Calcium fluoride as an efficient mineralizer for low-temperature portland cement clinkering: a mechanistic mini review

Reducing the clinkering temperature of Portland cement is a key strategy for lowering energy consumption and CO 2 emissions. Among various mineralizers, calcium fluoride (CaF 2 ) has been widely reported as an effective additive for promoting clinker formation at reduced temperatures. This mini review summarizes recent mechanistic insights into the role of CaF 2 in facilitating low temperature alite (C 3 S) formation. Available evidence suggests that CaF 2 exerts its mineralizing effect through interconnected mechanisms, including enhanced lattice defect formation, accelerated ionic diffusion, and early liquid-phase development. Fluoride ions (F − ) are proposed to substitute for oxygen sites in the C 3 S structure, generating calcium vacancies that facilitate the C 2 S-to-C 3 S transformation at lower temperatures. At the melt scale, CaF 2 reduces melting temperature and viscosity, thereby improving ionic transport and phase combination. CaF 2 addition is also frequently associated with the preferential formation of high symmetry alite polymorphs under reduced thermal conditions. When combined with metal oxides such as TiO 2 , CuO, and ZnO, CaF 2 often exhibits synergistic effects that further enhance clinker formation efficiency. In addition, waste-derived CaF 2 has been shown to retain mineralizing activity comparable to natural fluorite, supporting resource efficiency and circular-economy approaches. Overall, CaF 2 is a promising mineralizer for low-temperature, energy-efficient, and low-carbon cement manufacturing, while its effectiveness remains system-dependent.