Abstract:In order to improve the combined utilization of hazardous solid waste, red mud-gold tailings-slag based alkali-activated cementitious materials were prepared with red mud, gold tailings and slag from Bayer process as active materials and NaOH, KOH and Na2SiO3 as activators respectively. Its mechanical properties were tested, and microscopic mechanism was characterized by XRD, FT-IR, TGA/DSC and SEM. The experimental results show that different kinds of activators had great influence on mechanical properties of the system. When Na2SiO3 is used as activator, the excitation effect of the system is the best, and the flexural strength and compressive strength of the standard mortar specimen at 3 days are 5.5 MPa and 23.5 MPa respectively. The flexural strength and compressive strength of 28 d standard mortar specimens are 8.8 MPa and 43.21MPa respectively, which can reach the cement strength index of P?I42.5. Through microscopic analysis, it is known that main strength sources of specimens are ettringite and hydrated calcium aluminosilicate gel, and the materials with high mechanical properties have more dense microstructure and more alkali-stimulated hydration products.