Types of Cement

The various types of cement available in the market are as follows:-

1. Ordinary Portland Cement (OPC):- Ordinary Portland cement is the most widely used type of cement which is suitable for all general concrete construction. It is most widely produced and used type of cement around the world with annual global production of around 3.8 million cubic meters per year.  This cement is suitable for all type of concrete construction. It  should not  be used  for construction work exposed to sulphates in the soil.

Applications of 33 Grade Ordinary Portland Cement (OPC) :-

·         It is used for normal grade of concrete upto M-20, plastering, flooring, grouting of cable ducts in PSC works etc. The fineness should be between 225 and 280.

Application of 43 Grade Ordinary Portland Cement (OPC) :-

·         It is the most widely used general purpose cement. For concrete grades upto M-30, precast elements.

·         For marine structures but C3A should be between 5 – 8%.

Application of 53 Grade OPC Cement :-

·         For concrete grade higher than M-30, prestressed concrete works, bridge, roads, multi-storied buildings etc.

·         For use in cold weather concreting.

·         For marine structures but C3A should be between 5 – 8%.

2. Portland Pozzolana Cement (PPC):- Portland pozzolana cement is prepared by grinding pozzolanic clinker with Portland cement. It is also produced by adding pozzolana with the addition of gypsum or calcium sulfate or by intimately and uniformly blending portland cement and fine pozzolana.

This cement has high resistance to various chemical attacks on concrete compared with ordinary portland cement and thus it is widely used. It is used in marine structures, sewage works, sewage works and for laying concrete under water such as bridges, piers, dams and mass concrete works etc..

Applications of Portland Pozzolana Cement :-

IS:1489(part-I ) -1991 (using flyash). It gives low heat of hydration and reduces the leaching of calcium hydroxide. This cement should be used only after proper evaluation. This should be tested as per IS:1489 (Pt I) – 1991. It is used for:

·         hydraulic structures-dams, retaining walls

·         Marine structures

·         Mass concrete works- like bridge footings

·         under aggressive conditions

·         Masonry mortar and plastering.

3. Rapid Hardening Cement:- Rapid hardening cement attains high strength in early days it is used in concrete where formworks are removed at an early stage and is similar to ordinary portland cement (OPC). This cement has increased lime content and contains higher c3s content and finer grinding which gives greater strength development than OPC at an early stage.

The strength of rapid hardening cement at the 3 days is similar to 7 days strength of OPC with the same water-cement ratio. Thus, advantage of this cement is that formwork can be removed earlier which increases the rate of construction and decreases cost of construction by saving formwork cost.

Rapid hardening cement is used in prefabricated concrete construction, road works, etc. It should not be used for massive concrete structure.

Applications of Rapid hardening cement :-

The Rapid Hardening Cement is used for repair and rehabilitation works and where speed of construction and early completion is required due to limitations of time, space or other reasons. The cement is to be used in cold weather concreting i.e. temperature < 5oC.

Rapid hardening cement is basically OPC but its fineness is 3250 cm2/g against 2250 cm2/g in case of OPC. The compressive strength after 1 day is 16 N/mm2 and that of 3 days 27 N/mm2.

These days higher grade OPC are available in the country to meet these requirements and therefore, this cement is not being manufactured and marketed on regular basis. The characteristics of this cement can be effectively met by only good quality 53 grade OPC.

4. Quick setting cement:-The difference between the quick setting cement and rapid hardening cement is that quick setting cement sets earlier while rate of gain of strength is similar to Ordinary Portland Cement, while rapid hardening cement gains strength quickly. Formworks in both cases can be removed earlier.

Quick setting cement is used where works is to be completed in very short period and for concreting in static or running water.

5. Low Heat Cement:- Low heat cement is prepared by maintaining the percentage of tricalcium aluminate below 6% by increasing the proportion of C2S. This makes the concrete to produce low heat of hydration and thus is used in mass concrete construction like gravity dams, as the low heat of hydration prevents the cracking of concrete due to heat.

This cement has increased power against sulphates and is less reactive and initial setting time is greater than OPC.

Applications of Low heat portland cement :-

Low Heat Portland Cement is particularly suited for making concrete for dams and many other types of water retaining structures, bridge abutments, massive retaining walls, piers and slabs etc. In mass concreting, there is often considerable rise in temperature because of the heat produced as the cement sets and hardens.

The shrinkage which occurs on subsequent cooling sets up tensile stresses in the concrete, may result in cracking. The use of low heat cement is advantageous since it evolves less heat than OPC. This cement is not available in the market on regular basis and has to be obtained on specific orders.

6. Sulphates Resisting Cement:- Sulfate resisting cement is used to reduce the risk of sulphate attack on concrete and thus is used in construction of foundations where soil has high sulphate content. This cement has reduced contents of C3A and C4AF.

Sulfate resisting cement is used in construction exposed to severe sulphate action by water and soil in places like canals linings, culverts, retaining walls, siphons etc.

Applications of Sulphate Resisting Cement :-

(C3A < 3%) Sulphate Resisting Portland Cement is a type of Portland Cement in which the amount of tricalcium aluminate (C3A) is restricted to lower than 5% and 2C 3A +C4AF lower than 25%. The SRC can be used for structural concrete wherever OPC or PPC or Slag Cement are usable under normal conditions.

The use of SRC is particularly beneficial in such conditions where the concrete is exposed to the risk of deterioration due to sulphate attack, for example, in contact with soils and ground waters containing excessive amounts of sulphates as well as for concrete in sea water or exposed directly to sea coast.

The use of Sulphate Resisting Cement is recommended for following applications:

·         Foundations, piles

·         Basement and underground structures

·         Sewage and water treatment plants

·         Chemical factories

·         Suitable for underground works where Sulphate is present in the Soil and water. Sulphate Resisting Cement is Not Suitable for:

·         Sulphate resisting cement is not suitable where there is danger of chloride attack. This will cause corrosion of rebar.

·         If both Chlorides and Sulphates are present, Ordinary Portland Cement with C3A between 5 & 8 should be used.

7. Blast Furnace Slag Cement:-Blast furnace slag cement is obtained by grinding the clinkers with about 60% slag and resembles more or less in properties of Portland cement. It can be used for works economic considerations is predominant.

8. High Alumina Cement:- High alumina cement is obtained by melting mixture of bauxite and lime and grinding with the clinker. It is a rapid hardening cement with initial and final setting time of about 3.5 and 5 hours respectively.

The compressive strength of this cement is very high and more workable than ordinary portland cement and is used in works where concrete is subjected to high temperatures, frost, and acidic action.

9. White Cement:- It is prepared from raw materials free from Iron oxide and is a type of ordinary portland cement which is white in color. It is costlier and is used for architectural purposes such as precast curtain wall and facing panels, terrazzo surface etc. and for interior and exterior decorative work like external renderings of buildings, facing slabs, floorings, ornamental concrete products, paths of gardens, swimming pools etc.

10. Colored cement:-It is produced by mixing 5- 10% mineral pigments with ordinary cement. They are widely used for decorative works in floors.

11. Air Entraining Cement:- Air entraining cement is produced by adding indigenous air entraining agents such as resins, glues, sodium salts of sulphates etc. during the grinding of clinker.

This type of cement is especially suited to improve the workability with smaller water cement ratio and to improve frost resistance of concrete.

12. Expansive Cement:- Expansive cement expands slightly with time and does not shrink during and after the time of hardening . This  cement is mainly used for grouting anchor bolts and prestressed concrete ducts.

13. Hydrographic cement:- Hydrographic cement is prepared by mixing water repelling chemicals and has high workability and strength. It has the property of repelling water and is unaffected during monsoon or rains. Hydrophobic cement is mainly used for the construction of water structures such dams, water tanks, spillways, water retaining structures etc.

Applications of Hydrophobic portland cement :-

Hydrophobic Portland Cement is manufactured on special requirement for high rainfall areas to improve the shelf life of the cement. The cement particles are given a chemical coating during manufacturing which provides water repelling property and the cement is not affected due to high humidity and can be stored for a longer period . This has to be obtained on special order from the cement manufactures.