Standard asphalt mixtures for road infrastructures consist of asphalt binder and natural aggregate. However, over the past 20–30 years, the search for recycling alternatives has led departments of transportation, in US, and road authorities, in Europe, to consider a variety of potentially recyclable materials for pavement application. The list includes Reclaimed Asphalt Pavement, waste tire rubber, waste glass, and more recently, industrial by-products such as steel slag. A number of research efforts have successfully investigated the possibility of replacing the conventional aggregate skeleton with slag originating from steel production. However, it is not yet entirely clear how this by-product affects mixtures functional performance and properties such as stiffness, fatigue, resistance to low temperature cracking and permanent deformation. This paper presents a comprehensive and extensive experimental investigation on the fundamental performance properties of different types of asphalt mixtures prepared with 100% LD slag aggregate. A conventional asphalt mixture containing natural Gabbro aggregate was also prepared for comparison purposes. Low temperature cracking was addressed through Thermal Stress Restrained Specimen Tests. Cyclic confined and unconfined compression tests were used to evaluate the response of asphalt mixture to permanent deformation due repeated loading. The cyclic indirect tensile test was selected for investigating both stiffness properties and fatigue resistance. The results from stiffness and fatigue tests served as input for the current mechanistic pavement design system to predict the theoretical service life (durability) of asphalt pavements with LD slag compared to asphalt pavements having natural Gabbro aggregate. In addition, skid resistance properties were analyzed with the Wehner/Schulze Polishing machine and by calculating the Polished Stone Value. The experimental results and the analysis conducted in the present investigation indicate that asphalt mixtures prepared with LD slag are suitable for asphalt pavement construction and that in most cases they perform better than conventional asphalt mixtures prepared with Gabbro aggregate.