Alumina, silica, lime and iron oxide are the basic raw material for the manufacture of Portland cement. The component of Portland cement which first hardens is_____________________?

(A) 5CaO. 3 Al2O3 ()
(B) 3CaO. Al2O3 (X)
(C) 3CaO. SiO2 (X)
(D) 2CaO. SiO2 (X)

Answers: Alumina, silica, lime and iron oxide are the basic raw material for the manufacture of Portland cement. The component of Portland cement which first hardens is_ 5CaO. 3 Al2O3.