Early hydration and mechanical properties of high-belite sulfoaluminate cement blended with ferrite

In this study, the effect of ferrite incorporation on the hydration of high-belite sulfoaluminate cement was investigated. The fluidity, compressive strength, heat of hydration, electrical resistivity, and scanning electron microscopy-energy dispersive X-ray spectroscopy results of the cement paste were evaluated. The results indicated that the incorporation of ferrite promoted the formation of strätlingite and accelerated the reaction of belite during the late stage. When the content of ferrite increased to 25 %, the heat release of the cement pastes at, 3 d decreased by 6 %, the compressive strength of the cement pastes at 28 d decreased by 65.6 %. The early hydration products of ferrite in cement pastes have multidirectional crystals (ettringite) and gels (calcium silicate hydrate). The Fe element was found to alter the structure of ettringite, resulting in an antler-like shape. Furthermore, according to the EDS results, ettringite contained more Fe, indicating that Fe migration was inclined toward the crystals. Thermodynamic modeling demonstrated that the growth of ettringite and strätlingite in the paste was promoted, which was consistent with the experimental results.