# The Role of Brownmillerite in Preparation of High-Belite Sulfoaluminate Cement Clinker
few results have been satisfactory. In fact, a third series of cement, named sulfoaluminate cement, was invented in the 1970s. Anhydrous calcium sulfoaluminate (C\({}_{4}\)A\({}_{3}\)$) is the main mineral in sulfoaluminate cement clinker. Sulfoaluminate cement clinker also has low calcination temperature and CaO content, which effectively reduces the use of fossil fuel and limestone [6]. At present, sulfoaluminate cement has been successfully used in emergency repair and construction projects, anti-seepage and plugging applications, construction in winter, GRC products, and other construction projects [7; 8], because of its fast setting, high mechanical performance, low alkalinity, microexpansion and corrosion resistance. However, a high-quality bauxite requirement, high expansibility and unstable strength growth have limited the sulfoaluminate cement production and application. Based on the characteristics of C\({}_{2}\)S and C\({}_{4}\)A\({}_{3}\)$ minerals, the combination of C\({}_{2}\)S and C\({}_{4}\)A\({}_{3}\)$ minerals in a high-belite sulfoaluminate cement (HBSC) system has been proposed to overcome the respective shortcomings of belite cement and sulfoaluminate cement [9; 10; 11; 12; 13; 14]. It is well known that an appropriate amount of brownmillerite can promote the sintering reaction and reduce the calcination temperature. In industrial-scale production, the aluminum material quality for HBSC is lower than that for sulfoaluminate cement, and higher Fe\({}_{2}\)O\({}_{3}\) usually exists in aluminum materials. Therefore, in this study, a large number of brownmillerite phases will be introduced in the firing process of HBSC. At the present time, the effects of tetradcium ferrite (C\({}_{4}\)AF) and brownmillerite on the sintering and properties of Portland cement clinker, high belite cement clinker and sulfoaluminate cement clinker have already been researched [15; 16; 17; 18; 19]. Some researchers pointed out that brownmillerite mainly influenced the later strength, while others believed that the role of brownmillerite in various types of cement should be correctly evaluated and understood. A poor cementitious property of brownmillerite was observed in high-alkalinity Portland cement paste, but its strength contribution was greater in low-alkalinity cement paste [20]. However, the role of brownmillerite in the preparation of HBSC clinker has not been made clear until now. This study aims to prepare a kind of green and low-carbon HBSC. Currently, the related research on high-belite sulfoaluminate cement is still in the laboratory stage, and it cannot be fully applied in production. The main reason is that the differing grades of industrial raw materials, especially changes in iron content, greatly influence its production and performance. In this study, low-grade aluminum material with high iron content was selected to investigate its influence on HBSC because it can improve the material selection and adaptation range for HBSC production. It can also promote this technology application to fill the gap between scientific research and application. In this study, HBSC clinkers containing different contents of brownmillerite were prepared. The role of brownmillerite in preparing HBSC clinker was investigated to provide references for the industrial production of HBSC clinker with high brownmillerite content.