Correct Answer : 2-6%
Explanation : Portland cement is made by mixing substances containing CaCO3 with substances containing SiO2, Al2O3, Fe2O3 and heating them to a clinker which is subsequently ground to powder and mixed with 2-6 % gypsum.
Correct Answer : Option (D) : Aluminum oxide
Explanation : Powder form of aluminum oxide is used for fine polishing process. It is surface treatment process.
Correct Answer : Option (B) : IS 456-2000
Explanation : Option can be eliminated because there is no such code. Maximum nominal size of aggregates to be used in concrete may be as large as possible within the limits prescribed by IS 456:2000.
Correct Answer : Option (C) : 3-4
Explanation : This type of cement was first of all developed in U.S.A. It is recommended that air contents should be 03-04 % by volume.
