Experimental study on influencing mechanism of the multiple effect of steel slag powder for coarse tailings cemented backfill

The gradation of aggregate and the hydration reaction of cementitious materials are important factors affecting the performance of backfill materials. Steel slag powder (SSP) can be used as both aggregate and cementitious material according to different particle size. SSP has multiple influencing effects on coarse tailings cemented backfill (CTCB). Experiment with different content SSP in the CTCB was designed. And uniaxial compression, nuclear magnetic resonance and scanning electron microscopy techniques were used to characterize its macro and micro characteristics. The relationship model of aggregate characteristics on strength and porosity was established by analyzing the characteristics of aggregate using gradation and fractal. The conclusions mainly include: (1) SSP plays three main roles in the CTCB: optimizing the gradation, generating hydration reaction and influencing the hydration reaction of cement. (2) There are good gradation and fractal characteristics between SSP and coarse tailings, with a grading index of 0.30–0.61 and a fractal dimension of 2.12–2.61. (3) The relationship between strength, porosity and gradation, fractal dimension was quadratic function relation, and then the grading index and fractal dimension for optimal strength and pore characteristics are 0.45–0.49 and 2.33–2.40 respectively.