CEMENT

CONTENTS

• What is Cement?• Composition • Manufacturing• Types of Cement• Storage • Tests • Drawbacks and Alternatives• Water Cement Ratio• Difference Between Plaster and Mortar•Difference Between RCC and PCC

• DEFINITION: A cement is a binder, a substance that sets and hardens and can bind other materials together.

The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling .

Manufacturing of Cement

Cement is typically made from limestone and clay or shale.

These raw materials are extracted from the quarry crushed to a very fine powder.

This blended raw material is called the 'raw feed' or 'kiln feed' and is heated in a rotary kiln where it reaches a temperature of about 1400 C to 1500 C then falls out of the kiln and cools down.

The material formed in the kiln is described as 'clinker‘.

After cooling, the clinker may be stored temporarily in a clinker store, or it may pass directly to the cement mill.

The cement mill grinds the clinker to a fine powder. A small amount of gypsum - a form of calcium sulfate - is normally ground up with the clinker. The gypsum controls the setting properties of the cement when water is added.

STORAGE OF CEMENT•Storage of cement is a noteworthy item, because proper arrangements for storing the cement have to be made in the factories before sale or on large construction projects before use.

•Proper Storage preserves its quality and fitness for use. To prevent its deterioration it is necessary to protect it from rain, sun, winds and moisture.

•Moisture is the first and the greatest danger .

•Cement should be stored in dry, leakproof and moisture proof sheds.

•The shed for the storage of cement should have minimum number of windows and close fitting doors.

Background and Need

The earliest binder used in masonry construction was plain mud (with or without straw) .

An early version of cement made with lime, sand, and gravel. 

Cement have binding property it hold bricks to stand.

Types of Cement

Types of Cements based on Indian Standards

1.      Ordinary Portland Cement- It is the most important type of cement. The 28 days strength of the cement will not

be less than  33N/mm2  . It is not in much use by masses today and had

been replaced by other cement called PPC (Portland Pozzolana Cement).

Still, it is used in construction activities of large scale.

 

2.      Rapid Hardening Cement-

The name is itself an explanation of the nature of the cement i.e. it gets hardened at a very rapid pace.

Apart from rapid hardening it also develops high strength at an early stage than OPC.

Used in pre-fabricated concrete construction works or at places where formwork has to be removed or sometimes in road repair works too.

 

3.  Sulphate Resisting Cement-

It resist easily to sulphate attacks.

Thus it find its use in concreting done in marine conditions or in concrete foundation which soil contain sulphate’s compounds or sometimes in sewage treatment works too.

4.      Portland Slag Cement-

This type of cement is manufactured by mixing Portland cement and Ground Granulated Blast Slag in suitable proportions. The resultant cement is more resistant to chemical attacks.

It is thus generally used in water retaining structures or where structure is vulnerable to any form of chemical attack.

5.      Super Sulphated Cement-

This cement is like sulphate resistance cement with higher sulphate resistance and fineness higher than that of OPC.

It is mostly used in Belgium and recommended for used in foundation works (or sea works) where very high degree of sulphate resistance is required.

 

6.      Low Heat Cement-

It has low heat of hydration.

High Heat of hydration is responsible for building cracks in the structure.   Thus it finds its use in massive construction work.

7.      Portland Pozzolana Cement

PPC is obtained by mixing OPC with suitable Pozzolans at a certain temperature to produce PPC.

Pozzolans are materials that are said to show similar properties as that of cement when they comes in contact with water.

It is very popular now days and used by masses for all general construction activities.

 

8.      Coloured Cement-

As per IS code it is white but can be turned to any colour by adding suitable coloured pigments in OPC or PPC.

It is manufactured from limestone that is available only near Jodhpur in India.

It is use to aesthetically enhance the structure appearance and finish.

9.      Hydrophobic Cement-

It is manufactured by grinding together OPC clinker with substances such as oleic acid or stearic acid.

It reduces the rate of deterioration of cement and thus gives long storage life to cement.

10.  Masonry Cement. It is used for masonry works.

Properties resembling to lime mortar instead of cement mortar.

It is manufactured using certain admixtures.

 

11.  Oil Well Cement- It is used in the oil wells.

This cement is manufactured using special set of admixtures at high temperature and pressure inside the oil wells while maintaining its mobility.

12.  Concrete Sleeper Grade Cement-

It is special cement and is manufactured as specifications formulated by Indian Railways. Particularly used in concrete sleepers but can also be use in high rise building where high early strength is required.

 

13.  High Alumina Cement-

It is the cement with very high content of alumina.

Having a unique property of extensively high rate of strength development.

APPLICATIONS

DIFFERENCE BETWEEN PLASTER

AND MORTAR•Plaster is a building material used for coating walls and ceilings.• Plaster is manufactured as a dry powder and is mixed with water to form a paste when used.• The reaction with water liberates heat through crystallization and the hydrated plaster then hardens.

•  •Mortar is a workable paste used to bind building blocks such as stones, bricks, and concrete masonry units together, fill and seal the irregular gaps between them.• Mortar comes from Latin mortarium meaning crushed.

Mortar binding bricks Plaster

Difference Between RCC and PCC

Reinforced cement concrete  (RCC) is a composite material in

which concrete's relatively low tensile strength and ductility .

Reinforcement having higher tensile strength and/or ductility.

The reinforcement is usually, though not necessarily, steel reinforcing bars (rebar) and is usually embedded passively in the concrete before the concrete sets.

Reinforcing schemes are generally designed to resist tensile stresses in particular regions of the concrete that might cause unacceptable cracking and/or structural failure.

Plain Cement Concrete is a composite material composed mainly of water, aggregate, and cement.

Additives are included in the mixture to achieve the desired physical properties of the finished material.

When all these ingredients are mixed together, they form a fluid mass that is easily molded into shape.

Over time, the cement forms a hard matrix which binds the rest of the ingredients together into a durable stone-like material with many uses.

Drawbacks of cement

From an environmental standpoint cement has a negative impact, because manufacturing it emits about a ton of greenhouse gas (CO2) into the atmosphere for every ton of cement manufactured.

Cement is also a rather cold, unyeilding material to live in. 

 

Alternative for Cement

Lime and Geopolymer are the alternative of cement.

Geopolymer is twice as strong as cement in compression, three-times as strong in flexure and can set up in one day.

Besides using geopolymer to make concrete, this novel material can be used for fire and corrosion resistant coatings, water and air filtration, CO2 sequestration materials, projectile armor, substrates for solar and fuel cells, and even a paint substitute.

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Water- Cement ratio

The water–cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix and has an important influence on the quality of concrete produced.

A lower water-cement ratio leads to higher strength and durability.

but may make the mix more difficult to place. the water–cement ratio is characterized as the water to

cement plus pozzolan ratio, w/(c+p). The pozzolan is typically a fly ash, or blast furnace slag. It can include a number of other materials, such as silica

fume, rice husk ash or natural pozzolans. The addition of pozzolans will influence the strength gain

of the concrete. 

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Submitted by : Urvashi pareek

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