Utilization of high-magnesium ferronickel slag activated by wet grinding in MKPC under humid conditions

Magnesium phosphate cement (MPC) is competitive in engineering repair and reinforcement. Enhancing the activity of furnace ferronickel slag (EFS), as a substitution of MgO, is of great significance for mitigating the high carbon emissions and high cost of MPC. In present study, the technology of wet grinding was provided to tackle the issues of sluggish dissolution and limited activity of EFS. The properties of EFS-MKPC composites were systematically analyzed cured in humid condition, including three different fineness levels of EFS (D50 : 14.5 μm, 10.5 μm, 6.12 μm) and three varying contents of EFS (15 %, 30 %, 45 %). Heat of hydration, X-ray diffractometer (XRD), thermogravimetric analysis (TG), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) were used to explore the hydration reaction and microstructures changes. The results showed that wet grinding enhances the dissolution of magnesium and substantially improves the initial hydration activity of EFS. The 1 d compressive strength of EFS-MPC with 30 % and 45 % EFS reaches 119 % and 100 % of that of the control. The results of XRD and TG also proved that the hydration reaction of EFS is promoted and the effect is more significant with the extension of grinding duration. Meanwhile, the microstructures of EFS-MPC were optimized by incorporating fine EFS under humid conditions, which may be related to the activated silica from EFS. The findings suggested that wet grinding is an effective method that could enhance phase separation of EFS, which is a viable alternative for improving the utilization of EFS and water resistant of MPC.