Abstract: In order to explore the influence of the high magnesium nickel slag addition on the coalgulation time， hardening mechanical properties and microstructure， the coalgulation time and mechanical properties of high magnesium nickel slag/cement slurry under different mix ratio was studied. The influence of high magnesium nickel slag addition on the phase composition and microstructure of the hardened body was analyzed by XRD and SEM and the relationship between high magnesium nickel slag addition and the pore structure development of hardened body was analyzed by using specific surface area analyzer. The results showed that: ① the incorporation of high magnesium nickel slag postpones the coalgulation time of slurry. In the case of high magnesium nickel slag addition of 30%， the initial and final setting times of the hardened body of high magnesium nickel slag/cement were 103 min and 314 min， respectively， which were 66.13% and 69.73% longer than those without high magnesium nickel slag.②With the addition of high magnesium nickel slag， the compressive strength of hardened body at each age increases first and then decreases. When the contents of high magnesium nickel slag was 20%， the compressive strength of hardened body at 7 d and 28 d were 39.4 MPa and 52.8 MPa， respectively， which were 17.61% and 16.82% higher than that of blank group.With the addition of high magnesium nickel slag， the flexural strength of hardened body at each age increases first and then decreases. When the contents of high magnesium nickel slag was 20%， the flexural strength of hardened body at 7 d and 28 d reached 6.5 MPa and 8.2 MPa， respectively， which increased by 16.07% and 7.89% compared with blank group. ③X-ray diffraction analysis showed that the addition of high magnesium nickel slag promoted the occurrence of secondary hydration. Scanning electron micrograph showed that the high magnesium nickel slag could optimize the microstructure compaction of the hardened body. The pore structure analysis proves the filling effect of high magnesium nickel slag particles and refines the pores. The research results could provide technical support for the application of high magnesium nickel slag in cement.

Key words: high magnesium nickel slag, time of coagulation, mechanical properties, microstructures, pores distribution