Remarks on the use of granulated slags in bituminous mixtures for road and airport pavements

The requirement for mineral aggregate for civil infrastructures has progressively increased in recent years, with the consequent serious environmental problems that can no longer be ignored. The use of marginal materials (by-products and wastes) in road and airport construction should be, in this context, very interesting and positive, because the succedaneum materials allow to limit the supply of natural high-quality aggregate, to make savings and avoid the environmental impact of waste disposal. The paper presents the results of a laboratory study aimed at verifying the suitability of non-conventional materials (blast furnace slags) as aggregate for road and airport flexible pavements. Both traditional and high-performance bituminous mixes were tested (porous asphalt, non-skid surfacings, high modulus mixes, etc.). The mix-design was based on the use of the customary Marshall methodology as well as a gyratory compactor, which allowed useful information to be acquired about the shear strength and the density of mixes during compaction. The mechanical behaviour was evaluated by means of the Marshall test, indirect tensile strength test, dynamic modulus, creep test and fatigue behaviour. This work forms a part of a wider context of theoretical, applied and regulatory studies being done at the University of Padova to learn more about the charateristics of recycled materials and their possible applications in road and airport construction.