The environmental benefits of industrial symbiosis: A case study on substituting sand with steel slag as filler in epoxy mortar

Electric arc furnace (EAF) slag, a by-product of steelmaking commonly utilized as artificial aggregate, still faces significant landfilling despite extensive reuse. This study explores sustainable alternatives to minimize landfilling by investigating the environmental benefits of incorporating EAF slag as filler in epoxy mortar, as a substitute for a natural material such as river sand. Experimental results demonstrate that slag-filled mortar exhibits comparable or superior mechanical performance to sand-filled mortar, making it a technically feasible substitute. Moreover, the heavy metals leaching of slag, which is one of the major concerns about the reuse of this material, is reduced thanks to the incorporation into the polymeric matrix, ensuring a safe reuse. To quantify these sustainability benefits, a comparative life cycle assessment is conducted for two scenarios involving the production of a functional unit of 1 m2 of epoxy mortar, typically applied in epoxy screeds, using sand or slag at equal volume fraction. Scenario 1 encompasses slag landfilling and sand extraction, while scenario 2 involves slag reuse as a filler, avoiding landfilling and sand extraction. Life cycle impact assessment using the Environmental Footprint 3.0 method reveals across-the-board reductions. The majority of analyzed impact categories experience a reduction of over 90% attributed to the avoidance of slag disposal and landfill inertization. Overall, reusing slag as an epoxy filler presents significant sustainability benefits compared to disposal, promoting the adoption of this industrial symbiosis application.