The raw materials used for the manufacture of Portland cement are
[amp_mcq option1=”Lime, silica and sulphur dioxide” option2=”Lime, silica and carbon dioxide” option3=”Lime, silica and alumina” option4=”Lime, silica and boric acid” correct=”option3″]
This question was previously asked in
UPSC NDA-2 – 2019
– These compounds are formed by heating a mixture of calcareous material (like limestone, source of CaO) and argillaceous material (like clay, source of SiO2 and Al2O3) in a kiln.
– Minor components like iron oxide and gypsum (added during grinding) are also involved but lime, silica, and alumina are the core raw material oxides.
– Clay provides silica (SiO2), alumina (Al2O3), and iron(III) oxide (Fe2O3).
– Sulphur dioxide and boric acid are not standard raw materials for Portland cement. Carbon dioxide is a byproduct of the calcination process, not a raw material that is added.