Study on the characteristics of compressive strength and hydration mechanism of high-water-content materials modified by furnace slag and silica fume

Abstract In order to reduce the economic cost of high-water-content materials used in mine filling and improve the resource utilization rate of furnace slag and silica fume, furnace slag and silica fume were mixed into high-water-content materials by the admixture method. The variation law of compressive strength, hydration mechanism and microstructure were analyzed. When the furnace slag content is 10%, the compressive strength of high-water-content materials modified with furnace slag is consistent with that of pure high-water-content materials. When the silica fume content is 10% and 20% respectively, the compressive strength of high-water-content materials modified with silica fume increases by 8.54% and 3.66% respectively compared with pure high-water-content materials. When the furnace slag content is 30%, SiO2 in slag snatches Ca2+ and OH—from the solution to form a large amount of c-s-h gel, and the insufficient Ca2+ greatly hinders the formation of AFt crystals. When the silica fume content is 40%, the diffraction peak of AFt crystals cannot be observed in the diffraction pattern, which further indicates that the content of AFt crystals is an important factor affecting the compressive strength of high-water-content materials. When the content of slag and silica fume is low, AFt crystals are mostly in fine needle shape, the overall structure is uniform and dense. When the content of furnace slag and silica fume is high, AFt crystals are mostly of coarse columnar shape, and the overlapping mode becomes sparse and chaotic, and the dense degree of structure is seriously reduced.