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Building Materials - Engineering

Q1:

For the manufacture of Portland cement, the proportions of raw materials used, are

A lime 63% ; silica 22% ; other ingredients 15%

B lime 22% ; silica 63% ; other ingredients 15%

C silica 40% ; lime 40% ; other ingredients 20%

D silica 70% ; lime 20% ; other ingredients 10%.

ANS:A - lime 63% ; silica 22% ; other ingredients 15%

Lime(CaO)---> 60-67%.
Silica(SiO2)---> 17-25%.
Aluminium(Al2O3)---> 3-8%.
Iron oxide (Fe2O3)---> 0.5-6%.
Magnesia(MgO)---> 0.1-4%.
Sulphur trioxide (SO3)---> 1-2%.
Soda and potash (Na2O+K2O)---> 0.5-1.3%.
Gypsum (CaSO4.2H2O)---> 3-4%.