually used are acidol, naphtenesoap, etc. These substances form a thin film around the cement grains. When water is added to this cement, the absorption films are torn off the surface and they do not in any way prevent the normal hardening of cement. However, in the initial stage the gain of strength is less as the hydrophobic films of cement grains prevent the interaction with water.
- Air entraining cement: Air content of 2–6 per cent is introduced in the cement by grinding air entraining agents with the cement clinker during the manufacture of cement. The addition of air entraining agents introduces large amount of air which results in the formation of voids and increases the workability of concrete. The weight as well as the strength of the concrete is reduced.
- White cement: White cement is manufactured from china clay and white chalk in place of limestone and clay. It is used as a decorative feature for high-quality plasterwork. The white colouring effect is due to the absence of iron oxide. The cement is about four times costlier than Ordinary Portland Cement. It has quick drying properties, high strength and superior aesthetic values. It is used in swimming pools where it replaces the use of glazed tiles with coloured shades, for moulding sculptures and statues, for painting garden furniture and for fixing marbles and glazed tiles.
- Blast furnace slag cement: The iron and steel industry produces large quantities of blast furnace slag as a by-product. The slag is a waste product in the manufacturing of pig iron and it contains the basic elements of cement, namely alumina, lime and silica. The clinkers of cement are ground with 60–65 per cent of the slag. This cement has a slow rate of hardening and less heat of hydration. It is not affected by sea water and, hence, is used for marine structures. Its strength in the early days is less and, hence, requires longer curing period.
DIFFERENT TYPES OF CEMENT AND USES