Abstract： Taking red mud and metakaolin with different ratios as raw materials, the red mud-metakaolin geopolymers were prepared. The effect of different ratios of the red mud and metakaolin on characteristics was researched. The hydration mechanism of the red mud-metakaolin geopolymers was investigated. The results show that the preparation of red mudmetakaolin geopolymers by recover iron of red mud is feasible. The compressive strength can reach 67.1 MPa, the water absorption and solvent density are respectively 1.897 kg/m² and 1 073.1 kg/m³, and the sodium silicate modulus is 1.5 after curing 7 d. The study of hydration mechanism indicates that the hydration mechanisms of geopolymer prepared by adding red mud and the blank control group are the same. Adding red mud can speed up the hydration of geopolymers, and the hydration degree is larger than that of the blank control group after curing 7 d.

Keywords: red mud; metakaolin; geopolymers; compressive strength; hydration mechanism