The transport infrastructure team of the CiRMat project at the University of Minho defined the requirements and specifications for the use of steel slag aggregates (ASIC) in road pavements, both in wear (AC 14 surf) and bonding (AC 14) bituminous mixtures. 20 bin). The ASIC materials were characterized with specific tests based on the aforementioned requirements, concluding that this by-product can be used in bituminous mixtures. Then the formulations of the two aforementioned bituminous mixtures were developed to incorporate 75% ASIC, and these mixtures (AC 14 surf and AC 20 bin) were successfully produced. Finally, the mechanical performance of these new products was evaluated and compared with conventional mixtures regarding water sensitivity, deformation resistance, fatigue cracking resistance and stiffness modulus. This project brought many challenges, most of which were successfully overcome with the hard work and collaboration of all CirMat partners.