Hydraulic and mechanical behavior of compacted silts modified by waste steel slag

Abstract

Steel slag (SS) is a by-product from the steel industry with properties that make it useful in civil and geoenvironmental constructions. There is increasing interest in finding new applications for this type of material due to the need to both minimize the consumption of natural resources and to reduce the amount of waste materials disposed of. This research tested compacted mixtures of soil–slag to evaluate the potential use of SS to enhance the mechanical and hydraulic properties of compacted silts. The silt tested was aeolian sediment, which is widely used around the world as construction material for liners, embankments, and levees. The experimental tests included grain-size distribution, specific gravity, confocal microscope, hydraulic conductivity, and confined compression tests under zero lateral displacement. Soil mixtures with different amounts of SS and different curing periods were evaluated. Micro-structural changes were identified by confocal microscope observations that allowed the formation of hydration products associated with pozzolanic reactions to be seen. The results indicate that the formation of hydrogels helps to reduce hydraulic conductivity, and that pozzolanic reactions generate a natural weak cementation that increases the stiffness of compacted SS–soil mixtures. The findings offer new possibilities for reusing steel slag as an economical and sustainable construction material.