Geotechnical properties of steel slag aggregates: Shear strength and stiffness

Abstract

Steel slag is an industrial by-product formed in the furnace during the steelmaking process. Electric arc furnace slag (EAFS) and ladle furnace slag (LFS) are the primary by-products of steelmaking from steel scraps. This research evaluates the physical, geotechnical and engineering properties of LFS, EAFS and a blend comprising 50% LFS and 50% EAFS (LFS50 + EAFS50) through laboratory testing. The specialized laboratory tests undertaken in this study include California bearing ratio (CBR) and unconfined compressive strength (UCS) tests, direct shear tests (DSTs), consolidated drained (CD) triaxial tests and repeated load triaxial (RLT) tests. The shear strength responses of the steel slag were found to vary with the dilatancy-induced peak strength of the LFS and the LFS50 + EAFS50 mixture and the dilatancy-associated strain-hardening behavior of the EAFS. Based on the high shear strength parameters and the adequate stiffness that were attained, the steel slag was found to have the potential for usage as a geo-material. LFS and LFS50 + EAFS50 were well-graded and had high CBR values, which would deem them suitable for roadwork applications. EAFS, however, was found to be poorly graded and to have relatively lower CBR values, which would deem it suitable for less stringent applications such as engineering fill and pipe bedding. The viability of using these by-products as geo-materials in civil infrastructures can transform these current waste by-products, particularly LFS, from being stockpiled at steel company plants to being used as alternative green material.