Pakistan is a Country That is Wealthy in Cement Raw Material

7/31/2019 Pakistan is a Country That is Wealthy in Cement Raw Material

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Pakistan is a country that is wealthy in cement raw material. Cement, being one of

Pakistans major industries, has been playing an essential role in the socio-economic

growth of the country. While the industry has seen its highs and lows in the recent past, ithas improved during the last couple of years. The growth in current years is the result of

the development of export markets and an increase in production ability

History

In 1921 the first cement plant was established in the city of Wah.

During its independence in 1947, Pakistan acquired four cement plants.

In 1972 the cement industry was nationalized and the State Cement Corporation ofPakistan was established.

The cement industry was privatized in 1990 which led to the setting up of new

plants.

Cement Market

Pakistan's cement market, which at present consists of 29 cement plants, is divided into two

separate regions, North and South.

The northern region consists of the provinces of Punjab and NWFP.

Some of the major cement manufacturers in this region are:

o D.G. Khano Lucky Cement

o Maple Leap

The southern region consists of the province of Sindh and lower parts of Balochistan.

Some of the major cement manufacturers in this region are:

o Attock

o Zeal Pak

o Thatta

Cement production capacity in the North is 35.18 million tons {80 percent} while in the

South it is only 8.89 million tons {20 percent}.


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Exports

According to the Global Cement Report, Pakistan has been ranked 5th

in the worldscement exports because of high demands in nearby countries

Pakistan Cement Industry produces a surplus of cement which is exported mainly to

Afghanistan, India, Africa and the Middle East.

Demands

Factors behind the increase of demand in cement:

Major construction projects such as dams

Reconstruction of schools and stores

Real estate development projects

Cement Information

What is Cement?

Cement is a material with adhesive and cohesive properties that makes it capable of bonding

mineral fragment into a compact and rigid mass. The word cement seems to have been derivedfrom the middle age English cyment, and Latin caementum. The latter word

caementum meant rough quarried stone or chips of marble from which a kind of mortar wasmade more than 2000 years ago in Italy. During the Middle Ages term cement or sement


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generally was made for a mortar. Common lime, hydraulic lime, gypsum plaster, pozzolana,

natural and Portland cement are few of the material, which are used for cementing purposes.

These cementing material may be classified into two groups:

Non-Hydraulic:

Non-hydraulic cement do not have the ability to set and harden under water but

requires carbon dioxide from air to harden e.g. non-hydraulic lime and plaster of Paris.Their cementing prosperity arises from the re absorption of gases that were expelled

during their processing. Their products of hydration are not resistant to water.

Hydraulic:

Hydraulic cement is defined as cement having the ability to set and develop strength in

air or under water and which are insoluble in water after they have set. Such cementharden even in the absence of air and form a solid product which is stable in water and

can be safely used in all structures in contact with water. Hydraulic cement includes

hydraulic limes, Portland cement (both basic and blended), oil-well cement, whitecement, colored cement, high alumna cement, expensive cement regulated and

hydrophobic cement etc.

Quarrying and crushing

The primary raw material for cement manufacture is calcium carbonate or limestone. This isobtained from the quarry where, after the removal of overburden, the rock is blasted, loaded

into trucks and transported to the crusher. A multistage crushing process reduces the rock tostone less than 25 mm in diameter. Most modern cement factories are located close to a

source of limestone as about 1.5 tons of limestone is needed to produce one ton of cement.

Blending and storage

The crushed rock is stored in stockpiles where, by a carefully controlled process of stacking andreclaiming across the stockpile, blending takes place and a uniform quality of raw material is

achieved. Systematic sampling and laboratory testing monitor this process. The other rawmaterials, normally shale, iron ore and sand, are also stored in stockpiles.


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Raw milling and homogenization

Carefully

measured quantities of the various raw materials are fed, via raw mill feed silos, to mills where

steel balls grind the material to a fine powder called raw meal. Homogenizing silos are used tostore the meal where it is mixed thoroughly to ensure that the kiln feed is uniform, a

prerequisite for the efficient functioning of the kiln and for good quality clinker.

Burning

The most critical step in the manufacturing process takes place in the huge rotary kilns. Rawmeal is fed into one end of the kiln, either directly or via a preheater system, and pulverizedcoal is burnt at the other end. The raw meal slowly cascades down the inclined kiln towards the

heat and reaches a temperature of about 1 450 C in the burning zone where a process calledclinkering occurs. The nodules of clinker drop into coolers and are taken away by conveyors to

the clinker storage silos. The gas leaving the kiln is cleaned by electrostatic precipitators priorto discharge into the atmosphere.


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Cement milling

The cement mills use steel balls of various sizes to grind the clinker, along with a smallquantity of gypsum to a fine powder, which is then called cement. Without gypsum, cement

would flash set when water is added and gypsum is therefore required to control setting times.The finished cement is stored in silos where further blending ensures consistency.

Quality assurance

Extensive sampling and testing during the manufacturing process ensures the consistency and

quality of the end product. Testing takes place at the stages of the manufacturing processindicated by the symbol.

Cement despatch

Cement is despatched either in bulk or packed in 50 kg bags and distributed from the factory

in rail trucks or road vehicles. The 50kg bags are either packed directly onto trucks or can bepalletised. The pallets can be covered by a layer of plastic to offer further protection from the

elements.

Types Of Cement:

The types of special cement now being produced can be roughly classified in the following sixcategories according to the special purpose for which these have been designed. These are:

1. Rapid hardening cement.


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2. Cement resistant to chemical attack of certain soil and aggregates.

3. Low heat of hydration cement.4. Better protecting cement for steel reinforcement.

5. Better workability and whether resisting cement.

6. Decorative cement and other special cement.

Rapid Hardening Cement:

Under this category following two cement have the desired properties of fast

development of strength viz. the Portland Rapid Hardening Cement and High

Aluminum Cement. Their specific characteristics are as follows:

Rapid Hardening Cement (Type III of A.S.T.M):

This cement has high early strength, its equal to or better than 3 Days strength

of OPC. This is achieved by having high contents of tricalcium silicates in its

composition. It is mostly used in intended to release the framework within 24

hours or so for subsequent use in the mass production of RCC elements.

The respective 1,2,3,7 and 28 days strengths (in equivalent P.S.I figures) of this

cement under British specifications, German standard, and A.S.T.M. Japanese

and Pakistan standards for mortar cubes are as follows:

B.S.

German

Standard Astm Japanese Pakistan

1 day strength - - 1800 923 -

2 days strength - 4350 - - -

3 days strength 4200 - 3500 1846 4205

7 days strength - - - 3266 5220

28 days

strength

6670 7975 - 4686 6670

The difference in strengths given above is basically due to difference in all

standards the 3 days strength is nearly 1-1/2 to 2 times of O.P.C. Thedisadvantages of this cement beside its higher cost are its high heat of

hydration, which renders it unsuitable for mass concreting projects.

High Aluminum Structural Cement:

This cement is used where very rapid setting and very high early strength are

required. This cement has strength at one day nearly equal to 28 days strength

of O.P.C. Its setting is so fast that it must be put in place within a few minutes of


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its mixing. It is

generally used

in plugging

leakage indams etc. or

putting in pile

foundations where limited time is available for setting of cement before the

seepage water build up occurs. In Pakistan it has been used in some specific

locations in terbela dam. Abroad it has been used in buildings where it was found

essential to remove the framework after one or two days.

This cement besides its high cost has the disadvantages of the high heat of hydration

and retrogression in strength in time. There have been some structural failures due to

miscalculation of its final strength after some years of use especially in humid and hot

atmosphere. This cement has however excellent heat registering qualities and is

therefore extensively used in Kilns, boilers and Furnace linengings. Cement resistant to

chemical attack especially of Sulphate and Organic acids or Soil and active Silica of

aggregate. In this category the following cement can be included:

2-A Highly Sulphate Resistant Cement

2-B Moderately Sulphate Resisting Cement

2-C Portland Blast France Slag Cement.

2-D pozzolana Cement

2-E Low Alkali Cement

2-A Highly Sulphate Resisting Cement H.F.R.C

The most important and the most widely used chemical resistant cement is

H.S.R.C cement High concentration of sulphate salts is present in seawater and

in the soil near seashores. These salts are sometimes present in soil and in the

submit water even thousands of miles away from the sea. Even Terbela Dam site

was found not free from sulphate and H.S.R.C had to be used in foundations at


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the site. The sulphate salt severally attack concrete can start within months. This

cement has lower 3 days strength than OPC and also its capacity to protect

reinforcement steel in structures exposed to atmosphere action is lower than

OPC and hence not recommended for usual R.C.C. work in super structures.

2-B Moderately Sulphate Resisting Cement (M.S.R.C.)

This cement has been developed as a compromise Cement having the good

properties of sulphate resistance to some extent and of good alkalinity like that

of OPC which useful for reinforcement protection and also of early strength

development better than Highly Sulphate Resisting Cement. No standard exists

for this cement in the B.S and P.S. specifications but under ASTM it is designed

as Type II. The three days minimum strength of OPC, H.S.R.C & H.S.R.C is

1800, 1200 and 1500 PSI respectively under ASTM.

This cement though better than H.S.R.C in many respects is not as resistant to

sulphate as H.S.R.C and should not be used in foundations near the seashore.

Incidentally the O. P. cement produced in most of the Cement Factories around

Karachi are confirming to the ASTM specifications for this type II and hence

more resistant to mild sulphate attack than the cement produced in the factories

in other parts of country.

2-C Portland Blast Furnace Slag Cement:

This cement has well to moderate resistance to sulphate attack from soil. This

cement has some other very desirable qualities of stability details of which follow

below under item 3C.

2-D Pozzolana Cement:

This cement has well to moderate resistance to sulphate attack from seawater or

soil containing sulphate.

2-E Low Alkali Cement:

This is a variety of ordinary Portland cement in which the total alkali contents of

cement has been controlled to remain below 0.6%. With this reduced percentage


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of alkali contents the danger of alakie of cement attacking the active silica

contents of aggregate is eliminated. Generally we do not have active aggregate

of this type in Pakistan but on each large scale-concreting project, test of alkaliaggregate reaction must be performed to enshore safety of the project. Certain

varieties of Chert-stone found in Pakistan contain active Silica and would require

low alkali for making concrete.

Low Heat of Hydration Cement:

Normal and Rapid Hardening Cement generate lot of heat during the setting and

hardening process so much so that the structure under concreting can crack.

This can occur specially while poring large messes of concrete in confine spaces

like those of Dam and Bridge pier foundations. In order to avoid this problem

cement of low Heat of hydration have been developed some of which are as

listed below:

3-A Low Hear of Hydration Cement (type IV of A.S.T.M.)

3-B Portland blast Furnace Slag Cement

3-C Pozzolana Cement

3-D Super Sulphate Cement

3-A Low Hear of Hydration Cement (type IV of A.S.T.M.):

This is cement specially meant for the concreting of structures where large

masses of concrete have to be poured at one time. Generally it is specified that

heat of hydration on 7 days will not exceed 250Kg. This is achieved by making

this cement with larger percentage of di-calcium silicates in its contents than

normally presents in OPC. In A.S.T.M this cement is designated as type IV and

under BS as LHP. Under German standards its type is LAHORE with symbol as

N.W. while the Japanese equivalent is type L.H.P with symbol as M.H.C. The

disadvantage of this cement is its slow development of strength and is therefore

not used at sited where rapid hardening or other specific qualities are required.

3-B Slag Cement:

This is another variety of low heat cement. Grinding 35% to 65 % of granulated


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blast furnace slag with ordinary Portland cement clinker produces it. The higher

the slag contents, the lower are the 3 and 7 days strengths but better is the

resistance to chemical attack. Under German standards as much as 90% slagcan be used with type HOZ cement and under Japanese standard up to 70% in

the type BSCC. This cement is slower hardening compared to OPC- its strength

compared to OPC in ASTM being as follows:

OPC B.F SLAG CEMENT

3 days strength 1,800 760

7 days strength 2,800 1,400

28 days strength 4,000 3,000

This cement besides being a low heat cement has also the advantage of being

medley sulphate resistant although it cannot replace the highly sulphate

resistance cement for marine piles and foundations. This cement has excellent

resistance to weak organic acids present in the soil and has also the verydesirable quality of protecting reinforcement steel better than any other cement.

3-C Pozzolana:

Grinding various proportions of natural pozzolana, tars or volcanic ash with

ordinary Portland clinker makes this cement. It is very good cement in the sensethat it has good workability properties in addition to having low heat and

moderate sulphate resisting properties. It has been used extensively in the 37KMlong causeway connecting Dhahran with Bahrain in the gulf. So far in Pakistan

we have not been able to locate useful pozzolana deposits, but there are

indication that there may be good deposits of this material in the overburden ofcoal deposits of Sindh.

3-D Super Sulphate Cement:

This is another variety of low heat cement. Its standards exist under B.S but not

under A.S.T.M. it is made by grinding about 70-80% B. F. Slag with about 10%

gypsum and 1-2 % Portland clinker or lime. This cement is also middy resistant

to sulphate attack. It is very finely ground cement and its early strength at 3 day

is comparable to OPC although under the BS its 7 days strength is required to be

comparable to at least the 3 days strength of OPC. This cement is also good

masonry cement due to its good workability but it can be used in RCC and other

construction work in the same manner as OPC is used with excellent results.

Cement For Better Protection of Reinforcement against Corrosion:

The basic steps for the prevention of resulting of steel in concrete is to use such cement


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aggregate and mixing water as are basically free from chlorides, maximum contents of

chlorides in concrete being limited to 0.02 % by weight. The following properties in

cement are essential for greater protection of steel:

1. Cement to be with minimum percentage of Chlorides says not exceeding 0.01 per

cent.

2. Portland Cement preferably having about 6 to 8 per cent Tricalcium Aluminates.

3. Cement made with slag as additive.

If the Tricalcium Aluminates is less than 5 per cent as per ASTM the cement will not

have the capacity to neutralize the stray Chloride entering into concrete and thus fail

toward off the effects of Chlorides. The properties of slag cement with about 35 percent

slag and 60 per cent Portland Clinker are superior to other cement in this respect.

Cement for Better Workability and Wealth E.W. Resistance

These are cement, which are render the corresponding concrete more workable than

other normal cement. This quality is necessary where high compatibility and better

weather resistance is demanded. Because of greater workability the concrete made

from this cement can achieve much higher strength due to lower water cement ratios

achievable compared with other cement.

This property is given to the cement by addition of the entraining agents like lime or

other plasticisers so that the remix and to place in position. Some of the cement belong

to this category are:

Air Entraining Cement:

Under ASTM four different types of cement have been classified as air-entraining

version for normal Rapid-hardening and Sulphate Resisting Cement and each concrete

thus made is more workable and attains higher weather resisting property compared to

their non-air entrained versions.

Blended Hydraulic and Masonry Cement and Grouts:

This cement is basically made for plastering and grouting. Standards have been laid

down for this cement both in the British and ASTM specifications. In fact under ASTM


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there are at least 10 versions of Masonry cement. Some of the standards are for OPC

based cement with or without air entraining agents while others are for sulphate

resistance and low heat versions. This masonry cement is made by addition of

plasticizing materials like lime, ground silica, slag or Pozzolana and air- entrainingagents etc. Portland Cement clinkers during grinding.

Decorative Cement Oil Well and other Special Purpose Cement:

This cement is basically of properties similar to O.P.C except that it is made from such

raw materials, which contain the least amounts of coloring pigments like traces of iron,

manganese and chrome. Basically this cement has higher Tricalcium Aluminates in its

contents than OPC and therefore subjects to sharp attack by sulphate from any source.

Portland cement is the most commonly used type of cement in the world today. Portland

cement can be found in both concrete and mortar, not to mention other constructionmediums such as stucco and some types of grout, where it acts as a binding agent. On a

chemical level, Portland cement is a fine powder comprised of a minimum of 66% calcium

silicate, with the remainder largely being a mix of aluminum, and iron. Portland cement is ahydraulic material, which requires the addition of water in order to form exothermic bonds,

and is not soluble in water


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Portland Pozzolana Cement is manufactured by blending pozzolanic materials, OPCclinker, and gypsum either grinding them together or separately. Today Portland Pozzolana

Cement is widely in demand for industrial and residential buildings, roads, dams, and

machine foundations.
http://www.ordinaryportlandcement.com/wp-content/uploads/portland_cement.jpg


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1 Askari Cement Limited - Wah 1,050,000 1,102,500

2 Askari Cement - Nizampur 1,500,000 1,575,000

3 Bestway Cement Limited - Hattar 1,170,000 1,228,500

4 Bestway Cement Limited - Chakwal 3,428,571 3,600,000

5 Bestway-Mustehkum Cement Limited - Hattar 1,035,000 1,086,750

6 Cherat Cement Company Limited-Nowshera 1,050,000 1,102,500

7 Dandot Cement Limited - Jehlum 480,000 504,000

8 Dewan Hattar Cement Limited - Hattar 1,080,000 1,134,000

9 D.G.Khan Cement Limited - D.G.Khan 2,010,000 2,110,500

10 D.G.Khan Cement Limited - Chakwal 2,010,000 2,110,500

11 Fauji Cement Company Limited - Fateh Jang 3,270,000 3,433,500

12 Fecto Cement Limited - Sangjani 780,000 819,000

13 Flying Cement Limited - Lilla 1,140,000 1,197,000

14 GharibWal Cement Limited - Jehlum 2,010,000 2,110,500

15 Kohat Cement Company Limited - Kohat 2,550,000 2,677,500

16 Lucky Cement Limited - Pezu 3,725,714 3,912,000

17 Maple Leaf Cement Factory Limited - Daudkhel 3,210,000 3,370,500

18 Lafarge Pakistan Cement Company Limited - Chakwal 1,950,000 2,047,500

19 Pioneer Cement Limited - Khushab 1,933,571 2,030,250

Al-Abbas Cement Limited - Nooriabad, Dadu 540,000 567,000

Attock Cement Pakistan Limited - Hub Chowki, Lasbela 1,710,000 1,795,500

Dewan Cement Limited - Dhabeji 750,000 787,500

Lucky Cement Limited, - Indus Highway, Karachi 3,428,571 3,600,000

Thatta Cement Limited - Thatta 300,000 315,000


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Pakistan is a Country That is Wealthy in Cement Raw Material