Different Varieties Of Cements

 

The cements produced by inter grinding of cement clinker prepared in rotary cement kiln along with 3-5 % gypsum only are called as Ordinary Portland Cement (OPC). Depending upon the strength requirement OPC is further classified as OPC-33 grade, OPC-43 grade and OPC-53 grade. The range of applications, the Physical / Chemical requirements as per Bureau of Indian Standards (BIS) and strength of OPC are discussed in the following sections.

53 Grade OPC is a higher strength cement to meet the needs of the consumer for higher strength concrete. As per BIS requirements the minimum 28 days compressive strength of 53 Grade OPC should not be less than 53 MPa. For certain specialised works, such as pre-stressed concrete and certain items of pre-cast concrete requiring consistently high strength concrete, the use of 53 grade OPC is found very useful. 53 grade OPC produces higher-grade concrete at very economical cement content. In concrete mix design, for concrete M-20 and above grades a saving of 8 to 10 % of cement may be achieved with the use of 53 grade OPC.

53 Grade OPC can be used for the following applications.
 

Physical Characteristics of 53 Grade OPC (BIS Requirement)

Chemical Characteristics of 53 Grade OPC (BIS Requirement)

43 Grade OPC
The 43 grade OPC is the most popular general-purpose cement in the country today. The production of 43 grade OPC is nearly 50% of the total production of cement in the country.

The 43 grade OPC can be used for following applications:
 

General Civil Engineering construction work RCC works(preferably where grade of concrete is up to M-30) Pre-cast items such as blocks, tiles, pipes etc Asbestos products such as sheets and pipes Non-structural works such as plastering, flooring etc.

The compressive strength of cement when tested as per IS code shall be minimum 43 MPa. The physical and chemical properties of this cement are given in the table:

Physical Characteristics of 43 Grade OPC (BIS Requirement)
 

Chemical Characteristics of 43 Grade OPC (BIS Requirement)

33 Grade OPC
This cement is used for general civil construction work under normal environmental conditions. The compressive strength of cement after 28 days test as per IS specification is 33 MPa. Due to low compressive strength, this cement is normally not used where high grade of concrete viz, M-20 and above is required. The availability of higher grades of OPC in the market are affecting the use of 33 grade OPC and now a days 43 grade OPC is normally used for general construction work instead of 33 grade OPC. More useful for mass concreting and plain cement concreting. Normally made to order basis. It can be used for plastering and single storeyed individual houses. The physical and chemical requirement as per BIS are given in table below:

Physical Characteristics of 33 Grade OPC (BIS Requirement)

Chemical Characteristics of 33 Grade OPC (BIS Requirement)

Portland Pozzolana Cement (PPC)
The Portland Pozzolana Cement is a kind of Blended Cement which is produced by either intergrinding of OPC clinker along with gypsum and pozzolanic materials in certain proportions or grinding the OPC clinker, gypsum and Pozzolanic materials separately and thoroughly blending them in certain proportions.

Pozzolana is a natural or artificial material containing silica in a reactive form. It may be further discussed as siliceous or siliceous and aluminous material which in itself possesses little, or no cementitious properties but will in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties. It is essential that pozzolana be in a finely divided state as it is only then that silica can combine with calcium hydroxide (liberated by the hydrating Portland Cement) in the presence of water to form stable calcium silicates which have cementitious properties. The pozzolanic materials commonly used are:
 

Volcanic ash Calcined clay Fly ash Silica fumes

The Indian standards for Portland Pozzolana Cement have been issued in two parts based on the type of pozzolanic materials to be used in manufacturing of Portland Pozzolana Cement as given below:

IS 1489 (Part 1) 1991, Portland Pozzolana Cement – specification (fly ash based) IS 1489 (Part 2) 1991, Portland Pozzolana Cement – specification (Calcined clay based)

The quality of flyash or calcined clay to be used in manufacturing of PPC is also specified by BIS in the following standards:

IS 3812 1981 – specification for flyash as pozzolana and admixture IS 1344 1981 – specification for calcined clay pozzolana

The Portland Pozzolana Cement produces less heat of hydration and offers greater resistance to the attack of aggressive waters than normal Portland Cement. Moreover it reduces the leaching of calcium hydroxide liberated during the setting and hydration of cement.

The Portland Pozzolana Cement is ideally suited for the following construction.
 

Hydraulic structures Mass concreting works Marine structures Masonry mortars and plastering Under aggressive conditions. All other application where OPC is used.

Physical Characteristics of PPC (BIS Requirement)

Chemical Characteristics of PPC (BIS Requirement)

X – Declared % of Flyash.


Sulphate Resisting Portland Cement (SRC)
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 (2 C3A + C4AF) lower than 25%. The SRC can be used for structural concrete wherever OPC or PPC or Slag Cement is 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 seawater or exposed directly to seacoast. The IS 456 2000 (revised draft code) has made elaborate provisions for use of particular type of cement against different percentages of soluble sulphate salts. These provisions are given in table below:

 

OPC-Ordinary Portland cement,
PPC- Portland Pozzolana Cement,
PSC- Portland Slag Cement,

SSC- Super Sulphated Cement,
SRC- Sulphate Resisting Cement.

The use of SRC is recommended for following applications:
 

Foundations, piles Basements and underground structures Sewage and Water treatment plants Chemical, Fertilizers and Sugar factories Food processing industries and Petrochemical projects Coastal works. Also for normal construction works where opc is used. Construction of building along the coastal area is within 50 km from sea.

The physical and chemical requirement as per BIS are given in table below:

Phphysical Characteristics of SRC (BIS Requirement)

Chemical Characteristics of SRC (BIS Requirement)