Influence of Raw Material Fineness on Clinker Burnability and Cement Performance

The particle size of raw materials is crucial for clinker formation, ultimately affecting cement performance. However, the specific effects of the fineness of individual raw materials on clinker burnability remain insufficiently understood. In this study, the fineness of limestone, shale, and iron-bearing materials was systematically varied to explore its influence on raw meal burnability and the resulting cement properties. Raw materials were prepared with controlled residue levels (5-20%) retained on an 80 μm sieve. Their impact was evaluated based on free lime content (f-CaO), clinker phase composition, cement strength development, and hydration behavior. Among the variables studied, limestone fineness was found to be the predominant factor affecting f-CaO levels, confirming its dominant role in governing clinker burnability. In contrast, fineness adjustments of aluminosilicate and iron-bearing components produced comparatively minor effects. Despite variations in raw meal fineness, clinkers produced with sieve residues between 10% and 15% exhibited consistent phase compositions, primarily comprising tricalcium silicate (C₃S), dicalcium silicate (C₂S), tricalcium aluminate (C₃A), and tetracalcium aluminoferrite (C₄AF). Furthermore, cement pastes derived from these clinkers demonstrated similar setting times, mechanical strengths, and hydration product assemblages. These results highlight the robustness of cement performance with respect to moderate variations in raw material fineness, particularly when limestone fineness is adequately controlled.