Rheological Optimization and Strength Development of Silica Fume-Modified All-Solid-Waste Grouting Material

With the continuous expansion of grouting material applications, solid waste to prepare grouting materials can effectively mitigate the environmental issues caused by waste accumulation. In this work, an all-solid-waste grouting material (ASWGM) was prepared with silica fume, coal gangue, desulphurization gypsum, fly ash, steel slag and carbide slag. The impact of water-cement ratio (W/C), environmental temperature, silica fume content, and hydration time on the fluidity of grouting materials was systematically analyzed. The chemical substances of such ASWGM were investigated by performing XRD and Fourier transform infrared spectroscopy measurements, while its fluidity was comprehensively evaluated by conducting apparent viscosity, yield stress, fluidity, and thixotropy tests. Based on our analysis, the optimal silica fume content was determined to be 5%, and 20 °C identified as the optimal environmental temperature. Under the preferred performing combination within the tested scope, the yield stress of the materials was 126.4 Pa. The incorporation of silica fume would decrease the early strength of the materials. The strength greatly increased in the late phase as the hydration continued. The strength exceeded 50 MPa at 12 h and 80 MPa at 28 d. Not only can the use of all-solid waste effectively solve the environmental pollution caused by solid waste stacking and facilitate green development, but also obtain grouting materials with satisfying fluidity and mechanical properties through design optimization. The research results can serve as a reference for guiding engineering practice.