Effect of amorphous silica content in clay on mechanical properties of the mixture of clay and converter steelmaking slag

Abstract

A mixture of dredged soil and steelmaking slag solidifies owing to the pozzolanic reaction between the silica and alumina in the dredged soil and the calcium in the steelmaking slag. Previous studies have reported that, for the same steelmaking slag, the concentration of dissolved silica and the shear strength of a mixture of dredged soil and steelmaking slag increases as the content of amorphous silica in the clay increases. However, the relationship between factors that affect solidification strength, such as the ratio of amorphous silica content and the humic acid content, and the solidification strength of a mixture of clayey soil and steelmaking slag has not been clarified. In this study, focusing on the ratio of amorphous silica contents in clay, clays containing different ratios of amorphous silica content were prepared by mixing kaolin clay and metakaolin. The unconfined compressive strengths of the clay mixed with steelmaking slag were measured. For the same curing time and up to an amorphous silica content ratio of 15%, the strength increases with an increase in the ratio. In addition, the shear strength develops earlier for higher content ratios of amorphous silica. Compared with studies on dredged soils mixed with steelmaking slag, the amorphous silica content ratio of the clay in this study was higher than that of dredged soils. However, the shear strength in the dredged soil with amorphous silica from diatoms and minerals mixed with steelmaking slag developed earlier than that of the clay with amorphous silica from minerals mixed with steelmaking slag. The differences in the development of shear strength can be attributed to the difference of the amorphous silica from minerals or that from diatoms.