AbstractThis paper studies the feasibility of replacing fly ash in cement-based grouting material with gold tailings after compound activation. Through mercury intrusion porosimetry (MIP), X-ray diffractometer (XRD), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS), the activation mechanism of gold tailings and the effect of activated gold tailings on the macroscopic properties, pore structure, hydration products, and microstructure of cement-based grouting material were studied. The results show that after the tailings are treated by compound mechanical-chemical-thermal activation, the activity index (28 days) of the cement tailings mortar is as high as 76.83%, and the pozzolanic activity meets the requirements. When activated gold tailings replace 60% fly ash in cement-based grouting material, the macroscopic properties of the grouting material reach the optimal value, the microstructure is denser, and the hydration products are calcium hydroxide, calcium–silicate–hydrate (C─ S─ H) gel, and ettringite. This research provides a new method for the effective utilization of gold tailings and a reference for the practical application of gold tailings as supplementary cementitious materials in the future.