Maximum permissible limit of magnesia content in ordinary Portland cement is

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WBMSC Sub-Assistant Engineer (Civil) 05 Jun 2022 Official Paper

Answer 1

Concept-

Chemical Requirements for Ordinary Portland Cement, 33 Grade-

Characteristic	Requirement
The ratio of the percentage of lime to percentages of silica, alumina, and iron oxide	0.66-1.02
The ratio of the percentage of alumina to that of iron oxide, Min	0.66
Insoluble residue, percent by mass, Max	5.0
Magnesia, percent by mass, Max	6.0
Total sulphur content calculated as sulphuric anhydride, percent by mass, Max	3.5
Loss on ignition, percent by mass, Max	5.0
Chloride content, percent by mass, Max	0.1
Alkali content	0.05

So as per IS 269∶1989 for 33-grade cement weight of the magnesia is not more than 0.06 or 6 % in composition.