What is Cement?
Defination: Crystalline Substance Which Have Adhasive And Cohesive Like Properties Is Called Cement.
Types Of Cement:
1).Ordinary Portland Cement (OPC):
➤ Ordinary portland cement has components like C3A, C4AF, C2S, C3S and small
➤ amount of Gypsum. It is used as building and structure material in construction.
2). Sulphate Resistant Cement:
✪ Higher C2S/C3S ratio
✪ Lowest C3A
✪ Can resist sea water corrosion & sulpate attack
3). Super Sulphate Cement:
➔ Mixture of small amount of lime, blast furnace slag & large amount of Gypsum.
➔ Used for sea water environment.
➔ It has very high water & sulphate resistance (because it reacts with excess
➔ Ca(OH)2 to form additional calcium silicate hydrate gel).
➔ Used to make highways.
4). Slag Cement:
➤ Mixture of portland cement clinkers, blast furnace slag & small amount of Gypsum.
➤ It has high water & sulphate resistance (because it reacts with excess
➤ Ca(OH) 2 to form additional calcium silicate hydrate gel).
➤ Used for sea water environment.
5). High Alumina Cement:
✪ Made by fusing lime stone & bauxite at 1550-1600°C
✪ Contains C2A and C2AS [Reason for sulphate and corrosion resistance:
✪ Absance of Ca(OH)2, formation of diff. aluminate crystals]
✪ Fast strength & resistance to sea-water and ground-water having sulphate.
✪ Resistant to dilute acid solutions, dilute sulphur solutions & hydrogen sulphide solutions.
6). Water-proof Cement:
➤ During grinding, water-proofing substance e.g. Calcium stearate, Aluminium stearate and Gypsum+tannic acid, Oleic acid are added to OPC.
➤ This prevents penetration of water under pressure and also prevents absorption of water.
7). Hydraulic Hydrated (Lime) Cement:
➔ (Hydraulic= hardens under water)
➔ Major constituent is Calcium hydroxide.
➔ C2S and C3A are minor ingredients.
➔ Used for brick-mortar compositions.
8). Acid Resistant Cement:
✪ Mixture of quartzite, Na/K silicon ester and setting agent such as KF, ethyl acetate etc.
✪ The resistance and cementing nature is due to silica sol-gel formation.
✪ The gel shrinks on drying, so it should be kept wet.
9). Sorel Cement (Magnesium Oxychloride Cement):
➤ Obtained from calcined magnesia (MgO) and Magnesium choride (MgCl2).
3MgO+MgCl2+11H2O➔3MgO.MgCl2.11H2O (Sorel Cement)
➤ Sets in 3-4 hours.
➤ Used in composite flooring.
➤ This floor is Non-slip, non-scratchable, durable, good for wax/oil polish
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10).White Portland Cement:
➤ No colour due to absence of iron compounds.
➤ It is made from raw materials free from iron oxide.
➤ It is expensive and used for joining marble pillars & blocks, manufacturing of tiles & mosaic work.
11).Coloured Cement:
✪ Different colours of cement are due to different ingredients:
➤ Blue : Cobalt Blue/Ultramarine
➤ Green : Chromium oxide
➤ Black : Carbon black/MnO2/Fe3O4
➤ Red : Fe2O3
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