Different types of Cement

In the past, continuous efforts were made to produce different kinds of cement, suitable for different situations by changing oxide composition and fineness of grinding. With the extensive use of cement, for widely varying conditions, the types of cement that could be only by varying the relative proportions of the oxide compositions, were not found to be sufficient. 

The use of additives, changing chemical composition, and use of different raw materials have resulted in the availability of many types of cement to cater to the need of the construction industries for specific purposes. These cements are classified as Portland cements and non-Portland cements. The distinction is mainly based on the methods of manufacture. The Portland and Non-Portland cements generally used as per Indian Standards are listed below: 

• Ordinary Portland Cement.
• Portland Pozzolana Cement. 
• Portland Slag Cement. 
• High Alumina Cement 
• Rapid Hardening Cement. 
• Oil-Well Cement. 
• Sulphate Resisting Cement  
• Low Heat Portland Cement. 
• White Cement. 
• Super Sulphated Cement. 
• Hydrophobic Cement. 
• Masonry Cement. 
• Composite Cement. 

Ordinary Portland Cement 

Ordinary Portland Cement(OPC) is by far the most important type of cement. The details of this specifications is given in IS 269:2015. It is available in three grades i.e., OPC-33, OPC-43 & OPC-53 depending upon the strength of the cement at 28 days. If the 28 days strength is not less than 33N/mm², it is called 33 grade cement, if the strength is not less than 43N/mm², it is called 43 grade cement, and if the strength is not less than 53N/mm², it is called 53 grade cement. But the actual strength obtained by these cements at the factory are much higher than the BIS specifications. 

Portland Pozzolana Cement 

Portland Pozzolana Cement (PPC) is manufactured by the intergrinding of OPC clinker with 15-35% pozzolana and fly ash of calcined clay. It's details are given in IS 1489-2015. The fly ash shall confirm to IS 3812-2013 and calcined clay to IS 1344-1981 if intermixing route is adopted for manufacture of Portland Pozzolana Cement. 

Portland Pozzolana Cement produces less heat of heat of hydration and offers greater resistance to the essence of aggressive water than Ordinary Portland Cement. Moreover, it reduces the leaching of calcium hydroxide when used in hydraulic structures. It is particularly useful in marine and hydraulic construction and other mass concrete constructions. Technically, PPC has considerable advantages over OPC when made by using optimum percentage of right quality fly ash. 

Portland Slag Cement (PSC) 

Portland Slag Cement is obtained by mixing Portland cement clinker, gypsum and granulated blast furnace slag in suitable proportions and grinding mixture to get a through and intimate mixture between the constituents. It may also be manufactured by separately grinding Portland cement clinker, gypsum and ground granulated blast furnace slag and later mixing them intimately. The resultant product is a cement which has physical properties similar to those of Ordinary Portland Cement. In addition, it has low heat of hydration and is relatively better resistant to chlorides, soil and water containing excessive amount of sulphates or alkali metals, alumina and iron. 

High Alumina Cement 

High Alumina Cement is obtained by fusing or sintering a mixture, in suitable proportions of alumina and calcareous materials and grinding the resultant product to a fine powder. The raw materials used for the manufacture of high alumina cement are lime and bauxite. These raw materials with the required proportion of coke were charged into the furnace. The furnace is fired with pulverized coal or oil with a hot air blast. The fusion takes place at a temperature of about 1550-1600°C. The cement is maintained in a liquid state in the furnace. 

The pigs of fused cement, after cooling are crushed and then ground with tube mills to a fineness of about 3000 sq. cm/gm. 

Rapid Hardening Cement 

This cement is similar to OPC. As the name indicates it develops strength rapidly and as such it may be more appropriate to call it as high early strength cement. It is pointed out that rapid hardening cement which develops higher rate rate of development of strength is not same as quick setting cement which sets quickly. Rapid hardening cement develops at the age of three days, the same strength as that is expected from Ordinary Portland Cement at seven days. 

The use of rapid hardening cement is recommended in the following situations: 

• In pre-fabricated concrete construction.  
• When framework is required to be removed early for re-use elsewhere. 
• Road repair works. 
• In cold weather concrete where the rapid rate of development of strength reduces the vulnerability of concrete to the frost damage. 

Oil-Well Cement 

Oil-wells are drilled through stratified sedimentary rocks through a great depth in search of oil. Cement slurry is used to seal off any other fissures or cavities in the sedimentary rock layer. The cement slurry has to be pumped into position, at considerable depth where the prevailing temperature may be up-to 175°C. The pressure required to go may be up-to 1300 kg/cm. The slurry should remain sufficiently mobile to be able to flow under these conditions for periods up-to several hours and then hardened fairly rapidly. It may also have to resist corrosive conditions from Sulphur gases or waters containing dissolved salts. The type of cement suitable for the above condition is known as Oil-well cement. 

Sulphate Resisting Cement 

Ordinary Portland Cement is susceptible to the attack of sulphates, in particular to the action of magnesium sulphate. In many of its physical properties, sulphate resisting cement is similar to Ordinary Portland Cement. The use of sulphate resisting cement is recommended under the following conditions: 

• Concrete to be used in marine conditions. 
• Concrete to be used in foundation and basement, where soil is infested with sulphates. 
• Concrete used for fabrication of pipes which are likely to be buried in marshy region or sulphate bearing soils. 
• Concrete to be used in the construction of sewage treatment works. 

Low Heat Cement 

Cement having this property was developed in U.S.A. during 1930 for use in mass concrete construction, such as dams, where temperature rise by the heat of hydration can become excessively large. A low-heat evolution is achieved by reducing the contents of tri-calcium silicate and tri-calcium aluminate which are the compounds evolving the max. heat of hydration. Thus by increasing di-calcium silicate, a reduction of temperature will retard the chemical action of hardening and restrict the rate of evolution of heat.  

The specific surface of low heat cement as found out by air-permeability method is not less than 3200 sq. cm/gm. The 7 days strength of low heat cement is not less than 16 MPa in contrast to 22 MPa. Other properties such as soundness and setting time are same as Ordinary Portland Cement. 

White Cement 

The process of manufacture of White Portland Cement is nearly same as OPC. As the raw materials, particularly the kind of limestone required for manufacturing white cement is available around Jodhpur, Rajasthan. Two famous brands of white cement namely Birla White and J.K. White Cements are manufactured near Jodhpur. 

The properties of white cement is nearly same as OPC. Generally white cement is ground finer than grey cement. Whiteness of white cement as measured by ISI scale shall not be less than 70%. The strength of white cement is much higher than what stated in IS 8042:1989. 

Super Sulphated Cement 

Super sulphated cement is manufactured by grinding together a mixture of 80-85 per cent granulated slag, 10-15 per cent hard burnt gypsum, and about 5% Portland cement clinker. This cement is rather more sensitive to deterioration during storage than Portland cement as it has high sulphate resistance. Because of this property this cement is particularly recommended for use in foundation, where chemically aggressive conditions exist. 

Like high alumina cement it combines with more water on hydration than Portland cement. SSC is found useful in variety of aggressive conditions. It is mainly used for following applications: 

    Marine and coastal works.

    Mass concrete jobs. 

    Aggressive conditions. 

    RCC pipes in ground water. 

    Chemical works where concrete is exposed to high concentrations of sulphates.  

Hydrophobic Cement 

The properties of hydrophobic cement is same as that of ordinary Cement cement except that it entrains a small quantity of air bubbles. The hydrophobic cement is made actually from Ordinary Portland Cement clinker. After grinding, the cement particle is sprayed in one direction and film forming materials such as oleic acid, stearic acid, pentachlorophenol, calcium oleate etc. are sprayed from another direction such that every particle of cement is coated with a very fine film of this water repellant material which protects them from the bad effect of moisture during storage and transportation. The cost of this cement is nominally higher than OPC. 

Masonry Cement 

Masonry cement is obtained by intimately grinding a mixture of Portland cement clinker and gypsum with pozzolanic materials in suitable proportions. Masonry cement is mainly used for masonry mortars, stone and concrete block as well as for rendering and plastering work. Because of its property of producing a smooth, plastic, cohesive and strong, masonry cement is considered superior to lime cement mortar.  

At present masonry cement is unavailable at market due to the fear that it may be used in the structural work. The use of masonry cement will improve the quality of masonry mortars and help in saving the precious mineral resources and utilize other industrial waste materials. Masonry cement is not used for structural concrete, flooring works, foundation works or for prestressed concrete works. 

Composite Cement 

In composite cement, the use of two supplementary cementitious materials, viz, fly ash and GGBS (Ground Granulated Blast Slag) is permitted simultaneously by replacing OPC clinker in certain proportions. The code of composite cement allows following material compositions: 

    Portland Cement clinker/Cement m - 35% - 65% 

    Fly ash                                              - 15% - 35% 

    GGBS                                               - 20% - 50% 

The chemical gypsum may be added as required to meet the performance of cement. 

Composite cement can be used for any application where PPC/PSC are used. It is general purpose cement. The Composite Cement is not readily available in market now-a-days and its awareness is still very low among consumers and trade channels.