On hydration in the presence of calcium and sulfate ions, it forms the insoluble, fibrous mineral ettringite, which provides the strength in sulfoaluminate concretes, and/or monosulfoaluminate, and aluminium hydroxide.
The formation of ettringite from hydration in the presence of calcium and sulfate ions is a key factor contributing to the strength of sulfoaluminate concretes, as well as monosulfoaluminate and aluminum hydroxide.