Cement is a substance used for binding and hardening other materials. Water and cement set and harden through a chemical reaction known as ‘hydration’. The process of hardening is described as ‘curing’, which requires particular conditions of temperature and humidity. Cement can be mixed with a fine aggregate and water to produce mortar, used in masonry construction as a bedding and adhesive to bind and fill the gaps between adjacent blocks of brick, concrete or stone. It can be also be mixed with water, aggregates (such as gravel, sand or rock), and sometimes admixtures, to form concrete, and can be used to make renders, screeds and so on. The ratio of water and cement will determine the overall strength and quality of the mix.
Different Types of Cement
1- Ordinary Portland Cement (OPC)
Ordinary Portland cement is the most common type of cement which is manufactured and widely used worldwide. It is used for all ordinary purposes such as making concrete, mortar, plaster etc. OPC is available in three different grades namely grade 33, 43 and 53.
Uses
Ordinary Portland cement is mixed with aggregates, and water to make concrete, which is an essential modern building material. It is also used to make mortar for joining masonry and plaster to give perfectly finished walls. OPC has many applications such as in the manufacturing of grout, wall putty, solid concrete blocks, AAC blocks, and other types of cement.
2- Portland Pozzolana Cement (PPC)
Portland Pozzolana Cement (PPC) is a variation of ordinary Portland cement (OPC), which includes a mixture of pozzolanic materials, OPC and gypsum. The different pozzolanic materials used are fly ash, rice husk ash, volcanic tuffs, etc. Fly ash is most commonly used pozzolanic material. The heat of hydration rate is lower in this type of cement. There are many advantages of PPC over PPC, which has made it prominent in the construction industry. Nowadays, some manufacturers are only manufacturing PPC.
Uses:
Portland pozzolanic cement is now used as a replacement of OPC. Apart from common applications, it is used in mass concrete constructions like high-rise buildings, underwater concrete structures such as bridges, piers, dams etc.
3- Rapid Hardening Cement
Rapid hardening cement attains high strength in early days as compared to OPC. It has other properties quite similar to that of Ordinary Portland cement, but it is a bit finer than OPC. It has more lime and C3S than OPC which helps in gaining strength early.
Uses:
Rapid hardening cement is used when there is a need to remove formwork at an early stage for saving the cost of construction. It is also used in prefabricated concrete construction.
4- Extra Rapid Hardening Cement
Extra rapid hardening cement is obtained by addition of calcium chloride to rapid hardening cement. Calcium chloride added helps in accelerating the hardening and setting processes. The compressive strength of Extra Rapid Hardening cement is about 25% higher than that of Rapid Hardening Cement at one or two days.
Uses:
Extra rapid hardening cement is used in cold weather concreting, to set the cement fast. It is also used in situations when formwork is to be removed early.
5- Quick Setting Cement
Quick setting cement sets faster as compared to OPC, but the rate of gain of strength remains the same. In these types of cement, the quantity of gypsum, which acts as a retarder is reduced. It has an initial setting time of 5 minutes and a final setting time of 30 minutes.
Uses:
This types of cement is used where a quick setting is needed in a very short period like underwater structures, cold and rainy weather conditions etc. Quick setting cement is also used in structural repairs where the setting is an important criterion.
6- Low Heat Cement
Low heat cement is obtained by reducing the content of C3A and increasing the content of C2A. The name itself indicates this types of cement will release low heat of hydration. Low heat cement has more initial setting time as compared to OPC.
Uses:
It is used in massive concrete construction like large footings, large raft slabs, gravity dams, thick pavements etc. Low heat cement is also used in the construction of hydraulic structures and retaining walls.
7- Sulphate Resisting Cement
Sulphate resisting cement is beneficial in the area where the concrete is vulnerable to sulphates attack. This types of cement have less contents of C3S and C4AF.
Uses:
Sulphate resisting cement is used where concrete has exposure to sea coast or soil or saline groundwater.
8- Portland Slag Cement
It is special blended cement with low heat of hydration. The by-product from a blast furnace, i.e. slag is used in the manufacturing of Portland slag cement. It is less expensive as compared to OPC. Portland slag cement has less heat of hydration as compared to OPC.
Uses:
It is used in mass concrete structures like dams, water treatment plants, marine and off-shore structures.
9- High Alumina Cement
High alumina cement is obtained by melting bauxite during the manufacturing process of OPC. It has a high compressive strength and is more workable as compared to OPC. It attains high strength in less time and has initial and final setting time of 3.5 hours and 5 hours respectively.
Uses:
This type of cement is used where concrete structures are subjected to high temperatures like workshop, refractory, foundries etc. Also, it can be used where concrete is subjected to frost action and acidic action.
10- White Cement
White cement is obtained by using raw materials which are free from iron oxide in the manufacturing of cement. Lime and china clay are used in more amounts in its manufacturing. White cement has all other properties similar to an ordinary Portland cement. It is expensive as compared to OPC.
Uses:
White cement is used for architectural purposes such as pre-cast curtain wall and facing panels etc. It is also used in making wall putty, tile grout, tile adhesive, etc. White cement is also used for external rendering as it provides a smooth and pleasing finish. It is also preferred for terrazzo flooring works.
11- Coloured Cement
Coloured cement is obtained by mixing ordinary portland cement with 5 – 10% mineral pigments. The pigments impart colours to the cement.
Uses:
This types of cement is widely used for decorative works in floors and ceiling. Coloured cement is commonly used in grouting of tiles. The cement is selected such that the colour of the grout and colour of tiles match perfectly for finishing the flooring.
12- Air Entraining Cement
Various air entraining agents such as resins, glues, sodium sulphate, etc. are added along with the clinker to produce air entraining cement. For the same water-cement ratio, air entraining cement has more workability as compared to OPC. This types of cement has more resistance to frost. But as it contains voids, it has less durability.
Uses:
Air entraining cement is used to fill up the gaps in concrete which are produced by the excessive amount of water during the casting of concrete members. It also used in cold weather when frost resistance in concrete is an important criterion.
13- Hydrophobic Cement
Hydrophobic cement is made by adding admixtures such as naphthalene soap, acidol, oxidised petroleum, etc. in the ordinary Portland cement. A water-repellent layer around the cement particles is formed, which would facilitate its storage for longer periods in extremely wet climatic conditions
Uses:
Hydrophobic cement is used in the construction of dams, spillways, underwater constructions. It can also be used in cold and rainy weather conditions.
14- Masonry Cement
This type of cement is obtained by added plasticising materials such as limestone, hydrated lime, etc. in the clinker during manufacturing of OPC. It remains in the plastic state for a longer time so that the masonry units can be placed properly.
Uses:
The masonry cement is often used in brick, concrete block and stone masonry construction; also used to produce plaster.
15- Expansive Cement
OPC shrinks after setting, due to which shrinkage cracks are formed. Expansive cement is used to avoid formation of shrinkage cracks. Expansive cement expands as it starts setting, and does not shrink during and after hardening. The purpose of this type of cement is to reduce the size and amount of shrinkage cracks.
Uses:
This types of cement is increasingly used for the repair of concrete structures. Expansive cement is used in grouting anchor bolts and prestressed concrete ducts.
16- Oil Well Cement
Oil well cement is manufactured by adding retarders to ordinary Portland cement. There is no chemical effect of oils on oil well cement. This cement can be used under high temperature and high-pressure conditions. It is costly, when compared with OPC.
Uses:
Oil well cement is used in the petroleum industry for cementing work during the drilling of gas and oil well. It is also used in filling up the gaps between rocks and steel casing of the oil wells.
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