Cement chemistry proportions: identify the correct order and typical percentage proportions of the principal chemical constituents of Portland cement clinker

Introduction / Context:
The performance of cement is governed by the proportions of its major oxides: CaO (lime), SiO2 (silica), Al2O3 (alumina), and Fe2O3 (iron oxide). Recognizing their typical proportions is basic to cement technology.

Given Data / Assumptions:

• Representative proportions are approximate and vary with manufacturer.
• The sequence requested is in decreasing typical percentage.

Concept / Approach:
In Portland clinker, lime is the dominant constituent (~60–65%), followed by silica (~20–25%), then alumina (~4–8%) and iron oxide (~2–4%). The order Lime > Silica > Alumina > Iron oxide matches the ratio 63 : 22 : 6 : 3.

Step-by-Step Solution:
List typical ranges for CaO, SiO2, Al2O3, Fe2O3.Compare with options and choose the sequence that matches.Answer: Lime : Silica : Alumina : Iron oxide :: 63 : 22 : 6 : 3.

Verification / Alternative check:
Textbooks on cement chemistry present similar ranges; the selected ratio is a commonly cited representative set.

Why Other Options Are Wrong:

• Other sequences invert the dominant constituents and do not reflect actual clinker composition.

Common Pitfalls:

• Confusing compound percentages (C3S, C2S, etc.) with oxide percentages (CaO, SiO2, etc.).

Final Answer:
Lime : Silica : Alumina : Iron oxide :: 63 : 22 : 6 : 3