Question

Four main oxides present in ordinary Portland cement are $CaO,A{l}_2{O}_{3}Si{O}_{2}andF{e}_2{O}_3.$ Identify the correct ascending order of their proportions in a typical composition of OPC

• A. $A{l}_2{O}_3,F{e}_2{O}_3,CaO,Si{O}_2$
• B. $A{l}_2{O}_3,CaO,F{e}_2{O}_3,Si{O}_2$
• C. $F{e}_2{O}_3,A{l}_2{O}_3,Si{O}_2,CaO,$
• D. $A{l}_2{O}_3,F{e}_2{O}_3,CaO,Si{O}_2$

Answer 1

The correct option is C $F{e}_2{O}_3,A{l}_2{O}_3,Si{O}_2,CaO,$

Constituents	Percentage	Average
$\text{1. Lime}\left(CaO\right)$	62 - 67%	62%
$\text{2. Silica}\left(Si{O}_2\right)$	17 - 25%	22%
$\text{3. Alumina}\left(A{l}_2{O}_3\right)$	3 - 8%	5%
$\text{4. Calcium sulphate}\text{(Gypsum) -}\left(CaS{O}_4\right)$	0.1 - 0.5%	0.3%
$\text{5. Iron oxide}\left(F{e}_2{O}_3\right)$	0.5 - 6%	3%
$\text{6. Magnesia}\left(MgO\right)$	1 - 3%	2 %
$\text{7. Sulphur Trioxide}\left(S{O}_3\right)$	1 - 3%	1%
$\text{8. Soda \& Potash}(N{a}_{2}O+K_{2}O)$	0.5 - 1.3%	1%