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).

HOW TO CALCULATE THE WEIGHT OF HOLLOW STEEL PIPES

Given;
External Diameter (D) =150mm = 0.15m
Internal Diameter  (d)  =140mm = 0.14m
Thickness of pipe        =10mm
Length of pipe       (L) =1m
Density of Steel           = 7850 kg/m3

To calculate the weight of hollow steel pipe we have to apply following formula;

WEIGHT = VOLUME x DENSITY OF STEEL

First of all we calculate the volume

Volume = { Area x Length}
             = { 𝝅/4 (D^2 - d^2) } x Length
             = {3.14/4 (0.15)^2 - (0.14)^2 } x 1
             =  0.002276 cum

Now we have the volume = 0.002276 cum
Put this volume value in weight formula

Weight = Volume x Density of steel
            = 0.002276 m3 x 7850 kg/m3
            = 17.87 kg.

Hence 17.87 kg is the weight of 1m size steel hollow pipe whose external dia = 150mm & internal dia = 140mm.

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.

WHAT IS D²/162

DERIVATION OF D²/162

We know that D²/162 is being used for calculate unit weight of reinforcement per meter.

Given;

Density of steel bar = 7850 kg/m³ = 7850/1000X1000X1000 kg/mm³.

Length of steel bar = 1m =1000mm.

                            

Weight of bar per meter = {Area of steel X Length of steel bar} X Density of steel

                                       = {(𝝅/4 X D²)X Length of steel bar} X Density of steel

                                       = { 3.14/4 X  D² X 1000} X 7850/1000X1000X1000

                                       =  D² X 0.785 X0.00785

                                       =  D² X 0.00616225

                                       =  D²/ (1/0.00616225)

                                       =  D²/162.27  ≃   D²/162

                                           = D²/162   Proved

                                      

NOTE:This formula is only applicable for circular shape steel bar whose density is 7850 kg/m³.

FORMULA: Weight of steel bar formula = { D²/162 X Length of bar } KG.

                   (Note: Dia is always in mm & Length of bar is in meter)

Example: Find the weight of steel bar of dia 10mm & length of bar 12m.

Sol: Weight of steel = D²/162 X Length of bar 

                                = 10X10/162 X 12

                                = 100/162 X 12

                                =1200/162

                                = 7.40 Kg.

                                       

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.
  

WEIGHT OF STEEL BARS OF DIFFERENT DIAMETER

Derivation Of D2/162

ORDINARY PORTLAND CEMENT AND ITS CONSTITUENTS

Ordinary Portland Cement and Its Constituents.

Ordinary portland cement is one of the most widely used cement worldwide.This type of cement is manufactured to powder by mixing limestone and other raw materials which consists of argillaceous,calcareous and gypsum.

The ingredients are mixed in proportion of about two parts of calcareous materials to one part of argillaceous materials and then crushed and ground in ball mill in a dry state or mixed in wet state.The dry powder or wet slurry is then brunt in a rotary kiln at a temperature between 1400 degree C to 1500 degree C.The clinker obtained from the kiln is first cooled and then passed on to ball mills where gypsum is added and it is ground to requisite fineness acccording to the class of product.

This cement is available in market in three grades namely OPC 33,OPC 43 and OPC 53.It was developed by Joseph Aspdin in 1824 due to the similarity in colour and its quantity when it harden like Portland Stone.Portland stone is white grey limestone in island of Portland Dorset.

The Constituents of Portland Cement.

CONSTITUENTS	PERCENTAGE
Lime   (CaO)	60 To 67 %
Silica  (SiO2)	17 To 25 %
Alumina (Al2O3)	3 To 8 %
Calcium Sulphate (CaSO4)	3 To 4 %
Iron Oxide (Fe2O3)	0.5 To 6%
Magnesia (MgO)	0.1 To 4%
Sulphur Trioxide (SO3)	1 To 3 %
Alkalies (Na2 + K2O)	0.5 To 1.3 %

Uses of Portland Cement;

• Used in general construction purposes.
• Used in masonry work.