Cement types are available in the market. It is a ground material having adhesive, cohesive properties, act as an abiding medium for the discrete ingredients, used as a building material
Given below are the 13 cement types available in the market.
- OPC, Ordinary portland cement
- Acid-resistant cement.
- Blast furnace cement.
- Coloured cement.
- Expanding cement
- High alumina cement
- Hydrophobic cement
- Low heat cement
- Pozzolana cement
- Quick setting cement.
- Rapid hardening cement
- Sulphate resisting cement.
- White cement.
Manufacture of OPC, Ordinary Portland cement
By pulverising the stones and burning the stones containing lime carbonates, clay, and magnesium carbonates natural cement is obtained.
The content of clay in those stones varies from 20 to 40%.
Its colour is brown and its most suitable variety is known as Roman cement.
By burning a mixture of argillaceous and calcareous materials at a very high-temperature artificial cement is achieved. This calcined outcome is termed as Clinker.
Gypsum is added in small quantity to the clinker and it is then crushed into a very fine powder which is known as the Cement.
Alumina or Iron oxide, calcareous (chalk or limestone), argillaceous (clay or shale), and silica materials proper grinding is done.
At a temperature of 1300 degrees to 1500 degrees, the above mixture is burnt in a kiln.
Gypsum of about 2 to 3% is mixed to prevent flash setting & mixture is ground to required fineness.
To control the strength and sounds CaO is utilised. 60 to 65% is its ingredients composition.
The function of Sio2 is to give strength and its composition is 20 to 25%
This is responsible for quick setting. Its composition is 4 to 8%.
It gives colour and helps the fusion of different ingredients. Its composition is 2 to 4%
It imparts in colour and hardness. Its composition is 1 to 3%.
Bogue’s Composition of cement clinker
i. Tricalcium silicate, C3S.
The chemical formula of tricalcium silicate is 3CaO.SiO2. 45% is its ingredient composition.
ii. Dicalcium silicate, C2S.
The Chemical formula of dicalcium silicate is 2CaO.SiO2. 25% is its ingredient composition.
iii.Tricalcium aluminate ,C3A.
The Chemical formula of tricalcium aluminate is 3CaO.Al2O3. 11% is its ingredient composition in cement.
iv.Tricalcium alumnioferrite (C4AF).
The chemical formula of tricalcium aluminoferrite is 4CaO.Al2O3.Fe2O3.9% is its ingredient composition.
If the percentage of C3S is increased and that of C2S is decreased, high early strength is obtained.
The development strength becomes very slow if the C3S percentage is decreased and the percentage of C2S is increased.
The function of Bogue’s composition
The initial setting time is responsible by tricalcium aluminate, C3A
C3S is responsible for the early gaining strength.
From 14 days to 28 days the strength gaining is responsible by dicalcium silicate, C2S
C4AF gives a higher resistance of sulfates.
Grades of cement
Infield cement is available in three grades.
1. 33 grade OPC
The compressive strength when tested after 28 days reaches 33 N/mm2, then such type is termed as 33-grade OPC.
2. 43 grade OPC
The compressive strength when tested after 28 days reaches 43 N/mm2 , then such type is termed as 43-grade OPC.
3. 53 grade OPC
The compressive strength when tested after 28 days reaches 53 N/mm2, then such type is termed as 53 grade OPC.
The other cement types of details are given below.
An acid-resistant cement is composed of
a.acid -resistant aggregates such as quartz, quartiles etc.
b.An additive such as sodium fluosilicate Na2SiF6
and sodium silicate of an aqueous solution.
2.Blast furnace cement
Blast furnace cement is manufactured by mixing OPC clinker with blast furnace slag about 65% of the mass of the mixture.
It has a low heat of hydration, more durability and its better resistant to soil and water containing an excessive amount of sulphate’s, alkalies, metals as well as acidic water.
It is used in Marine works.
3. Coloured Portland cement-IS:8042-1989
Iron oxide is added to give red and yellow colour
Cobalt is added to give blue.
Manganese is added to give black colour.
The cracks in concrete will be evaded by applying a little volume of expanding cement
This cement is used for Hydraulic structures.
5.High Alumina Cement-IS:6452-1989
High alumina cement composition consists of calcareous material and aluminous material(lime
The following are the high alumina cement uses
1.high alumina cement is used in chimneys, kilns for withstanding huge temperature.
2. It is also used in waterworks and Undersea.
Hydrophobic cement is manufactured by grinding OPC clinker with 0.1 to 0.4% of oleic acid,
stearic acid or pentachlorophenol.
The storage of ordinary Portland cement (OPC) in humid places caused deterioration in the quality of cement.
For such places hydrophobic cement is used.
7.Low heat Portland cement-IS:12600-1989
By decreasing the percentage of C2A, C3S in OPC manufacture of Low heat cement is done.
For mass concrete work, this low heat portland cement is used. Example: dams.
The heat of hydration is comparatively lower than OPC.
8.Portland Pozzuolona cement-IS:1489-1991(part 1 and part 2)
Puzzuolana :Flyassh,burnt clay ad pumicite.
Puzzolana cement is manufactured by grinding Portland cement clinker with 10 to 25% of pozzuolana.
2. Increased workability less heat of hydration.
3. This portland pozzolana cement gives higher protection to dynamic water.
9.Quick cement lime.
The Gypsum percentage is reduced for manufacturing this type of cement.
After adding water to it, within 5 minutes this cement starts setting and become hard within 30 minutes.
10.Rapid Hardening cement-IS:8041-1990
Hardening of cement is the gaining of the strength of set cement.
7 days compressive strength of OPC is equal to 3 days compressive strength of this cement.
During the manufacture of this type, the property of Rapid hardening is obtained by adding a higher quantity of tricalcium silicate, C3S.
Setting time of this cement is same an Ordinary Portland cement.
1. Using this de-shuttering of concrete works can be done early.
2. Used in repair works of road.
11.Sulphate resisting Portland cement-IS:12330-1988
This cement is comparable to OPC but it contains higher silicate content and fewer volume of aluminates.
Sulphate resisting cement is used for underwater structures particularly exposed to alkali action.
White chalk and China clay are used as raw material which imparts white colour.
For all architectural works, this white cement is used.
Field tests for Cement types
The following test are done for different cement types.
Grey colour with a light greenish shade.
a. When it is touched with fingers it will feel like smooth power.
b. The cement feels cool when a hand is inserted in a heap or bag of cement.
c.If a tiny volume of cement will sink if it is thrown in a container of water and will not float on the surface.
3.Presence of Lumps
Cement should be free from lumps.
4.Permissible limits of impurities in water
i.Organic- 200 mg/L
ii.Inorganic -3000 mg/L
iii.Sulphates (SO3)-400 mg/l
iv.Chlorides(Cl)-2000 mg/L for PCC and 500 mg/L for RCC.
v.Suspended matter- 2000 mg/L
Laboratory tests for Cement types
1.Chemical composition test
a. (LSF)Lime Saturation Factor is the ratio of the percentage of Lime to the percentage of Alumina, Silica and Iron Oxide
When calculated by the formula: (CaO-0.7 SO3)/(28 SiO2+12 Al2O3+0.65 Fe2O3),
should not be lesser than 0.66 and not larger than 1.02.
b.The ratio of the percentage of Alumina (Al2O3) to that of Iron Oxide (Fe2O3) shall not be less than 0.66.
c. Insoluble residue weight shall not be higher than 4%.
d.Magnesia weight shall not be higher than 6%.
e.Total loss on ignition shall not be smaller than 5%.
2.Normal Consistency Test for cement types
If the consistency of cement permit to allow a Vicat plunger such consistency is termed as normal or standard consistency.
This Vicat plunger has length 50m, diameter 10mm and to penetrate a depth up to 35 mm from top or 5 to 7mm from the mould bottom.
Vicat apparatus: Its assembly consists of a plunger with 50m length,10mm dia, weight 300gm and with a depth of 40mm and dia 80 mm mould.
3.Setting times for cement types
Setting time is a shift of cement from liquid to a hard state.
This test is done to identify the decay of cement due to storage.
This test is carried out to determine the initial setting time and final setting time.
I.Initial setting time
i. The cement measuring 300 grams is used and combined in water.
ii. The cement paste is filled in the Vicat apparatus.
iii. The cross-section of the 1mmx1mm square needle is connected to the stirring rod of the Vicat apparatus.
iv. The nidle is quickly released and it is allowed to penetrate in cement paste.
v. The initial setting period should not be shorter than 30 mins for OPC
II. Final setting time
i. The paste of cement is developed and it is loaded in Vicat’s apparatus.
II. Attachment of annular collar to the needle is done to the Vicat apparatus moving rod and this needle is release gently.
iii. Final setting time should not be more than 10 hours for ordinary Portland cement. (OPC)
4.Soundness Test for cement types
The soundness test is done either by Le chatelier’s method or utilizing the Autoclave method.
5. Strength Test for cement types
a. Compressive strength test
Three cubes are tested for compressive strength at 1 day, 3 days,7 days and 28 days.
The compressive strength will be the average of the strengths of the three cubes for each period respectively.
The compressive strength of 33 grade OPC at 3 days, 7 day and 28 day is 16MPa,22MPa,33MPa respectively.
b. Tensile strength
of 6 numbers are tested and calculation of average tensile strength is done.
The application of load is done firmly and regularly starting from 0 and will increase
at the speed of 0.7 N/sq.mm in every 12 seconds.
OPC should have a tensile strength of not less than 2 MPa and 2.5Mpa after 3 days and 7 days respectively.
Generally, tensile strength is 10 to 15% of compressive strength.
6.Fineness Test for cement types
Fineness tests can be executed in three ways
a. Sieve method
b. Air permeability method
c. Wagner Turbidimeter tests
a. Sieve method
100 gm of cement specimen is taken and specimens are sliced in fingers.
The specimen placed on a 90-micron sieve and sieving is done continuously for 15 minutes.
The following limits should not be exceeded by cement residue by weight.
i.Ordinary Portland cement- 10% residue by weight
ii.Rapid Hardening cement-5% residue by weight
iii.Portland Pozzolana cement-5% residue by weight.
b.Air Permeability Method for cement types
The representation of cement fineness is done by its specific surface i.e Total surface area in Sq.cm per one gram of cement.
c.Wagner Turbidimeter Test different cement types
The dispersion of cement is done evenly in a glass rectangular tank loaded with kerosene.
Parallel light rays are passed through the solution which strikes the sensitivity plate of a photoelectric cell.
7.The Hydration test for different cement types
The calorimeter is equipment utilised to determine the hydration of cement
The hydration test for low heat Portland cement should not be more than 66 and 75 cal/gm for 7 and 28 days respectively.
8.Specific gravity test for different cement types
Le Chatelier’s flask is used for determining cement specific gravity.