Abstract:Given to the expand problem of road base materials based on steel slag, steel slag, blast furnace slag micro-powder and soil were mixed and combined with soil solidification technology to prepare a road base material – steel slag mixed soil. The compaction, expansion rate and unconfined compressive strength tests were carried out on 16 soil samples with different ratios. The results showed that the optimum moisture content of the steel slag mixed soil presented little effect by the ratio, which maintained at 12~14%.The maximal dry density decreases with the decrease in the loading of steel slag, and decreases with the increase in the loading of blast furnace slag micro-powder mixed. The incorporation of blast furnace slag micro-powder could significantly reduce the expansion rate of steel slag mixed soil and increase its unconfined compressive strength. The unconfined compressive strengths of steel slag mixed soil for 7d, 14d, 28d and 90d were firstly increased then decreased with steel slag loading,which reached the maximal value when the ratio was 50% steel slag with 50% soil. Microstructural analysis confirmed that the change of the surface electrode of soil particles enhance the compactness of steel slag mixed soil in molding process. The hydration reaction of f-CaO in the steel slag was inhibited during the solidification process, and which conduct digestion reaction with SiO2 in the mineral slag to form hydrated calcium silicate gel (C-S-H). At the same time, inter-particle stacking effect between steel slag and soil and self-compacting effect produced by C-S-H gel could enhance strength of steel slag mixed soil, and thus prepared steel slag mixed soil with high strength and stability.