White cement is same as that of grey Portland cement but the only differ is in the colour and fineness. This colour of this cement is determined by its raw materials and the process of manufacture. In this article we study about manufacture, properties, uses and difference of white cement.
Manufacture of White Cement
The manufacturing process of white cement is same as that of grey cement, but the selection of raw material is an important part in the manufacturing process. The oxides of chromium, manganese, iron, copper, vanadium, nickel and titanium imparts the grey colour to the cement. In white cement manufacture, these raw materials are kept to least percentage.
Limestone and clay is used as a prominent raw material for the manufacture of white cement. The manufacture process are same as that of OPC cement, the only differences are the heat required for the burning of raw material is more and fineness is more.
Following Raw material are used to make white cement
- Lime Stone -High Carbonate & Low Iron.
- Clay – High Alumina and Low Iron
- Oil / Pet Coke / Rubber
- Gypsum / Salenile
Properties of White Cement
Table 1: Properties of white cement and their values.
|Setting Time||100 min|
|1 day||21 MPa|
|2 day||38 MPa|
|7 day||61 MPa|
|28 day||74 MPa|
|Compact Density||3150 kg/m3|
|Bulk Density||1100 kg/m3|
Uses of White Cement
- Used for prestige construction projects and decorative works.
- Used for coloured concrete with the use of inorganic pigments to produce brightly coloured concretes and mortars.
- Due to its whiteness, it finds its application in architectural beauty, interior and exterior decorations, floorings, ornamental concrete products such as idols while grey cement is mostly used for construction purposes.
- Used in roads due the property of high reflectiveness to add visibility to highway medians.
- White cement is also used in a high amount for manufacturing precast members. Beautiful precast members are made utilising the white Portland cement.
- They are also used widely for making cast stones of appealing appearance.
- White cement is comparatively a costly cement type and is, therefore, used only selectively.
Differences between White Cement and Grey Cement
Table 2: Difference between grey and white cement.
|Properties||Grey Cement||White Cement|
|Raw Materials||Raw materials contain a high amount of Iron Oxide and Manganese Oxide.||Raw materials contain a very little amount of Iron Oxide and Manganese Oxide.|
|Fineness||Usually less fine than white cement.||Usually finer than gray cement.|
|Kiln Fuel||Coal, petroleum coke, fuel oil, natural gas.||Oil is used to avoid contamination by coal ash.|
|Cost||Less expensive.||Expensive than gray cement.|