The effects of steel-to-slag ratio

sodium sulfate content

and water-to-solid ratio on the unconfined compressive strength

setting time

and fluidity of steel slag-slag composite cementitious materials were investigated through single-factor experiments.The study aimed to investigate the engineering performance and strength enhancement mechanism of sodium sulfate activated steel slag-slag composite cementitious materials

thus improving the application and ecological benefits. Additionally

X-ray diffraction (XRD) and other microscopic tests were used to investigate the matrix enhancement mechanism of composite cementitious materials.The results indicate that a steel slag-to-slag ratio of 3∶7 achieves the best synergistic effect

while the optimal dosage of sodium sulfate is 9%. The water-solid ratio is negatively correlated with the strength

whereas sodium sulfate improves slurry fluidity and shortens the setting time

confirming its engineering applicability as an activator.Moreover

sodium sulfate promotes the production of C-S-H gel and facilitates the generation of C-A-S-H gel within the steel slag-slag matrix. Sodium sulfate activation also enhances the formation of ettringite and metal cations in the composite cementitious material

increases the slurry pH

accelerates hydration

and promotes the dissolution of silicon and alumina oxides.This process leads to the formation of C-S-H and C-A-S-H gels

and significantly improving the compressive properties of the material.