A cement is a binder, which is used for construction that hardens and adheres to other materials to bind them with each other together. There are two forms of cement: Geopolymer cement and Portland Cement. Cement is rarely used on its own, but rather to bind sand and aggregate together.
Cement is manufactured through a chemical reaction of calcium, silicon, aluminum, iron, and other ingredients. Common materials used to make cement contain limestone, shells, and chalk or marl combined with clay, slate, shale, blast furnace slag, and silica sand.
It hold of Calcium oxide(CaO),Silicon dioxide(SiO2),Aluminum oxide(Al2O3),Iron oxide(Fe2O3),Water(H2O),Sulphate(SO3). It do not have any specific formula.
Types of Cement:
Following are the different types of cement:
1 Rapid Hardening Cement:
Rapid hardening cement is the same as ordinary portland cement (OPC). It holds higher c3s content and smaller grinding. Therefore it provides greater strength at an early stage than OPC. The strength of this cement of 3 days is almost similar to the 7 days strength of OPC with a similar water-cement ratio.
The main profit of using rapid hardening cement is that the formwork can be removed within a few days and reused in other areas which saves the cost of formwork. This cement can be utilized in prefabricated concrete construction, bridges, road works, etc.
2 Low Heat Cement:
Low heat cement is made by increasing the ratio of C2S and by decreasing the C3S and C3A content. This cement is low reactive and its initial setting time is more than OPC. This cement is mostly taken out in mass concrete construction.
3 Sulphate Resisting Cement:
Sulphate resisting cement is manufacture by reacting C3A and C4AF content. Cement with this composition has high resistance to sulphate attack. This cement is used in the construction of the foundation, where subsoil contains very high ratios of sulphate.
4. White Cement:
White cement is a type of OPC, which is pure white in color and has practically the similar composition and strength as OPC, to obtain the white color the FeO content is considerably reduced. The materials used in this cement are limestone and china clay.
This cement is mainly used for interior and exterior decorative work like internal renderings of buildings, slabs, floorings, ornamental concrete parts, way of gardens, etc.
5. Portland Pozzolana Cement:
Portland pozzolana cement is produced by grinding together, portland cement clinkers and pozzolana with the sum of gypsum or calcium sulphate or by uniformly blending Portland cement and fine pozzolana.
It produces lesser heat of hydration and has more resistance to the attack of chemical agencies than OPC. Concrete made with PPC is suitable for construction in seawater, hydraulic works and for mass concrete works.
6. Hydrophobic Cement:
Hydrophobic cement is manufactured by the sum of water able to repel chemicals to ordinary portland cement in the process of grinding. Hence the cement stored does not get damaged during monsoon. This cement remains unchanged when transported during rains also. Hydrophobic cement is used for the construction of water structures such as dams, spillways, water retaining structures, etc.
7. Colored Cement:
This Cement is manufactured by adding 5- 10% pigments with portland cement during the time of grinding. Due to the different color combinations, this cement is used for interior and exterior works.
8. Waterproof Portland Cement:
It is manufactured by mixing with rapid hardening cement, a less percentage of metal stearates (Ca, Al, etc) at the time of grinding. This cement is utilized for the construction of water-retaining structures like tanks, reservoirs, retaining walls, dams, bridges, etc.
9. Portland Blast Furnace Cement:
In this cement, the normal cement clinkers are mixed up to 65% of the blast furnace slag for the grinding. This type of cement can be used in mass concrete work such as dams, foundations, and, construction in seawater.
10. Air Entraining Cement:
It is prepared by air-entraining agents such as resins, glues, sodium salts of sulphate with OPC cement.
11. High Alumina Cement:
High alumina cement (HAC) is a cement, produced by the mixing of bauxite and lime at a certain temperature. This cement is also called calcium aluminum cement. The compressive strength of this cement is high and has more workability than OPC.
12. Expansive Cement:
The cement which does not compress during and after the time of hardening but expands with time is known as expansive cement. This type of cement is usually used for grouting anchor bolts.
GRADE OF CEMENT WITH PROPORTION:
|TYPE||Grade||Mix Ratio||Compressive Strength (N/mm2)|
|Ordinary Concrete||M5||1 : 5 : 10||5|
|M7.5||1 : 4 : 8||7.5|
|M10||1 : 3 : 6||10|
|M15||1 : 2 : 4||15|
|M20||1 : 1.5 : 3||20|
|Standard Concrete||M25||1 : 1 : 2||25|
|High Strength Concrete||M55||Design Mix||55|