The raw materials used for the manufacture of Portland cement are

Portland cement is primarily manufactured from a mixture of calcareous and argillaceous materials. The three essential raw materials are lime (calcium oxide), silica (silicon dioxide), and alumina (aluminum oxide) [1][4]. Limestone serves as the primary source of lime (CaO), typically accounting for 60-67% of the cement mix. Silica (SiO2) and alumina (Al2O3) are sourced from clay, shale, or bauxite, contributing approximately 17-25% and 3-8% respectively. These components are heated at high temperatures (1300–1450°C) to form clinker, which consists of hydraulic silicates that provide the cement its strength [4]. While iron oxide is also a major component, the combination of lime, silica, and alumina forms the fundamental chemical basis of Portland cement [2]. Carbon dioxide is a byproduct of the calcination process rather than a raw material [3], and boric acid is not a standard constituent.

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Composition > p. 66
2. [4] https://www.sciencedirect.com/topics/materials-science/portland-cement
3. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 8: Nature of Matter: Elements, Compounds, and Mixtures > 8.5 What Are Minerals? > p. 129
4. [3] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Figure 1.4 > p. 8