Types of Cement used in Construction Industry
In addition to ordinary cement, the following are the other varieties of cement.
Acid Resistance Cement: This is consists of acid resistance aggregates such as quartz, quartzite’s, etc, additive such as sodium fluro silicate (Na 2 SiO 6 ) and aqueous solution of sodium silicate. This is used for acid- resistant and heat resistant coating of installations of chemical Industry. By adding 0.5 percent of unseed oil or 2 percent of ceresil, its resistance to water is increased and known as acid water resistant cement.
Blast Furnace Cement: For this cement slag as obtained from blast furnace in the manufacture of pig iron and it contains basic elements of cement, namely alumina, lime and silica. The properties of this cement are more or less the same as those of ordinary cement and prove to be economical as the slag, which is waste product, is used in its manufacture.
Coloured Cement: Cement of desired colour may be obtained by intimately mixing mineral pigments withordinary cement. The amount of colouring may vary from 5 to 10 percent and strength of cement if it is exceeds 10 percent. Chromium oxide gives brown, red or yellow for different proportions. Coloured cements are used for finishing of floors, external surfaces, artificial marble, windows
Expanding Cement : This type of cement is produced by adding an expanding medium like sulpho – aluminate and a stabilizing agent to ordinary cement. Hence this cement expands where as other cement shrinks. Expanding cement is used for the construction of water retaining structures and also for repairing the damaged concrete surfaces.
High alumina Cement: This cement is produced by grinding clinkers formed by calcining bauxite and lime. The total content should not be less than 32 percent and the ratio by weight of alumina to lime should be between 0.85 and 1.30.
Hydrophobic Cement: This type of cement contains admixtures, which decreases the wetting ability of cement grains. The usual hydrophobic admixtures are acidol napthene soap, oxidized petrolatum etc when hydrophobic cement is used, the fire pores in concrete are uniformly distributed and thus the frost resistance and the water resistance of such concrete are considerably increased.
Low Heat Cement: Considerable heat is produced during the setting action of cement. In order to reduce the amount of heat,this type of cement is used. It contains lower percentage of tri calcium aluminates C 3 A and higher percentage of dicalcium silicate C 2 s. This type of cement is used for mass concrete works because it processes less compressor strength.
Pozzuolona Cement: Pozzuolona is a volcanic powder and the percentage should be between 10 to 30.
Quick Setting Cement: This cement is prepared by adding a small percentage aluminum sulphate which reduce the percentage of gypsum or retarded for setting action and accelerating the setting action of cement. As this cement hardness less than 30 minutes, mixing and placing operations should be completed. This cement is used to lay concrete under static water or running water.
Rapid Hardening cement: This cement has same initial and final setting times as that of ordinary cement. But it attains high strength in early days due to
- Burning at high temperature.
- Increased lime content in cement composition.
- Very fine grinding.
Sulphate Resisting Cement: In this cement percentage of tricalcium aluminates is kept below 5 to 6 percent and it results in the increase in resisting power against sulphate. This cement is used for structure which are likely to be damaged by sever alkaline condition such as canal linings, culverts, siphons etc.
White Cement: This is a variety of ordinary cement and it is prepared form such raw materials which are practically free from colouring oxides of Iron, manganese or chromium. For burning of this cement, oil fuel is used instead of coal. It is used for floor finish; plaster work, ornamental works etc.