Cement is the binder material used for the making of concrete.Before starting construction purpose, we should know about the behaviour of each type of cement for construction and choose the best cement that would give its best performance for your construction purpose.
Different cement classification
1.Ordinary Portland cement
Ordinary Portland cement is most important types of cement classification for construction.The OPC is classified into three grades, namely such as 33 grade,43 grade and 53 grade.The grade depends upon the strength of cement tested at its 28 days in N/mm2.
The is done with the source of information from IS 4031-1988.If the 28-day strength not less than 33N/mm2 it is called 33-grade cement.If the 28-day strength is not less than 43 N/mm2 then it is called 43-grade cement.
If the 28-day strength is not less than 53 N/mm2, then it is called 53-grade cement.By using high-quality limestone modern equipment, it is possible to upgrade the quality of cement.
2.Rapid hardening cement
As the name indicates it develops strength rapidly.This cement is similar to ordinary Portland cement.The rapid hardening cement acquires strength rapidly, it acquires the desired strength at 3 days whether the same strength is only obtained after 7 days in ordinary portland cement.
This rapid strength is acquired by the higher fineness of grinding and higher C3S content and lower C2S content.Higher fineness of cement particles expose the greater surface area for the action of water and gives a higher rate of hydration.
Application of rapid hardening cement
- Formwork is required to removed early for re-use.
- Road repair works.
- In pre fabricated concrete construction.
- Extra Rapid hardening cement.
The extra rapid hardening cement is made by mixing calcium chloride with ordinary Portland cement.
The amount of calcium chloride should not exceed 2 percent of the weight of the rapid hardening cement.The cement should not be stored more than 1 month, also it should be compacted, transported and placed within 20 minutes after mixing.
This cement is very suitable for the construction work in cold weather, also it evolves large quantity of heat during setting and hardening time.The usage of extra rapid hardening cement in prestressing is prohibited.
3.Sulphate Resisting cement
The name itself, sulphate resisting cement is resisted to the action of sulphate such as manganese sulphate.
Sulphate react with hydrate of calcium aluminate to form sulphoaluminate and free calcium hydroxide to form calcium sulphate.Their reaction with cement caused cracks in the hardened concrete.
The remedy for the sulphate attack is the use of cement with low C3A and C4AF content, such cement is called sulphate resisting cement
Uses of Sulphate resisting cement
- Concrete used in the foundation and basement
- Concrete used in the marine condition
- Concrete used in the fabrication of pipes
- Construction of sewage treatment works
4.Portland pozzolana cement
The PPC is prepared by mixing OPC with 10 to 20 percent of the pozzolana materials.The pozzolana material is composed of siliceous or aluminous material
The pozzolana material has no cementitious properties.It can react with the calcium hydroxide liberated during the hydration process to form compounds possessing cementitious properties.The pozzolana material is finely divided materials.
It reduces the leaching of calcium hydroxide, and it produces less heat of hydration and offers greater resistance the attack of aggressive waters than ordinary Portland cement.
The calcium hydroxide is a useless compound in the cement, they are produced by a large number of calcium silicates.Such useless materials can be converted into cementitious property materials which improve the quality of concrete.
Advantages of PPC cement classification
The advantages of PPC cement are described below
- PPC consumes calcium hydroxide which causes leaching, it can be converted into useful compounds.
- It does not produce calcium hydroxide as much as OPC producing.
- In PPC the costlier clinker is replaced by cheaper pozzolanic material Hence economical.
- The heat of hydration is low
- The long-term strength is higher than the OPC
- PPC gives more volume of mortar than OPC
- The soluble calcium hydroxide is converted into insoluble cementitious products and resulting improvement in the permeability of the concrete.
The air-entraining cement is produced by mixing a ordinary portland cement with air entraining agent at the time of grinding.
The air-entraining cement materials are
- Alkali salt of wood resins
- Calcium salts of glues and other proteins
- Synthetic detergents
- Calcium lignosulfonate
- Animal and vegetable fats
The air-entraining cement modify the properties such as
- Resistance to frost action
- Improves the workability of concrete and reduces the sand fraction
- The air entrained concrete is more watertight than the non air entrained concrete
- Coloured Cement
Coloured Cement consists of Portland cement with 5-10 percent of pigment.The process of manufacture of coloured cement is nearly same as OPC