Evaluation of active silica-alumina content and reactivity in bayer process red mud

Abstract

Cement concrete plays a crucial role in modern construction, but its production process results in significant CO2 emissions, posing a substantial threat to the environment. To achieve green production, the use of industrial waste slag as a raw material for concrete has been widely accepted. This study focuses on the potential utilization of Bayer Process Red Mud (RM), a by-product of the alumina refining process, characterized by high alkalinity and low pozzolanic activity, limiting its application in cement concrete. The reactive activity of RM after calcination treatment was investigated to overcome this challenge and enhance the reactivity of RM. Fourier Transform Infrared Spectroscopy (FTIR) was employed to determine the degree of polymerization of RM at different calcination temperatures, and thus evaluate its pozzolanic activity. Integrating physical tests, chemical experiments, and microscopic analysis, this study thoroughly analyzes the relationships between different evaluation methods and finds a negative correlation between the degree of polymerization and the pozzolanic activity index, boasting a correlation coefficient of 0.904. The results indicate that RM exhibits the highest pozzolanic activity at a calcination temperature of 700 °C. Therefore, this method has been proven effective and can serve as a quick and convenient means of evaluating the pozzolanic activity of RM. The findings of this study are expected to promote the green development of the cement industry, better utilize waste slag resources, reduce CO2 emissions, and enhance the performance of building materials.