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
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.
Chemical composition
1.CaO
2.SiO2
3.Al2O3
4.Fe2O3
5.MgO
1.CaO
To control the strength and sounds CaO is utilised. 60 to 65% is its ingredients composition.
2.SiO2
The function of Sio2 is to give strength and its composition is 20 to 25%
3.Al2O3
This is responsible for quick setting. Its composition is 4 to 8%.
4.Fe2o3
It gives colour and helps the fusion of different ingredients. Its composition is 2 to 4%
5.MgO
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.
when tested
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.
1.Acid-resistant cement
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.
4.Expanding cement
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
+Bauxite).
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.
6.Hydrophobic cement-IS:8043-1991
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.
Advantages:
1.Reduces cost
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.
Uses:
1. Using this de-shuttering of concrete works can be done early.
Ashwini Kumar is a graduate in civil engineering from NIT Warangal. He has 8+ years of experience in the construction field.
He is the author, founder of the Easy Home Builds blog
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