Influence of silica crystallinity and fineness in clinker raw meal on the formation of tri-calcium silicate polymorphs

Abstract

This study aims to deepen the understanding of the formation of tricalcium silicate (alite) polymorphs in synthetic clinker, produced under controlled conditions that simulate industrial scenarios, with the goal of contributing to more sustainable practices in Portland cement production. The innovation of this research lies in the combined evaluation of the effects of crystallinity and particle size of silica—in the forms of crystalline quartz and amorphous silica gel, across different granulometric ranges—on the nucleation and stabilization of the M1 and M3 monoclinic polymorphs of alite. Using advanced characterization techniques such as laser granulometry, X-ray fluorescence, X-ray diffraction, and optical microscopy, it was demonstrated that increasing the silica particle size, regardless of crystallinity, reduces the alite content and promotes an increase in the content of free lime and belite. Furthermore, the silica particle size directly influences the size of alite crystals, while the interaction between crystallinity and particle size has a significant impact on the stabilization of alite polymorphs. These findings are essential for optimizing the clinker manufacturing process, potentially reducing energy consumption and promoting the production of more reactive forms of cement, thereby contributing to sustainability in the cement industry.

Keywords:
Alite; Crystallinity; Rietveld Refinement; Quartz