Abstract: In order to break through the key technical barriers of poor cementitious properties of steel slag and realize the resource utilization and high value-added utilization of steel slag, this paper uses a large amount of steel slag as the main raw material, and uses alkali activator to stimulate the cementitious properties of steel slag. At the same time, appropriate silicon sources are introduced and the ratio of cementitious materials is optimized to reduce the activator content. The results show that in the steel slag-slag binary system, when the steel slag content is 60% (mass fraction, the same below) and the activator content is 17%, the compressive strength of the system is the largest, which is 74.2 MPa. When silica fume is introduced as silicon source, the activator content decreases from 17% to 11%, and the compressive strength of the system can still reach 72.7 MPa. When quartz powder is introduced as silicon source, the compressive strength of the system decreases to 63.7 MPa. Compared with the microstructure of the system with an activator content of 17%, when the activator content is reduced to 11%, the generated number of hydrated calcium silicate (C-S-H) gels in the system changes very little after the introduction of silica fume, and the internal structure is highly dense. The main reason is that silica fume, as a silicon source material, can provide corrosion-type SiO^2-₃ to participate in the formation of C-S-H gels, thereby forming sufficient compressive strength. After the introduction of quartz powder, the activity of quartz powder has not been effectively activated under the condition of humid-heat-treating at 60 ℃, and it is dominated by filling effect in the system, resulting in a certain degree of reduction in the generated number of C-S-H gels and the density of internal structure.

Key words: steel slag, silica source, cementitious property, humid-heat-treating, SiO^2-₃, C-S-H gel