In the past decade, numerous industrial and public initiatives have been launched in order to make knowledge, practices, and mentalities evolve in relation to the acceptability of using waste instead of raw materials as construction materials (Ahmed, 1993). The objectives of the initiatives have been to evaluate current practices and to make new solutions and channels for beneficial use emerge. At the same time, the scientific and standardization communities have developed methodologies and tools to fit the assessment needs (Sherwood, 2001). This part of the research presents the results of research involving metal slag as the base material for road constructions in Istanbul, Turkey. The design parameters for the roads constructed using the discarded metal slag were presented based on laboratory model studies. Numerical analysis and field performances were also conducted for the metal slag. Groundwater and surface water analyses conducted before and after the construction were taken into consideration. The metal slag contains some compounds that have pollution potential. Although the leachability of most compounds is low (below the maximum limit) for conditions in civil engineering applications, corrosion occurs at the exposed parts of the metal slag in poor drainage conditions. The conclusion of this research supports the view that the selected waste material is an environmentally acceptable base material for use as an alternative soil stabilization method in road construction. Consequently, it is concluded that the usage of metal slag waste material as the base of road construction is possible for every aspect of this research.