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INTRODUCTION
What is Portland Cement?
It is a hydraulic cement (cement that not only hardens by reacting with water but also forms a water-resistant product) produced by pulverising clinkers (diameters, 5-25mm) consisting essentially of hydraulic calcium silicates, usually containing one or more forms of calcium sulphate as an inter ground addition.
There are 8 types of Portland Cement namely I, II, III, IV, V, IA, IIA, IIIA characterised by their composition.
CHEMISTRY
Cement Composition
Phase compositions in Portland Cement are:
• Tricalcium Silicate (C3S)
• Dicalcium Silicate (C2S)
• Tricalcium Silicate (C3S)
• Tetracalcium Aluminoferrite (C4AF)
The actual components are often complex chemical crystalline and amorphous structures, denoted by cement chemists as ‘elite’ (C3S), ‘belite’ (C2S), and various forms of aluminates. The behaviour of each type of cement depends on the contents of these components.
Additives such as air-entraining agents, water reducers or retarders and other chemical admixtures can be added to change the properties of cement.
Approximate Word count = 775
Approximate Pages = 3.1
(250 words per page double spaced)
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