above remains constant at 44.7 mass % as illustrated in the table here below. Behavior in cements Calcium aluminoferrite () has little effect upon the physical properties of cement. On hydration it forms hydrogarnet and hydrated iron oxide gel. In principle, this is a fast and energetic exothermic reaction, but precipitation of an insoluble layer of hydrated iron oxide upon the calcium aluminoferrite crystal surface forms a barrier to further reaction. In the case of Portland cement, subsequent slow reaction with dissolved sulfate forms an AFm phase, which has negligible strength-giving properties. In the case of calcium aluminate cements (CAC), the situation is less clear-cut, but there is little contribution to early strength. Calcium aluminoferrite is also present in calcium sulfoaluminate (CSA) cements, and again contributes no strength. See also The three other main mineral phases of Portland cement clinker are: Alite, , or Belite, , or Tricalcium aluminate, , or References Further reading Cement Calcium compounds Aluminium compounds Iron compounds Ferrites Oxide minerals