Portland cement (J. Aspdin) contains maximum % of CaO. Cement clinker contains

A) limestone & clay as raw materials

B) SiO2 to Al2O3 ratio 2.5 to 4.0 or [tex]\frac{CaO}{SiO2 + Al2O3+ Fe2O3}[/tex]

C) gypsum, fly ash and black ash (Na2CO3 + CaS)

D) [tex]Ca_{2}SiO_{4}-26%, Ca_{3}SiO_{5} -51%, Ca_{3}Al_{2}O_{6}-11% [/tex]