Constituents of concrete- Cement

Presented by: Dr. H.M.A.MahzuzAssistant Professor, Department of Civil and Environmental EngineeringShahjalal University of Science and Technology, Sylhet

Cement is a binder, a substance that sets and hardens and can bind other materials together.

Cement is the mixture of calcareous, siliceous, argillaceous and other substances.

Cement is the principal binding material of modern time.

Property Portland Cement

SiO2 content (%) (Silica) 17-25%

Al2O3 content (%) (Alumina) 3-8%

Fe2O3 content (%) (Iron oxide) 0.5-6%

CaO content (%) (lime) 60-67%

Gypsum (Calcium Sulphate) 1-4%

Specific gravity 3.15

General use in concrete Primary binder

Components of CementComparison of Chemical and Physical Characteristics

Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete and mortar.

Functions of Cement

Manufacturing

Constituents

(i) Lime (CaO):Lime forms nearly two-third (2/3) of the cement. Therefore sufficient quantity of the lime must be in the raw materials for the manufacturing of cement. Its proportion has an important effect on the cement. Sufficient quantity of lime forms di-calcium silicate (C2SiO2) and tri-calcium silicate in the manufacturing of cement.

Lime in excess, causes the cement to expand and disintegrate.

(ii) Silica (SiO2):

The quantity of silica should be enough to form di-calcium silicate and tri-calcium silicate in the manufacturing of cement. Silica gives strength to the cement.

Silica in excess causes the cement to set slowly.

(iii) Alumina (Al2O3):Alumina supports to set quickly to the cement. It also lowers the clinkering temperature.

Alumina in excess, reduces the strength of the cement.

(iv) Iron Oxide (Fe2O3):Iron oxide gives colour to the cement. It gives hardness and strength to the cement.

(v) Magnesia (MgO):It also helps in giving colour to the cement. Magnesium in excess makes the cement unsound.

(vi) Calcium Sulphate (or) Gypsum (Ca SO4) :At the final stage of manufacturing, gypsum is added to increase the setting of cement.

Mineral Compounds in Portland cement: There are four main phases present in the clinker or non-hydrated Portland cement. The four compounds referred as C3S, C2S, C3A and C4AF.They are formed at high temperature (1 450 °C) in the cement kiln and are the following:

Cement chemist notation (CCN)

Actual Formula Name Mineral Phase

C3S 3 CaO • SiO2 Tricalcium silicate Alite

C2S 2 CaO • SiO2 Dicalcium silicate Belite

C3A 3 CaO • Al2O3 Tricalcium aluminate Aluminate or Celite

C4AF4 CaO • Al2O3 •

Fe2O3

Tetracalcium alumino ferrite

Ferrite

Hydrated cement paste:Hydration products formed in hardened cement pastes (HCP) are more complicated, because many of these products have nearly the same formula and some are solid-solutions with overlapping formula. Some examples are given below:

Cement chemist notation (CCN)

Actual Formula Name or Mineral Phase

CH Ca(OH)2 or CaO • H2O Calcium hydroxide

C-S-H2(CaO) • SiO2 • 0.9-1.25(H2O), and/or;

CaO • SiO2 • 1.1(H2O), and/or;0.8-1.5(CaO) • SiO2 • 1.0-2.5(H2O)

Calcium Silicate Hydrate

C-A-H This is even more complex than C-S-H Calcium Aluminate Hydrate

Aft C3AS3H30-32 Aluminum trisulfate, or ettringite

AFm C2ASH12 Aluminum monosulfate

C3AH6 3CaO • Al2O3 • 6 H2O Hydrogarnet

Cement chemist notation:

C3S + H2O → CSH(gel) + CaOH

Standard notation:

Ca3SiO5 + H2O → (CaO)•(SiO2)•(H2O)(gel) + Ca(OH)2

Balanced:

2Ca3SiO5 + 7H2O → 3(CaO)•2(SiO2)•4(H2O)(gel) + 3Ca(OH)2

Reaction

Belite hydration:

Belite + water → C-S-H phase + portlandite2 Ca2SiO4 or 2 CaO • SiO2+4 H2O→ 3 CaO · 2 SiO2 · 3 H2O(a crystalline phase)+Ca(OH)2

2 C2S + 4 H → C3S2H3 (a crystalline phase)+ CH

PRODUCTION PROCESSESThe production of cement takes place with several steps:

Quarrying, Dredging, and DiggingQuarrying of limestone and shale is accomplished by using explosives to blast the rocks from the ground. After blasting, Excavators (or power shovels) are used to load dump trucks or small railroad cars for transportation to the cement plant, which is usually nearby.Limestone is a sedimentary rock . The ocean floor is dredged to obtain the shells, while clay and marl are dug out of the ground with power shovels. All of the raw materials are transported to the plant.

• Grinding• After the raw materials have been transported to the plant, the limestone and shale

which have been blasted out of the quarry must be crushed into smaller pieces. Some of the pieces, when blasted out, are quite large. The pieces are then dumped into primary crushers which reduce them to the size of a softball.

• After that the pieces are carried by conveyors to secondary crushers which crush the rocks into fragments usually no larger than 3/4 inch across.

Process of Grinding• This is done by one of two methods:

– Wet process, or

– Dry process

• The wet process of fine grinding is the older process, having been used in Europe prior to the manufacture of cement in the United States. This process is used more often when clay and marl, which are very moist, are included in the composition of the cement. In the wet process, the blended raw materials are moved into ball or tube mills which are cylindrical rotating drums which contain steel balls. These steel balls grind the raw materials into smaller fragments of up to 200 of an inch. As the grinding is done, water is added until a slurry (thin mud) forms, and the slurry is stored in open tanks where additional mixing is done. Some of the water may be removed from the slurry before it is burned, or the slurry may be sent to the kiln as is and the water evaporated during the burning.

Wet process:

In this process, the raw materials are changed to powdered form in the presence of water.

In this process, raw materials are pulverized by using a Ball mill, which is a rotary steel cylinder with hardened steel balls. When the mill rotates, steel balls pulverize the raw materials which form slurry (liquid mixture). The slurry is then passed into storage tanks, where correct proportioning is done. Proper composition of raw materials can be ensured by using wet process than dry process. Corrected slurry is then fed into rotary kiln for burning.

•This process is generally used when raw materials are soft because complete mixing is not possible unless water is added.

•Actually the purpose of both processes is to change the raw materials to fine powder.

The dry process

The dry process of fine grinding is accomplished with a similar set of ball or tube mills; however, water is not added during the grinding. The dry materials are stored in silos where additional mixing and blending may be done.

In this process calcareous material such as lime stone (calcium carbonate) and argillaceous material such as clay are ground separately to fine powder in the absence of water and then are mixed together in the desired proportions. Water is then added to it for getting thick paste and then its cakes are formed, dried and burnt in kilns. This process is usually used when raw materials are very strong and hard.

In this process, the raw materials are changed to powdered form in the absence of water.

• In the wet process, each raw material is proportioned to meet a desired chemical composition and fed to a rotating ball mill with water. The raw materials are ground to a size where the majority of the materials are less than 75 microns. Materials exiting the mill are called "slurry" and have flowability characteristics. This slurry is pumped to blending tanks and homogenized to insure the chemical composition of the slurry is correct. Following the homogenization process, the slurry is stored in tanks until required.

• In the dry process, each raw material is proportioned to meet a desired chemical composition and fed to either a rotating ball mill or vertical roller mill. The raw materials are dried with waste process gases and ground to a size where the majority of the materials are less than 75 microns. The dry materials exiting either type of mill are called "kiln feed". The kiln feed is pneumatically blended to insure the chemical composition of the kiln feed is well homogenized and then stored in silos until required.

• These are two different processes of manufacturing cement.In wet process minerals are wet ground (by adding water) to form a slurry and then dried up.In dry process minerals are dry ground to form a powder like substance.Both the processes are in use and have their own advantages and disadvantages.While in wet process grinding is easier,in dry process there is a saving in fuel costs involved in drying up the slurry.

• In wet manufacturing water is added to ingredients before mixing them and in dry process, water is added at the time of mixing

What is the difference between wet and dry cement manufacturing?

• Blending• After the rock is crushed, plant chemists analyze the rock and raw

materials to determine their mineral content. The chemists also determine the proportions of each raw material to utilize in order to obtain a uniform cement product. The various raw materials are then mixed in proper proportions and prepared for fine grinding.

BurningBurning the blended materials is the key in the process of making cement. The wet or dry mix is fed into the kiln, which is one of the largest pieces of moving machinery in the industry. It is generally twelve feet or more in diameter and 500 feet or more in length, made of steel and lined with firebrick. It revolves on large roller bearings and is gradually slanted with the intake end higher than the output end.As the kiln revolves, the materials roll and slide downward for approximately four hours. In the burning zone, where the heat can reach 3,000 degrees Fahrenheit, the materials become incandescent and change in color from purple to violet to orange. Here, the gases are driven from the raw materials, which actually change the properties of the raw materials. What emerges is “clinker” which is round, marble-sized, glass-hard balls which are harder than the quarried rock. The clinker is then fed into a cooler where it is cooled for storage.

Figure: Schematic diagram of rotary kiln. Cement kilns are used for the pyroprocessing stage of manufacture of Portland and other types of hydraulic cement , in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates. Over a billion tonnes of cement are made per year, and cement kilns are the heart of this production process: their capacity usually defines the capacity of the cement plant. As the main energy-consuming and greenhouse-gas–emitting stage of cement manufacture, improvement of kiln efficiency has been the central concern of cement manufacturing technology.

Clinker is the solid material produced by the cement kiln stage that has sintered into lumps or nodules, typically of diameter 3-25 mm.

Finish GrindingThe cooled clinker is mixed with a small amount of gypsum, which will help regulate the setting time when the cement is mixed with other materials and becomes concrete. Here again there are primary and secondary grinders. The primary grinders leave the clinker , ground to the fineness of sand, and the secondary grinders leave the clinker ground to the fineness of flour, which is the final product ready for marketing.Packaging/ShippingThe final product is shipped either in bulk (ships, barges, tanker trucks, railroad cars, etc.) or in strong paper bags which are filled by machine. In the United States, one bag of Portland cement contains 94 pounds of cement, and a “barrel” weighs four times that amount, or 376 pounds. In Canada, one bag weighs 87 1/2 pounds and a “barrel” weighs 350 pounds.Masonry cement bags contain only seventy pounds of cement.When cement is shipped, the shipping documents may include “sack weights.” This must be verified by the auditor since only the cement is taxable. “Sack weights” must be excluded.

Clinker:Cement clinkers are formed by the heat processing of cement elements in a kiln. Limestone, clay, bauxite, and iron ore sand in specific proportions are heated in a rotating kiln at 2,770° Fahrenheit (1,400° Celsius) until they begin to form cinder lumps, which are also known as cement clinkers.

Types of cement• Different standards are used for classification of Portland cement. The two major standards

are the ASTM C150 used primarily in the USA and European EN 197. EN 197 cement types CEM I, II, III, IV, and V do not correspond to the similarly named cement types in ASTM C150.

• ASTM C150

• The five types of Portland cements exist, with variations of the first three according to ASTM C150.

• Type I Portland cement is known as common or general-purpose cement. It is generally assumed unless another type is specified. It is commonly used for general construction especially when making precast and precast-prestressed concrete that is not to be in contact with soils or ground water. The typical compound compositions of this type are:

• 55% (C3S), 19% (C2S), 10% (C3A), 7% (C4AF), 2.8% MgO, 2.9% (SO3), 1.0% Ignition loss, and 1.0% free CaO

• A limitation on the composition is that the (C3A) shall not exceed 15%.

• Type II gives off less heat during hydration. This type of cement costs about the same as type I. Its typical compound composition is:

• 51% (C3S), 24% (C2S), 6% (C3A), 11% (C4AF), 2.9% MgO, 2.5% (SO3), 0.8% Ignition loss, and 1.0% free CaO

• A limitation on the composition is that the (C3A) shall not exceed 8%, which reduces its vulnerability to sulfates. This type is for general construction exposed to moderate sulfate attack and is meant for use when concrete is in contact with soils and ground water, especially in the western United States due to the high sulfur content of the soils. Because of similar price to that of type I, type II is much used as a general purpose cement, and the majority of Portland cement sold in North America meets this specification.

• Note: Cement meeting (among others) the specifications for types I and II has become commonly available on the world market.

• Type III has relatively high early strength. Its typical compound composition is: 57% (C3S), 19% (C2S), 10% (C3A), 7% (C4AF), 3.0% MgO, 3.1% (SO3), 0.9% Ignition loss, and 1.3% free CaO. This cement is similar to type I, but ground finer. Some manufacturers make a separate clinker with higher C3S and/or C3A content, but this is increasingly rare, and the general purpose clinker is usually used, ground to a specific surface area typically 50–80% higher. The gypsum level may also be increased a small amount. This gives the concrete using this type of cement a three-day compressive strength equal to the seven-day compressive strength of types I and II. Its seven-day compressive strength is almost equal to 28-day compressive strengths of types I and II. The only downside is that the six-month strength of type III is the same or slightly less than that of types I and II. Therefore, the long-term strength is sacrificed a little. It is usually used for precast concrete manufacture, where high one-day strength allows fast turnover of molds. It may also be used in emergency construction and repairs and construction of machine bases and gate installations.

• Type IV Portland cement is generally known for its low heat of hydration. Its typical compound composition is: 28% (C3S), 49% (C2S), 4% (C3A), 12% (C4AF), 1.8% MgO, 1.9% (SO3), 0.9% Ignition loss, and 0.8% free CaO. The percentages of (C2S) and (C4AF) are relatively high and (C3S) and (C3A) are relatively low. A limitation on this type is that the maximum percentage of (C3A) is seven, and the maximum percentage of (C3S) is thirty-five. This causes the heat given off by the hydration reaction to develop at a slower rate. However, as a consequence the strength of the concrete develops slowly. After one or two years the strength is higher than the other types after full curing. This cement is used for very large concrete structures, such as dams, which have a low surface to volume ratio. This type of cement is generally not stocked by manufacturers but some might consider a large special order. This type of cement has not been made for many years, because Portland-pozzolan cements and ground granulated blast furnace slag addition offer a cheaper and more reliable alternative.

• Type V is used where sulfate resistance is important. Its typical compound composition is: 38% (C3S), 43% (C2S), 4% (C3A), 9% (C4AF), 1.9% MgO, 1.8% (SO3), 0.9% Ignition loss, and 0.8% free CaO. This cement has a very low (C3A) composition which accounts for its high sulfate resistance. The maximum content of (C3A) allowed is 5% for type V Portland cement. Another limitation is that the (C4AF) + 2(C3A) composition cannot exceed 20%. This type is used in concrete to be exposed to alkali soil and ground watersulfates which react with (C3A) causing disruptive expansion. It is unavailable in many places, although its use is common in the western United States and Canada. As with type IV, type V Portland cement has mainly been supplanted by the use of ordinary cement with added ground granulated blast furnace slag or tertiary blended cements containing slag and fly ash.

• EN 197• EN- 197-1 defines five classes of common cement that comprise Portland cement as a main constituent. 

These classes differ from the ASTM classes.

• I-Portland cement Comprising Portland cement and up to 5% of minor additional constituents• II-Portland-composite cement Portland cement and up to 35% of other single constituents

• III-Blast furnace cement Portland cement and higher percentages of blast furnace slag• IV-Pozzolanic cement Portland cement and up to 55% of pozzolanic constituents(volcanic ash)

• V-Composite cement Portland cement, blastfurnace slag or fly ash and pozzolana Constituents that are permitted in Portland-composite cements are artificial pozzolans (blast furnace slag, silica fume, and fly ashes) or natural pozzolans (siliceous or siliceous aluminous materials such as volcanic ash glasses, calcined clays and shale).

TYPES OF CEMENT:1. Ordinary Portland Cement2. Sulphate Resisting Cement3. Rapid Hardening Cement (or) High Early Strength cement

4. Quick Setting Cement5. Low Heat Cement6. High Alumina Cement7. Air Entraining Cement8. White Cement

(1) ORDINARY PORTLAND CEMENT:It is the variety of artificial cement. It is called Portland cement because on hardening (setting) its colour resembles to rocks near Portland in England. It was first of all introduced in 1824 by Joseph Asp din, a bricklayer of Leeds, England.

Chemical Composition of O.P.Cement:O.P.C has the following approximate chemical 

composition:

The major constituents are:1. Lime  (CaO) 60- 63% 2. Silica (SiO2) 17- 25%   3. Alumina   (Al2O3) 03- 08%

Chemical Composition of O.P.Cement: Continued-------

The auxiliary constituents are:1. Iron oxide  (Fe2O3) 0.5- 06%

2. Magnesia  (MgO)  1.5- 03%

3. Sulphur Tri Oxide (SO3)  01- 02%

4. Gypsum 01 to 04%

(2) SULPHATE RESISTING CEMENT:

It is modified form of O.P.C and is specially manufactured to resist the sulphates. In certain regions/areas where water and soil may have alkaline contents and O.P.C is liable to disintegrate, because of unfavourable chemical reaction between cement and water, S.R.C is used. This cement contains a low %age of C3A not more than 05%.

This cement requires longer period of curing. This cement is used for hydraulic structures in alkaline water and for canal and water courses lining. It develops strength slowly, but ultimately it is as strong as O.P.C.

(3) RAPID HARDENING CEMENT:This cement contains more %age of C3S and less %age of C2S. This is infact high early strength cement. The high strength at early stage is due to finer grinding, burning at higher temperature and increased lime content. The strength obtained by this cement in 04 days is same as obtained by O.P.C in 14 days. This cement is used in highway slabs which are to be opened for traffic quickly. This is also suitable for use in cold weather areas. One type of this cement is manufactured by adding calcium chloride (CaCl2) to the O.P.C in small proportions. Calcium chloride (CaCl2) should not be more than 02%. When this type of cement is used, shuttering material can be removed earlier.

(4) QUICK SETTING CEMENT:When concrete is to be laid under water, quick setting cement is to used. This cement is manufactured by adding small %age of aluminum sulphate (Al2SO4) which accelerates the setting action. The setting action of such cement starts with in 05 minutes after addition of water and it becomes stone hard in less than half an hour.

(5) LOW HEAT CEMENT:In this cement the heat of hydration is reduced by tri calcium aluminate (C3 A ) content. It contains less %age of lime than ordinary port land cement. It is used for mass concrete works such as dams etc.

(6) HIGH ALUMINA CEMENT:This cement contains high aluminate %age usually between 35-55%. It gains strength very rapidly with in 24 hours. It is also used for construction of dams and other heavy structures. It has resistance to sulphates and action of frost also.

(7) AIR ENTRAINING CEMENT:This type of cement was first of all developed in U.S.A to produce such concrete which would have resistance to weathering actions and particularly to the action of frost. It is found that entrainment of air or gas bubbles while applying cement, increases resistance to frost action. Air entraining cement is produced by grinding minute air entraining materials with clinker or the materials are also added separately while making concrete. Entrainment of air also improves workability and durability. It is recommended that air contents should be 03-04 % by volume.Natural resins, fats, oils are used as air entraining agents.

(8) WHITE CEMENT:

This cement is called snowcrete. As iron oxide gives the grey colour to cement, it is therefore necessary for white cement to keep the content of iron oxide as low as possible. Lime stone and china clay free from iron oxide are suitable for its manufacturing. This cement is costlier than O.P.C. It is mainly used for architectural finishing in the buildings.

TO CHECK THE QUALITY OF CEMENT IN THE FILED:

1.Colour greenish grey.

2.One feels cool by thrusting one’s hand in the cement bag.

3.It is smooth when rubbed in between fingers.

4. A handful of cement thrown in a bucket of water should float at first and after few seconds it will go under water.

QUALITY TESTS OF CEMENT:(1) Fineness Test,(2) Consistency test / setting time test(3) Setting Time Test(4) Compressive strength test

(1) Fineness Test:Finer cements react quicker with water and develop early strength, though the ultimate strength is not affected. However finer cements increase the shrinkage and cracking of concrete. The fineness is tested by: By Sieve analysis:Break with hands any lumps present in 100 grams of cement placed in IS sieve No.9 and sieve it by gentle motion of the wrist for 15 minutes continuously. The residue when weighed should not exceed 10 percent by weight of the cement sample.

(2) Consistency Test /Setting Time Test :This test is performed to determine the quantity of water required to produce a cement paste of standard or normal consistency.Standard consistency of cement paste may be defined as the consistency which permits the Vicate’s plunger (10 mm, 40 to 50 mm in length) to penetrate to a point 5 mm to 7 mm from the bottom ( or 35 mm to 33 mm from top) of Vicat mould. When the cement paste is tested within the gauging time ( 3 to 5 minutes) after the cement is thoroughly mixed with water.Vicat apparatus is used for performing this test.

(3) Setting Time Test:

In cement hardening process, two instants are very important, i.e. initial setting and final setting.

Initial Setting Time:

The process elapsing between the time when water is added to the cement and the time at which the needle ( 1 mm square or 1.13 mm dia., 50 mm in length) fails to pierce the test block ( 80 mm dia. and 40 mm high) by about 5 mm, is known as Initial Setting Time of Cement.

Final Setting Time:

The process elapsing between the time when water is added to the cement and the time at which a needle used for testing final setting upon applying gently to the surface of the test block, makes an impression thereon, while the attachment of the needle fails to do so, is known as final Setting Time of Cement.

Important Notes on Setting Time Test of Cement• o It is essential that cement set neither too rapidly nor too slowly. In the first case there

might be insufficient time to transport and place the concrete before it becomes too rigid. In the second case too long a setting period tends to slow up the work unduly, also it might postpone the actual use of the structure because of inadequate strength at the desired age.

• o Setting should not be confused with hardening, which refers to the gain in mechanical strength after the certain degree of resistance to the penetration of a special attachment pressed into it.

• o Setting time is the time required for stiffening of cement paste to a defined consistency.• o Indirectly related to the initial chemical reaction of cement with water to form aluminum-

silicate compound.

• o Initial setting time is the time when the paste starts losing its plasticity.

• o Initial setting time test is important for transportation, placing and compaction of cement concrete.

• o Initial setting time duration is required to delay the process of hydration or hardening.• o Final setting time is the time when the paste completely loses its plasticity.

• o It is the time taken for the cement paste or cement concrete to harden sufficiently and attain the shape of the mould in which it is cast.

• o Determination of final setting time period facilitates safe removal of scaffolding or form.

• o During this period of time primary chemical reaction of cement with water is almost completed.

(4) Compressive Strength test of Cement:

This test is very important. In this test, three moulds of (face area 50 cm2) are prepared and cured under standard temperature conditions and each cube tested by placing it between movable jaws of the compressive strength testing machine. The rate of increasing load is zero in the beginning and varies at 350 kg/cm2 per minute. The load at which the cube gets fractured divided by the cross sectional area of the cube, is the compressive strength of the cube. The average of the compressive strengths of three cubes is the required compressive strength of the cement sample.

Cement Sector of Bangladeshref:

Research Report: Cement Sector of Bangladesh Date: April 05, 2011

Bangladesh cement industry is the 40th largest market in the world.

Per capita consumption remains poor when compared with the world average; only 65 kg (FY2009) while our neighboring countries, India and Pakistan, have per capita consumption of 135kg and 130 kg respectively.

Four major costs are associated with the production of cement as provided:

Cost elements % of cost of sales Power and fuel costs 10% Raw material costs (mainly clinker) 75% Transportation costs 5% Other expenses 10%

The common technology which is widely used in our industry from the year 2003 is Portland Composite Cement (PCC) which is made following European Standard Methods (ESM). Earlier, Ordinary Portland Cement (OPC) had been used which was made following the American Standard Method (ASM). PCC gives equal strength and durability like OPC. The basic difference between them is in the manufacturing technology. Only 65%-80% of clinker is required to produce PCC while 95% of clinker is required to produce OPC. So, worldwide PCC has become popular which requires less clinker.

Currently, Heidelberg, Holcim and Lafarge are the leaders among multinational cement manufacturers and Shah and Meghna are the leading domestic manufacturers. Shah cement is the market leader with close to 14.20% of the market share, followed by Heidelberg with about 9.30% of the market share. During the 2010, many small local manufacturers like Premier, Seven Circle, Crown, Fresh and King cement increased their sales drastically riding on their benefits of economies of scale, backward linkage and aggressive marketing effort.

In Bangladesh, cement consumers are categorized as follows: 1. Individual home makers (25%) 2. Real estate developers (35%) 3. Govt. organizations, i.e., LGED, RHW etc. (40%)

Cement Consumption (kg) Per Capita

There were mainly four dominant players in the cement industry in the year 1998 that produced their own cement to meet the demand of their customers. These companies were: Meghna Cement (owned by Bashundhara group) Eastern Cement (currently known as Seven Horse) Chatok Cement Chittagong Cement (taken over by Heidelberg where the local brand is called Ruby)

Cost Elements

8.0 EXPORT OF CEMENT: SIZE OF EXPORT IS 260 K MT/YEAR Cement industry started export from FY2007. Currently, companies exporting cement to north-eastern states of India are as below: Shah Cement Holcim Bangladesh Limited Seven Circle Unique Cement MI Cement Confidence Cement Premier Cement Aramit

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