GREEN CEMENT - TYPES, APPLICATION AND ADVANTAGES

Green Cement

Green cement is a form of cement produced with the help of a carbon-negative manufacturing process.This cement is environmentally friendly product that minimizes carbon footprint of cement production.The concept of green cement emerged with the discovery of geopolymer cement in 1950s.Geopolymer cement is manufactured by using aluminosilicates instead of calcium oxide which damaging the environmental badely. The silicates can be obtained from industrial waste materials such as fly ash and blast furnace slag.

Green cement manufacturing reduces the cement intake.This cement reduces the carbon footprint upto 40%. Apart from reducing carbon dioxide emissions, the green cement manufacturing process also helps to maintain cement strength.It is composed of calcined clay and powdered limestone,it has desired characteristics such as reduced porosity and enhanced mechanical strength.

Benefits of Green Cement

1. Make Use of Industrial Waste

Fly ash a by-product of thermal power plant is produced in a large quantity which requires large area to disposed it.Green cement not only makes use of the fly ash waste but also protects the land from harmful environmental effects.

2. Requires Less Energy

The materials used in the traditional cement manufacturing process requires large amount of natural gas/coal for heating purposes.In green cement manufacturing industrial by-products are used as raw material which requires less energy. Green cement is more resistant to changes in temperature, therefore reducing the costs associated with both heating and cooling.

3. Lower Carbon Dioxide Emission

Clay, sand and pulverized limestone are some of the ingredients used in traditional cement.These ingredients requires heat releasing approx 5% to 8% of the total carbon dioxide.Green cement on the other hand does not requires as much heat during its production releasing upto 80% less carbon dioxide.

4. Long Lasting

Green concrete has a lower shrinkage rate and also becomes stronger far more quickly than concrete made with traditional cement.And since green concrete can withstand temperature as high as 2400℉, it makes building significantly more fire resistant.

Types of Green Cement

1. Ekkomaxx Cement

It is a type of green cement produced by Ceratech company in the USA.It is composed of 95% fly ash and 5% of renewable liquid additives.

The main characteristics of Ekkomaxx cement are high early strength, resilience, crack resistance, low chloride permeability, sulphate attack resistance, durability, corrosion resistance which is more than three times of conventional cement and the resistance to freezing and thawing is greater than that of normal cement.

2. Geopolymer Cement

Geopolymer, cement is a binding system that hardens at room temperature.It is also known as alkali-activated cement,is produced from aluminosilicates instead of the more environmentally damaging calcium oxide.The aluminosilicates are obtained from industrial by-product like fly ash.

3. Magnesium Oxychloride Cement

Magnesium oxychloride cement is also known as Solar cement.It is an environment friendly and carbon neutral cement.It is produced from magnesium oxide powder and concentrated solution of magnesium chloride.

The magnesium oxychloride cement has high compressive strength and set quickly and magnesium oxide absorb carbon dioxide from the atmosphere, but water can reduce its strength.However this weakness of MOC can be tackled to certain extent by introducing 15% of fly ash and the same amount of silica fume.The additives fill the pore structure in MOC which makes the concrete denser.Both strength and durability of concrete is improved considerably.

4. Ferrocrete

The ferrocrete cement is manufactured by mixing silica and iron which are waste byproduct from steel and glass industry.This material mixture is then cured with CO2, and consequently, it potentially becomes carbon negative materials.

5. Calcium Sulfoaluminate Cement

The calcium sulfoaluminate cement is a specially used in many applications where high early strength and fast setting development are necessary such as bridge decks, airport runways, patching roadways, tunneling etc.The calcium sulfoaluminate cement is produced of a kiln that requires a temperature of 2250℉ rather than 2500℉ of conventional cement.The calcium sulfoaluminate cement sets rapidely gain 28day strength of conventional concrete in 24 hours.

6. Cement Produced Using Superheated Steam

The superheated steam cycle will be used to modify the cement particles and render them more sensitive.The CO2 generated may be detected through this phase after it has been extracted.

7. Cement Produced With Reactive Hydrothermal Liquid Phase Densification

This form of cement is manufactured using the same raw materials as Ordinary Portland cement but at lower temperatures and through specific chemical reactions which generate less CO2 compared to convention Portland cement production processes.

Advantages of Green Cement

• Reduces the emission of CO2 as it does not requires as much heat during production, releasing upto 80% less carbon dioxide.
• Make use of industrial waste such as fly ash, silica fume and last furnace that may require several acres of land to dispose it.
• Requires less energy.

MAGNESIUM PHOSPHATE CEMENT - PROPERTIES, APPLICATION, ADVANTAGES AND DISADVANTAGES

Magnesium Phosphate Cement

Magnesium phosphate cement is a new type of phosphate repair materials with early strength and super rapid hardening ability. When compare magnesium phosphate cement with Portland cement, it has high bond strength, minimal dry shrinkage,good abrasion and frost resistance.Therefore, it is widely used in the quick repair of roads,bridges and airport runways.

The magnesium phosphate cement binder is produced from the reaction between magnesium oxide and phosphate in water at room temperature.The Magnesium phosphate cement is able to bond with different substances like concrete, metal, wood, asphalt and various plastics.

Properties of Magnesium Phosphate Cement

• Good durability
• High strength
• Low shrinkage rate
• Low permeability
• Low electrical conductivity
• Good thermal conductivity
• Abrasion resistance

Applications of Magnesium Phosphate Cement

• It is used in the production of high early strength concrete.
• It is used in repair of reinforced concrete stracture.
• It is used in shortcrete application.
• It is used in the production of magnesium based refractory concrete for fireproofing coatings.

Advantages of Magnesium Phosphate Cement

• It sets quickly and gain early strength.
• It has good corrosion resistance ability.
• It resist water penetration due to the formation of insoluble complexes.
• It has little shrinkage properties and hence shrinkage cracks are eliminated.
• Non combustible and resist fire.
• Excellent freeze and thaw resistance.

Disadvantages of Magnesium Phosphate Cement

• It can be easily washed off with plenty of water.
• It cannot be placed in a dry pack condition and hard troweling is not possible.
• It is very difficult to remove it once it has set.

TEST ON CEMENT AT CONSTRUCTION SITE OR FIELD TEST OF CEMENT

Quality test on cement at construction site is also called field test on cement.Sometimes it may be required to perform cement test at construction site at a very short period of time to check quality of cement based on colour,smoothness,feel etc.These test does not provided accurate results but it provides some basic ideas regarding the quality of cement.

Test on Cement at Construction Site

• Date of manufacturing test
• Color test
• Smoothness test
• Temperature test
• Float test
• Presence of lumps
• Smell test
• Setting test
• Strength test

1. Date of Manufacturing Test

As the strength of cement reduces with age,the date of manufacturing of cement bags should be checked.

2. Color Test

The color of cement should be uniform.It should be grey in color with a light greenish shades. 

3. Smoothness Test

When cement is rubbed or touched in between fingers it should give a smooth feeling.If it felt rough it indicates adulteration with sand.

4. Temperature Test

If hand is inserted in a bag of cement or heap of cement, it should feel cool and not warm.

5. Float Test

If a small quantity of cement is throw in water, the particles should float for some time before it sinks.

6. Presence of Lumps

The cement should be free from lumps. Such lumps are formed by the absorption of moisture from the atmosphere.If any cement bags containing such lumps they are rejected.

7. Smell Test

Take a pinch of cement and smell it.If the cement contains clay and silt as an adulterant the paste will give an earthy smell.

8. Setting Test

A thick paste of cement with water is made on a piece of glass plate and it is kept under water for 24hr.It should set and not crack.

9. Strength Test

A block of cement 25mm x 25mm x 200mm long is prepared and it is immersed for 7 days in water.It is then placed on supports 15000 mm apart and it is loaded with a weight 340 N.The block should not show any sign of failure.

EXPANSIVE CEMENT - MANUFACTURE, PROPERTIES, TYPES AND USES

Expansive Cement

Expansive cement is a special type of cement when mixed with water,which forms a paste that, during and after setting and hardening increases significantly in volume.Shrinkage compensating concrete motor in an expansive cement concrete motor in which expansion if restained induces compressive stresses which approximately offset tensile stresses in concrete induced by drying shrinkage.

Manufacture of Expansive Cement

The process of manufacture of expansive cement is same as that of Portland cement,but the raw materials used for formation of clinkers are different.Firstly limestone and clay are heated together at a temperature of around 2600 ℉ and clinkers are formed and in the next batch limestone,calcium sulphate and buxite together heated  at a temperature about 2300 ℉,where sulfoaluminate clinkers are formed.These two clinkers are grounded together to form expansive cement, when this cement is exposed or mixed with water,sulfoaluminate expands in volume.

Types of Expansive Cement

There are three types of expansive cement:

1. K Type Expansive Cement

The raw material in this type of cement contains,Portland cement,anhydrous tetracalcium sulfate (C4A3S), calcium sulfate (CaSO4) and lime (CaO). which are grounded and expansive cement is formed.

2. M Type Expansive Cement

In this type of cement, the Portland cement clinkers are grounded with calcium sulfate.

3.  S Type Expansive Cement

In this type of cement a Portland cement containing a high computed tricalcium aluminate (C3A) content and an amount of calcium sulfate above the usual amount found in Portland cement.

Physical Properties of Expansive Cement

PROPERTIES	VALUE
Setting Time	75 min
Air Content	12 %
7 DAYS EXPANSION
Min	0.04 %
Max	0.10 %
COMPRESSIVE STRENGTH
7 Days	14.7 %
28 Days	24.5 %

Uses of Expansive Cement

• This cement is used in large continuous floor slabs without joints.
• In the construction of pre-stressed concrete compound.
• Used in the construction of water retaining structure.
• Used in repairing of damaged concrete surfaces.
• Used in grouting of anchor bolts.

AIR ENTRAINED CEMENT - MANUFACTURE, PROPERTIES, ADVANTAGES AND DISADVANTAGES

Air Entrained Cement

Air Entrained Portland Cement is a special cement that contains billions of microscopic air bubbles per cubic foot.These air bubbles provides the space for expansion of minute droplets of water in the concrete due to freezing and thawing.The air bubbles increase the workability of the concrete and lower the water cement ratio.However because of air entrained the strength of concrete reduces and as such the quantity of air so entrained should not exceed 5%.

Manufacture of Air Entrained Cement

The manufacturing process of air entrained cement is same as OPC cement,when the cement clinkers are formed, during grinding process the cement clinker are added with some air entraining materials which makes the cement as air entrained cement.

Air Entraining Admixture

• Natural wood resins
• Vinsol resin and Darex 
• Animals and vegetable fatty acids.
• Water soluble soaps of resin acids.
• Aluminium powder,zinc powder and hydrogen peroxide.
• Alkali salts or sulphated and sulphonated organic compounds.
• Sodium salts of petroleum sulphonic acids,hydrogen peroxide and aluminium powder etc.
• Animals and vegitables fats and oils, such as olive oil and their fatty acids.

Properties of Air Entrained Cement

1. Workability

The workability property of air entrained cement is high due to the air bubbles which act as lubricant betweeen aggregates,which reduce water and sand requirements and increase the strength of concrete.

2. Strength

In air entrained cement water cement ratio is kept low and hence the strength parameter of the concrete is not compromised.

3. Freezing and Thawing Durability

In cold condition,due to low temperature the water inside the concrete freezed and expands.The expansion of water as it freezes in concrete can create enough pressure to rapture the concrete.These entrained air bubbles serve as reservoirs for the expanded water,thereby relieving expansion pressure and preventing concrete damage. 

4. Sulphate Resistance

The resistance ability of sulphate attack is high in the air entrained cement as the water cement ratio can be kept low which initiates the sulphate attacks.

5. Abrasion Resistance

Air entrained concrete has the same abrasion resistance as that of non air entrained concrete of the same compressive strength.Abrasion resistance increases as the compressive strength increases.

6. De-Icing Resistance

In the sloped structure,the ice is formed on the building.To remove these ice, de-icing chemicals are used.When we used this chemicals it forms a layer of scales in the concrete.Because entrained air prevents scaling caused by de-icing chemicals and is recommended for all applications where the concrete contacts de-icing chemicals.

Advantages of Air Entrained Cement

• Workability of concrete increased.
• Reduced bleeding and segregation.
• Improved cohesiveness of concrete.
• Reduces cracks formation in the concrete surface.

Disadvantages of Air Entrained Cement

• The strength of concrete decreases.
• The use of air entraining agent increases the porosity of concrete thereby reducing the unit weight.

HYDROPHOBIC CEMENT - MANUFACTURE, PROPERTIES AND USES

Hydrophobic Cement

Hydrophobic cement contains admixtures which decreases the wetting ability of cement grains.The usual hydrophobic admixtures are acidol,naphthensoap,oxidized petrolatum etc.Hydrophobic cement is obtained by grinding Ordinary Portland Cement clinkers with water repellent film-forming substance such as stearic acid and oleic acid in order to reduce the rate of deterioration when the cement stored under unfavourable conditions.It is also known as Hydrophobic Cement.

Manufacture of Hydrophobic Cement

Hydrophobic cement is manufactured from ordinary portland cement clinkers.After grinding cement into fine particles these fine particles are sprayed in one direction and water repellent film forming substance such as stearic acid or oleic acid is sprayed from opposite direction.Using this method each particle of cement gets uniformly coated with repellent film forming substance.This layer protects cement from the bad effect of moisture during storage and transportation.

Properties of Hydrophobic Cement

PROPERTIES	VALUE
Fineness	350m2/kg
SOUNDNESS
Lechatelier (mm)	10mm
Autoclave	0.8%
SETTING TIME
Initial Setting	30min
Final Setting	600min
COMPRESSIVE STRENGTH
3 Days	16 MPa
7 Days	22 MPa
28 Days	30 MPa
Water Absorption	0.3-1  %

Uses of Hydrophobic Cement

• Used in water treatment plant.
• Used in dams and retaining walls.
• Used in hydro technical construction.
• Used in marine structures. 
• Used in mass concrete work.
• Used in longer storage periods and extremely wet climatic condition.

Advantages of Hydrophobic Cement

• Its strength is same as that of ordinary cement after 28 days.
• It sets and hardens fast,normally three minutes after being mixed with water.
• It is used in the construction of water structures such as dams,spillway etc.
• It is used in cold climatic conditions.

Disadvantages of Hydrophobic Cement

• It can not be used when temperature is below 40℉.
• It does not work on frozen surfaces.
• It required skilled labour.
• It is very costly.

WHITE CEMENT- MANUFACTURE, PROPERTIES AND USES

White Cement

White cement or White Portland cement is same as grey Portland Cement the only difference is in its colour and fineness.The colour of white cement is determined by its raw materials and the manufacturing process.Metal oxides,primarily iron and manganese,influence the whiteness and undertone of the materials.

India is the 5th largest producer of White Cement with appox 1 metric ton produced per year.

Manufacture of White Cement

The manufacture of white cement is same as that of grey cement.The raw materials such as limestone and clay are used as prominent materials along with least percentage of chromium,manganese,iron, copper. vanadium,nickel and titanium.The manufacture process are same as that of Ordinary Portland

Cement.White cement is produced at temperature over and around 1450-1500℃.This temperature is more when compared with ordinary grey cement that is why heat required for burning is more and fineness is more.

Properties of White Cement

PROPERTIES	VALUE
Fineness	395 m2/kg
Setting Time	100 min
COMPRESSIVE STRENGTH
1Day	21 MPa
2 Day	38 MPa
7 Day	61 MPa
28 Day	74 MPa
Compact Density	3150 kg/m3
Bulk Density	1100 kg/m3
Brightness	87 %

Uses of White Cement

• It is used for decorative works.
• It is used in architectural decorative designs.
• It is used in flooring.
• It is used in Tile grouting.
• It is used in making sculptures.
• It is used as sealants.

BLAST FURNACE SLAG CEMENT - MANUFACTURE, PROPERTIES, ADVANTAGES, DISADVANTAGES AND USES

Blast Furnace Cement

Blast Furnace Cement is the mixture of Ordinary Portland Cement and fine granulated blast furnace slag.This slag is obtained in steel plant as the by product of steel making is produced during the seperation of the molten steel from impurities in steel making furnaces.

About 70% of slag is used in the manufacturing of blast furnace cement.Although blast furnace slag cement has low heat of hydration and it gives better resistance to chloride,sulphate and alkalies attacks.

Manufacture of Blast Furnace Cement

Ground granulated blast furnace slag cement (GGBFC) is obtained as a by products in the extraction of iron from its ore.The process of extraction of iron is called blast furnace.The slag that is obtained by quenching molten iron slag from a blast furnace in water or steam,to produce a glassy,granular product that is then dried and ground into a fine powder.

Constituents of the Ground Granulated Blast Furnace Slag Cement

CONSTITUENTS	PERCENTAGE BY MASS
CaO	38-50%
SiO2	27-39%
Al2O3	8-12%
MgO	Less than 10%

Properties of Blast Furnace Slag Cement

Density (g/cm3)   - 3.04

Specific Surface Area (cm2/g) -4050

SETTING TIME:

Initial Setting -  60 min

Final  Setting - 600 min

COMPRESSIVE STRENGTH (N/mm2)

  3 Days    - 23.5

  7 Days   - 36.1

28 Days  - 62.4

CHEMICAL COMPOSITION (%)

Magnesium oxide - 2.88

Sulphur tri oxide  - 2.19

Ignition loss          - 1.47

Uses Of Blast Furnace Slag Cement

1.It is used in ready mix concrete plants.

2.It is used in sub-structure,marine structure and pre-cast piles because it prevents sulphate and chloride attacks.

3.It is used in foundation because it requires low heat of hydration.

Advantages Of Blast Furnace Slag Cement

1.It provides good resistance to chemical attacks.

2.It provides good resistance to alkali-silica reaction.

3.Greater durability and reduced permeability due to fineness.

4.Initial setting time is more due to slow hydration process.

5.High workability (Due to its capicity to fill pores efficiently).

6..More economical compared to OPC.

7.Eco-friendly.

Disadvantages of Blast Furnace Cement

1.Initial Strength is low,so it cannot be used in RCC works.

2.It cannot be used in repair works because its initial setting time is high.

SULPHATE RESISTANT CEMENT- PROPERTIES,ADVANTAGES ,DISADVANTAGES AND USES

Sulphate Resistant Cement

Sulphate Resistant 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%,which reduces the formation of sulphate salts.The reduction of sulphate salts lowers the possibility of sulphate attack on the concrete.

Properties of Sulphate Resisting Cement

Fineness - 280+ or -10 sqm/kg

Setting Time:

Initial - 80  min

Final  - 240 min

Soundness:

Lechatelier (mm) - 2     (max)

Autoclave              - 0.25 (max)

Compressive Strength:

 3 Days  - 30+ or -3

 7 Days  - 45+ or -3

28 Days - 65+ or -3

Tri calcium aluminate- 0.035

Magnesia                         - 0.02

Loss on ignition            - 0.02

Characteristics of Sulphate Resisting Cement

1.It provides maximum resistance to chloride ions,hence reduce the risk of corrosion in reinforced steel.

2.It increased workability and pumpability.

Uses of Sulphate Resisting Cement

1.It is used in foundation.

2.It is used in piling work.

3.It is used in effluent treatment plants.

4.It is used in the construction of chimney & cooling towers.

5.It is used in the construction of building near seacoast.

6.It is suitable for underground works where sulphate is present in the soil and water.

Advantages of Sulphate Resisting Cement

1.It protects the structure from the sulphate attack.

2.It has very high compressive strength.

3.Very low heat of hydration helps to avoid shrinkage cracks.

4.High durability under aggressive conditions.

5.Good for the construction of underground structure where sulphate resistant is needed much.

Disadvantages of Sulphate Resisting Cement

1.Not suitable for marine construction.

2.Not ideal for the area where their is a danger of chloride attacks.

3.Curing should be done properly with great care for min 8-10 days.

4.It is costly.

RAPID HARDENING CEMENT- MANUFACTURE, PROPERTIES, ADVANTAGES, DISADVANTAGES AND USES

Rapid Hardening Cement

Rapid Hardening is a special type of cement that achieves high strength in less time as compared to Ordinary Portland Cement.Normally the strength produced by rapid hardening cement in 3 days is equal to 7 days strength of Ordinary Portland Cement with same water cement ratio.

Manufacture of Rapid Hardening Cement

The manufacture of rapid hardening cement is done by dry process of cement manufacture.The raw materials such as limestone and shales are used.The limestones and shales are heated at extremely high temperature to form clinkers,then these clinkers are mixed with small amount of gypsum and grinded into very fine particles to form rapid hardening cement.

The reason behind developing early strength is the increase of Tricalcium aluminate (C3A) and Tricalcium silicate (C3S) and due to increasing the fineness (min 3250 cm2/gm) of the cement.Increase the fineness of cement and the amount of C3A and C3S will result in a higher rate of hydration and rapid gaining of strength.

Properties of Rapid Hardening Cement

1.It gains strength faster than OPC.

2.Its initial setting time is 30 mins and final setting time is 600 mins which is same as OPC.

3.The specific surface of rapid hardening cement is greater than 3250 cm2/gm.

4.This cement is lighter and costiler than OPC.

Uses of Rapid Hardening Cement

1.It is used where high early strength is required.

2.It is used where formwork has to be removed early.

3.It is used in cold weather condition because rapid evolution of heat during hydration protects the concrete against freezing. 

Advantages of Rapid Hardening Cement

1.It requires less curing time.

2.It is resistance to sulphate attacks.

3.Rapid hardening cement is used in construction of road pavements so that traffic can be opened early.

4.It is used in the manufacturing of precast slabs,posts,electric poles etc so that formwork has to be removed early as possible.

Disadvantage of Rapid Hardening Cement

1.In mass concreting rapid hardening cement is avoided because it creates a large amount of heat which may leads to stracture cracks.

2.The cost of rapid hardening cement is higher than OPC.

QUICK SETTING CEMENT & USES

Quick Setting Cement & Uses.

Quick setting cement is a the types of cement as the name indicates,these types of cement are used where quick setting is required.In this cement setting time is very high as compare to ordinary portland cement. Initial setting time is 5 min and final set achived in 30 min. 

The quick setting cement is manufactured by grinded cement clinkers with aluminium sulfate,which accelerates the setting time of cement.Aluminium sulphate is used as an accelerating admixture (1% to 3%) by weight of cement clinkers.

The mechanism of function of aluminium sulphate is that it increases the rate of hydration of Tricalcium silicate (C3S) and Tricalcium aluminate (C3A) phase of cement,thereby providing earlier heat evolution and strength development.It acts as a catalyst in the hydration of tricalcium silicate (C3S) and Tricalcium aluminate(C3A). 

Concrete specimens with varying percentage of aluminium sulphate were tested for compressive strength,splitting tensile strength and flexual strength.

Uses of Quick Setting Cement

1.It is used in underwater constructions.

2.It is used in river bridge constructions.

3.It is used for fixing concrete steps.

4.It is used where quick strength is required in short duration.

5.Used in higher temperature where water evaporates easily.

6.It is used in cold and rainy weather conditions.

Advantages of Quick Setting Cement

1.Quick setting cement has high resistance towards water.

2.The amount of water required during hydration is also low.

3.Work can be finished in short period of time.

Disadvantages of Quick Setting Cement

1.Due to the quick setting property it should be placed quickly within its initial setting time (5min) otherwise the concrete paste start setting and is very difficult to place concrete.

2.Due to quick setting a large amount of heat emitted during hydration of cement which may leads to shrinkage cracks.

3.Due to the present of sulphur in the cement may leads sulphate attack on the  reinforcement.

4.It is costly as compared to OPC.

5.It is not widely available.

LOW HEAT CEMENT - COMPOSITION, PROPERTIES, ADVANTAGES, DISADVANTAGES AND USES

Low Heat Cement

Low Heat Cement is a special tailored cement which generates low heat of hydration during setting.This cement is less reactive than Ordinary Portland Cement because it is obtained by increasing the proportion of C2S and reducing the proportion of C3S and C3A.This reduction in the content of more rapidly hydrating compounds C3S and C3A results in a slow development of strength but the ultimate strength is the same as that of ordinary Portland cement.As per Indian Standard Specification the heat of hydration of low heat cement shall be:

      7  Days - Not more than 65 calories per gram.

     28 Days - Not more than 75 calories per gram. 

Composition of Low Heat Cement

Low Heat Cement contains 5% of Tricalcium aluminate (C3A) and 46% of Dicalcium Silicate (C2S).

Properties of Low Heat Cement

ITEM	STANDARD VALUE
Specific Surface Area	250  m2/kg Min
Initial Setting	60  Min
Final Setting	12  hours Max
Compressive Strength at 7 Day	13   Mpa Min
Compressive Strength at 28 Day	42.5Mpa Min
Breaking Strength at 7 Day	3.5  Mpa Min
Breaking Strength at 28 Day	6.5  Mpa Min
Heat of Hydration at 3 Day	230 KJ/kg Max
Heat of Hydration at 7 Day	260 KJ/kg Max

Characteristics of Low Heat Cement

1.Low heat of hydration is 20% lesser than OPC.

2.The amount of water required for hydration is low.

3.Initial strength is low but high grouth rate of final strength.

4.High workability is obtained as the concrete is fluidly in nature.

5.Excellent impact erosion.

6.Excellent wear resistance.

7.Excellent resistance to drying shrinkage.

8.Excellent resistance to rapture.

Uses of Low Heat Cement

1.Mainly used in constructing dams,large footings,large raft slabs,wind turbine plinths.

2.To make workroom surface of factories such as chemical plants and sulphuric acid factories.

Advantage of Low Heat Cement

1.It is used in hot weather condition.

2.Improvised durability performance.

3.Good resistant to sulphate attack.

4.Assists in minimising the potential for thermal cracking in thick concrete sections.

Disadvantage of Low Heat Cement

1.This cement cannot be used in the cold weather conditions.

2.Cost of the cement is higher than that of ordinary cement.

3.It will also need more curing time.

4.Initial strength gained is lower than that of OPC concrete,but the final strength is same as that of OPC.

HIGH ALUMINA CEMENT -MANUFACTURE,CHARACTERISTICS AND USES

High Alumina Cement 

High Alumina Cement also known as calcium aluminate cement or aluminous cement is composed of calcium aluminate.It is manufactured from limestone or chalk and bauxite.

High Alumina Cement (HAC) was first developed in 1925 by a cement producer name Lafarge in United Kingdom.Initially it was used particularly for marine construction because it has good resistant to chemical attacks.It become popular in the year 1950, 60s, 70s because of its property to developed strength rapidly.It was widely used in structural concrete such as pre-cast beams.

Composition of High Alumina Cement

Constituents	Percentage
Silica	3-8 %
Alumina	37-41 %
Lime	36-40 %
Iron Oxide	9-10 %
Titanium	1.5-2 %
Magnesium	1 %
Insoluble Resides	1 %

Manufacture of High Alumina Cement

The process of manufacturing of High Alumina Cement is different as compared to Ordinary Portland Cement.The raw materials used are bauxite,chalks and limestone.Bauxite is a residual deposite formed by weathering under tropical conditions of rocks containing aluminium.The raw materials are mixed in a required propertion and grinded into small fragments not larger than 100 mm.These lumps are fed in kiln and heated up to their fusion point which is 1600℃. The moltan materials fall down on steel plate and is send to cool down in rotary kiln.

These clinkers are then grounded finely in tube mills upto the fineness not less than 2500cm^2/gram is achived.

Characteristics of High Alumina Cement

1. It is very resistant to chemical attacks.

2. It has high durability in sulphuric acid.

3. Hardening property of this cement is high.

4. The pH level is low.

5. It has high resistant chemical corrosion that is why is widely used in marine construction,costal construction,sewage pipes etc.

6. The refractive index of this cement is high.

Uses of High Alumina Cement

1. Due to the property of rapid hardening.it is widely used in marine construction and sewer infrastracture.

2. It is also used as refractory concrete where it requirs more strength at very high temperature.

Advantage of High Alumina Cement

1. It has high compressive strength.

2. It can stand at high temperature.

3. It has good resistance against chemical attack.

4. High resistant to fire.

5. It evolves great heat during setting.It is therefore not affected by frost.

Disadvantage of High Alumina Cement

1.Its manufacturing cost is high.

2. As the heat evolution while setting is high,it cannot be used in mass concreting works.

DIFFERENT GRADES OF PORTLAND CEMENT AND ITS USES

Grade of Cement

A cement is a binder a substance used for construction that sets,hardens and adheres to other materials to bind them together.Cement generally refers to a very fine powdery substance made up of limestone,clay.bauxite & iron ore and may include shells,chalk,marl,blast furnace slag,slate etc.The raw ingredients are processed in cement manufacturing plants and heated to form a rock hard substance,which then grounded into a fine powder.Cement mixed with water causes a chemical reaction and forms a paste that sets and hardens to bind structures of building materials.

Now a days cement is an integral part of the urban infrastructure.Cement was first discovered in 1824 by Joseph Aspadin in England.Due to the similarity in colour and quality when harden like Portland stone Aspadin called it  Portland cement.Aspadin cement was nothing like modern Portland cement but was the first step in its development.Now there are 3 different Grade of Ordinary Portland Cement available in market.

The Grade of cement indicate the strength of cement.Strength is generally measured as compressive strength.

 Three Grade of OPC are;

• Grade - 33
• Grade - 43
• Grade - 53

GRADE -33

Grade 33 Portland cement refers that cement has a compressive strength of 33 N/mm^2 at the end of 28 days of curing. This grade has high workability as compare to the other grade.In motor for plaster and for masonry, the grade 33 was commonly used.

Fineness = 300 kg/m^2

Compressive strength after   3 days = 16 N/mm^2

Compressive strength after   7 days = 22 N/mm^2

Compressive strength after 28 days = 33 N/mm^2

 Grade 33 - Should always cover the specification (IS CODE 269).

GRADE - 43

Grade 43 Portland cement refers that cement has a compressive strength of 43 N/mm^2 at the end of 28 days of curing.Grade 43 Portland cement was generally used in reinforced cement concrete construction which also called as RCC.

Grade 43 cement is mainly used in;

• Ready mix concrete
• RCC works
• Pre-cast concrete
• Silos and chimneys

Fineness = 225 kg/m^2

Compressive strength after  3 days = 23 N/mm^2

Compressive strength after  7 days = 33 N/mm^2

Compressive strength after 28days = 43 N/mm^2

The Grade 43 - Should always cover the specification (IS CODE 8112).

GRADE - 53 

Grade 53 Portland cement refers that cement has a compressive strength of 53 N/mm^2 at the end of 28 days of curing.In grade 53 Portland cement chloride content is low and cement has a good ability to resist sulphate.The quantity of the cement is required less in volume because this grade has high strength as we compare to other Portland cement grade.

Grade 53 cement is mainly used in;

• RCC Bridges
• Pre-cast concrete
• Construction of industrial buildings
• Construction of roads and subways
• Concrete sleepers for railways

Fineness = 225 kg/m^2

Compressive strength after  3 days = 27 N/mm^2

Compressive strength after  7 days = 37 N/mm^2

Compressive strength after 28days = 53 N/mm^2

The Grade 53 - Should always cover the specification (IS CODE 12269).

CEMENT INGREDIENTS AND ITS FUNCTION

Cement Ingredients

INGREDIENTS	PERCENTAGE	AVERAGE
LIME (CaO)	60 To 67%	62
SILICA  (SiO2)	17 To 25%	22
ALUMINA (Al2O3)	3 To 8%	5
CALCIUM SULPHATE (CaSO4)	3 To 4%	4
IRON OXIDE  (Fe2O3)	0.5 To 6%	3
MAGNESIA (MgO)	0.1 To 4%	2
SULPHUR TRIOXIDE (SO3)	1 To 3%	1
ALKALIS 'OR' SODA & POTASH   (Na2 + K2O)	0.5 To 1.3 %	1

Chemical Compounds in Manufacturing of cement.

C3S (45-65%)  Tricalcium silicate       (3 CaO. SiO2)

C2S (15-35%)  Dicalcium silicate        (2 CaO. SiO2)

C3A (4-14%)   Tricalcium Aluminate (3CaO. Al2O3)

Functions of Different Ingredients of Cement.

LIME: Lime is called calcium oxide or calcium hydroxide.Deficiency in Lime reduces the strength of cement.

SILICA: Silica or silica dioxide is second largest quantity of cement.It helps in maintaining the          consistency & workability of cement.

ALUMINA: Aluminum or aluminum oxide it imparts quick setting property to cement.

CALCIUM SULPHATE: Present in form of gypsum in cement.It increase initial setting time of            cement.

IRON OXIDE: It provides hardness & strength to the cement.It also grant colour to cement.

MAGNESIA: Magnesia or magnesia oxide give colour to the cement.Excess of magnesia makes      cement sound.

SULPHUR: Sulphur or sulphur trioxide present in small quantity & make cement sound.

ALKALIES: Soda & Potash not present more than 1%.Excess quantity causes efflorescence.

PORTLAND POZZOLANA CEMENT- MANUFACTUREING, PROPERTIES, ADVANTAGES, DISADVANTAGES AND USES.

Portland Pozzolana Cement

Portland Pozzolana Cement is a varition of OPC cement. Pozzolana is a volcanic powder found in Italy near Vesuvius.A pozzolanic materials can be natural or artifical which contains silica and aluminous in a reactive form.

      1.Natural Pozzolana:

• Brunt clay
• Pumicite
• Diatomaceous earth

      2.Artifical Pozzolana:

• Fly ash
• Silica fumes
• Rice husk
• Blast furnace slag

Portland Pozzolana Cement is a king of blended cement which is produced by either intergrinding of OPC clinker along with gypsum and pozzolanic materials in certain proportion or grinding the OPC clinker, gypsum and pozzolanic materials separately and thoroughly blending them in certain proportions.

It may be further discussed as siliceous or siliceous and aluminous materials 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 cement properties.It is essential that Pozzolana be finely divided state as it is only then that silica can combine with calcium hydroxide in the presence of water to form stable calcium silicates which have cement properties.

Manufacture Process of Portland Pozzolana Cement:

The primary raw materials used for manufacture are limestone (CaCO2) & clay (SiO2,AI2,O3,Fe2O3) where it is crushed into fine particles,then fed into air swept ball mill in desired proportions and mixed it before sent to silios for storing.The mixture is then pre heated upto 800-1000C where calcinations of CACO3 to CaO takes place after that pre heated mixture is sent into kiln where the mixture is heated at 1450C in rotary kiln.The modules formed from the burning process called clinker.

The clinker is cooled by a rotary cooler.This clinker is now mixed with gypsum and pozzolana materials in the required proportion and thus the Pozzolana cement is obtained.

Properties of Portland Pozzolana Cement:

• Initial setting time   = 30  min (Minimum)
• Final setting time    = 600 min (Maximum) 

Compressive Strength:

          3  Days = 13 MPa  (Minimum)

          7  Days = 22 MPa  (Minimum)

         28 Days = 33 MPa  (Minimum)

• Drying shrinkage should not be more than 0.15%
• Fineness should not be less than 300 m2/kg
• Initial strength of PPC is less than OPC but final strength is equal to OPC
• PPC has lower rate of development strength than OPC

Uses of Portland Pozzolana Cement:

• Used in marine structure
• Used in hydraulic stracture 
• Construction near sea shore,dam construction etc.
• Used in pre-stressed and post-tensioned concrete member.
• Used in masonry works
• Used in plastering work.
• Used in manufacture of precast sewage pipes.
• Used in manufacture of precast sewage pipe.

Advantages of Portland Pozzolana Cement:

• Pozzolana cement have good resistance against sulphate attack.
• It is very fine cement hence good for plastering works.
• Pozzolana consists of silica material hence it reduce cost of cement making it economical to use.
• It is eco-friendly cement manufacture from natural recycled waste.
• It reduces the carbon monoxide emission from the concrete making it environmental friendly.

Disadvantage of Portland Pozzolana Cement:

• The initial strength is less,which effect the de-shuttering of supports early.
• PPC have less setting time compare to OPC.
• Reduction in alkanity reduces the resistance to corrosion of steel reinforcement.