Abstract:  Blast furnace slag is accumulated as waste of smelting metal around steel mills. It occupies land resources and pollutes the adjacent environment. This paper presents a large scale directing program on the blast furnace slag samples in order to apply these waste materials in the soil improvement projects. The impact of sand content in slags on the shear strength of the mixtures were thoroughly investigated.  The results indicate that, the shear strength of slagsand mixture increases with the sand content to a maximum value at sand content of 23.79%. After this sand content, the shear strength decreases rapidly with the increase of the sand content. The sand content has larger influence on the apparent cohesion, which increases with sand content to a maximum value and then decreases with the sand content, whereas, the sand content has less impact on the internal friction angle of the slagsand mixtures. From the engineering point of view, the sand content should be controlled to be under 23.79% when the slagsand mixtures are used in the soil improvement projects.

Key words: Blast Furnace Slag Modified Mixture, LargeScale Direct Shear Test, Shear Strength