The growing tendency of sustainable building and development is transforming the way in which construction projects are faced. These changes are saving the natural environment, as well as, minimising the quantity of industrial waste. In line with this initiative, the following project studies the potential recovery of Electric Arc Furnace Slag and its use as material fill in gabion cages. From a sustainability point of view, the recovery of steel slag is positive from all perspectives. (a) Economically: steel slag is cheaper in comparison to natural rock considering that it does not need to be mined and if used steel companies do not have to pay a disposal tax. (b) Environmentally: natural resources are spared and space is being reserved in landfills. (c) Socially: steel slag is thought to have a low potential impact on human health and the environment. The focus on gabion cages was chosen as the stability of the structure relies on the density of the material used to fill the metal cages. Additionally, gabion cages should be promoted as a sustainable solution to scour and erosion protection, as well as, retaining walls. These structures blend in with the environment and can even create a habitat for wildlife. In order to verify this application, technical and environmental aspects have to be considered. A series of leaching tests, based on the developing European harmonised framework, have been carried out to determine the environmental impact of EAF Slag. Basic characterisation tests were used to determine the main leaching mechanisms of EAF Slag, whereas, conformity test verify the release of constituents in comparison with the limits defined by legislation.