Proposta de ajuste da relação enxofre/álcalis para otimização do cimento portland: estudo da influência do So3 na mineralogia do clínquer e nas propriedades mecânicas

Abstract

This study aimed to analyze the influence of sulfur trioxide (SO₃) on clinker mineralogy and on the mechanical properties of Portland cement, using data from a cement plant. The research sought to propose an adjustment to the workable range of the Sulfur-to-Alkalis Ratio (SAR), and its methodology involved physicochemical analyses and a literature review. The analysis of the results indicated that SO₃ plays a complex and decisive role. A higher SO₃ content in the clinker reduced the cement strength at one day, but contributed to a significant increase in strength at 28 days. From a mineralogical perspective, the study concluded that SO₃ favored the formation of the M1 polymorph of alite over the M3 polymorph. The data showed that the M3 phase is associated with higher early strengths, while the M1 phase contributes to strength development at later ages. The study also observed that SO₃ increased clinker porosity but, paradoxically, raised the energy consumption during grinding, which may be related to the growth of C₃S crystals. As its main practical contribution, the study suggests that an ideal SAR range between 1.50 and 1.60 is essential to optimize the final strength of cement while mitigating operational risks, such as the formation of build-ups in the clinker kiln.