JEE Main 2021 · 31 August · morning · Single correct · +4 / −1
The major component/ingredient of Portland Cement is :
- (a) tricalcium aluminate
- (b) tricalcium silicate
- (c) dicalcium aluminate
- (d) dicalcium silicate
Answer and solution
Answer (b) tricalcium silicate
Solution
Chemistry ma’am · 3 steps
Silicates, not aluminates, make up most of cement, and the tricalcium one is the biggest share.
- What cement is. Portland cement is made by heating limestone (CaO source) with clay (SiO₂ and Al₂O₃ source). The product is a mix of calcium silicates and calcium aluminates.
Component Formula Approximate share Tricalcium silicate 3CaO.SiO₂ about 51% Dicalcium silicate 2CaO.SiO₂ about 26% Tricalcium aluminate 3CaO.Al₂O₃ about 11% - Why it matters. Tricalcium silicate reacts quickly with water and gives cement most of its early strength. That is why it is the largest single ingredient.
- So. The major component of Portland cement is tricalcium silicate, option (b).
The idea to keep. For cement, remember the order 3-silicate > 2-silicate > 3-aluminate, roughly 51%, 26% and 11%. Silicates together are over three quarters of it.
Answer from the NTA final answer key. Solution by PrepWiser.